Switch to libsecp256k1-based validation for ECDSA

src/script/interpreter.cpp

@@ -9,7 +9,6 @@
 #include "crypto/ripemd160.h"
 #include "crypto/sha1.h"
 #include "crypto/sha256.h"
-#include "eccryptoverify.h"
 #include "pubkey.h"
 #include "script/script.h"
 #include "uint256.h"
@@ -165,16 +164,8 @@ bool static IsLowDERSignature(const valtype &vchSig, ScriptError* serror) {
     if (!IsValidSignatureEncoding(vchSig)) {
         return set_error(serror, SCRIPT_ERR_SIG_DER);
     }
-    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 (!eccrypto::CheckSignatureElement(S, nLenS, true))
-        return set_error(serror, SCRIPT_ERR_SIG_HIGH_S);
-
-    return true;
+    std::vector<unsigned char> vchSigCopy(vchSig.begin(), vchSig.begin() + vchSig.size() - 1);
+    return CPubKey::CheckLowS(vchSigCopy);
 }
 
 bool static IsDefinedHashtypeSignature(const valtype &vchSig) {