From 17fa3913ef7ba5f569ebc3695fab15b10dd914f0 Mon Sep 17 00:00:00 2001 From: Jack Grigg Date: Tue, 6 Jun 2017 19:21:34 +1200 Subject: [PATCH] Specify ECDSA constant sizes as constants --- src/key.cpp | 24 +++++++++++++++--------- src/key.h | 12 +++++++----- src/pubkey.cpp | 20 ++++++++++---------- src/pubkey.h | 21 ++++++++++++--------- 4 files changed, 44 insertions(+), 33 deletions(-) diff --git a/src/key.cpp b/src/key.cpp index 31d485722ac..3b679414d11 100644 --- a/src/key.cpp +++ b/src/key.cpp @@ -87,9 +87,13 @@ static int ec_privkey_import_der(const secp256k1_context* ctx, unsigned char *ou * . The optional parameters and publicKey fields are * included. * + * privkey must point to an output buffer of length at least 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 >= PRIVATE_KEY_SIZE); secp256k1_pubkey pubkey; size_t pubkeylen = 0; if (!secp256k1_ec_pubkey_create(ctx, &pubkey, key32)) { @@ -115,10 +119,11 @@ 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 = COMPRESSED_PUBLIC_KEY_SIZE; secp256k1_ec_pubkey_serialize(ctx, ptr, &pubkeylen, &pubkey, SECP256K1_EC_COMPRESSED); ptr += pubkeylen; *privkeylen = ptr - privkey; + assert(*privkeylen == COMPRESSED_PRIVATE_KEY_SIZE); } else { static const unsigned char begin[] = { 0x30,0x82,0x01,0x13,0x02,0x01,0x01,0x04,0x20 @@ -140,10 +145,11 @@ 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 = PUBLIC_KEY_SIZE; secp256k1_ec_pubkey_serialize(ctx, ptr, &pubkeylen, &pubkey, SECP256K1_EC_UNCOMPRESSED); ptr += pubkeylen; *privkeylen = ptr - privkey; + assert(*privkeylen == PRIVATE_KEY_SIZE); } return 1; } @@ -165,8 +171,8 @@ 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); @@ -176,7 +182,7 @@ CPrivKey CKey::GetPrivKey() const { CPubKey CKey::GetPubKey() const { assert(fValid); secp256k1_pubkey pubkey; - size_t clen = 65; + size_t clen = PUBLIC_KEY_SIZE; CPubKey result; int ret = secp256k1_ec_pubkey_create(secp256k1_context_sign, &pubkey, begin()); assert(ret); @@ -189,8 +195,8 @@ CPubKey CKey::GetPubKey() const { bool CKey::Sign(const uint256 &hash, std::vector& vchSig, uint32_t test_case) const { if (!fValid) return false; - vchSig.resize(72); - size_t nSigLen = 72; + vchSig.resize(SIGNATURE_SIZE); + size_t nSigLen = SIGNATURE_SIZE; unsigned char extra_entropy[32] = {0}; WriteLE32(extra_entropy, test_case); secp256k1_ecdsa_signature sig; @@ -218,7 +224,7 @@ bool CKey::VerifyPubKey(const CPubKey& pubkey) const { bool CKey::SignCompact(const uint256 &hash, std::vector& vchSig) const { if (!fValid) return false; - vchSig.resize(65); + vchSig.resize(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, NULL); @@ -248,7 +254,7 @@ bool CKey::Derive(CKey& keyChild, ChainCode &ccChild, unsigned int nChild, const std::vector> vout(64); if ((nChild >> 31) == 0) { CPubKey pubkey = GetPubKey(); - assert(pubkey.size() == 33); + assert(pubkey.size() == COMPRESSED_PUBLIC_KEY_SIZE); BIP32Hash(cc, nChild, *pubkey.begin(), pubkey.begin()+1, vout.data()); } else { assert(size() == 32); diff --git a/src/key.h b/src/key.h index 2c6f151727b..dc7b941f42c 100644 --- a/src/key.h +++ b/src/key.h @@ -1,5 +1,6 @@ // Copyright (c) 2009-2010 Satoshi Nakamoto // 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. @@ -17,17 +18,18 @@ /** * secp256k1: - * const unsigned int PRIVATE_KEY_SIZE = 279; - * const unsigned int PUBLIC_KEY_SIZE = 65; - * const unsigned int SIGNATURE_SIZE = 72; - * + */ +const unsigned int PRIVATE_KEY_SIZE = 279; +const unsigned int COMPRESSED_PRIVATE_KEY_SIZE = 214; +/** * see www.keylength.com * script supports up to 75 for single byte push */ /** * secure_allocator is defined in allocators.h - * CPrivKey is a serialized private key, with all parameters included (279 bytes) + * CPrivKey is a serialized private key, with all parameters included + * (PRIVATE_KEY_SIZE bytes) */ typedef std::vector > CPrivKey; diff --git a/src/pubkey.cpp b/src/pubkey.cpp index da02fec7a27..7e7b1592232 100644 --- a/src/pubkey.cpp +++ b/src/pubkey.cpp @@ -185,7 +185,7 @@ bool CPubKey::Verify(const uint256 &hash, const std::vector& vchS } bool CPubKey::RecoverCompact(const uint256 &hash, const std::vector& vchSig) { - if (vchSig.size() != 65) + if (vchSig.size() != COMPACT_SIGNATURE_SIZE) return false; int recid = (vchSig[0] - 27) & 3; bool fComp = ((vchSig[0] - 27) & 4) != 0; @@ -197,8 +197,8 @@ bool CPubKey::RecoverCompact(const uint256 &hash, const std::vector> 31) == 0); - assert(size() == 33); + assert(size() == COMPRESSED_PUBLIC_KEY_SIZE); unsigned char out[64]; BIP32Hash(cc, nChild, *begin(), begin()+1, out); memcpy(ccChild.begin(), out+32, 32); @@ -239,8 +239,8 @@ bool CPubKey::Derive(CPubKey& pubkeyChild, ChainCode &ccChild, unsigned int nChi if (!secp256k1_ec_pubkey_tweak_add(secp256k1_context_verify, &pubkey, out)) { return false; } - unsigned char pub[33]; - size_t publen = 33; + unsigned char pub[COMPRESSED_PUBLIC_KEY_SIZE]; + size_t publen = COMPRESSED_PUBLIC_KEY_SIZE; secp256k1_ec_pubkey_serialize(secp256k1_context_verify, pub, &publen, &pubkey, SECP256K1_EC_COMPRESSED); pubkeyChild.Set(pub, pub + publen); return true; @@ -252,8 +252,8 @@ void CExtPubKey::Encode(unsigned char code[BIP32_EXTKEY_SIZE]) const { code[5] = (nChild >> 24) & 0xFF; code[6] = (nChild >> 16) & 0xFF; code[7] = (nChild >> 8) & 0xFF; code[8] = (nChild >> 0) & 0xFF; memcpy(code+9, chaincode.begin(), 32); - assert(pubkey.size() == 33); - memcpy(code+41, pubkey.begin(), 33); + assert(pubkey.size() == COMPRESSED_PUBLIC_KEY_SIZE); + memcpy(code+41, pubkey.begin(), COMPRESSED_PUBLIC_KEY_SIZE); } void CExtPubKey::Decode(const unsigned char code[BIP32_EXTKEY_SIZE]) { diff --git a/src/pubkey.h b/src/pubkey.h index dbf0e23f207..6e25ad7c49d 100644 --- a/src/pubkey.h +++ b/src/pubkey.h @@ -1,5 +1,6 @@ // Copyright (c) 2009-2010 Satoshi Nakamoto // 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. @@ -15,10 +16,12 @@ /** * secp256k1: - * const unsigned int PRIVATE_KEY_SIZE = 279; - * const unsigned int PUBLIC_KEY_SIZE = 65; - * const unsigned int SIGNATURE_SIZE = 72; - * + */ +const unsigned int PUBLIC_KEY_SIZE = 65; +const unsigned int COMPRESSED_PUBLIC_KEY_SIZE = 33; +const unsigned int SIGNATURE_SIZE = 72; +const unsigned int COMPACT_SIGNATURE_SIZE = 65; +/** * see www.keylength.com * script supports up to 75 for single byte push */ @@ -44,15 +47,15 @@ private: * Just store the serialized data. * Its length can very cheaply be computed from the first byte. */ - unsigned char vch[65]; + unsigned char vch[PUBLIC_KEY_SIZE]; //! Compute the length of a pubkey with a given first byte. unsigned int static GetLen(unsigned char chHeader) { if (chHeader == 2 || chHeader == 3) - return 33; + return COMPRESSED_PUBLIC_KEY_SIZE; if (chHeader == 4 || chHeader == 6 || chHeader == 7) - return 65; + return PUBLIC_KEY_SIZE; return 0; } @@ -127,7 +130,7 @@ public: void Unserialize(Stream& s) { unsigned int len = ::ReadCompactSize(s); - if (len <= 65) { + if (len <= PUBLIC_KEY_SIZE) { s.read((char*)vch, len); } else { // invalid pubkey, skip available data @@ -166,7 +169,7 @@ public: //! Check whether this is a compressed public key. bool IsCompressed() const { - return size() == 33; + return size() == COMPRESSED_PUBLIC_KEY_SIZE; } /**