Novacoin/ScriptCode.cs

   1 /**
   2  *  Novacoin classes library
   3  *  Copyright (C) 2015 Alex D. (balthazar.ad@gmail.com)
   4
   5  *  This program is free software: you can redistribute it and/or modify
   6  *  it under the terms of the GNU Affero General Public License as
   7  *  published by the Free Software Foundation, either version 3 of the
   8  *  License, or (at your option) any later version.
   9
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU Affero General Public License for more details.
  14
  15  *  You should have received a copy of the GNU Affero General Public License
  16  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 using System;
  20 using System.Collections.Generic;
  21 using System.Diagnostics.Contracts;
  22 using System.Linq;
  23 using System.Numerics;
  24 using System.Text;
  25
  26 namespace Novacoin
  27 {
  28     /// <summary>
  29     /// Script instructions
  30     /// </summary>
  31     public enum instruction
  32     {
  33         // push value
  34         OP_0 = 0x00,
  35         OP_FALSE = OP_0,
  36         OP_PUSHDATA1 = 0x4c,
  37         OP_PUSHDATA2 = 0x4d,
  38         OP_PUSHDATA4 = 0x4e,
  39         OP_1NEGATE = 0x4f,
  40         OP_RESERVED = 0x50,
  41         OP_1 = 0x51,
  42         OP_TRUE = OP_1,
  43         OP_2 = 0x52,
  44         OP_3 = 0x53,
  45         OP_4 = 0x54,
  46         OP_5 = 0x55,
  47         OP_6 = 0x56,
  48         OP_7 = 0x57,
  49         OP_8 = 0x58,
  50         OP_9 = 0x59,
  51         OP_10 = 0x5a,
  52         OP_11 = 0x5b,
  53         OP_12 = 0x5c,
  54         OP_13 = 0x5d,
  55         OP_14 = 0x5e,
  56         OP_15 = 0x5f,
  57         OP_16 = 0x60,
  58
  59         // control
  60         OP_NOP = 0x61,
  61         OP_VER = 0x62,
  62         OP_IF = 0x63,
  63         OP_NOTIF = 0x64,
  64         OP_VERIF = 0x65,
  65         OP_VERNOTIF = 0x66,
  66         OP_ELSE = 0x67,
  67         OP_ENDIF = 0x68,
  68         OP_VERIFY = 0x69,
  69         OP_RETURN = 0x6a,
  70
  71         // stack ops
  72         OP_TOALTSTACK = 0x6b,
  73         OP_FROMALTSTACK = 0x6c,
  74         OP_2DROP = 0x6d,
  75         OP_2DUP = 0x6e,
  76         OP_3DUP = 0x6f,
  77         OP_2OVER = 0x70,
  78         OP_2ROT = 0x71,
  79         OP_2SWAP = 0x72,
  80         OP_IFDUP = 0x73,
  81         OP_DEPTH = 0x74,
  82         OP_DROP = 0x75,
  83         OP_DUP = 0x76,
  84         OP_NIP = 0x77,
  85         OP_OVER = 0x78,
  86         OP_PICK = 0x79,
  87         OP_ROLL = 0x7a,
  88         OP_ROT = 0x7b,
  89         OP_SWAP = 0x7c,
  90         OP_TUCK = 0x7d,
  91
  92         // splice ops
  93         OP_CAT = 0x7e,
  94         OP_SUBSTR = 0x7f,
  95         OP_LEFT = 0x80,
  96         OP_RIGHT = 0x81,
  97         OP_SIZE = 0x82,
  98
  99         // bit logic
 100         OP_INVERT = 0x83,
 101         OP_AND = 0x84,
 102         OP_OR = 0x85,
 103         OP_XOR = 0x86,
 104         OP_EQUAL = 0x87,
 105         OP_EQUALVERIFY = 0x88,
 106         OP_RESERVED1 = 0x89,
 107         OP_RESERVED2 = 0x8a,
 108
 109         // numeric
 110         OP_1ADD = 0x8b,
 111         OP_1SUB = 0x8c,
 112         OP_2MUL = 0x8d,
 113         OP_2DIV = 0x8e,
 114         OP_NEGATE = 0x8f,
 115         OP_ABS = 0x90,
 116         OP_NOT = 0x91,
 117         OP_0NOTEQUAL = 0x92,
 118
 119         OP_ADD = 0x93,
 120         OP_SUB = 0x94,
 121         OP_MUL = 0x95,
 122         OP_DIV = 0x96,
 123         OP_MOD = 0x97,
 124         OP_LSHIFT = 0x98,
 125         OP_RSHIFT = 0x99,
 126
 127         OP_BOOLAND = 0x9a,
 128         OP_BOOLOR = 0x9b,
 129         OP_NUMEQUAL = 0x9c,
 130         OP_NUMEQUALVERIFY = 0x9d,
 131         OP_NUMNOTEQUAL = 0x9e,
 132         OP_LESSTHAN = 0x9f,
 133         OP_GREATERTHAN = 0xa0,
 134         OP_LESSTHANOREQUAL = 0xa1,
 135         OP_GREATERTHANOREQUAL = 0xa2,
 136         OP_MIN = 0xa3,
 137         OP_MAX = 0xa4,
 138
 139         OP_WITHIN = 0xa5,
 140
 141         // crypto
 142         OP_RIPEMD160 = 0xa6,
 143         OP_SHA1 = 0xa7,
 144         OP_SHA256 = 0xa8,
 145         OP_HASH160 = 0xa9,
 146         OP_HASH256 = 0xaa,
 147         OP_CODESEPARATOR = 0xab,
 148         OP_CHECKSIG = 0xac,
 149         OP_CHECKSIGVERIFY = 0xad,
 150         OP_CHECKMULTISIG = 0xae,
 151         OP_CHECKMULTISIGVERIFY = 0xaf,
 152
 153         // expansion
 154         OP_NOP1 = 0xb0,
 155         OP_NOP2 = 0xb1,
 156         OP_NOP3 = 0xb2,
 157         OP_NOP4 = 0xb3,
 158         OP_NOP5 = 0xb4,
 159         OP_NOP6 = 0xb5,
 160         OP_NOP7 = 0xb6,
 161         OP_NOP8 = 0xb7,
 162         OP_NOP9 = 0xb8,
 163         OP_NOP10 = 0xb9,
 164
 165         // template matching params
 166         OP_SMALLDATA = 0xf9,
 167         OP_SMALLINTEGER = 0xfa,
 168         OP_PUBKEYS = 0xfb,
 169         OP_PUBKEYHASH = 0xfd,
 170         OP_PUBKEY = 0xfe,
 171
 172         OP_INVALIDOPCODE = 0xff,
 173     };
 174
 175     /// <summary>
 176     /// Transaction output types.
 177     /// </summary>
 178     public enum txnouttype
 179     {
 180         TX_NONSTANDARD,
 181
 182         // 'standard' transaction types:
 183         TX_PUBKEY,
 184         TX_PUBKEYHASH,
 185         TX_SCRIPTHASH,
 186         TX_MULTISIG,
 187         TX_NULL_DATA,
 188     };
 189
 190     /// <summary>
 191     /// Signature hash types/flags
 192     /// </summary>
 193     public enum sigflag
 194     {
 195         SIGHASH_ALL = 1,
 196         SIGHASH_NONE = 2,
 197         SIGHASH_SINGLE = 3,
 198         SIGHASH_ANYONECANPAY = 0x80,
 199     };
 200
 201     /** Script verification flags */
 202     public enum scriptflag
 203     {
 204         SCRIPT_VERIFY_NONE = 0,
 205         SCRIPT_VERIFY_P2SH = (1 << 0), // evaluate P2SH (BIP16) subscripts
 206         SCRIPT_VERIFY_STRICTENC = (1 << 1), // enforce strict conformance to DER and SEC2 for signatures and pubkeys
 207         SCRIPT_VERIFY_LOW_S = (1 << 2), // enforce low S values in signatures (depends on STRICTENC)
 208         SCRIPT_VERIFY_NOCACHE = (1 << 3), // do not store results in signature cache (but do query it)
 209         SCRIPT_VERIFY_NULLDUMMY = (1 << 4), // verify dummy stack item consumed by CHECKMULTISIG is of zero-length
 210     };
 211
 212     public static class ScriptCode
 213     {
 214         public static string GetTxnOutputType(txnouttype t)
 215         {
 216             switch (t)
 217             {
 218                 case txnouttype.TX_NONSTANDARD: return "nonstandard";
 219                 case txnouttype.TX_PUBKEY: return "pubkey";
 220                 case txnouttype.TX_PUBKEYHASH: return "pubkeyhash";
 221                 case txnouttype.TX_SCRIPTHASH: return "scripthash";
 222                 case txnouttype.TX_MULTISIG: return "multisig";
 223                 case txnouttype.TX_NULL_DATA: return "nulldata";
 224             }
 225             return string.Empty;
 226         }
 227
 228         /// <summary>
 229         /// Get the name of instruction
 230         /// </summary>
 231         /// <param name="opcode">Instruction</param>
 232         /// <returns>Instruction name</returns>
 233         public static string GetOpName(instruction opcode)
 234         {
 235             if (opcode == instruction.OP_0) // OP_0 and OP_FALSE are synonyms
 236                 return "OP_0";
 237             if (opcode == instruction.OP_1) // OP_1 and OP_TRUE are synonyms
 238                 return "OP_1";
 239
 240             return Enum.GetName(typeof(instruction), opcode);
 241         }
 242
 243         /// <summary>
 244         /// Get next instruction from list of bytes and extract push arguments if there are some.
 245         /// </summary>
 246         /// <param name="codeBytes">ByteQueue reference.</param>
 247         /// <param name="opcodeRet">Found instruction.</param>
 248         /// <param name="bytesRet">IEnumerable out param which is used to get the push arguments.</param>
 249         /// <returns>Result of operation</returns>
 250         public static bool GetOp(ref ByteQueue codeBytes, out instruction opcodeRet, out byte[] bytesRet)
 251         {
 252             bytesRet = new byte[0];
 253             opcodeRet = instruction.OP_INVALIDOPCODE;
 254
 255             instruction opcode;
 256
 257             try
 258             {
 259                 // Read instruction
 260                 opcode = (instruction)codeBytes.Get();
 261             }
 262             catch (ByteQueueException)
 263             {
 264                 // No instruction found there
 265                 return false;
 266             }
 267
 268             // Immediate operand
 269             if (opcode <= instruction.OP_PUSHDATA4)
 270             {
 271                 var szBytes = new byte[4] { 0, 0, 0, 0 }; // Zero length
 272                 int nSize = 0;
 273
 274                 try
 275                 {
 276                     if (opcode < instruction.OP_PUSHDATA1)
 277                     {
 278                         // Zero value instructions (OP_0, OP_FALSE)
 279                         nSize = (int) opcode;
 280                     }
 281                     else if (opcode == instruction.OP_PUSHDATA1)
 282                     {
 283                         // The next byte contains the number of bytes to be pushed onto the stack,
 284                         //    i.e. you have something like OP_PUSHDATA1 0x01 [0x5a]
 285                         nSize = codeBytes.Get();
 286                     }
 287                     else if (opcode == instruction.OP_PUSHDATA2)
 288                     {
 289                         // The next two bytes contain the number of bytes to be pushed onto the stack,
 290                         //    i.e. now your operation will seem like this: OP_PUSHDATA2 0x01 0x00 [0x5a]
 291                         nSize = BitConverter.ToInt16(codeBytes.Get(2), 0);
 292                     }
 293                     else if (opcode == instruction.OP_PUSHDATA4)
 294                     {
 295                         // The next four bytes contain the number of bytes to be pushed onto the stack,
 296                         //   OP_PUSHDATA4 0x01 0x00 0x00 0x00 [0x5a]
 297                         nSize = BitConverter.ToInt32(codeBytes.Get(4), 0);
 298                     }
 299                 }
 300                 catch (ByteQueueException)
 301                 {
 302                     // Unable to read operand length
 303                     return false;
 304                 }
 305
 306                 if (nSize > 0)
 307                 {
 308                     // If nSize is greater than zero then there is some data available
 309                     try
 310                     {
 311                         // Read found number of bytes into list of OP_PUSHDATAn arguments.
 312                         bytesRet = codeBytes.Get(nSize);
 313                     }
 314                     catch (ByteQueueException)
 315                     {
 316                         // Unable to read data
 317                         return false;
 318                     }
 319                 }
 320             }
 321
 322             opcodeRet = opcode;
 323
 324             return true;
 325         }
 326
 327         /// <summary>
 328         /// Convert value bytes into readable representation.
 329         ///
 330         /// If list lengh is equal or lesser than 4 bytes then bytes are interpreted as integer value. Otherwise you will get hex representation of supplied data.
 331         /// </summary>
 332         /// <param name="bytes">Collection of value bytes.</param>
 333         /// <returns>Formatted value.</returns>
 334         public static string ValueString(byte[] bytes)
 335         {
 336             var sb = new StringBuilder();
 337
 338             if (bytes.Length <= 4)
 339             {
 340                 sb.Append(new BigInteger(bytes));
 341             }
 342             else
 343             {
 344                 return Interop.ToHex(bytes);
 345             }
 346
 347             return sb.ToString();
 348         }
 349
 350         /// <summary>
 351         /// Convert list of stack items into human readable representation.
 352         /// </summary>
 353         /// <param name="stackList">List of stack items.</param>
 354         /// <returns>Formatted value.</returns>
 355         public static string StackString(IList<byte[]> stackList)
 356         {
 357             var sb = new StringBuilder();
 358             foreach (var bytes in stackList)
 359             {
 360                 sb.Append(ValueString(bytes));
 361             }
 362
 363             return sb.ToString();
 364         }
 365
 366         /// <summary>
 367         /// Decode instruction to integer value
 368         /// </summary>
 369         /// <param name="opcode">Small integer instruction (OP_1_NEGATE and OP_0 - OP_16)</param>
 370         /// <returns>Small integer</returns>
 371         public static int DecodeOP_N(instruction opcode, bool AllowNegate = false)
 372         {
 373             // Only OP_n instructions are supported, throw exception otherwise.
 374             Contract.Requires<ArgumentException>((opcode == instruction.OP_1NEGATE && AllowNegate) || (opcode >= instruction.OP_0 && opcode <= instruction.OP_16), "Invalid integer instruction.");
 375
 376             switch (opcode)
 377             {
 378                 case instruction.OP_1NEGATE:
 379                     return -1;
 380                 case instruction.OP_0:
 381                     return 0;
 382                 default:
 383                     return (int)opcode - (int)(instruction.OP_1 - 1);
 384             }
 385         }
 386
 387         /// <summary>
 388         /// Converts integer into instruction
 389         /// </summary>
 390         /// <param name="n">Small integer from the range of -1 up to 16.</param>
 391         /// <returns>Corresponding instruction.</returns>
 392         public static instruction EncodeOP_N(int n, bool allowNegate = false)
 393         {
 394             // The n value must be in the range of 1 to 16.
 395             Contract.Requires<ArgumentException>((n == -1 && allowNegate) || (n >= 0 && n <= 16), "Invalid integer value.");
 396
 397             switch (n)
 398             {
 399                 case -1:
 400                     return instruction.OP_1NEGATE;
 401                 case 0:
 402                     return instruction.OP_0;
 403                 default:
 404                     return (instruction.OP_1 + n - 1);
 405             }
 406         }
 407
 408         public static int ScriptSigArgsExpected(txnouttype t, IList<byte[]> solutions)
 409         {
 410             switch (t)
 411             {
 412                 case txnouttype.TX_NONSTANDARD:
 413                     return -1;
 414                 case txnouttype.TX_NULL_DATA:
 415                     return 1;
 416                 case txnouttype.TX_PUBKEY:
 417                     return 1;
 418                 case txnouttype.TX_PUBKEYHASH:
 419                     return 2;
 420                 case txnouttype.TX_MULTISIG:
 421                     if (solutions.Count < 1 || solutions.First().Length < 1)
 422                         return -1;
 423                     return solutions.First()[0] + 1;
 424                 case txnouttype.TX_SCRIPTHASH:
 425                     return 1; // doesn't include args needed by the script
 426             }
 427             return -1;
 428         }
 429
 430         /// <summary>
 431         /// Is it a standart type of scriptPubKey?
 432         /// </summary>
 433         /// <param name="scriptPubKey">CScript instance</param>
 434         /// <param name="whichType">utut type</param>
 435         /// <returns>Checking result</returns>
 436         public static bool IsStandard(CScript scriptPubKey, out txnouttype whichType)
 437         {
 438             IList<byte[]> solutions;
 439
 440             if (!Solver(scriptPubKey, out whichType, out solutions))
 441             {
 442                 // No solutions found
 443                 return false;
 444             }
 445
 446             if (whichType == txnouttype.TX_MULTISIG)
 447             {
 448                 // Additional verification of OP_CHECKMULTISIG arguments
 449                 var m = solutions.First()[0];
 450                 var n = solutions.Last()[0];
 451
 452                 // Support up to x-of-3 multisig txns as standard
 453                 if (n < 1 || n > 3)
 454                 {
 455                     return false;
 456                 }
 457                 if (m < 1 || m > n)
 458                 {
 459                     return false;
 460                 }
 461             }
 462
 463             return whichType != txnouttype.TX_NONSTANDARD;
 464         }
 465
 466         /// <summary>
 467         /// Return public keys or hashes from scriptPubKey, for 'standard' transaction types.
 468         /// </summary>
 469         /// <param name="scriptPubKey">CScript instance</param>
 470         /// <param name="typeRet">Output type</param>
 471         /// <param name="solutions">Set of solutions</param>
 472         /// <returns>Result</returns>
 473         public static bool Solver(CScript scriptPubKey, out txnouttype typeRet, out IList<byte[]> solutions)
 474         {
 475             byte[] scriptBytes = scriptPubKey;
 476
 477             solutions = new List<byte[]>();
 478
 479             // There are shortcuts for pay-to-script-hash and pay-to-pubkey-hash, which are more constrained than the other types.
 480
 481             // It is always OP_HASH160 20 [20 byte hash] OP_EQUAL
 482             if (scriptPubKey.IsPayToScriptHash)
 483             {
 484                 typeRet = txnouttype.TX_SCRIPTHASH;
 485
 486                 // Take 20 bytes with offset of 2 bytes
 487                 var hashBytes = scriptBytes.Skip(2).Take(20);
 488                 solutions.Add(hashBytes.ToArray());
 489
 490                 return true;
 491             }
 492
 493             // It is always OP_DUP OP_HASH160 20 [20 byte hash] OP_EQUALVERIFY OP_CHECKSIG
 494             if (scriptPubKey.IsPayToPubKeyHash)
 495             {
 496                 typeRet = txnouttype.TX_PUBKEYHASH;
 497
 498                 // Take 20 bytes with offset of 3 bytes
 499                 var hashBytes = scriptBytes.Skip(3).Take(20);
 500                 solutions.Add(hashBytes.ToArray());
 501
 502                 return true;
 503             }
 504
 505             var templateTuples = new List<Tuple<txnouttype, byte[]>>();
 506
 507             // Sender provides pubkey, receiver adds signature
 508             // [ECDSA public key] OP_CHECKSIG
 509             templateTuples.Add(
 510                 new Tuple<txnouttype, byte[]>(
 511                     txnouttype.TX_PUBKEY,
 512                     new byte[] {
 513                         (byte)instruction.OP_PUBKEY,
 514                         (byte)instruction.OP_CHECKSIG
 515                     })
 516             );
 517
 518             // Sender provides N pubkeys, receivers provides M signatures
 519             // N [pubkey1] [pubkey2] ... [pubkeyN] M OP_CHECKMULTISIG
 520             // Where N and M are small integer instructions (OP1 ... OP_16)
 521             templateTuples.Add(
 522                 new Tuple<txnouttype, byte[]>(
 523                     txnouttype.TX_MULTISIG,
 524                     new byte[] {
 525                         (byte)instruction.OP_SMALLINTEGER,
 526                         (byte)instruction.OP_PUBKEYS,
 527                         (byte)instruction.OP_SMALLINTEGER,
 528                         (byte)instruction.OP_CHECKMULTISIG
 529                     })
 530             );
 531
 532             // Data-carrying output
 533             // OP_RETURN [up to 80 bytes of data]
 534             templateTuples.Add(
 535                 new Tuple<txnouttype, byte[]>(
 536                     txnouttype.TX_NULL_DATA,
 537                     new byte[] {
 538                         (byte)instruction.OP_RETURN,
 539                         (byte)instruction.OP_SMALLDATA
 540                     })
 541             );
 542
 543             // Nonstandard tx output
 544             typeRet = txnouttype.TX_NONSTANDARD;
 545
 546             foreach (var templateTuple in templateTuples)
 547             {
 548                 var script1 = scriptPubKey;
 549                 var script2 = new CScript(templateTuple.Item2);
 550
 551                 instruction opcode1, opcode2;
 552
 553                 // Compare
 554                 var bq1 = script1.GetByteQueue();
 555                 var bq2 = script2.GetByteQueue();
 556
 557                 byte[] args1, args2;
 558
 559                 int last1 = ((byte[])script1).Length - 1;
 560                 int last2 = ((byte[])script2).Length - 1;
 561
 562                 while (true)
 563                 {
 564                     if (bq1.Index == last1 && bq2.Index == last2)
 565                     {
 566                         // Found a match
 567                         typeRet = templateTuple.Item1;
 568                         if (typeRet == txnouttype.TX_MULTISIG)
 569                         {
 570                             // Additional checks for TX_MULTISIG:
 571                             var m = solutions.First().First();
 572                             var n = solutions.Last().First();
 573
 574                             if (m < 1 || n < 1 || m > n || solutions.Count - 2 != n)
 575                             {
 576                                 return false;
 577                             }
 578                         }
 579                         return true;
 580                     }
 581
 582                     if (!GetOp(ref bq1, out opcode1, out args1))
 583                     {
 584                         break;
 585                     }
 586                     if (!GetOp(ref bq2, out opcode2, out args2))
 587                     {
 588                         break;
 589                     }
 590
 591                     // Template matching instructions:
 592                     if (opcode2 == instruction.OP_PUBKEYS)
 593                     {
 594                         while (args1.Count() >= 33 && args1.Count() <= 120)
 595                         {
 596                             solutions.Add(args1);
 597                             if (!GetOp(ref bq1, out opcode1, out args1))
 598                             {
 599                                 break;
 600                             }
 601                         }
 602                         if (!GetOp(ref bq2, out opcode2, out args2))
 603                         {
 604                             break;
 605                         }
 606                         // Normal situation is to fall through
 607                         // to other if/else statements
 608                     }
 609                     if (opcode2 == instruction.OP_PUBKEY)
 610                     {
 611                         int PubKeyLen = args1.Count();
 612                         if (PubKeyLen < 33 || PubKeyLen > 120)
 613                         {
 614                             break;
 615                         }
 616                         solutions.Add(args1);
 617                     }
 618                     else if (opcode2 == instruction.OP_PUBKEYHASH)
 619                     {
 620                         if (args1.Count() != 20) // hash160 size
 621                         {
 622                             break;
 623                         }
 624                         solutions.Add(args1);
 625                     }
 626                     else if (opcode2 == instruction.OP_SMALLINTEGER)
 627                     {
 628                         // Single-byte small integer pushed onto solutions
 629                         try
 630                         {
 631                             var n = (byte)DecodeOP_N(opcode1);
 632                             solutions.Add(new byte[] { n });
 633                         }
 634                         catch (Exception)
 635                         {
 636                             break;
 637                         }
 638                     }
 639                     else if (opcode2 == instruction.OP_SMALLDATA)
 640                     {
 641                         // small pushdata, <= 80 bytes
 642                         if (args1.Length > 80)
 643                         {
 644                             break;
 645                         }
 646                     }
 647                     else if (opcode1 != opcode2 || !args1.SequenceEqual(args2))
 648                     {
 649                         // Others must match exactly
 650                         break;
 651                     }
 652                 }
 653             }
 654
 655             solutions.Clear();
 656             typeRet = txnouttype.TX_NONSTANDARD;
 657
 658             return false;
 659         }
 660
 661         /// <summary>
 662         /// Generation of SignatureHash. This method is responsible for removal of transaction metadata. It's necessary signature can't sign itself.
 663         /// </summary>
 664         /// <param name="script">Spending instructions</param>
 665         /// <param name="txTo">Instance of transaction</param>
 666         /// <param name="nIn">Input number</param>
 667         /// <param name="nHashType">Hash type flag</param>
 668         /// <returns></returns>
 669         public static Hash256 SignatureHash(CScript script, CTransaction txTo, int nIn, int nHashType)
 670         {
 671             if (nIn >= txTo.vin.Length)
 672             {
 673                 var sb = new StringBuilder();
 674                 sb.AppendFormat("ERROR: SignatureHash() : nIn={0} out of range\n", nIn);
 675                 throw new ArgumentOutOfRangeException("nIn", sb.ToString());
 676             }
 677
 678             // Init a copy of transaction
 679             var txTmp = new CTransaction(txTo);
 680
 681             // In case concatenating two scripts ends up with two codeseparators,
 682             // or an extra one at the end, this prevents all those possible incompatibilities.
 683             script.RemoveInstruction(instruction.OP_CODESEPARATOR);
 684
 685             // Blank out other inputs' signatures
 686             for (int i = 0; i < txTmp.vin.Length; i++)
 687             {
 688                 txTmp.vin[i].scriptSig = new CScript();
 689             }
 690             txTmp.vin[nIn].scriptSig = script;
 691
 692             // Blank out some of the outputs
 693             if ((nHashType & 0x1f) == (int)sigflag.SIGHASH_NONE)
 694             {
 695                 // Wildcard payee
 696                 txTmp.vout = new CTxOut[0];
 697
 698                 // Let the others update at will
 699                 for (int i = 0; i < txTmp.vin.Length; i++)
 700                 {
 701                     if (i != nIn)
 702                     {
 703                         txTmp.vin[i].nSequence = 0;
 704                     }
 705                 }
 706             }
 707             else if ((nHashType & 0x1f) == (int)sigflag.SIGHASH_SINGLE)
 708             {
 709                 // Only lock-in the txout payee at same index as txin
 710                 int nOut = nIn;
 711                 if (nOut >= txTmp.vout.Length)
 712                 {
 713                     StringBuilder sb = new StringBuilder();
 714                     sb.AppendFormat("ERROR: SignatureHash() : nOut={0} out of range\n", nOut);
 715                     throw new ArgumentOutOfRangeException("nOut", sb.ToString());
 716                 }
 717                 Array.Resize(ref txTmp.vout, nOut + 1);
 718
 719                 for (int i = 0; i < nOut; i++)
 720                 {
 721                     txTmp.vout[i] = new CTxOut();
 722                 }
 723
 724                 // Let the others update at will
 725                 for (int i = 0; i < txTmp.vin.Length; i++)
 726                 {
 727                     if (i != nIn)
 728                     {
 729                         txTmp.vin[i].nSequence = 0;
 730                     }
 731                 }
 732             }
 733
 734             // Blank out other inputs completely, not recommended for open transactions
 735             if ((nHashType & (int)sigflag.SIGHASH_ANYONECANPAY) != 0)
 736             {
 737                 txTmp.vin[0] = txTmp.vin[nIn];
 738                 Array.Resize(ref txTmp.vin, 1);
 739             }
 740
 741             // Concatenate and hash
 742             var txBytes = (byte[])txTmp;
 743             var nHashTypeBytes = BitConverter.GetBytes(nHashType);
 744
 745             return Hash256.Compute256(ref txBytes, ref nHashTypeBytes);
 746         }
 747
 748         //
 749         // Script is a stack machine (like Forth) that evaluates a predicate
 750         // returning a bool indicating valid or not.  There are no loops.
 751         //
 752
 753         /// <summary>
 754         /// Script machine exception
 755         /// </summary>
 756         [Serializable]
 757         public class StackMachineException : Exception
 758         {
 759             public StackMachineException()
 760             {
 761             }
 762
 763             public StackMachineException(string message)
 764                 : base(message)
 765             {
 766             }
 767
 768             public StackMachineException(string message, Exception inner)
 769                 : base(message, inner)
 770             {
 771             }
 772         }
 773
 774         /// <summary>
 775         /// Remove last element from stack
 776         /// </summary>
 777         /// <param name="stack">Stack reference</param>
 778         private static void popstack(ref List<byte[]> stack)
 779         {
 780             int nCount = stack.Count;
 781             if (nCount == 0)
 782             {
 783                 throw new StackMachineException("Stack is empty");
 784             }
 785
 786             stack.RemoveAt(nCount - 1);
 787         }
 788
 789         /// <summary>
 790         /// Get element at specified stack depth
 791         /// </summary>
 792         /// <param name="stack">Stack reference</param>
 793         /// <param name="nDepth">Depth</param>
 794         /// <returns>Byte sequence</returns>
 795         private static byte[] stacktop(ref List<byte[]> stack, int nDepth)
 796         {
 797             Contract.Requires<StackMachineException>(nDepth < 0, "Positive stack depth makes no sense.");
 798             Contract.Requires<StackMachineException>(stack.Count + nDepth > 0, "Value exceeds real stack depth.");
 799
 800             return stack[stack.Count + nDepth];
 801         }
 802
 803         /// <summary>
 804         /// Cast argument to boolean value
 805         /// </summary>
 806         /// <param name="value">Some byte sequence</param>
 807         /// <returns></returns>
 808         private static bool CastToBool(byte[] arg)
 809         {
 810             for (var i = 0; i < arg.Length; i++)
 811             {
 812                 if (arg[i] != 0)
 813                 {
 814                     // Can be negative zero
 815                     if (i == arg.Length - 1 && arg[i] == 0x80)
 816                     {
 817                         return false;
 818                     }
 819
 820                     return true;
 821                 }
 822             }
 823
 824             return false;
 825         }
 826
 827         /// <summary>
 828         /// Cast argument to integer value
 829         /// </summary>
 830         /// <param name="value"></param>
 831         /// <returns></returns>
 832         private static BigInteger CastToBigInteger(byte[] value)
 833         {
 834             Contract.Requires<StackMachineException>(value.Length <= 4, "Size limit failed.");
 835
 836             return new BigInteger(value);
 837         }
 838
 839         /// <summary>
 840         /// Execution of script
 841         /// </summary>
 842         /// <param name="stack"></param>
 843         /// <param name="script">Script to execute</param>
 844         /// <param name="txTo">Transaction instance</param>
 845         /// <param name="nIn">Input number</param>
 846         /// <param name="flags">Signature checking flags</param>
 847         /// <param name="nHashType">Hash type flag</param>
 848         /// <returns></returns>
 849         public static bool EvalScript(ref List<byte[]> stack, CScript script, CTransaction txTo, int nIn, int flags, int nHashType)
 850         {
 851             var scriptBytes = ((byte[])script);
 852
 853             if (scriptBytes.Length > 10000)
 854             {
 855                 return false; // Size limit failed
 856             }
 857
 858             var vfExec = new List<bool>();
 859
 860             int nOpCount = 0;
 861             int nCodeHashBegin = 0;
 862
 863             var falseBytes = new byte[0];
 864             var trueBytes = new byte[] { 0x01 };
 865
 866             var CodeQueue = script.GetByteQueue();
 867             var altStack = new List<byte[]>();
 868
 869             try
 870             {
 871                 instruction opcode;
 872                 byte[] pushArg;
 873
 874                 while (GetOp(ref CodeQueue, out opcode, out pushArg)) // Read instructions
 875                 {
 876                     bool fExec = vfExec.IndexOf(false) == -1;
 877
 878                     if (pushArg.Length > 520)
 879                     {
 880                         return false; // Script element size limit failed
 881                     }
 882
 883                     if (opcode > instruction.OP_16 && ++nOpCount > 201)
 884                     {
 885                         return false;
 886                     }
 887
 888                     if (fExec && 0 <= opcode && opcode <= instruction.OP_PUSHDATA4)
 889                     {
 890                         stack.Add(pushArg); // Push argument to stack
 891                     }
 892                     else if (fExec || (instruction.OP_IF <= opcode && opcode <= instruction.OP_ENDIF))
 893                         switch (opcode)
 894                         {
 895                             //
 896                             // Disabled instructions
 897                             //
 898                             case instruction.OP_CAT:
 899                             case instruction.OP_SUBSTR:
 900                             case instruction.OP_LEFT:
 901                             case instruction.OP_RIGHT:
 902                             case instruction.OP_INVERT:
 903                             case instruction.OP_AND:
 904                             case instruction.OP_OR:
 905                             case instruction.OP_XOR:
 906                             case instruction.OP_2MUL:
 907                             case instruction.OP_2DIV:
 908                             case instruction.OP_MUL:
 909                             case instruction.OP_DIV:
 910                             case instruction.OP_MOD:
 911                             case instruction.OP_LSHIFT:
 912                             case instruction.OP_RSHIFT:
 913                                 return false;
 914
 915                             //
 916                             // Push integer instructions
 917                             //
 918                             case instruction.OP_1NEGATE:
 919                             case instruction.OP_1:
 920                             case instruction.OP_2:
 921                             case instruction.OP_3:
 922                             case instruction.OP_4:
 923                             case instruction.OP_5:
 924                             case instruction.OP_6:
 925                             case instruction.OP_7:
 926                             case instruction.OP_8:
 927                             case instruction.OP_9:
 928                             case instruction.OP_10:
 929                             case instruction.OP_11:
 930                             case instruction.OP_12:
 931                             case instruction.OP_13:
 932                             case instruction.OP_14:
 933                             case instruction.OP_15:
 934                             case instruction.OP_16:
 935                                 {
 936                                     // ( -- value)
 937                                     BigInteger bn = DecodeOP_N(opcode, true);
 938                                     stack.Add(bn.ToByteArray());
 939                                 }
 940                                 break;
 941
 942                             //
 943                             // Extension
 944                             //
 945                             case instruction.OP_NOP:
 946                             case instruction.OP_NOP1:
 947                             case instruction.OP_NOP2:
 948                             case instruction.OP_NOP3:
 949                             case instruction.OP_NOP4:
 950                             case instruction.OP_NOP5:
 951                             case instruction.OP_NOP6:
 952                             case instruction.OP_NOP7:
 953                             case instruction.OP_NOP8:
 954                             case instruction.OP_NOP9:
 955                             case instruction.OP_NOP10:
 956                                 {
 957                                     // Just do nothing
 958                                 }
 959                                 break;
 960
 961                             //
 962                             // Control
 963                             //
 964                             case instruction.OP_IF:
 965                             case instruction.OP_NOTIF:
 966                                 {
 967                                     // <expression> if [statements] [else [statements]] endif
 968                                     var fValue = false;
 969                                     if (fExec)
 970                                     {
 971                                         if (stack.Count() < 1)
 972                                         {
 973                                             return false;
 974                                         }
 975                                         var vch = stacktop(ref stack, -1);
 976                                         fValue = CastToBool(vch);
 977                                         if (opcode == instruction.OP_NOTIF)
 978                                         {
 979                                             fValue = !fValue;
 980                                         }
 981                                         popstack(ref stack);
 982                                     }
 983                                     vfExec.Add(fValue);
 984                                 }
 985                                 break;
 986
 987                             case instruction.OP_ELSE:
 988                                 {
 989                                     int nExecCount = vfExec.Count();
 990                                     if (nExecCount == 0)
 991                                     {
 992                                         return false;
 993                                     }
 994                                     vfExec[nExecCount - 1] = !vfExec[nExecCount - 1];
 995                                 }
 996                                 break;
 997
 998                             case instruction.OP_ENDIF:
 999                                 {
1000                                     int nExecCount = vfExec.Count();
1001                                     if (nExecCount == 0)
1002                                     {
1003                                         return false;
1004                                     }
1005                                     vfExec.RemoveAt(nExecCount - 1);
1006                                 }
1007                                 break;
1008
1009                             case instruction.OP_VERIFY:
1010                                 {
1011                                     // (true -- ) or
1012                                     // (false -- false) and return
1013                                     if (stack.Count() < 1)
1014                                     {
1015                                         return false;
1016                                     }
1017
1018                                     bool fValue = CastToBool(stacktop(ref stack, -1));
1019                                     if (fValue)
1020                                     {
1021                                         popstack(ref stack);
1022                                     }
1023                                     else
1024                                     {
1025                                         return false;
1026                                     }
1027                                 }
1028                                 break;
1029
1030                             case instruction.OP_RETURN:
1031                                 {
1032                                     return false;
1033                                 }
1034
1035                             //
1036                             // Stack ops
1037                             //
1038                             case instruction.OP_TOALTSTACK:
1039                                 {
1040                                     if (stack.Count() < 1)
1041                                     {
1042                                         return false;
1043                                     }
1044                                     altStack.Add(stacktop(ref stack, -1));
1045                                     popstack(ref stack);
1046                                 }
1047                                 break;
1048
1049                             case instruction.OP_FROMALTSTACK:
1050                                 {
1051                                     if (altStack.Count() < 1)
1052                                     {
1053                                         return false;
1054                                     }
1055                                     stack.Add(stacktop(ref stack, -1));
1056                                     popstack(ref altStack);
1057                                 }
1058                                 break;
1059
1060                             case instruction.OP_2DROP:
1061                                 {
1062                                     // (x1 x2 -- )
1063                                     if (stack.Count() < 2)
1064                                     {
1065                                         return false;
1066                                     }
1067                                     popstack(ref stack);
1068                                     popstack(ref stack);
1069                                 }
1070                                 break;
1071
1072                             case instruction.OP_2DUP:
1073                                 {
1074                                     // (x1 x2 -- x1 x2 x1 x2)
1075                                     if (stack.Count() < 2)
1076                                     {
1077                                         return false;
1078                                     }
1079                                     var vch1 = stacktop(ref stack, -2);
1080                                     var vch2 = stacktop(ref stack, -1);
1081                                     stack.Add(vch1);
1082                                     stack.Add(vch2);
1083                                 }
1084                                 break;
1085
1086                             case instruction.OP_3DUP:
1087                                 {
1088                                     // (x1 x2 x3 -- x1 x2 x3 x1 x2 x3)
1089                                     if (stack.Count() < 3)
1090                                     {
1091                                         return false;
1092                                     }
1093                                     var vch1 = stacktop(ref stack, -3);
1094                                     var vch2 = stacktop(ref stack, -2);
1095                                     var vch3 = stacktop(ref stack, -1);
1096                                     stack.Add(vch1);
1097                                     stack.Add(vch2);
1098                                     stack.Add(vch3);
1099                                 }
1100                                 break;
1101
1102                             case instruction.OP_2OVER:
1103                                 {
1104                                     // (x1 x2 x3 x4 -- x1 x2 x3 x4 x1 x2)
1105                                     if (stack.Count() < 4)
1106                                     {
1107                                         return false;
1108                                     }
1109                                     var vch1 = stacktop(ref stack, -4);
1110                                     var vch2 = stacktop(ref stack, -3);
1111                                     stack.Add(vch1);
1112                                     stack.Add(vch2);
1113                                 }
1114                                 break;
1115
1116                             case instruction.OP_2ROT:
1117                                 {
1118                                     int nStackDepth = stack.Count();
1119                                     // (x1 x2 x3 x4 x5 x6 -- x3 x4 x5 x6 x1 x2)
1120                                     if (nStackDepth < 6)
1121                                     {
1122                                         return false;
1123                                     }
1124                                     var vch1 = stacktop(ref stack, -6);
1125                                     var vch2 = stacktop(ref stack, -5);
1126                                     stack.RemoveRange(nStackDepth - 6, 2);
1127                                     stack.Add(vch1);
1128                                     stack.Add(vch2);
1129                                 }
1130                                 break;
1131
1132                             case instruction.OP_2SWAP:
1133                                 {
1134                                     // (x1 x2 x3 x4 -- x3 x4 x1 x2)
1135                                     int nStackDepth = stack.Count;
1136                                     if (nStackDepth < 4)
1137                                     {
1138                                         return false;
1139                                     }
1140                                     stack.Swap(nStackDepth - 4, nStackDepth - 2);
1141                                     stack.Swap(nStackDepth - 3, nStackDepth - 1);
1142                                 }
1143                                 break;
1144
1145                             case instruction.OP_IFDUP:
1146                                 {
1147                                     // (x - 0 | x x)
1148                                     if (stack.Count() < 1)
1149                                     {
1150                                         return false;
1151                                     }
1152
1153                                     var vch = stacktop(ref stack, -1);
1154
1155                                     if (CastToBool(vch))
1156                                     {
1157                                         stack.Add(vch);
1158                                     }
1159                                 }
1160                                 break;
1161
1162                             case instruction.OP_DEPTH:
1163                                 {
1164                                     // -- stacksize
1165                                     BigInteger bn = new BigInteger((ushort)stack.Count());
1166                                     stack.Add(bn.ToByteArray());
1167                                 }
1168                                 break;
1169
1170                             case instruction.OP_DROP:
1171                                 {
1172                                     // (x -- )
1173                                     if (stack.Count() < 1)
1174                                     {
1175                                         return false;
1176                                     }
1177
1178                                     popstack(ref stack);
1179                                 }
1180                                 break;
1181
1182                             case instruction.OP_DUP:
1183                                 {
1184                                     // (x -- x x)
1185                                     if (stack.Count() < 1)
1186                                     {
1187                                         return false;
1188                                     }
1189
1190                                     var vch = stacktop(ref stack, -1);
1191                                     stack.Add(vch);
1192                                 }
1193                                 break;
1194
1195                             case instruction.OP_NIP:
1196                                 {
1197                                     // (x1 x2 -- x2)
1198                                     int nStackDepth = stack.Count();
1199                                     if (nStackDepth < 2)
1200                                     {
1201                                         return false;
1202                                     }
1203
1204                                     stack.RemoveAt(nStackDepth - 2);
1205                                 }
1206                                 break;
1207
1208                             case instruction.OP_OVER:
1209                                 {
1210                                     // (x1 x2 -- x1 x2 x1)
1211                                     if (stack.Count() < 2)
1212                                     {
1213                                         return false;
1214                                     }
1215
1216                                     var vch = stacktop(ref stack, -2);
1217                                     stack.Add(vch);
1218                                 }
1219                                 break;
1220
1221                             case instruction.OP_PICK:
1222                             case instruction.OP_ROLL:
1223                                 {
1224                                     // (xn ... x2 x1 x0 n - xn ... x2 x1 x0 xn)
1225                                     // (xn ... x2 x1 x0 n - ... x2 x1 x0 xn)
1226
1227                                     int nStackDepth = stack.Count();
1228                                     if (nStackDepth < 2)
1229                                     {
1230                                         return false;
1231                                     }
1232
1233                                     int n = (int)CastToBigInteger(stacktop(ref stack, -1));
1234                                     popstack(ref stack);
1235
1236                                     if (n < 0 || n >= stack.Count())
1237                                     {
1238                                         return false;
1239                                     }
1240
1241                                     var vch = stacktop(ref stack, -n - 1);
1242                                     if (opcode == instruction.OP_ROLL)
1243                                     {
1244                                         stack.RemoveAt(nStackDepth - n - 1);
1245                                     }
1246
1247                                     stack.Add(vch);
1248                                 }
1249                                 break;
1250
1251                             case instruction.OP_ROT:
1252                                 {
1253                                     // (x1 x2 x3 -- x2 x3 x1)
1254                                     //  x2 x1 x3  after first swap
1255                                     //  x2 x3 x1  after second swap
1256                                     int nStackDepth = stack.Count();
1257                                     if (nStackDepth < 3)
1258                                     {
1259                                         return false;
1260                                     }
1261                                     stack.Swap(nStackDepth - 3, nStackDepth - 2);
1262                                     stack.Swap(nStackDepth - 2, nStackDepth - 1);
1263
1264                                 }
1265                                 break;
1266
1267                             case instruction.OP_SWAP:
1268                                 {
1269                                     // (x1 x2 -- x2 x1)
1270                                     int nStackDepth = stack.Count();
1271                                     if (nStackDepth < 2)
1272                                     {
1273                                         return false;
1274                                     }
1275                                     stack.Swap(nStackDepth - 2, nStackDepth - 1);
1276                                 }
1277                                 break;
1278
1279                             case instruction.OP_TUCK:
1280                                 {
1281                                     // (x1 x2 -- x2 x1 x2)
1282                                     int nStackDepth = stack.Count();
1283                                     if (nStackDepth < 2)
1284                                     {
1285                                         return false;
1286                                     }
1287                                     var vch = stacktop(ref stack, -1);
1288                                     stack.Insert(nStackDepth - 2, vch);
1289                                 }
1290                                 break;
1291
1292
1293                             case instruction.OP_SIZE:
1294                                 {
1295                                     // (in -- in size)
1296                                     if (stack.Count() < 1)
1297                                     {
1298                                         return false;
1299                                     }
1300
1301                                     var bnSize = new BigInteger((ushort)stacktop(ref stack, -1).Count());
1302                                     stack.Add(bnSize.ToByteArray());
1303                                 }
1304                                 break;
1305
1306
1307                             //
1308                             // Bitwise logic
1309                             //
1310                             case instruction.OP_EQUAL:
1311                             case instruction.OP_EQUALVERIFY:
1312                                 //case instruction.OP_NOTEQUAL: // use OP_NUMNOTEQUAL
1313                                 {
1314                                     // (x1 x2 - bool)
1315                                     if (stack.Count() < 2)
1316                                     {
1317                                         return false;
1318                                     }
1319
1320                                     var vch1 = stacktop(ref stack, -2);
1321                                     var vch2 = stacktop(ref stack, -1);
1322                                     bool fEqual = (vch1.SequenceEqual(vch2));
1323                                     // OP_NOTEQUAL is disabled because it would be too easy to say
1324                                     // something like n != 1 and have some wiseguy pass in 1 with extra
1325                                     // zero bytes after it (numerically, 0x01 == 0x0001 == 0x000001)
1326                                     //if (opcode == instruction.OP_NOTEQUAL)
1327                                     //    fEqual = !fEqual;
1328                                     popstack(ref stack);
1329                                     popstack(ref stack);
1330                                     stack.Add(fEqual ? trueBytes : falseBytes);
1331
1332                                     if (opcode == instruction.OP_EQUALVERIFY)
1333                                     {
1334                                         if (fEqual)
1335                                         {
1336                                             popstack(ref stack);
1337                                         }
1338                                         else
1339                                         {
1340                                             return false;
1341                                         }
1342                                     }
1343                                 }
1344                                 break;
1345
1346
1347                             //
1348                             // Numeric
1349                             //
1350                             case instruction.OP_1ADD:
1351                             case instruction.OP_1SUB:
1352                             case instruction.OP_NEGATE:
1353                             case instruction.OP_ABS:
1354                             case instruction.OP_NOT:
1355                             case instruction.OP_0NOTEQUAL:
1356                                 {
1357                                     // (in -- out)
1358                                     if (stack.Count() < 1)
1359                                     {
1360                                         return false;
1361                                     }
1362
1363                                     var bn = CastToBigInteger(stacktop(ref stack, -1));
1364                                     switch (opcode)
1365                                     {
1366                                         case instruction.OP_1ADD:
1367                                             bn = bn + 1;
1368                                             break;
1369                                         case instruction.OP_1SUB:
1370                                             bn = bn - 1;
1371                                             break;
1372                                         case instruction.OP_NEGATE:
1373                                             bn = -bn;
1374                                             break;
1375                                         case instruction.OP_ABS:
1376                                             bn = BigInteger.Abs(bn);
1377                                             break;
1378                                         case instruction.OP_NOT:
1379                                             bn = bn == 0 ? 1 : 0;
1380                                             break;
1381                                         case instruction.OP_0NOTEQUAL:
1382                                             bn = bn != 0 ? 1 : 0;
1383                                             break;
1384                                     }
1385
1386                                     popstack(ref stack);
1387                                     stack.Add(bn.ToByteArray());
1388                                 }
1389                                 break;
1390
1391                             case instruction.OP_ADD:
1392                             case instruction.OP_SUB:
1393                             case instruction.OP_BOOLAND:
1394                             case instruction.OP_BOOLOR:
1395                             case instruction.OP_NUMEQUAL:
1396                             case instruction.OP_NUMEQUALVERIFY:
1397                             case instruction.OP_NUMNOTEQUAL:
1398                             case instruction.OP_LESSTHAN:
1399                             case instruction.OP_GREATERTHAN:
1400                             case instruction.OP_LESSTHANOREQUAL:
1401                             case instruction.OP_GREATERTHANOREQUAL:
1402                             case instruction.OP_MIN:
1403                             case instruction.OP_MAX:
1404                                 {
1405                                     // (x1 x2 -- out)
1406                                     if (stack.Count() < 2)
1407                                     {
1408                                         return false;
1409                                     }
1410
1411                                     var bn1 = CastToBigInteger(stacktop(ref stack, -2));
1412                                     var bn2 = CastToBigInteger(stacktop(ref stack, -1));
1413                                     BigInteger bn = 0;
1414
1415                                     switch (opcode)
1416                                     {
1417                                         case instruction.OP_ADD:
1418                                             bn = bn1 + bn2;
1419                                             break;
1420                                         case instruction.OP_SUB:
1421                                             bn = bn1 - bn2;
1422                                             break;
1423                                         case instruction.OP_BOOLAND:
1424                                             bn = (bn1 != 0 && bn2 != 0) ? 1 : 0;
1425                                             break;
1426                                         case instruction.OP_BOOLOR:
1427                                             bn = (bn1 != 0 || bn2 != 0) ? 1 : 0;
1428                                             break;
1429                                         case instruction.OP_NUMEQUAL:
1430                                             bn = (bn1 == bn2) ? 1 : 0;
1431                                             break;
1432                                         case instruction.OP_NUMEQUALVERIFY:
1433                                             bn = (bn1 == bn2) ? 1 : 0;
1434                                             break;
1435                                         case instruction.OP_NUMNOTEQUAL:
1436                                             bn = (bn1 != bn2) ? 1 : 0;
1437                                             break;
1438                                         case instruction.OP_LESSTHAN:
1439                                             bn = (bn1 < bn2) ? 1 : 0;
1440                                             break;
1441                                         case instruction.OP_GREATERTHAN:
1442                                             bn = (bn1 > bn2) ? 1 : 0;
1443                                             break;
1444                                         case instruction.OP_LESSTHANOREQUAL:
1445                                             bn = (bn1 <= bn2) ? 1 : 0;
1446                                             break;
1447                                         case instruction.OP_GREATERTHANOREQUAL:
1448                                             bn = (bn1 >= bn2) ? 1 : 0;
1449                                             break;
1450                                         case instruction.OP_MIN:
1451                                             bn = (bn1 < bn2 ? bn1 : bn2);
1452                                             break;
1453                                         case instruction.OP_MAX:
1454                                             bn = (bn1 > bn2 ? bn1 : bn2);
1455                                             break;
1456                                     }
1457
1458                                     popstack(ref stack);
1459                                     popstack(ref stack);
1460                                     stack.Add(bn.ToByteArray());
1461
1462                                     if (opcode == instruction.OP_NUMEQUALVERIFY)
1463                                     {
1464                                         if (CastToBool(stacktop(ref stack, -1)))
1465                                         {
1466                                             popstack(ref stack);
1467                                         }
1468                                         else
1469                                         {
1470                                             return false;
1471                                         }
1472                                     }
1473                                 }
1474                                 break;
1475
1476                             case instruction.OP_WITHIN:
1477                                 {
1478                                     // (x min max -- out)
1479                                     if (stack.Count() < 3)
1480                                     {
1481                                         return false;
1482                                     }
1483
1484                                     var bn1 = CastToBigInteger(stacktop(ref stack, -3));
1485                                     var bn2 = CastToBigInteger(stacktop(ref stack, -2));
1486                                     var bn3 = CastToBigInteger(stacktop(ref stack, -1));
1487
1488                                     bool fValue = (bn2 <= bn1 && bn1 < bn3);
1489
1490                                     popstack(ref stack);
1491                                     popstack(ref stack);
1492                                     popstack(ref stack);
1493
1494                                     stack.Add(fValue ? trueBytes : falseBytes);
1495                                 }
1496                                 break;
1497
1498                             //
1499                             // Crypto
1500                             //
1501                             case instruction.OP_RIPEMD160:
1502                             case instruction.OP_SHA1:
1503                             case instruction.OP_SHA256:
1504                             case instruction.OP_HASH160:
1505                             case instruction.OP_HASH256:
1506                                 {
1507                                     // (in -- hash)
1508                                     if (stack.Count() < 1)
1509                                     {
1510                                         return false;
1511                                     }
1512                                     Hash hash = null;
1513                                     var data = stacktop(ref stack, -1);
1514
1515                                     switch (opcode)
1516                                     {
1517                                         case instruction.OP_HASH160:
1518                                             hash = Hash160.Compute160(data);
1519                                             break;
1520                                         case instruction.OP_HASH256:
1521                                             hash = Hash256.Compute256(data);
1522                                             break;
1523                                         case instruction.OP_SHA1:
1524                                             hash = SHA1.Compute1(data);
1525                                             break;
1526                                         case instruction.OP_SHA256:
1527                                             hash = SHA256.Compute256(data);
1528                                             break;
1529                                         case instruction.OP_RIPEMD160:
1530                                             hash = RIPEMD160.Compute160(data);
1531                                             break;
1532                                     }
1533                                     popstack(ref stack);
1534                                     stack.Add(hash);
1535                                 }
1536                                 break;
1537
1538                             case instruction.OP_CODESEPARATOR:
1539                                 {
1540                                     // Hash starts after the code separator
1541                                     nCodeHashBegin = CodeQueue.Index;
1542                                 }
1543                                 break;
1544
1545                             case instruction.OP_CHECKSIG:
1546                             case instruction.OP_CHECKSIGVERIFY:
1547                                 {
1548                                     // (sig pubkey -- bool)
1549                                     if (stack.Count() < 2)
1550                                     {
1551                                         return false;
1552                                     }
1553
1554                                     var sigBytes = stacktop(ref stack, -2);
1555                                     var pubkeyBytes = stacktop(ref stack, -1);
1556
1557                                     // Subset of script starting at the most recent codeseparator
1558                                     var scriptCode = new CScript(scriptBytes.Skip(nCodeHashBegin).ToArray());
1559
1560                                     // There's no way for a signature to sign itself
1561                                     scriptCode.RemovePattern(sigBytes);
1562
1563                                     bool fSuccess = IsCanonicalSignature(sigBytes, flags) && IsCanonicalPubKey(pubkeyBytes, flags) && CheckSig(sigBytes, pubkeyBytes, scriptCode, txTo, nIn, nHashType, flags);
1564
1565                                     popstack(ref stack);
1566                                     popstack(ref stack);
1567
1568                                     stack.Add(fSuccess ? trueBytes : falseBytes);
1569
1570                                     if (opcode == instruction.OP_CHECKSIGVERIFY)
1571                                     {
1572                                         if (fSuccess)
1573                                         {
1574                                             popstack(ref stack);
1575                                         }
1576                                         else
1577                                         {
1578                                             return false;
1579                                         }
1580                                     }
1581                                 }
1582                                 break;
1583
1584                             case instruction.OP_CHECKMULTISIG:
1585                             case instruction.OP_CHECKMULTISIGVERIFY:
1586                                 {
1587                                     // ([sig ...] num_of_signatures [pubkey ...] num_of_pubkeys -- bool)
1588
1589                                     int i = 1;
1590                                     if (stack.Count() < i)
1591                                     {
1592                                         return false;
1593                                     }
1594
1595                                     int nKeysCount = (int)CastToBigInteger(stacktop(ref stack, -i));
1596                                     if (nKeysCount < 0 || nKeysCount > 20)
1597                                     {
1598                                         return false;
1599                                     }
1600                                     nOpCount += nKeysCount;
1601                                     if (nOpCount > 201)
1602                                     {
1603                                         return false;
1604                                     }
1605                                     int ikey = ++i;
1606                                     i += nKeysCount;
1607                                     if (stack.Count() < i)
1608                                     {
1609                                         return false;
1610                                     }
1611
1612                                     int nSigsCount = (int)CastToBigInteger(stacktop(ref stack, -i));
1613                                     if (nSigsCount < 0 || nSigsCount > nKeysCount)
1614                                     {
1615                                         return false;
1616                                     }
1617                                     int isig = ++i;
1618                                     i += nSigsCount;
1619                                     if (stack.Count() < i)
1620                                     {
1621                                         return false;
1622                                     }
1623
1624                                     // Subset of script starting at the most recent codeseparator
1625                                     var scriptCode = new CScript(scriptBytes.Skip(nCodeHashBegin).ToArray());
1626
1627                                     // There is no way for a signature to sign itself, so we need to drop the signatures
1628                                     for (int k = 0; k < nSigsCount; k++)
1629                                     {
1630                                         var vchSig = stacktop(ref stack, -isig - k);
1631                                         scriptCode.RemovePattern(vchSig);
1632                                     }
1633
1634                                     bool fSuccess = true;
1635                                     while (fSuccess && nSigsCount > 0)
1636                                     {
1637                                         var sigBytes = stacktop(ref stack, -isig);
1638                                         var pubKeyBytes = stacktop(ref stack, -ikey);
1639
1640                                         // Check signature
1641                                         bool fOk = IsCanonicalSignature(sigBytes, flags) && IsCanonicalPubKey(pubKeyBytes, flags) && CheckSig(sigBytes, pubKeyBytes, scriptCode, txTo, nIn, nHashType, flags);
1642
1643                                         if (fOk)
1644                                         {
1645                                             isig++;
1646                                             nSigsCount--;
1647                                         }
1648                                         ikey++;
1649                                         nKeysCount--;
1650
1651                                         // If there are more signatures left than keys left,
1652                                         // then too many signatures have failed
1653                                         if (nSigsCount > nKeysCount)
1654                                         {
1655                                             fSuccess = false;
1656                                         }
1657                                     }
1658
1659                                     while (i-- > 1)
1660                                     {
1661                                         popstack(ref stack);
1662                                     }
1663
1664                                     // A bug causes CHECKMULTISIG to consume one extra argument
1665                                     // whose contents were not checked in any way.
1666                                     //
1667                                     // Unfortunately this is a potential source of mutability,
1668                                     // so optionally verify it is exactly equal to zero prior
1669                                     // to removing it from the stack.
1670                                     if (stack.Count() < 1)
1671                                     {
1672                                         return false;
1673                                     }
1674                                     if ((flags & (int)scriptflag.SCRIPT_VERIFY_NULLDUMMY) != 0 && stacktop(ref stack, -1).Count() != 0)
1675                                     {
1676                                         return false; // CHECKMULTISIG dummy argument not null
1677                                     }
1678                                     popstack(ref stack);
1679
1680                                     stack.Add(fSuccess ? trueBytes : falseBytes);
1681
1682                                     if (opcode == instruction.OP_CHECKMULTISIGVERIFY)
1683                                     {
1684                                         if (fSuccess)
1685                                         {
1686                                             popstack(ref stack);
1687                                         }
1688                                         else
1689                                         {
1690                                             return false;
1691                                         }
1692                                     }
1693                                 }
1694                                 break;
1695
1696                             default:
1697                                 return false;
1698                         }
1699
1700                     // Size limits
1701                     if (stack.Count() + altStack.Count() > 1000)
1702                     {
1703                         return false;
1704                     }
1705                 }
1706             }
1707             catch (Exception)
1708             {
1709                 // If there are any exceptions then just return false.
1710                 return false;
1711             }
1712
1713             if (vfExec.Count() != 0)
1714             {
1715                 // Something went wrong with conditional instructions.
1716                 return false;
1717             }
1718
1719             return true;
1720         }
1721
1722
1723         public static bool IsCanonicalPubKey(byte[] pubKeyBytes, int flags)
1724         {
1725             if ((flags & (int)scriptflag.SCRIPT_VERIFY_STRICTENC) == 0)
1726                 return true;
1727
1728             if (pubKeyBytes.Length < 33)
1729                 return false;  // Non-canonical public key: too short
1730             if (pubKeyBytes[0] == 0x04)
1731             {
1732                 if (pubKeyBytes.Length != 65)
1733                     return false; // Non-canonical public key: invalid length for uncompressed key
1734             }
1735             else if (pubKeyBytes[0] == 0x02 || pubKeyBytes[0] == 0x03)
1736             {
1737                 if (pubKeyBytes.Length != 33)
1738                     return false; // Non-canonical public key: invalid length for compressed key
1739             }
1740             else
1741             {
1742                 return false; // Non-canonical public key: compressed nor uncompressed
1743             }
1744             return true;
1745         }
1746
1747         public static bool IsCanonicalSignature(byte[] sigBytes, int flags)
1748         {
1749             // STUB
1750
1751             return true;
1752         }
1753
1754         /// <summary>
1755         /// Check signature.
1756         /// </summary>
1757         /// <param name="sigBytes">Signature</param>
1758         /// <param name="pubkeyBytes">Public key</param>
1759         /// <param name="script">Spending script</param>
1760         /// <param name="txTo">CTransaction instance</param>
1761         /// <param name="nIn">Input number</param>
1762         /// <param name="nHashType">Hashing type flag</param>
1763         /// <param name="flags">Signature checking flags</param>
1764         /// <returns>Checking result</returns>
1765         public static bool CheckSig(byte[] sigBytes, byte[] pubkeyBytes, CScript script, CTransaction txTo, int nIn, int nHashType, int flags)
1766         {
1767             CPubKey pubkey;
1768
1769             try
1770             {
1771                 // Trying to initialize the public key instance
1772
1773                 pubkey = new CPubKey(pubkeyBytes);
1774             }
1775             catch (Exception)
1776             {
1777                 // Exception occurred while initializing the public key
1778
1779                 return false;
1780             }
1781
1782             if (!pubkey.IsValid)
1783             {
1784                 return false;
1785             }
1786
1787             if (sigBytes.Length == 0)
1788             {
1789                 return false;
1790             }
1791
1792             // Hash type is one byte tacked on to the end of the signature
1793             if (nHashType == 0)
1794             {
1795                 nHashType = sigBytes.Last();
1796             }
1797             else if (nHashType != sigBytes.Last())
1798             {
1799                 return false;
1800             }
1801
1802             // Remove hash type
1803             Array.Resize(ref sigBytes, sigBytes.Length - 1);
1804
1805             var sighash = SignatureHash(script, txTo, nIn, nHashType);
1806
1807             if (!pubkey.VerifySignature(sighash, sigBytes))
1808             {
1809                 return false;
1810             }
1811
1812             return true;
1813         }
1814
1815         /// <summary>
1816         /// Evaluates the both scriptSig and scriptPubKey.
1817         /// </summary>
1818         /// <param name="scriptSig"></param>
1819         /// <param name="scriptPubKey"></param>
1820         /// <param name="txTo">Transaction</param>
1821         /// <param name="nIn">Input number</param>
1822         /// <param name="flags">Script validation flags</param>
1823         /// <param name="nHashType">Hash type flag</param>
1824         /// <returns></returns>
1825         public static bool VerifyScript(CScript scriptSig, CScript scriptPubKey, CTransaction txTo, int nIn, int flags, int nHashType)
1826         {
1827             var stack = new List<byte[]>();
1828             List<byte[]> stackCopy = null;
1829
1830             if (!EvalScript(ref stack, scriptSig, txTo, nIn, flags, nHashType))
1831             {
1832                 return false;
1833             }
1834
1835             if ((flags & (int)scriptflag.SCRIPT_VERIFY_P2SH) != 0)
1836             {
1837                 stackCopy = new List<byte[]>(stack);
1838             }
1839
1840             if (!EvalScript(ref stack, scriptPubKey, txTo, nIn, flags, nHashType))
1841             {
1842                 return false;
1843             }
1844
1845             if (stack.Count == 0 || CastToBool(stack.Last()) == false)
1846             {
1847                 return false;
1848             }
1849
1850             // Additional validation for spend-to-script-hash transactions:
1851             if ((flags & (int)scriptflag.SCRIPT_VERIFY_P2SH) != 0 && scriptPubKey.IsPayToScriptHash)
1852             {
1853                 if (!scriptSig.IsPushOnly) // scriptSig must be literals-only
1854                 {
1855                     return false;
1856                 }
1857
1858                 // stackCopy cannot be empty here, because if it was the
1859                 // P2SH  HASH <> EQUAL  scriptPubKey would be evaluated with
1860                 // an empty stack and the EvalScript above would return false.
1861
1862                 if (stackCopy.Count == 0)
1863                 {
1864                     throw new StackMachineException("Fatal script validation error.");
1865                 }
1866
1867                 var pubKey2 = new CScript(stackCopy.Last());
1868                 popstack(ref stackCopy);
1869
1870                 if (!EvalScript(ref stackCopy, pubKey2, txTo, nIn, flags, nHashType))
1871                     return false;
1872                 if (stackCopy.Count == 0)
1873                     return false;
1874
1875                 return CastToBool(stackCopy.Last());
1876             }
1877
1878             return true;
1879         }
1880     };
1881 }