src/util/message.cpp


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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2020 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include <hash.h>            // For CHashWriter
#include <key_io.h>          // For DecodeDestination()
#include <pubkey.h>          // For CPubKey
#include <script/standard.h> // For CTxDestination, IsValidDestination(), PKHash
#include <serialize.h>       // For SER_GETHASH
#include <util/message.h>
#include <util/strencodings.h> // For DecodeBase64()

#include <string>
#include <vector>

const std::string strMessageMagic = "Bitcoin Signed Message:\n";

MessageVerificationResult MessageVerify(
    const std::string& address,
    const std::string& signature,
    const std::string& message)
{
    CTxDestination destination = DecodeDestination(address);
    if (!IsValidDestination(destination)) {
        return MessageVerificationResult::ERR_INVALID_ADDRESS;
    }

    if (boost::get<PKHash>(&destination) == nullptr) {
        return MessageVerificationResult::ERR_ADDRESS_NO_KEY;
    }

    bool invalid = false;
    std::vector<unsigned char> signature_bytes = DecodeBase64(signature.c_str(), &invalid);
    if (invalid) {
        return MessageVerificationResult::ERR_MALFORMED_SIGNATURE;
    }

    CHashWriter ss(SER_GETHASH, 0);
    ss << strMessageMagic;
    ss << message;

    CPubKey pubkey;
    if (!pubkey.RecoverCompact(ss.GetHash(), signature_bytes)) {
        return MessageVerificationResult::ERR_PUBKEY_NOT_RECOVERED;
    }

    if (!(CTxDestination(PKHash(pubkey)) == destination)) {
        return MessageVerificationResult::ERR_NOT_SIGNED;
    }

    return MessageVerificationResult::OK;
}