393 lines
12 KiB
C++
393 lines
12 KiB
C++
// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2011 The Bitcoin developers
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// Distributed under the MIT/X11 software license, see the accompanying
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// file license.txt or http://www.opensource.org/licenses/mit-license.php.
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#ifndef BITCOIN_KEY_H
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#define BITCOIN_KEY_H
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#include <stdexcept>
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#include <vector>
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#include <openssl/ec.h>
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#include <openssl/ecdsa.h>
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#include <openssl/obj_mac.h>
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#include "serialize.h"
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#include "uint256.h"
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#include "base58.h"
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// secp160k1
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// const unsigned int PRIVATE_KEY_SIZE = 192;
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// const unsigned int PUBLIC_KEY_SIZE = 41;
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// const unsigned int SIGNATURE_SIZE = 48;
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//
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// secp192k1
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// const unsigned int PRIVATE_KEY_SIZE = 222;
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// const unsigned int PUBLIC_KEY_SIZE = 49;
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// const unsigned int SIGNATURE_SIZE = 57;
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//
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// secp224k1
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// const unsigned int PRIVATE_KEY_SIZE = 250;
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// const unsigned int PUBLIC_KEY_SIZE = 57;
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// const unsigned int SIGNATURE_SIZE = 66;
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//
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// secp256k1:
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// const unsigned int PRIVATE_KEY_SIZE = 279;
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// const unsigned int PUBLIC_KEY_SIZE = 65;
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// const unsigned int SIGNATURE_SIZE = 72;
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//
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// see www.keylength.com
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// script supports up to 75 for single byte push
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// Generate a private key from just the secret parameter
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int static inline EC_KEY_regenerate_key(EC_KEY *eckey, BIGNUM *priv_key)
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{
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int ok = 0;
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BN_CTX *ctx = NULL;
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EC_POINT *pub_key = NULL;
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if (!eckey) return 0;
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const EC_GROUP *group = EC_KEY_get0_group(eckey);
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if ((ctx = BN_CTX_new()) == NULL)
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goto err;
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pub_key = EC_POINT_new(group);
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if (pub_key == NULL)
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goto err;
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if (!EC_POINT_mul(group, pub_key, priv_key, NULL, NULL, ctx))
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goto err;
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EC_KEY_set_private_key(eckey,priv_key);
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EC_KEY_set_public_key(eckey,pub_key);
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ok = 1;
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err:
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if (pub_key)
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EC_POINT_free(pub_key);
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if (ctx != NULL)
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BN_CTX_free(ctx);
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return(ok);
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}
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// Perform ECDSA key recovery (see SEC1 4.1.6) for curves over (mod p)-fields
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// recid selects which key is recovered
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// if check is nonzero, additional checks are performed
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int static inline ECDSA_SIG_recover_key_GFp(EC_KEY *eckey, ECDSA_SIG *ecsig, const unsigned char *msg, int msglen, int recid, int check)
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{
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if (!eckey) return 0;
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int ret = 0;
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BN_CTX *ctx = NULL;
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BIGNUM *x = NULL;
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BIGNUM *e = NULL;
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BIGNUM *order = NULL;
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BIGNUM *sor = NULL;
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BIGNUM *eor = NULL;
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BIGNUM *field = NULL;
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EC_POINT *R = NULL;
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EC_POINT *O = NULL;
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EC_POINT *Q = NULL;
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BIGNUM *rr = NULL;
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BIGNUM *zero = NULL;
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int n = 0;
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int i = recid / 2;
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const EC_GROUP *group = EC_KEY_get0_group(eckey);
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if ((ctx = BN_CTX_new()) == NULL) { ret = -1; goto err; }
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BN_CTX_start(ctx);
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order = BN_CTX_get(ctx);
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if (!EC_GROUP_get_order(group, order, ctx)) { ret = -2; goto err; }
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x = BN_CTX_get(ctx);
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if (!BN_copy(x, order)) { ret=-1; goto err; }
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if (!BN_mul_word(x, i)) { ret=-1; goto err; }
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if (!BN_add(x, x, ecsig->r)) { ret=-1; goto err; }
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field = BN_CTX_get(ctx);
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if (!EC_GROUP_get_curve_GFp(group, field, NULL, NULL, ctx)) { ret=-2; goto err; }
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if (BN_cmp(x, field) >= 0) { ret=0; goto err; }
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if ((R = EC_POINT_new(group)) == NULL) { ret = -2; goto err; }
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if (!EC_POINT_set_compressed_coordinates_GFp(group, R, x, recid % 2, ctx)) { ret=0; goto err; }
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if (check)
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{
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if ((O = EC_POINT_new(group)) == NULL) { ret = -2; goto err; }
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if (!EC_POINT_mul(group, O, NULL, R, order, ctx)) { ret=-2; goto err; }
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if (!EC_POINT_is_at_infinity(group, O)) { ret = 0; goto err; }
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}
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if ((Q = EC_POINT_new(group)) == NULL) { ret = -2; goto err; }
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n = EC_GROUP_get_degree(group);
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e = BN_CTX_get(ctx);
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if (!BN_bin2bn(msg, msglen, e)) { ret=-1; goto err; }
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if (8*msglen > n) BN_rshift(e, e, 8-(n & 7));
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zero = BN_CTX_get(ctx);
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if (!BN_zero(zero)) { ret=-1; goto err; }
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if (!BN_mod_sub(e, zero, e, order, ctx)) { ret=-1; goto err; }
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rr = BN_CTX_get(ctx);
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if (!BN_mod_inverse(rr, ecsig->r, order, ctx)) { ret=-1; goto err; }
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sor = BN_CTX_get(ctx);
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if (!BN_mod_mul(sor, ecsig->s, rr, order, ctx)) { ret=-1; goto err; }
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eor = BN_CTX_get(ctx);
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if (!BN_mod_mul(eor, e, rr, order, ctx)) { ret=-1; goto err; }
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if (!EC_POINT_mul(group, Q, eor, R, sor, ctx)) { ret=-2; goto err; }
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if (!EC_KEY_set_public_key(eckey, Q)) { ret=-2; goto err; }
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ret = 1;
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err:
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if (ctx) {
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BN_CTX_end(ctx);
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BN_CTX_free(ctx);
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}
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if (R != NULL) EC_POINT_free(R);
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if (O != NULL) EC_POINT_free(O);
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if (Q != NULL) EC_POINT_free(Q);
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return ret;
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}
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class key_error : public std::runtime_error
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{
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public:
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explicit key_error(const std::string& str) : std::runtime_error(str) {}
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};
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// secure_allocator is defined in serialize.h
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// CPrivKey is a serialized private key, with all parameters included (279 bytes)
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typedef std::vector<unsigned char, secure_allocator<unsigned char> > CPrivKey;
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// CSecret is a serialization of just the secret parameter (32 bytes)
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typedef std::vector<unsigned char, secure_allocator<unsigned char> > CSecret;
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class CKey
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{
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protected:
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EC_KEY* pkey;
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bool fSet;
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public:
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CKey()
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{
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pkey = EC_KEY_new_by_curve_name(NID_secp256k1);
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if (pkey == NULL)
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throw key_error("CKey::CKey() : EC_KEY_new_by_curve_name failed");
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fSet = false;
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}
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CKey(const CKey& b)
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{
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pkey = EC_KEY_dup(b.pkey);
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if (pkey == NULL)
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throw key_error("CKey::CKey(const CKey&) : EC_KEY_dup failed");
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fSet = b.fSet;
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}
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CKey& operator=(const CKey& b)
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{
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if (!EC_KEY_copy(pkey, b.pkey))
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throw key_error("CKey::operator=(const CKey&) : EC_KEY_copy failed");
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fSet = b.fSet;
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return (*this);
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}
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~CKey()
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{
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EC_KEY_free(pkey);
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}
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bool IsNull() const
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{
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return !fSet;
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}
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void MakeNewKey()
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{
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if (!EC_KEY_generate_key(pkey))
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throw key_error("CKey::MakeNewKey() : EC_KEY_generate_key failed");
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fSet = true;
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}
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bool SetPrivKey(const CPrivKey& vchPrivKey)
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{
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const unsigned char* pbegin = &vchPrivKey[0];
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if (!d2i_ECPrivateKey(&pkey, &pbegin, vchPrivKey.size()))
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return false;
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fSet = true;
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return true;
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}
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bool SetSecret(const CSecret& vchSecret)
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{
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EC_KEY_free(pkey);
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pkey = EC_KEY_new_by_curve_name(NID_secp256k1);
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if (pkey == NULL)
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throw key_error("CKey::SetSecret() : EC_KEY_new_by_curve_name failed");
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if (vchSecret.size() != 32)
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throw key_error("CKey::SetSecret() : secret must be 32 bytes");
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BIGNUM *bn = BN_bin2bn(&vchSecret[0],32,BN_new());
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if (bn == NULL)
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throw key_error("CKey::SetSecret() : BN_bin2bn failed");
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if (!EC_KEY_regenerate_key(pkey,bn))
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throw key_error("CKey::SetSecret() : EC_KEY_regenerate_key failed");
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BN_clear_free(bn);
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fSet = true;
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return true;
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}
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CSecret GetSecret() const
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{
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CSecret vchRet;
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vchRet.resize(32);
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const BIGNUM *bn = EC_KEY_get0_private_key(pkey);
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int nBytes = BN_num_bytes(bn);
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if (bn == NULL)
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throw key_error("CKey::GetSecret() : EC_KEY_get0_private_key failed");
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int n=BN_bn2bin(bn,&vchRet[32 - nBytes]);
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if (n != nBytes)
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throw key_error("CKey::GetSecret(): BN_bn2bin failed");
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return vchRet;
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}
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CPrivKey GetPrivKey() const
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{
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unsigned int nSize = i2d_ECPrivateKey(pkey, NULL);
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if (!nSize)
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throw key_error("CKey::GetPrivKey() : i2d_ECPrivateKey failed");
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CPrivKey vchPrivKey(nSize, 0);
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unsigned char* pbegin = &vchPrivKey[0];
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if (i2d_ECPrivateKey(pkey, &pbegin) != nSize)
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throw key_error("CKey::GetPrivKey() : i2d_ECPrivateKey returned unexpected size");
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return vchPrivKey;
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}
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bool SetPubKey(const std::vector<unsigned char>& vchPubKey)
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{
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const unsigned char* pbegin = &vchPubKey[0];
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if (!o2i_ECPublicKey(&pkey, &pbegin, vchPubKey.size()))
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return false;
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fSet = true;
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return true;
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}
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std::vector<unsigned char> GetPubKey() const
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{
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unsigned int nSize = i2o_ECPublicKey(pkey, NULL);
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if (!nSize)
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throw key_error("CKey::GetPubKey() : i2o_ECPublicKey failed");
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std::vector<unsigned char> vchPubKey(nSize, 0);
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unsigned char* pbegin = &vchPubKey[0];
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if (i2o_ECPublicKey(pkey, &pbegin) != nSize)
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throw key_error("CKey::GetPubKey() : i2o_ECPublicKey returned unexpected size");
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return vchPubKey;
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}
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bool Sign(uint256 hash, std::vector<unsigned char>& vchSig)
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{
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vchSig.clear();
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unsigned char pchSig[10000];
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unsigned int nSize = 0;
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if (!ECDSA_sign(0, (unsigned char*)&hash, sizeof(hash), pchSig, &nSize, pkey))
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return false;
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vchSig.resize(nSize);
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memcpy(&vchSig[0], pchSig, nSize);
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return true;
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}
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// create a compact signature (65 bytes), which allows reconstructing the used public key
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// The format is one header byte, followed by two times 32 bytes for the serialized r and s values.
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// The header byte: 0x1B = first key with even y, 0x1C = first key with odd y,
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// 0x1D = second key with even y, 0x1E = second key with odd y
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bool SignCompact(uint256 hash, std::vector<unsigned char>& vchSig)
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{
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bool fOk = false;
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ECDSA_SIG *sig = ECDSA_do_sign((unsigned char*)&hash, sizeof(hash), pkey);
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if (sig==NULL)
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return false;
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vchSig.clear();
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vchSig.resize(65,0);
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int nBitsR = BN_num_bits(sig->r);
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int nBitsS = BN_num_bits(sig->s);
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if (nBitsR <= 256 && nBitsS <= 256)
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{
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int nRecId = -1;
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for (int i=0; i<4; i++)
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{
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CKey keyRec;
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keyRec.fSet = true;
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if (ECDSA_SIG_recover_key_GFp(keyRec.pkey, sig, (unsigned char*)&hash, sizeof(hash), i, 1) == 1)
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if (keyRec.GetPubKey() == this->GetPubKey())
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{
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nRecId = i;
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break;
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}
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}
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if (nRecId == -1)
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throw key_error("CKey::SignCompact() : unable to construct recoverable key");
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vchSig[0] = nRecId+27;
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BN_bn2bin(sig->r,&vchSig[33-(nBitsR+7)/8]);
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BN_bn2bin(sig->s,&vchSig[65-(nBitsS+7)/8]);
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fOk = true;
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}
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ECDSA_SIG_free(sig);
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return fOk;
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}
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// reconstruct public key from a compact signature
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// This is only slightly more CPU intensive than just verifying it.
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// If this function succeeds, the recovered public key is guaranteed to be valid
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// (the signature is a valid signature of the given data for that key)
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bool SetCompactSignature(uint256 hash, const std::vector<unsigned char>& vchSig)
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{
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if (vchSig.size() != 65)
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return false;
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if (vchSig[0]<27 || vchSig[0]>=31)
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return false;
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ECDSA_SIG *sig = ECDSA_SIG_new();
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BN_bin2bn(&vchSig[1],32,sig->r);
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BN_bin2bn(&vchSig[33],32,sig->s);
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EC_KEY_free(pkey);
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pkey = EC_KEY_new_by_curve_name(NID_secp256k1);
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if (ECDSA_SIG_recover_key_GFp(pkey, sig, (unsigned char*)&hash, sizeof(hash), vchSig[0] - 27, 0) == 1)
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{
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fSet = true;
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ECDSA_SIG_free(sig);
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return true;
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}
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return false;
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}
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bool Verify(uint256 hash, const std::vector<unsigned char>& vchSig)
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{
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// -1 = error, 0 = bad sig, 1 = good
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if (ECDSA_verify(0, (unsigned char*)&hash, sizeof(hash), &vchSig[0], vchSig.size(), pkey) != 1)
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return false;
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return true;
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}
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// Verify a compact signature
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bool VerifyCompact(uint256 hash, const std::vector<unsigned char>& vchSig)
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{
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CKey key;
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if (!key.SetCompactSignature(hash, vchSig))
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return false;
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if (GetPubKey() != key.GetPubKey())
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return false;
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return true;
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}
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// Get the address corresponding to this key
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CBitcoinAddress GetAddress() const
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{
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return CBitcoinAddress(GetPubKey());
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}
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};
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#endif
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