You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
 
 
 
 
 
 

302 lines
9.3 KiB

// Copyright (c) 2009-2017 The Starwels 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.
#include <pubkey.h>
#include <secp256k1.h>
#include <secp256k1_recovery.h>
namespace
{
/* Global secp256k1_context object used for verification. */
secp256k1_context* secp256k1_context_verify = nullptr;
} // namespace
/** This function is taken from the libsecp256k1 distribution and implements
* DER parsing for ECDSA signatures, while supporting an arbitrary subset of
* format violations.
*
* Supported violations include negative integers, excessive padding, garbage
* at the end, and overly long length descriptors. This is safe to use in
* Starwels because since the activation of BIP66, signatures are verified to be
* strict DER before being passed to this module, and we know it supports all
* violations present in the blockchain before that point.
*/
static int ecdsa_signature_parse_der_lax(const secp256k1_context* ctx, secp256k1_ecdsa_signature* sig, const unsigned char *input, size_t inputlen) {
size_t rpos, rlen, spos, slen;
size_t pos = 0;
size_t lenbyte;
unsigned char tmpsig[64] = {0};
int overflow = 0;
/* Hack to initialize sig with a correctly-parsed but invalid signature. */
secp256k1_ecdsa_signature_parse_compact(ctx, sig, tmpsig);
/* Sequence tag byte */
if (pos == inputlen || input[pos] != 0x30) {
return 0;
}
pos++;
/* Sequence length bytes */
if (pos == inputlen) {
return 0;
}
lenbyte = input[pos++];
if (lenbyte & 0x80) {
lenbyte -= 0x80;
if (lenbyte > inputlen - pos) {
return 0;
}
pos += lenbyte;
}
/* Integer tag byte for R */
if (pos == inputlen || input[pos] != 0x02) {
return 0;
}
pos++;
/* Integer length for R */
if (pos == inputlen) {
return 0;
}
lenbyte = input[pos++];
if (lenbyte & 0x80) {
lenbyte -= 0x80;
if (lenbyte > inputlen - pos) {
return 0;
}
while (lenbyte > 0 && input[pos] == 0) {
pos++;
lenbyte--;
}
static_assert(sizeof(size_t) >= 4, "size_t too small");
if (lenbyte >= 4) {
return 0;
}
rlen = 0;
while (lenbyte > 0) {
rlen = (rlen << 8) + input[pos];
pos++;
lenbyte--;
}
} else {
rlen = lenbyte;
}
if (rlen > inputlen - pos) {
return 0;
}
rpos = pos;
pos += rlen;
/* Integer tag byte for S */
if (pos == inputlen || input[pos] != 0x02) {
return 0;
}
pos++;
/* Integer length for S */
if (pos == inputlen) {
return 0;
}
lenbyte = input[pos++];
if (lenbyte & 0x80) {
lenbyte -= 0x80;
if (lenbyte > inputlen - pos) {
return 0;
}
while (lenbyte > 0 && input[pos] == 0) {
pos++;
lenbyte--;
}
static_assert(sizeof(size_t) >= 4, "size_t too small");
if (lenbyte >= 4) {
return 0;
}
slen = 0;
while (lenbyte > 0) {
slen = (slen << 8) + input[pos];
pos++;
lenbyte--;
}
} else {
slen = lenbyte;
}
if (slen > inputlen - pos) {
return 0;
}
spos = pos;
/* Ignore leading zeroes in R */
while (rlen > 0 && input[rpos] == 0) {
rlen--;
rpos++;
}
/* Copy R value */
if (rlen > 32) {
overflow = 1;
} else {
memcpy(tmpsig + 32 - rlen, input + rpos, rlen);
}
/* Ignore leading zeroes in S */
while (slen > 0 && input[spos] == 0) {
slen--;
spos++;
}
/* Copy S value */
if (slen > 32) {
overflow = 1;
} else {
memcpy(tmpsig + 64 - slen, input + spos, slen);
}
if (!overflow) {
overflow = !secp256k1_ecdsa_signature_parse_compact(ctx, sig, tmpsig);
}
if (overflow) {
/* Overwrite the result again with a correctly-parsed but invalid
signature if parsing failed. */
memset(tmpsig, 0, 64);
secp256k1_ecdsa_signature_parse_compact(ctx, sig, tmpsig);
}
return 1;
}
bool CPubKey::Verify(const uint256 &hash, const std::vector<unsigned char>& vchSig) const {
if (!IsValid())
return false;
secp256k1_pubkey pubkey;
secp256k1_ecdsa_signature sig;
if (!secp256k1_ec_pubkey_parse(secp256k1_context_verify, &pubkey, &(*this)[0], size())) {
return false;
}
if (!ecdsa_signature_parse_der_lax(secp256k1_context_verify, &sig, vchSig.data(), vchSig.size())) {
return false;
}
/* libsecp256k1's ECDSA verification requires lower-S signatures, which have
* not historically been enforced in Starwels, so normalize them first. */
secp256k1_ecdsa_signature_normalize(secp256k1_context_verify, &sig, &sig);
return secp256k1_ecdsa_verify(secp256k1_context_verify, &sig, hash.begin(), &pubkey);
}
bool CPubKey::RecoverCompact(const uint256 &hash, const std::vector<unsigned char>& vchSig) {
if (vchSig.size() != COMPACT_SIGNATURE_SIZE)
return false;
int recid = (vchSig[0] - 27) & 3;
bool fComp = ((vchSig[0] - 27) & 4) != 0;
secp256k1_pubkey pubkey;
secp256k1_ecdsa_recoverable_signature sig;
if (!secp256k1_ecdsa_recoverable_signature_parse_compact(secp256k1_context_verify, &sig, &vchSig[1], recid)) {
return false;
}
if (!secp256k1_ecdsa_recover(secp256k1_context_verify, &pubkey, &sig, hash.begin())) {
return false;
}
unsigned char pub[PUBLIC_KEY_SIZE];
size_t publen = PUBLIC_KEY_SIZE;
secp256k1_ec_pubkey_serialize(secp256k1_context_verify, pub, &publen, &pubkey, fComp ? SECP256K1_EC_COMPRESSED : SECP256K1_EC_UNCOMPRESSED);
Set(pub, pub + publen);
return true;
}
bool CPubKey::IsFullyValid() const {
if (!IsValid())
return false;
secp256k1_pubkey pubkey;
return secp256k1_ec_pubkey_parse(secp256k1_context_verify, &pubkey, &(*this)[0], size());
}
bool CPubKey::Decompress() {
if (!IsValid())
return false;
secp256k1_pubkey pubkey;
if (!secp256k1_ec_pubkey_parse(secp256k1_context_verify, &pubkey, &(*this)[0], size())) {
return false;
}
unsigned char pub[PUBLIC_KEY_SIZE];
size_t publen = PUBLIC_KEY_SIZE;
secp256k1_ec_pubkey_serialize(secp256k1_context_verify, pub, &publen, &pubkey, SECP256K1_EC_UNCOMPRESSED);
Set(pub, pub + publen);
return true;
}
bool CPubKey::Derive(CPubKey& pubkeyChild, ChainCode &ccChild, unsigned int nChild, const ChainCode& cc) const {
assert(IsValid());
assert((nChild >> 31) == 0);
assert(size() == COMPRESSED_PUBLIC_KEY_SIZE);
unsigned char out[64];
BIP32Hash(cc, nChild, *begin(), begin()+1, out);
memcpy(ccChild.begin(), out+32, 32);
secp256k1_pubkey pubkey;
if (!secp256k1_ec_pubkey_parse(secp256k1_context_verify, &pubkey, &(*this)[0], size())) {
return false;
}
if (!secp256k1_ec_pubkey_tweak_add(secp256k1_context_verify, &pubkey, out)) {
return false;
}
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;
}
void CExtPubKey::Encode(unsigned char code[BIP32_EXTKEY_SIZE]) const {
code[0] = nDepth;
memcpy(code+1, vchFingerprint, 4);
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() == CPubKey::COMPRESSED_PUBLIC_KEY_SIZE);
memcpy(code+41, pubkey.begin(), CPubKey::COMPRESSED_PUBLIC_KEY_SIZE);
}
void CExtPubKey::Decode(const unsigned char code[BIP32_EXTKEY_SIZE]) {
nDepth = code[0];
memcpy(vchFingerprint, code+1, 4);
nChild = (code[5] << 24) | (code[6] << 16) | (code[7] << 8) | code[8];
memcpy(chaincode.begin(), code+9, 32);
pubkey.Set(code+41, code+BIP32_EXTKEY_SIZE);
}
bool CExtPubKey::Derive(CExtPubKey &out, unsigned int _nChild) const {
out.nDepth = nDepth + 1;
CKeyID id = pubkey.GetID();
memcpy(&out.vchFingerprint[0], &id, 4);
out.nChild = _nChild;
return pubkey.Derive(out.pubkey, out.chaincode, _nChild, chaincode);
}
/* static */ bool CPubKey::CheckLowS(const std::vector<unsigned char>& vchSig) {
secp256k1_ecdsa_signature sig;
if (!ecdsa_signature_parse_der_lax(secp256k1_context_verify, &sig, vchSig.data(), vchSig.size())) {
return false;
}
return (!secp256k1_ecdsa_signature_normalize(secp256k1_context_verify, nullptr, &sig));
}
/* static */ int ECCVerifyHandle::refcount = 0;
ECCVerifyHandle::ECCVerifyHandle()
{
if (refcount == 0) {
assert(secp256k1_context_verify == nullptr);
secp256k1_context_verify = secp256k1_context_create(SECP256K1_CONTEXT_VERIFY);
assert(secp256k1_context_verify != nullptr);
}
refcount++;
}
ECCVerifyHandle::~ECCVerifyHandle()
{
refcount--;
if (refcount == 0) {
assert(secp256k1_context_verify != nullptr);
secp256k1_context_destroy(secp256k1_context_verify);
secp256k1_context_verify = nullptr;
}
}