1  // Copyright (c) 2019-present The Bitcoin Core developers
 2  // Distributed under the MIT software license, see the accompanying
 3  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 4  
 5  #include <bech32.h>
 6  #include <test/fuzz/fuzz.h>
 7  #include <test/fuzz/FuzzedDataProvider.h>
 8  #include <util/strencodings.h>
 9  
10  #include <cassert>
11  #include <cstdint>
12  #include <string>
13  #include <vector>
14  
15  FUZZ_TARGET(bech32_random_decode)
16  {
17      auto limit = bech32::CharLimit::BECH32;
18      FuzzedDataProvider fdp(buffer.data(), buffer.size());
19      auto random_string = fdp.ConsumeRandomLengthString(limit + 1);
20      auto decoded = bech32::Decode(random_string, limit);
21  
22      if (decoded.hrp.empty()) {
23          assert(decoded.encoding == bech32::Encoding::INVALID);
24          assert(decoded.data.empty());
25      } else {
26          assert(decoded.encoding != bech32::Encoding::INVALID);
27          auto reencoded = bech32::Encode(decoded.encoding, decoded.hrp, decoded.data);
28          assert(CaseInsensitiveEqual(random_string, reencoded));
29      }
30  }
31  
32  // https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki and https://github.com/bitcoin/bips/blob/master/bip-0350.mediawiki
33  std::string GenerateRandomHRP(FuzzedDataProvider& fdp)
34  {
35      std::string hrp;
36      size_t length = fdp.ConsumeIntegralInRange<size_t>(1, 83);
37      for (size_t i = 0; i < length; ++i) {
38          // Generate lowercase ASCII characters in ([33-126] - ['A'-'Z']) range
39          char c = fdp.ConsumeBool()
40                   ? fdp.ConsumeIntegralInRange<char>(33, 'A' - 1)
41                   : fdp.ConsumeIntegralInRange<char>('Z' + 1, 126);
42          hrp += c;
43      }
44      return hrp;
45  }
46  
47  FUZZ_TARGET(bech32_roundtrip)
48  {
49      FuzzedDataProvider fdp(buffer.data(), buffer.size());
50      auto hrp = GenerateRandomHRP(fdp);
51  
52      auto input_chars = fdp.ConsumeBytes<unsigned char>(fdp.ConsumeIntegralInRange<size_t>(0, 82));
53      std::vector<uint8_t> converted_input;
54      ConvertBits<8, 5, true>([&](auto c) { converted_input.push_back(c); }, input_chars.begin(), input_chars.end());
55  
56      auto size = converted_input.size() + hrp.length() + std::string({bech32::SEPARATOR}).size() + bech32::CHECKSUM_SIZE;
57      if (size <= bech32::CharLimit::BECH32) {
58          for (auto encoding: {bech32::Encoding::BECH32, bech32::Encoding::BECH32M}) {
59              auto encoded = bech32::Encode(encoding, hrp, converted_input);
60              assert(!encoded.empty());
61  
62              const auto decoded = bech32::Decode(encoded);
63              assert(decoded.encoding == encoding);
64              assert(decoded.hrp == hrp);
65              assert(decoded.data == converted_input);
66          }
67      }
68  }