diff options
Diffstat (limited to 'src/key.cpp')
-rw-r--r-- | src/key.cpp | 75 |
1 files changed, 54 insertions, 21 deletions
diff --git a/src/key.cpp b/src/key.cpp index 9d4c4498d8..9893b88220 100644 --- a/src/key.cpp +++ b/src/key.cpp @@ -1,4 +1,5 @@ // Copyright (c) 2009-2016 The Bitcoin Core developers +// Copyright (c) 2017 The Zcash developers // Distributed under the MIT software license, see the accompanying // file COPYING or http://www.opensource.org/licenses/mit-license.php. @@ -15,43 +16,62 @@ static secp256k1_context* secp256k1_context_sign = nullptr; /** These functions are taken from the libsecp256k1 distribution and are very ugly. */ + +/** + * This parses a format loosely based on a DER encoding of the ECPrivateKey type from + * section C.4 of SEC 1 <http://www.secg.org/sec1-v2.pdf>, with the following caveats: + * + * * The octet-length of the SEQUENCE must be encoded as 1 or 2 octets. It is not + * required to be encoded as one octet if it is less than 256, as DER would require. + * * The octet-length of the SEQUENCE must not be greater than the remaining + * length of the key encoding, but need not match it (i.e. the encoding may contain + * junk after the encoded SEQUENCE). + * * The privateKey OCTET STRING is zero-filled on the left to 32 octets. + * * Anything after the encoding of the privateKey OCTET STRING is ignored, whether + * or not it is validly encoded DER. + * + * out32 must point to an output buffer of length at least 32 bytes. + */ static int ec_privkey_import_der(const secp256k1_context* ctx, unsigned char *out32, const unsigned char *privkey, size_t privkeylen) { const unsigned char *end = privkey + privkeylen; - int lenb = 0; - int len = 0; memset(out32, 0, 32); /* sequence header */ - if (end < privkey+1 || *privkey != 0x30) { + if (end - privkey < 1 || *privkey != 0x30u) { return 0; } privkey++; /* sequence length constructor */ - if (end < privkey+1 || !(*privkey & 0x80)) { + if (end - privkey < 1 || !(*privkey & 0x80u)) { return 0; } - lenb = *privkey & ~0x80; privkey++; + size_t lenb = *privkey & ~0x80u; privkey++; if (lenb < 1 || lenb > 2) { return 0; } - if (end < privkey+lenb) { + if (end - privkey < lenb) { return 0; } /* sequence length */ - len = privkey[lenb-1] | (lenb > 1 ? privkey[lenb-2] << 8 : 0); + size_t len = privkey[lenb-1] | (lenb > 1 ? privkey[lenb-2] << 8 : 0u); privkey += lenb; - if (end < privkey+len) { + if (end - privkey < len) { return 0; } /* sequence element 0: version number (=1) */ - if (end < privkey+3 || privkey[0] != 0x02 || privkey[1] != 0x01 || privkey[2] != 0x01) { + if (end - privkey < 3 || privkey[0] != 0x02u || privkey[1] != 0x01u || privkey[2] != 0x01u) { return 0; } privkey += 3; /* sequence element 1: octet string, up to 32 bytes */ - if (end < privkey+2 || privkey[0] != 0x04 || privkey[1] > 0x20 || end < privkey+2+privkey[1]) { + if (end - privkey < 2 || privkey[0] != 0x04u) { + return 0; + } + size_t oslen = privkey[1]; + privkey += 2; + if (oslen > 32 || end - privkey < oslen) { return 0; } - memcpy(out32 + 32 - privkey[1], privkey + 2, privkey[1]); + memcpy(out32 + (32 - oslen), privkey, oslen); if (!secp256k1_ec_seckey_verify(ctx, out32)) { memset(out32, 0, 32); return 0; @@ -59,7 +79,18 @@ static int ec_privkey_import_der(const secp256k1_context* ctx, unsigned char *ou return 1; } +/** + * This serializes to a DER encoding of the ECPrivateKey type from section C.4 of SEC 1 + * <http://www.secg.org/sec1-v2.pdf>. The optional parameters and publicKey fields are + * included. + * + * privkey must point to an output buffer of length at least CKey::PRIVATE_KEY_SIZE bytes. + * privkeylen must initially be set to the size of the privkey buffer. Upon return it + * will be set to the number of bytes used in the buffer. + * key32 must point to a 32-byte raw private key. + */ static int ec_privkey_export_der(const secp256k1_context *ctx, unsigned char *privkey, size_t *privkeylen, const unsigned char *key32, int compressed) { + assert(*privkeylen >= CKey::PRIVATE_KEY_SIZE); secp256k1_pubkey pubkey; size_t pubkeylen = 0; if (!secp256k1_ec_pubkey_create(ctx, &pubkey, key32)) { @@ -85,10 +116,11 @@ static int ec_privkey_export_der(const secp256k1_context *ctx, unsigned char *pr memcpy(ptr, begin, sizeof(begin)); ptr += sizeof(begin); memcpy(ptr, key32, 32); ptr += 32; memcpy(ptr, middle, sizeof(middle)); ptr += sizeof(middle); - pubkeylen = 33; + pubkeylen = CPubKey::COMPRESSED_PUBLIC_KEY_SIZE; secp256k1_ec_pubkey_serialize(ctx, ptr, &pubkeylen, &pubkey, SECP256K1_EC_COMPRESSED); ptr += pubkeylen; *privkeylen = ptr - privkey; + assert(*privkeylen == CKey::COMPRESSED_PRIVATE_KEY_SIZE); } else { static const unsigned char begin[] = { 0x30,0x82,0x01,0x13,0x02,0x01,0x01,0x04,0x20 @@ -110,10 +142,11 @@ static int ec_privkey_export_der(const secp256k1_context *ctx, unsigned char *pr memcpy(ptr, begin, sizeof(begin)); ptr += sizeof(begin); memcpy(ptr, key32, 32); ptr += 32; memcpy(ptr, middle, sizeof(middle)); ptr += sizeof(middle); - pubkeylen = 65; + pubkeylen = CPubKey::PUBLIC_KEY_SIZE; secp256k1_ec_pubkey_serialize(ctx, ptr, &pubkeylen, &pubkey, SECP256K1_EC_UNCOMPRESSED); ptr += pubkeylen; *privkeylen = ptr - privkey; + assert(*privkeylen == CKey::PRIVATE_KEY_SIZE); } return 1; } @@ -135,8 +168,8 @@ CPrivKey CKey::GetPrivKey() const { CPrivKey privkey; int ret; size_t privkeylen; - privkey.resize(279); - privkeylen = 279; + privkey.resize(PRIVATE_KEY_SIZE); + privkeylen = PRIVATE_KEY_SIZE; ret = ec_privkey_export_der(secp256k1_context_sign, (unsigned char*) privkey.data(), &privkeylen, begin(), fCompressed ? SECP256K1_EC_COMPRESSED : SECP256K1_EC_UNCOMPRESSED); assert(ret); privkey.resize(privkeylen); @@ -146,7 +179,7 @@ CPrivKey CKey::GetPrivKey() const { CPubKey CKey::GetPubKey() const { assert(fValid); secp256k1_pubkey pubkey; - size_t clen = 65; + size_t clen = CPubKey::PUBLIC_KEY_SIZE; CPubKey result; int ret = secp256k1_ec_pubkey_create(secp256k1_context_sign, &pubkey, begin()); assert(ret); @@ -159,8 +192,8 @@ CPubKey CKey::GetPubKey() const { bool CKey::Sign(const uint256 &hash, std::vector<unsigned char>& vchSig, uint32_t test_case) const { if (!fValid) return false; - vchSig.resize(72); - size_t nSigLen = 72; + vchSig.resize(CPubKey::SIGNATURE_SIZE); + size_t nSigLen = CPubKey::SIGNATURE_SIZE; unsigned char extra_entropy[32] = {0}; WriteLE32(extra_entropy, test_case); secp256k1_ecdsa_signature sig; @@ -188,7 +221,7 @@ bool CKey::VerifyPubKey(const CPubKey& pubkey) const { bool CKey::SignCompact(const uint256 &hash, std::vector<unsigned char>& vchSig) const { if (!fValid) return false; - vchSig.resize(65); + vchSig.resize(CPubKey::COMPACT_SIGNATURE_SIZE); int rec = -1; secp256k1_ecdsa_recoverable_signature sig; int ret = secp256k1_ecdsa_sign_recoverable(secp256k1_context_sign, &sig, hash.begin(), begin(), secp256k1_nonce_function_rfc6979, nullptr); @@ -218,10 +251,10 @@ bool CKey::Derive(CKey& keyChild, ChainCode &ccChild, unsigned int nChild, const std::vector<unsigned char, secure_allocator<unsigned char>> vout(64); if ((nChild >> 31) == 0) { CPubKey pubkey = GetPubKey(); - assert(pubkey.begin() + 33 == pubkey.end()); + assert(pubkey.size() == CPubKey::COMPRESSED_PUBLIC_KEY_SIZE); BIP32Hash(cc, nChild, *pubkey.begin(), pubkey.begin()+1, vout.data()); } else { - assert(begin() + 32 == end()); + assert(size() == 32); BIP32Hash(cc, nChild, 0, begin(), vout.data()); } memcpy(ccChild.begin(), vout.data()+32, 32); |