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-rw-r--r--src/script/interpreter.cpp76
1 files changed, 55 insertions, 21 deletions
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
index 56140f19db..ae66217b7c 100644
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -52,10 +52,7 @@ static inline void popstack(vector<valtype>& stack)
stack.pop_back();
}
-bool IsCanonicalPubKey(const valtype &vchPubKey, unsigned int flags) {
- if (!(flags & SCRIPT_VERIFY_STRICTENC))
- return true;
-
+bool static IsCompressedOrUncompressedPubKey(const valtype &vchPubKey) {
if (vchPubKey.size() < 33)
return error("Non-canonical public key: too short");
if (vchPubKey[0] == 0x04) {
@@ -70,10 +67,7 @@ bool IsCanonicalPubKey(const valtype &vchPubKey, unsigned int flags) {
return true;
}
-bool IsCanonicalSignature(const valtype &vchSig, unsigned int flags) {
- if (!(flags & SCRIPT_VERIFY_STRICTENC))
- return true;
-
+bool static IsDERSignature(const valtype &vchSig) {
// See https://bitcointalk.org/index.php?topic=8392.msg127623#msg127623
// A canonical signature exists of: <30> <total len> <02> <len R> <R> <02> <len S> <S> <hashtype>
// Where R and S are not negative (their first byte has its highest bit not set), and not
@@ -83,9 +77,6 @@ bool IsCanonicalSignature(const valtype &vchSig, unsigned int flags) {
return error("Non-canonical signature: too short");
if (vchSig.size() > 73)
return error("Non-canonical signature: too long");
- unsigned char nHashType = vchSig[vchSig.size() - 1] & (~(SIGHASH_ANYONECANPAY));
- if (nHashType < SIGHASH_ALL || nHashType > SIGHASH_SINGLE)
- return error("Non-canonical signature: unknown hashtype byte");
if (vchSig[0] != 0x30)
return error("Non-canonical signature: wrong type");
if (vchSig[1] != vchSig.size()-3)
@@ -117,17 +108,54 @@ bool IsCanonicalSignature(const valtype &vchSig, unsigned int flags) {
if (nLenS > 1 && (S[0] == 0x00) && !(S[1] & 0x80))
return error("Non-canonical signature: S value excessively padded");
- if (flags & SCRIPT_VERIFY_LOW_S) {
- // If the S value is above the order of the curve divided by two, its
- // complement modulo the order could have been used instead, which is
- // one byte shorter when encoded correctly.
- if (!CKey::CheckSignatureElement(S, nLenS, true))
- return error("Non-canonical signature: S value is unnecessarily high");
+ return true;
+}
+
+bool static IsLowDERSignature(const valtype &vchSig) {
+ if (!IsDERSignature(vchSig)) {
+ return false;
}
+ unsigned int nLenR = vchSig[3];
+ unsigned int nLenS = vchSig[5+nLenR];
+ const unsigned char *S = &vchSig[6+nLenR];
+ // If the S value is above the order of the curve divided by two, its
+ // complement modulo the order could have been used instead, which is
+ // one byte shorter when encoded correctly.
+ if (!CKey::CheckSignatureElement(S, nLenS, true))
+ return error("Non-canonical signature: S value is unnecessarily high");
return true;
}
+bool static IsDefinedHashtypeSignature(const valtype &vchSig) {
+ if (vchSig.size() == 0) {
+ return false;
+ }
+ unsigned char nHashType = vchSig[vchSig.size() - 1] & (~(SIGHASH_ANYONECANPAY));
+ if (nHashType < SIGHASH_ALL || nHashType > SIGHASH_SINGLE)
+ return error("Non-canonical signature: unknown hashtype byte");
+
+ return true;
+}
+
+bool static CheckSignatureEncoding(const valtype &vchSig, unsigned int flags) {
+ if ((flags & (SCRIPT_VERIFY_DERSIG | SCRIPT_VERIFY_LOW_S | SCRIPT_VERIFY_STRICTENC)) != 0 && !IsDERSignature(vchSig)) {
+ return false;
+ } else if ((flags & SCRIPT_VERIFY_LOW_S) != 0 && !IsLowDERSignature(vchSig)) {
+ return false;
+ } else if ((flags & SCRIPT_VERIFY_STRICTENC) != 0 && !IsDefinedHashtypeSignature(vchSig)) {
+ return false;
+ }
+ return true;
+}
+
+bool static CheckPubKeyEncoding(const valtype &vchSig, unsigned int flags) {
+ if ((flags & SCRIPT_VERIFY_STRICTENC) != 0 && !IsCompressedOrUncompressedPubKey(vchSig)) {
+ return false;
+ }
+ return true;
+}
+
bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const BaseSignatureChecker& checker)
{
CScript::const_iterator pc = script.begin();
@@ -670,8 +698,11 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
// Drop the signature, since there's no way for a signature to sign itself
scriptCode.FindAndDelete(CScript(vchSig));
- bool fSuccess = IsCanonicalSignature(vchSig, flags) && IsCanonicalPubKey(vchPubKey, flags) &&
- checker.CheckSig(vchSig, vchPubKey, scriptCode);
+ if (!CheckSignatureEncoding(vchSig, flags)) {
+ return false;
+ }
+
+ bool fSuccess = CheckPubKeyEncoding(vchPubKey, flags) && checker.CheckSig(vchSig, vchPubKey, scriptCode);
popstack(stack);
popstack(stack);
@@ -730,9 +761,12 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
valtype& vchSig = stacktop(-isig);
valtype& vchPubKey = stacktop(-ikey);
+ if (!CheckSignatureEncoding(vchSig, flags)) {
+ return false;
+ }
+
// Check signature
- bool fOk = IsCanonicalSignature(vchSig, flags) && IsCanonicalPubKey(vchPubKey, flags) &&
- checker.CheckSig(vchSig, vchPubKey, scriptCode);
+ bool fOk = CheckPubKeyEncoding(vchPubKey, flags) && checker.CheckSig(vchSig, vchPubKey, scriptCode);
if (fOk) {
isig++;