1// Copyright (c) 2009-2010 Satoshi Nakamoto
2// Copyright (c) 2009-present The Bitcoin Core developers
3// Distributed under the MIT software license, see the accompanying
4// file COPYING or http://www.opensource.org/licenses/mit-license.php.
5
6#include <common/signmessage.h>
7
8#include <addresstype.h>
9#include <hash.h>
10#include <key.h>
11#include <key_io.h>
12#include <pubkey.h>
13#include <uint256.h>
14#include <util/check.h>
15#include <util/strencodings.h>
16
17#include <optional>
18#include <span>
19#include <string>
20#include <variant>
21#include <vector>
22
23/**
24 * Text used to signify that a signed message follows and to prevent
25 * inadvertently signing a transaction.
26 */
27const std::string MESSAGE_MAGIC = "Bitcoin Signed Message:\n";
28
29MessageVerificationResult MessageVerify(
30    const std::string& address,
31    const std::string& signature,
32    const std::string& message)
33{
34    CTxDestination destination = DecodeDestination(address);
35    if (!IsValidDestination(destination)) {
36        return MessageVerificationResult::ERR_INVALID_ADDRESS;
37    }
38
39    if (std::get_if<PKHash>(&destination) == nullptr) {
40        return MessageVerificationResult::ERR_ADDRESS_NO_KEY;
41    }
42
43    auto signature_bytes = DecodeBase64(signature);
44    if (!signature_bytes) {
45        return MessageVerificationResult::ERR_MALFORMED_SIGNATURE;
46    }
47
48    CPubKey pubkey;
49    if (!pubkey.RecoverCompact(MessageHash(message), *signature_bytes)) {
50        return MessageVerificationResult::ERR_PUBKEY_NOT_RECOVERED;
51    }
52
53    if (!(PKHash(pubkey) == *std::get_if<PKHash>(&destination))) {
54        return MessageVerificationResult::ERR_NOT_SIGNED;
55    }
56
57    return MessageVerificationResult::OK;
58}
59
60bool MessageSign(
61    const CKey& privkey,
62    const std::string& message,
63    std::string& signature)
64{
65    std::vector<unsigned char> signature_bytes;
66
67    if (!privkey.SignCompact(MessageHash(message), signature_bytes)) {
68        return false;
69    }
70
71    signature = EncodeBase64(signature_bytes);
72
73    return true;
74}
75
76uint256 MessageHash(const std::string& message)
77{
78    HashWriter hasher{};
79    hasher << MESSAGE_MAGIC << message;
80
81    return hasher.GetHash();
82}
83
84std::string SigningResultString(const SigningResult res)
85{
86    switch (res) {
87        case SigningResult::OK:
88            return "No error";
89        case SigningResult::PRIVATE_KEY_NOT_AVAILABLE:
90            return "Private key not available";
91        case SigningResult::SIGNING_FAILED:
92            return "Sign failed";
93    } // no default case, so the compiler can warn about missing cases
94    assert(false);
95}
96