1  // Copyright (c) 2009-2010 Satoshi Nakamoto
 2  // Copyright (c) 2009-2022 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  #include <hash.h>
 8  #include <key.h>
 9  #include <key_io.h>
10  #include <pubkey.h>
11  #include <uint256.h>
12  #include <util/strencodings.h>
13  
14  #include <cassert>
15  #include <optional>
16  #include <string>
17  #include <variant>
18  #include <vector>
19  
20  /**
21   * Text used to signify that a signed message follows and to prevent
22   * inadvertently signing a transaction.
23   */
24  const std::string MESSAGE_MAGIC = "Bitcoin Signed Message:\n";
25  
26  MessageVerificationResult MessageVerify(
27      const std::string& address,
28      const std::string& signature,
29      const std::string& message)
30  {
31      CTxDestination destination = DecodeDestination(address);
32      if (!IsValidDestination(destination)) {
33          return MessageVerificationResult::ERR_INVALID_ADDRESS;
34      }
35  
36      if (std::get_if<PKHash>(&destination) == nullptr) {
37          return MessageVerificationResult::ERR_ADDRESS_NO_KEY;
38      }
39  
40      auto signature_bytes = DecodeBase64(signature);
41      if (!signature_bytes) {
42          return MessageVerificationResult::ERR_MALFORMED_SIGNATURE;
43      }
44  
45      CPubKey pubkey;
46      if (!pubkey.RecoverCompact(MessageHash(message), *signature_bytes)) {
47          return MessageVerificationResult::ERR_PUBKEY_NOT_RECOVERED;
48      }
49  
50      if (!(PKHash(pubkey) == *std::get_if<PKHash>(&destination))) {
51          return MessageVerificationResult::ERR_NOT_SIGNED;
52      }
53  
54      return MessageVerificationResult::OK;
55  }
56  
57  bool MessageSign(
58      const CKey& privkey,
59      const std::string& message,
60      std::string& signature)
61  {
62      std::vector<unsigned char> signature_bytes;
63  
64      if (!privkey.SignCompact(MessageHash(message), signature_bytes)) {
65          return false;
66      }
67  
68      signature = EncodeBase64(signature_bytes);
69  
70      return true;
71  }
72  
73  uint256 MessageHash(const std::string& message)
74  {
75      HashWriter hasher{};
76      hasher << MESSAGE_MAGIC << message;
77  
78      return hasher.GetHash();
79  }
80  
81  std::string SigningResultString(const SigningResult res)
82  {
83      switch (res) {
84          case SigningResult::OK:
85              return "No error";
86          case SigningResult::PRIVATE_KEY_NOT_AVAILABLE:
87              return "Private key not available";
88          case SigningResult::SIGNING_FAILED:
89              return "Sign failed";
90          // no default case, so the compiler can warn about missing cases
91      }
92      assert(false);
93  }