Differential D1572 Diff 4371 src/script/sigencoding.cpp

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src/script/sigencoding.cpp

// Copyright (c) 2009-2010 Satoshi Nakamoto		// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2016 The Bitcoin Core developers		// Copyright (c) 2009-2016 The Bitcoin Core developers
// Copyright (c) 2017-2018 The Bitcoin developers		// Copyright (c) 2017-2018 The Bitcoin developers
// Distributed under the MIT software license, see the accompanying		// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.		// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include "sigencoding.h"		#include "sigencoding.h"

#include "pubkey.h"		#include "pubkey.h"
#include "script_flags.h"		#include "script_flags.h"

		#include <boost/range/adaptor/sliced.hpp>

/**		/**
* A canonical signature exists of: <30> <total len> <02> <len R> <R> <02> <len		* 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		* S> <S> <hashtype>, where R and S are not negative (their first byte has its
* highest bit not set), and not excessively padded (do not start with a 0 byte,		* highest bit not set), and not excessively padded (do not start with a 0 byte,
* unless an otherwise negative number follows, in which case a single 0 byte is		* unless an otherwise negative number follows, in which case a single 0 byte is
* necessary and even required).		* necessary and even required).
*		*
* See https://bitcointalk.org/index.php?topic=8392.msg127623#msg127623		* See https://bitcointalk.org/index.php?topic=8392.msg127623#msg127623
▲ Show 20 Lines • Show All 65 Lines • ▼ Show 20 Lines	static bool IsValidSignatureEncoding(const valtype &sig) {
if (lenS > 1 && (sig[lenR + 6] == 0x00) && !(sig[lenR + 7] & 0x80)) {		if (lenS > 1 && (sig[lenR + 6] == 0x00) && !(sig[lenR + 7] & 0x80)) {
return false;		return false;
}		}

return true;		return true;
}		}

static bool IsLowDERSignature(const valtype &vchSig, ScriptError *serror) {		static bool IsLowDERSignature(const valtype &vchSig, ScriptError *serror) {
if (!IsValidSignatureEncoding(vchSig)) {		assert(vchSig.size() > 0);
return set_error(serror, SCRIPT_ERR_SIG_DER);		if (CPubKey::CheckLowS(vchSig \|
		boost::adaptors::sliced(0, vchSig.size() - 1))) {
		return true;
}		}
std::vector<uint8_t> vchSigCopy(vchSig.begin(),
vchSig.begin() + vchSig.size() - 1);
if (!CPubKey::CheckLowS(vchSigCopy)) {
return set_error(serror, SCRIPT_ERR_SIG_HIGH_S);		return set_error(serror, SCRIPT_ERR_SIG_HIGH_S);
}		}
return true;
}

bool CheckSignatureEncoding(const valtype &vchSig, uint32_t flags,		bool CheckSignatureEncoding(const valtype &vchSig, uint32_t flags,
ScriptError *serror) {		ScriptError *serror) {
// Empty signature. Not strictly DER encoded, but allowed to provide a		// Empty signature. Not strictly DER encoded, but allowed to provide a
// compact way to provide an invalid signature for use with CHECK(MULTI)SIG		// compact way to provide an invalid signature for use with CHECK(MULTI)SIG
if (vchSig.size() == 0) {		if (vchSig.size() == 0) {
return true;		return true;
}		}
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