2 using System.Collections.Generic;
6 using Org.BouncyCastle.Math;
10 public class Base58Exception : Exception
12 public Base58Exception()
16 public Base58Exception(string message)
21 public Base58Exception(string message, Exception inner)
22 : base(message, inner)
28 public class AddressTools
30 private const string strDigits = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
31 private static readonly BigInteger _base = BigInteger.ValueOf(58);
34 /// Encode a byte sequence as a base58-encoded string
36 /// <param name="bytes">Byte sequence</param>
37 /// <returns>Encoding result</returns>
38 public static string Base58Encode(byte[] input)
40 // TODO: This could be a lot more efficient.
41 var bi = new BigInteger(1, input);
42 var s = new StringBuilder();
43 while (bi.CompareTo(_base) >= 0)
45 var mod = bi.Mod(_base);
46 s.Insert(0, new[] { strDigits[mod.IntValue] });
47 bi = bi.Subtract(mod).Divide(_base);
49 s.Insert(0, new[] { strDigits[bi.IntValue] });
50 // Convert leading zeros too.
51 foreach (var anInput in input)
54 s.Insert(0, new[] { strDigits[0] });
63 /// Encode a byte sequence to a base58-encoded string, including checksum
65 /// <param name="bytes">Byte sequence</param>
66 /// <returns>Base58(data+checksum)</returns>
67 public static string Base58EncodeCheck(IEnumerable<byte> bytes)
69 byte[] dataBytes = bytes.ToArray();
70 Array.Resize(ref dataBytes, dataBytes.Length + 4);
72 byte[] checkSum = Hash256.Compute256(bytes).hashBytes.Take(4).ToArray();
74 checkSum.CopyTo(dataBytes, dataBytes.Length - 4); // add 4-byte hash check to the end
76 return Base58Encode(dataBytes);
80 /// // Decode a base58-encoded string into byte array
82 /// <param name="strBase58">Base58 data string</param>
83 /// <returns>Byte array</returns>
84 public static byte[] Base58Decode(string input)
86 var bytes = DecodeToBigInteger(input).ToByteArray();
87 // We may have got one more byte than we wanted, if the high bit of the next-to-last byte was not zero. This
88 // is because BigIntegers are represented with twos-compliment notation, thus if the high bit of the last
89 // byte happens to be 1 another 8 zero bits will be added to ensure the number parses as positive. Detect
90 // that case here and chop it off.
91 var stripSignByte = bytes.Length > 1 && bytes[0] == 0 && bytes[1] >= 0x80;
92 // Count the leading zeros, if any.
94 for (var i = 0; input[i] == strDigits[0]; i++)
98 var tmp = new byte[bytes.Length - (stripSignByte ? 1 : 0) + leadingZeros];
99 Array.Copy(bytes, stripSignByte ? 1 : 0, tmp, leadingZeros, tmp.Length - leadingZeros);
103 public static BigInteger DecodeToBigInteger(string input)
105 var bi = BigInteger.ValueOf(0);
106 // Work backwards through the string.
107 for (var i = input.Length - 1; i >= 0; i--)
109 var alphaIndex = strDigits.IndexOf(input[i]);
110 if (alphaIndex == -1)
112 throw new FormatException("Illegal character " + input[i] + " at " + i);
114 bi = bi.Add(BigInteger.ValueOf(alphaIndex).Multiply(_base.Pow(input.Length - 1 - i)));
119 public static IEnumerable<byte> Base58DecodeCheck(string strBase58Check)
121 byte[] rawData = Base58Decode(strBase58Check).ToArray();
123 if (rawData.Length < 4)
125 throw new Base58Exception("Data is too short.");
128 byte[] result = new byte[rawData.Length - 4];
129 byte[] resultCheckSum = new byte[4];
131 Array.Copy(rawData, result, result.Length);
132 Array.Copy(rawData, result.Length, resultCheckSum, 0, 4);
134 byte[] checkSum = Hash256.Compute256(result).hashBytes.Take(4).ToArray();
136 if (!checkSum.SequenceEqual(resultCheckSum))
138 throw new Base58Exception("Incorrect checksum.");