// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2012 The Bitcoin developers
// Distributed under the MIT/X11 software license, see the accompanying
// file license.txt or http://www.opensource.org/licenses/mit-license.php.
+#ifndef BITCOIN_KEY_H
+#define BITCOIN_KEY_H
+#include <stdexcept>
+#include <vector>
+
+#include <openssl/ec.h>
+#include <openssl/ecdsa.h>
+#include <openssl/obj_mac.h>
+
+#include "serialize.h"
+#include "uint256.h"
+#include "base58.h"
// secp160k1
// const unsigned int PRIVATE_KEY_SIZE = 192;
// see www.keylength.com
// script supports up to 75 for single byte push
+// Generate a private key from just the secret parameter
+int static inline EC_KEY_regenerate_key(EC_KEY *eckey, BIGNUM *priv_key)
+{
+ int ok = 0;
+ BN_CTX *ctx = NULL;
+ EC_POINT *pub_key = NULL;
+
+ if (!eckey) return 0;
+
+ const EC_GROUP *group = EC_KEY_get0_group(eckey);
+
+ if ((ctx = BN_CTX_new()) == NULL)
+ goto err;
+
+ pub_key = EC_POINT_new(group);
+
+ if (pub_key == NULL)
+ goto err;
+
+ if (!EC_POINT_mul(group, pub_key, priv_key, NULL, NULL, ctx))
+ goto err;
+
+ EC_KEY_set_private_key(eckey,priv_key);
+ EC_KEY_set_public_key(eckey,pub_key);
+
+ ok = 1;
+
+err:
+
+ if (pub_key)
+ EC_POINT_free(pub_key);
+ if (ctx != NULL)
+ BN_CTX_free(ctx);
+
+ return(ok);
+}
+
+// Perform ECDSA key recovery (see SEC1 4.1.6) for curves over (mod p)-fields
+// recid selects which key is recovered
+// if check is nonzero, additional checks are performed
+int static inline ECDSA_SIG_recover_key_GFp(EC_KEY *eckey, ECDSA_SIG *ecsig, const unsigned char *msg, int msglen, int recid, int check)
+{
+ if (!eckey) return 0;
+
+ int ret = 0;
+ BN_CTX *ctx = NULL;
+
+ BIGNUM *x = NULL;
+ BIGNUM *e = NULL;
+ BIGNUM *order = NULL;
+ BIGNUM *sor = NULL;
+ BIGNUM *eor = NULL;
+ BIGNUM *field = NULL;
+ EC_POINT *R = NULL;
+ EC_POINT *O = NULL;
+ EC_POINT *Q = NULL;
+ BIGNUM *rr = NULL;
+ BIGNUM *zero = NULL;
+ int n = 0;
+ int i = recid / 2;
+
+ const EC_GROUP *group = EC_KEY_get0_group(eckey);
+ if ((ctx = BN_CTX_new()) == NULL) { ret = -1; goto err; }
+ BN_CTX_start(ctx);
+ order = BN_CTX_get(ctx);
+ if (!EC_GROUP_get_order(group, order, ctx)) { ret = -2; goto err; }
+ x = BN_CTX_get(ctx);
+ if (!BN_copy(x, order)) { ret=-1; goto err; }
+ if (!BN_mul_word(x, i)) { ret=-1; goto err; }
+ if (!BN_add(x, x, ecsig->r)) { ret=-1; goto err; }
+ field = BN_CTX_get(ctx);
+ if (!EC_GROUP_get_curve_GFp(group, field, NULL, NULL, ctx)) { ret=-2; goto err; }
+ if (BN_cmp(x, field) >= 0) { ret=0; goto err; }
+ if ((R = EC_POINT_new(group)) == NULL) { ret = -2; goto err; }
+ if (!EC_POINT_set_compressed_coordinates_GFp(group, R, x, recid % 2, ctx)) { ret=0; goto err; }
+ if (check)
+ {
+ if ((O = EC_POINT_new(group)) == NULL) { ret = -2; goto err; }
+ if (!EC_POINT_mul(group, O, NULL, R, order, ctx)) { ret=-2; goto err; }
+ if (!EC_POINT_is_at_infinity(group, O)) { ret = 0; goto err; }
+ }
+ if ((Q = EC_POINT_new(group)) == NULL) { ret = -2; goto err; }
+ n = EC_GROUP_get_degree(group);
+ e = BN_CTX_get(ctx);
+ if (!BN_bin2bn(msg, msglen, e)) { ret=-1; goto err; }
+ if (8*msglen > n) BN_rshift(e, e, 8-(n & 7));
+ zero = BN_CTX_get(ctx);
+ if (!BN_zero(zero)) { ret=-1; goto err; }
+ if (!BN_mod_sub(e, zero, e, order, ctx)) { ret=-1; goto err; }
+ rr = BN_CTX_get(ctx);
+ if (!BN_mod_inverse(rr, ecsig->r, order, ctx)) { ret=-1; goto err; }
+ sor = BN_CTX_get(ctx);
+ if (!BN_mod_mul(sor, ecsig->s, rr, order, ctx)) { ret=-1; goto err; }
+ eor = BN_CTX_get(ctx);
+ if (!BN_mod_mul(eor, e, rr, order, ctx)) { ret=-1; goto err; }
+ if (!EC_POINT_mul(group, Q, eor, R, sor, ctx)) { ret=-2; goto err; }
+ if (!EC_KEY_set_public_key(eckey, Q)) { ret=-2; goto err; }
+
+ ret = 1;
+err:
+ if (ctx) {
+ BN_CTX_end(ctx);
+ BN_CTX_free(ctx);
+ }
+ if (R != NULL) EC_POINT_free(R);
+ if (O != NULL) EC_POINT_free(O);
+ if (Q != NULL) EC_POINT_free(Q);
+ return ret;
+}
class key_error : public std::runtime_error
{
// secure_allocator is defined in serialize.h
-typedef vector<unsigned char, secure_allocator<unsigned char> > CPrivKey;
-
-
+// CPrivKey is a serialized private key, with all parameters included (279 bytes)
+typedef std::vector<unsigned char, secure_allocator<unsigned char> > CPrivKey;
+// CSecret is a serialization of just the secret parameter (32 bytes)
+typedef std::vector<unsigned char, secure_allocator<unsigned char> > CSecret;
class CKey
{
EC_KEY* pkey;
bool fSet;
+ void SetCompressedPubKey()
+ {
+ EC_KEY_set_conv_form(pkey, POINT_CONVERSION_COMPRESSED);
+ }
+
public:
CKey()
{
return true;
}
+ bool SetSecret(const CSecret& vchSecret)
+ {
+ EC_KEY_free(pkey);
+ pkey = EC_KEY_new_by_curve_name(NID_secp256k1);
+ if (pkey == NULL)
+ throw key_error("CKey::SetSecret() : EC_KEY_new_by_curve_name failed");
+ if (vchSecret.size() != 32)
+ throw key_error("CKey::SetSecret() : secret must be 32 bytes");
+ BIGNUM *bn = BN_bin2bn(&vchSecret[0],32,BN_new());
+ if (bn == NULL)
+ throw key_error("CKey::SetSecret() : BN_bin2bn failed");
+ if (!EC_KEY_regenerate_key(pkey,bn))
+ {
+ BN_clear_free(bn);
+ throw key_error("CKey::SetSecret() : EC_KEY_regenerate_key failed");
+ }
+ BN_clear_free(bn);
+ fSet = true;
+ return true;
+ }
+
+ CSecret GetSecret() const
+ {
+ CSecret vchRet;
+ vchRet.resize(32);
+ const BIGNUM *bn = EC_KEY_get0_private_key(pkey);
+ int nBytes = BN_num_bytes(bn);
+ if (bn == NULL)
+ throw key_error("CKey::GetSecret() : EC_KEY_get0_private_key failed");
+ int n=BN_bn2bin(bn,&vchRet[32 - nBytes]);
+ if (n != nBytes)
+ throw key_error("CKey::GetSecret(): BN_bn2bin failed");
+ return vchRet;
+ }
+
CPrivKey GetPrivKey() const
{
- unsigned int nSize = i2d_ECPrivateKey(pkey, NULL);
+ int nSize = i2d_ECPrivateKey(pkey, NULL);
if (!nSize)
throw key_error("CKey::GetPrivKey() : i2d_ECPrivateKey failed");
CPrivKey vchPrivKey(nSize, 0);
return vchPrivKey;
}
- bool SetPubKey(const vector<unsigned char>& vchPubKey)
+ bool SetPubKey(const std::vector<unsigned char>& vchPubKey)
{
const unsigned char* pbegin = &vchPubKey[0];
if (!o2i_ECPublicKey(&pkey, &pbegin, vchPubKey.size()))
return true;
}
- vector<unsigned char> GetPubKey() const
+ std::vector<unsigned char> GetPubKey() const
{
- unsigned int nSize = i2o_ECPublicKey(pkey, NULL);
+ int nSize = i2o_ECPublicKey(pkey, NULL);
if (!nSize)
throw key_error("CKey::GetPubKey() : i2o_ECPublicKey failed");
- vector<unsigned char> vchPubKey(nSize, 0);
+ std::vector<unsigned char> vchPubKey(nSize, 0);
unsigned char* pbegin = &vchPubKey[0];
if (i2o_ECPublicKey(pkey, &pbegin) != nSize)
throw key_error("CKey::GetPubKey() : i2o_ECPublicKey returned unexpected size");
return vchPubKey;
}
- bool Sign(uint256 hash, vector<unsigned char>& vchSig)
+ bool Sign(uint256 hash, std::vector<unsigned char>& vchSig)
{
- vchSig.clear();
- unsigned char pchSig[10000];
- unsigned int nSize = 0;
- if (!ECDSA_sign(0, (unsigned char*)&hash, sizeof(hash), pchSig, &nSize, pkey))
+ unsigned int nSize = ECDSA_size(pkey);
+ vchSig.resize(nSize); // Make sure it is big enough
+ if (!ECDSA_sign(0, (unsigned char*)&hash, sizeof(hash), &vchSig[0], &nSize, pkey))
+ {
+ vchSig.clear();
return false;
- vchSig.resize(nSize);
- memcpy(&vchSig[0], pchSig, nSize);
+ }
+ vchSig.resize(nSize); // Shrink to fit actual size
return true;
}
- bool Verify(uint256 hash, const vector<unsigned char>& vchSig)
+ // create a compact signature (65 bytes), which allows reconstructing the used public key
+ // The format is one header byte, followed by two times 32 bytes for the serialized r and s values.
+ // The header byte: 0x1B = first key with even y, 0x1C = first key with odd y,
+ // 0x1D = second key with even y, 0x1E = second key with odd y
+ bool SignCompact(uint256 hash, std::vector<unsigned char>& vchSig)
+ {
+ bool fOk = false;
+ ECDSA_SIG *sig = ECDSA_do_sign((unsigned char*)&hash, sizeof(hash), pkey);
+ if (sig==NULL)
+ return false;
+ vchSig.clear();
+ vchSig.resize(65,0);
+ int nBitsR = BN_num_bits(sig->r);
+ int nBitsS = BN_num_bits(sig->s);
+ if (nBitsR <= 256 && nBitsS <= 256)
+ {
+ int nRecId = -1;
+ for (int i=0; i<4; i++)
+ {
+ CKey keyRec;
+ keyRec.fSet = true;
+ if (ECDSA_SIG_recover_key_GFp(keyRec.pkey, sig, (unsigned char*)&hash, sizeof(hash), i, 1) == 1)
+ if (keyRec.GetPubKey() == this->GetPubKey())
+ {
+ nRecId = i;
+ break;
+ }
+ }
+
+ if (nRecId == -1)
+ throw key_error("CKey::SignCompact() : unable to construct recoverable key");
+
+ vchSig[0] = nRecId+27;
+ BN_bn2bin(sig->r,&vchSig[33-(nBitsR+7)/8]);
+ BN_bn2bin(sig->s,&vchSig[65-(nBitsS+7)/8]);
+ fOk = true;
+ }
+ ECDSA_SIG_free(sig);
+ return fOk;
+ }
+
+ // reconstruct public key from a compact signature
+ // This is only slightly more CPU intensive than just verifying it.
+ // If this function succeeds, the recovered public key is guaranteed to be valid
+ // (the signature is a valid signature of the given data for that key)
+ bool SetCompactSignature(uint256 hash, const std::vector<unsigned char>& vchSig)
+ {
+ if (vchSig.size() != 65)
+ return false;
+ int nV = vchSig[0];
+ if (nV<27 || nV>=35)
+ return false;
+ ECDSA_SIG *sig = ECDSA_SIG_new();
+ BN_bin2bn(&vchSig[1],32,sig->r);
+ BN_bin2bn(&vchSig[33],32,sig->s);
+
+ EC_KEY_free(pkey);
+ pkey = EC_KEY_new_by_curve_name(NID_secp256k1);
+ if (nV >= 31)
+ {
+ SetCompressedPubKey();
+ nV -= 4;
+ }
+ if (ECDSA_SIG_recover_key_GFp(pkey, sig, (unsigned char*)&hash, sizeof(hash), nV - 27, 0) == 1)
+ {
+ fSet = true;
+ ECDSA_SIG_free(sig);
+ return true;
+ }
+ return false;
+ }
+
+ bool Verify(uint256 hash, const std::vector<unsigned char>& vchSig)
{
// -1 = error, 0 = bad sig, 1 = good
if (ECDSA_verify(0, (unsigned char*)&hash, sizeof(hash), &vchSig[0], vchSig.size(), pkey) != 1)
return true;
}
- static bool Sign(const CPrivKey& vchPrivKey, uint256 hash, vector<unsigned char>& vchSig)
+ // Verify a compact signature
+ bool VerifyCompact(uint256 hash, const std::vector<unsigned char>& vchSig)
{
CKey key;
- if (!key.SetPrivKey(vchPrivKey))
+ if (!key.SetCompactSignature(hash, vchSig))
+ return false;
+ if (GetPubKey() != key.GetPubKey())
return false;
- return key.Sign(hash, vchSig);
+ return true;
}
- static bool Verify(const vector<unsigned char>& vchPubKey, uint256 hash, const vector<unsigned char>& vchSig)
+ // Get the address corresponding to this key
+ CBitcoinAddress GetAddress() const
{
- CKey key;
- if (!key.SetPubKey(vchPubKey))
+ return CBitcoinAddress(GetPubKey());
+ }
+
+ bool IsValid()
+ {
+ if (!fSet)
return false;
- return key.Verify(hash, vchSig);
+
+ CSecret secret = GetSecret();
+ CKey key2;
+ key2.SetSecret(secret);
+ return GetPubKey() == key2.GetPubKey();
}
};
+
+#endif
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