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-rw-r--r--src/ecwrapper.cpp4
-rw-r--r--src/ecwrapper.h2
-rw-r--r--src/key.cpp4
-rw-r--r--src/key.h2
-rw-r--r--src/test/script_tests.cpp47
5 files changed, 52 insertions, 7 deletions
diff --git a/src/ecwrapper.cpp b/src/ecwrapper.cpp
index ebaa350264..3377dce0c1 100644
--- a/src/ecwrapper.cpp
+++ b/src/ecwrapper.cpp
@@ -193,7 +193,7 @@ bool CECKey::SetPubKey(const unsigned char* pubkey, size_t size) {
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();
ECDSA_SIG *sig = ECDSA_do_sign((unsigned char*)&hash, sizeof(hash), pkey);
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);
EC_GROUP_get_order(group, order, ctx);
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.
BN_sub(sig->s, order, sig->s);
}
diff --git a/src/ecwrapper.h b/src/ecwrapper.h
index 3457ca5f5a..a7847d190c 100644
--- a/src/ecwrapper.h
+++ b/src/ecwrapper.h
@@ -28,7 +28,7 @@ public:
bool SetPrivKey(const unsigned char* privkey, size_t size, bool fSkipCheck=false);
void GetPubKey(std::vector<unsigned char>& pubkey, bool fCompressed);
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 SignCompact(const uint256 &hash, unsigned char *p64, int &rec);
diff --git a/src/key.cpp b/src/key.cpp
index 1b539d073a..0ca9a681a3 100644
--- a/src/key.cpp
+++ b/src/key.cpp
@@ -102,7 +102,7 @@ CPubKey CKey::GetPubKey() const {
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)
return false;
#ifdef USE_SECP256K1
@@ -119,7 +119,7 @@ bool CKey::Sign(const uint256 &hash, std::vector<unsigned char>& vchSig, bool lo
#else
CECKey key;
key.SetSecretBytes(vch);
- return key.Sign(hash, vchSig, lowS);
+ return key.Sign(hash, vchSig);
#endif
}
diff --git a/src/key.h b/src/key.h
index f36e658dee..0bb05482c9 100644
--- a/src/key.h
+++ b/src/key.h
@@ -122,7 +122,7 @@ public:
CPubKey GetPubKey() const;
//! 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.
diff --git a/src/test/script_tests.cpp b/src/test/script_tests.cpp
index a41552fea1..cff1664a1e 100644
--- a/src/test/script_tests.cpp
+++ b/src/test/script_tests.cpp
@@ -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);
}
+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
{
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);
std::vector<unsigned char> vchSig, r, s;
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]);
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());