Do signature-s negation inside the tests

To avoid the need for libsecp256k1 to expose such functionality.
This commit is contained in:
Pieter Wuille 2014-11-05 10:53:59 -08:00
parent 5406f61373
commit f4e0aefadc
5 changed files with 52 additions and 7 deletions

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@ -193,7 +193,7 @@ bool CECKey::SetPubKey(const unsigned char* pubkey, size_t size) {
return o2i_ECPublicKey(&pkey, &pubkey, size) != NULL; return o2i_ECPublicKey(&pkey, &pubkey, size) != NULL;
} }
bool CECKey::Sign(const uint256 &hash, std::vector<unsigned char>& vchSig, bool lowS) { bool CECKey::Sign(const uint256 &hash, std::vector<unsigned char>& vchSig) {
vchSig.clear(); vchSig.clear();
ECDSA_SIG *sig = ECDSA_do_sign((unsigned char*)&hash, sizeof(hash), pkey); ECDSA_SIG *sig = ECDSA_do_sign((unsigned char*)&hash, sizeof(hash), pkey);
if (sig == NULL) if (sig == NULL)
@ -205,7 +205,7 @@ bool CECKey::Sign(const uint256 &hash, std::vector<unsigned char>& vchSig, bool
BIGNUM *halforder = BN_CTX_get(ctx); BIGNUM *halforder = BN_CTX_get(ctx);
EC_GROUP_get_order(group, order, ctx); EC_GROUP_get_order(group, order, ctx);
BN_rshift1(halforder, order); BN_rshift1(halforder, order);
if (lowS && BN_cmp(sig->s, halforder) > 0) { if (BN_cmp(sig->s, halforder) > 0) {
// enforce low S values, by negating the value (modulo the order) if above order/2. // enforce low S values, by negating the value (modulo the order) if above order/2.
BN_sub(sig->s, order, sig->s); BN_sub(sig->s, order, sig->s);
} }

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@ -28,7 +28,7 @@ public:
bool SetPrivKey(const unsigned char* privkey, size_t size, bool fSkipCheck=false); bool SetPrivKey(const unsigned char* privkey, size_t size, bool fSkipCheck=false);
void GetPubKey(std::vector<unsigned char>& pubkey, bool fCompressed); void GetPubKey(std::vector<unsigned char>& pubkey, bool fCompressed);
bool SetPubKey(const unsigned char* pubkey, size_t size); bool SetPubKey(const unsigned char* pubkey, size_t size);
bool Sign(const uint256 &hash, std::vector<unsigned char>& vchSig, bool lowS); bool Sign(const uint256 &hash, std::vector<unsigned char>& vchSig);
bool Verify(const uint256 &hash, const std::vector<unsigned char>& vchSig); bool Verify(const uint256 &hash, const std::vector<unsigned char>& vchSig);
bool SignCompact(const uint256 &hash, unsigned char *p64, int &rec); bool SignCompact(const uint256 &hash, unsigned char *p64, int &rec);

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@ -102,7 +102,7 @@ CPubKey CKey::GetPubKey() const {
return result; return result;
} }
bool CKey::Sign(const uint256 &hash, std::vector<unsigned char>& vchSig, bool lowS) const { bool CKey::Sign(const uint256 &hash, std::vector<unsigned char>& vchSig) const {
if (!fValid) if (!fValid)
return false; return false;
#ifdef USE_SECP256K1 #ifdef USE_SECP256K1
@ -119,7 +119,7 @@ bool CKey::Sign(const uint256 &hash, std::vector<unsigned char>& vchSig, bool lo
#else #else
CECKey key; CECKey key;
key.SetSecretBytes(vch); key.SetSecretBytes(vch);
return key.Sign(hash, vchSig, lowS); return key.Sign(hash, vchSig);
#endif #endif
} }

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@ -122,7 +122,7 @@ public:
CPubKey GetPubKey() const; CPubKey GetPubKey() const;
//! Create a DER-serialized signature. //! Create a DER-serialized signature.
bool Sign(const uint256& hash, std::vector<unsigned char>& vchSig, bool lowS = true) const; bool Sign(const uint256& hash, std::vector<unsigned char>& vchSig) const;
/** /**
* Create a compact signature (65 bytes), which allows reconstructing the used public key. * Create a compact signature (65 bytes), which allows reconstructing the used public key.

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@ -95,6 +95,48 @@ void DoTest(const CScript& scriptPubKey, const CScript& scriptSig, int flags, bo
BOOST_CHECK_MESSAGE(VerifyScript(scriptSig, scriptPubKey, flags, SignatureChecker(BuildSpendingTransaction(scriptSig, BuildCreditingTransaction(scriptPubKey)), 0)) == expect, message); BOOST_CHECK_MESSAGE(VerifyScript(scriptSig, scriptPubKey, flags, SignatureChecker(BuildSpendingTransaction(scriptSig, BuildCreditingTransaction(scriptPubKey)), 0)) == expect, message);
} }
void static NegateSignatureS(std::vector<unsigned char>& vchSig) {
// Parse the signature.
std::vector<unsigned char> r, s;
r = std::vector<unsigned char>(vchSig.begin() + 4, vchSig.begin() + 4 + vchSig[3]);
s = std::vector<unsigned char>(vchSig.begin() + 6 + vchSig[3], vchSig.begin() + 6 + vchSig[3] + vchSig[5 + vchSig[3]]);
unsigned char hashtype = vchSig.back();
// Really ugly to implement mod-n negation here, but it would be feature creep to expose such functionality from libsecp256k1.
static const unsigned char order[33] = {
0x00,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFE,
0xBA, 0xAE, 0xDC, 0xE6, 0xAF, 0x48, 0xA0, 0x3B,
0xBF, 0xD2, 0x5E, 0x8C, 0xD0, 0x36, 0x41, 0x41
};
while (s.size() < 33) {
s.insert(s.begin(), 0x00);
}
int carry = 0;
for (int p = 32; p >= 1; p--) {
int n = (int)order[p] - s[p] - carry;
s[p] = (n + 256) & 0xFF;
carry = (n < 0);
}
assert(carry == 0);
if (s.size() > 1 && s[0] == 0 && s[1] < 0x80) {
s.erase(s.begin());
}
// Reconstruct the signature.
vchSig.clear();
vchSig.push_back(0x30);
vchSig.push_back(4 + r.size() + s.size());
vchSig.push_back(0x02);
vchSig.push_back(r.size());
vchSig.insert(vchSig.end(), r.begin(), r.end());
vchSig.push_back(0x02);
vchSig.push_back(s.size());
vchSig.insert(vchSig.end(), s.begin(), s.end());
vchSig.push_back(hashtype);
}
namespace namespace
{ {
const unsigned char vchKey0[32] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1}; const unsigned char vchKey0[32] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
@ -194,7 +236,10 @@ public:
uint256 hash = SignatureHash(scriptPubKey, spendTx, 0, nHashType); uint256 hash = SignatureHash(scriptPubKey, spendTx, 0, nHashType);
std::vector<unsigned char> vchSig, r, s; std::vector<unsigned char> vchSig, r, s;
do { do {
key.Sign(hash, vchSig, lenS <= 32); key.Sign(hash, vchSig);
if ((lenS == 33) != (vchSig[5 + vchSig[3]] == 33)) {
NegateSignatureS(vchSig);
}
r = std::vector<unsigned char>(vchSig.begin() + 4, vchSig.begin() + 4 + vchSig[3]); r = std::vector<unsigned char>(vchSig.begin() + 4, vchSig.begin() + 4 + vchSig[3]);
s = std::vector<unsigned char>(vchSig.begin() + 6 + vchSig[3], vchSig.begin() + 6 + vchSig[3] + vchSig[5 + vchSig[3]]); s = std::vector<unsigned char>(vchSig.begin() + 6 + vchSig[3], vchSig.begin() + 6 + vchSig[3] + vchSig[5 + vchSig[3]]);
} while (lenR != r.size() || lenS != s.size()); } while (lenR != r.size() || lenS != s.size());