398 lines
12 KiB
C++
398 lines
12 KiB
C++
// Copyright (c) 2009-2012 The Bitcoin developers
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// Copyright (c) 2013-2014 Dogecoin Developers
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// Distributed under the MIT/X11 software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include <openssl/ecdsa.h>
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#include <openssl/rand.h>
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#include <openssl/obj_mac.h>
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#include "key.h"
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// anonymous namespace with local implementation code (OpenSSL interaction)
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namespace {
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// Generate a private key from just the secret parameter
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int 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 non-zero, additional checks are performed
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int 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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// RAII Wrapper around OpenSSL's EC_KEY
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class CECKey {
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private:
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EC_KEY *pkey;
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public:
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CECKey() {
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pkey = EC_KEY_new_by_curve_name(NID_secp256k1);
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assert(pkey != NULL);
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}
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~CECKey() {
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EC_KEY_free(pkey);
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}
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void GetSecretBytes(unsigned char vch[32]) const {
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const BIGNUM *bn = EC_KEY_get0_private_key(pkey);
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assert(bn);
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int nBytes = BN_num_bytes(bn);
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int n=BN_bn2bin(bn,&vch[32 - nBytes]);
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assert(n == nBytes);
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memset(vch, 0, 32 - nBytes);
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}
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void SetSecretBytes(const unsigned char vch[32]) {
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BIGNUM bn;
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BN_init(&bn);
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assert(BN_bin2bn(vch, 32, &bn));
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assert(EC_KEY_regenerate_key(pkey, &bn));
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BN_clear_free(&bn);
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}
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void GetPrivKey(CPrivKey &privkey, bool fCompressed) {
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EC_KEY_set_conv_form(pkey, fCompressed ? POINT_CONVERSION_COMPRESSED : POINT_CONVERSION_UNCOMPRESSED);
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int nSize = i2d_ECPrivateKey(pkey, NULL);
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assert(nSize);
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privkey.resize(nSize);
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unsigned char* pbegin = &privkey[0];
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int nSize2 = i2d_ECPrivateKey(pkey, &pbegin);
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assert(nSize == nSize2);
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}
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bool SetPrivKey(const CPrivKey &privkey) {
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const unsigned char* pbegin = &privkey[0];
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if (d2i_ECPrivateKey(&pkey, &pbegin, privkey.size())) {
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// d2i_ECPrivateKey returns true if parsing succeeds.
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// This doesn't necessarily mean the key is valid.
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if (EC_KEY_check_key(pkey))
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return true;
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}
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return false;
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}
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void GetPubKey(CPubKey &pubkey, bool fCompressed) {
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EC_KEY_set_conv_form(pkey, fCompressed ? POINT_CONVERSION_COMPRESSED : POINT_CONVERSION_UNCOMPRESSED);
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int nSize = i2o_ECPublicKey(pkey, NULL);
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assert(nSize);
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assert(nSize <= 65);
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unsigned char c[65];
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unsigned char *pbegin = c;
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int nSize2 = i2o_ECPublicKey(pkey, &pbegin);
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assert(nSize == nSize2);
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pubkey.Set(&c[0], &c[nSize]);
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}
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bool SetPubKey(const CPubKey &pubkey) {
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const unsigned char* pbegin = pubkey.begin();
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return o2i_ECPublicKey(&pkey, &pbegin, pubkey.size());
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}
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bool Sign(const uint256 &hash, std::vector<unsigned char>& vchSig) {
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unsigned int nSize = ECDSA_size(pkey);
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vchSig.resize(nSize); // Make sure it is big enough
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assert(ECDSA_sign(0, (unsigned char*)&hash, sizeof(hash), &vchSig[0], &nSize, pkey));
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vchSig.resize(nSize); // Shrink to fit actual size
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return true;
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}
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bool Verify(const uint256 &hash, const std::vector<unsigned char>& vchSig) {
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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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bool SignCompact(const uint256 &hash, unsigned char *p64, int &rec) {
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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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memset(p64, 0, 64);
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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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CPubKey pubkey;
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GetPubKey(pubkey, true);
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for (int i=0; i<4; i++) {
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CECKey keyRec;
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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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CPubKey pubkeyRec;
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keyRec.GetPubKey(pubkeyRec, true);
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if (pubkeyRec == pubkey) {
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rec = i;
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fOk = true;
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break;
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}
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}
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}
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assert(fOk);
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BN_bn2bin(sig->r,&p64[32-(nBitsR+7)/8]);
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BN_bn2bin(sig->s,&p64[64-(nBitsS+7)/8]);
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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 Recover(const uint256 &hash, const unsigned char *p64, int rec)
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{
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if (rec<0 || rec>=3)
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return false;
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ECDSA_SIG *sig = ECDSA_SIG_new();
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BN_bin2bn(&p64[0], 32, sig->r);
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BN_bin2bn(&p64[32], 32, sig->s);
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bool ret = ECDSA_SIG_recover_key_GFp(pkey, sig, (unsigned char*)&hash, sizeof(hash), rec, 0) == 1;
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ECDSA_SIG_free(sig);
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return ret;
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}
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};
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}; // end of anonymous namespace
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bool CKey::Check(const unsigned char *vch) {
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// Do not convert to OpenSSL's data structures for range-checking keys,
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// it's easy enough to do directly.
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static const unsigned char vchMax[32] = {
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0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
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0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFE,
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0xBA,0xAE,0xDC,0xE6,0xAF,0x48,0xA0,0x3B,
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0xBF,0xD2,0x5E,0x8C,0xD0,0x36,0x41,0x40
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};
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bool fIsZero = true;
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for (int i=0; i<32 && fIsZero; i++)
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if (vch[i] != 0)
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fIsZero = false;
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if (fIsZero)
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return false;
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for (int i=0; i<32; i++) {
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if (vch[i] < vchMax[i])
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return true;
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if (vch[i] > vchMax[i])
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return false;
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}
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return true;
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}
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void CKey::MakeNewKey(bool fCompressedIn) {
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do {
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RAND_bytes(vch, sizeof(vch));
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} while (!Check(vch));
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fValid = true;
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fCompressed = fCompressedIn;
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}
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bool CKey::SetPrivKey(const CPrivKey &privkey, bool fCompressedIn) {
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CECKey key;
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if (!key.SetPrivKey(privkey))
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return false;
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key.GetSecretBytes(vch);
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fCompressed = fCompressedIn;
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fValid = true;
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return true;
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}
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CPrivKey CKey::GetPrivKey() const {
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assert(fValid);
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CECKey key;
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key.SetSecretBytes(vch);
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CPrivKey privkey;
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key.GetPrivKey(privkey, fCompressed);
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return privkey;
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}
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CPubKey CKey::GetPubKey() const {
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assert(fValid);
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CECKey key;
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key.SetSecretBytes(vch);
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CPubKey pubkey;
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key.GetPubKey(pubkey, fCompressed);
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return pubkey;
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}
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bool CKey::Sign(const uint256 &hash, std::vector<unsigned char>& vchSig) const {
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if (!fValid)
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return false;
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CECKey key;
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key.SetSecretBytes(vch);
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return key.Sign(hash, vchSig);
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}
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bool CKey::SignCompact(const uint256 &hash, std::vector<unsigned char>& vchSig) const {
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if (!fValid)
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return false;
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CECKey key;
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key.SetSecretBytes(vch);
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vchSig.resize(65);
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int rec = -1;
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if (!key.SignCompact(hash, &vchSig[1], rec))
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return false;
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assert(rec != -1);
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vchSig[0] = 27 + rec + (fCompressed ? 4 : 0);
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return true;
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}
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bool CPubKey::Verify(const uint256 &hash, const std::vector<unsigned char>& vchSig) const {
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if (!IsValid())
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return false;
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CECKey key;
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if (!key.SetPubKey(*this))
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return false;
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if (!key.Verify(hash, vchSig))
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return false;
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return true;
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}
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bool CPubKey::RecoverCompact(const uint256 &hash, const std::vector<unsigned char>& vchSig) {
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if (vchSig.size() != 65)
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return false;
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CECKey key;
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if (!key.Recover(hash, &vchSig[1], (vchSig[0] - 27) & ~4))
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return false;
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key.GetPubKey(*this, (vchSig[0] - 27) & 4);
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return true;
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}
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bool CPubKey::VerifyCompact(const uint256 &hash, const std::vector<unsigned char>& vchSig) const {
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if (!IsValid())
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return false;
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if (vchSig.size() != 65)
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return false;
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CECKey key;
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if (!key.Recover(hash, &vchSig[1], (vchSig[0] - 27) & ~4))
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return false;
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CPubKey pubkeyRec;
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key.GetPubKey(pubkeyRec, IsCompressed());
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if (*this != pubkeyRec)
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return false;
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return true;
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}
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bool CPubKey::IsFullyValid() const {
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if (!IsValid())
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return false;
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CECKey key;
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if (!key.SetPubKey(*this))
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return false;
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return true;
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}
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bool CPubKey::Decompress() {
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if (!IsValid())
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return false;
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CECKey key;
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if (!key.SetPubKey(*this))
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return false;
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key.GetPubKey(*this, false);
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return true;
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}
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