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consensus: guard against openssl's new strict DER checks

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New versions of OpenSSL will reject non-canonical DER signatures. However,
it'll happily decode them. Decode then re-encode before verification in order
to ensure that it is properly consumed.
This commit is contained in:
Cory Fields 2015-01-09 16:39:12 -05:00
parent d0c97bbe70
commit 488ed32f2a
1 changed files with 13 additions and 3 deletions
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16
src/ecwrapper.cpp
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@ -117,10 +117,20 @@ bool CECKey::SetPubKey(const unsigned char* pubkey, size_t size) {
} }
bool CECKey::Verify(const uint256 &hash, const std::vector<unsigned char>& vchSig) { bool CECKey::Verify(const uint256 &hash, const std::vector<unsigned char>& vchSig) {
// -1 = error, 0 = bad sig, 1 = good // New versions of OpenSSL will reject non-canonical DER signatures. de/re-serialize first.
if (ECDSA_verify(0, (unsigned char*)&hash, sizeof(hash), &vchSig[0], vchSig.size(), pkey) != 1) unsigned char *norm_der = NULL;
ECDSA_SIG *norm_sig = ECDSA_SIG_new();
const unsigned char* sigptr = &vchSig[0];
d2i_ECDSA_SIG(&norm_sig, &sigptr, vchSig.size());
int derlen = i2d_ECDSA_SIG(norm_sig, &norm_der);
ECDSA_SIG_free(norm_sig);
if (derlen <= 0)
return false; return false;
return true;
// -1 = error, 0 = bad sig, 1 = good
bool ret = ECDSA_verify(0, (unsigned char*)&hash, sizeof(hash), norm_der, derlen, pkey) == 1;
OPENSSL_free(norm_der);
return ret;
} }
bool CECKey::Recover(const uint256 &hash, const unsigned char *p64, int rec) bool CECKey::Recover(const uint256 &hash, const unsigned char *p64, int rec)