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-rw-r--r--src/script/interpreter.cpp6
1 files changed, 6 insertions, 0 deletions
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
index 3c3f92fe46..62042e8e70 100644
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -173,7 +173,13 @@ bool static IsLowDERSignature(const valtype &vchSig, ScriptError* serror) {
if (!IsValidSignatureEncoding(vchSig)) {
return set_error(serror, SCRIPT_ERR_SIG_DER);
}
+ // https://bitcoin.stackexchange.com/a/12556:
+ // Also note that inside transaction signatures, an extra hashtype byte
+ // follows the actual signature data.
std::vector<unsigned char> vchSigCopy(vchSig.begin(), vchSig.begin() + vchSig.size() - 1);
+ // 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 (!CPubKey::CheckLowS(vchSigCopy)) {
return set_error(serror, SCRIPT_ERR_SIG_HIGH_S);
}