1//====- SHA256.cpp - SHA256 implementation ---*- C++ -* ======//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8/*
9 *  The SHA-256 Secure Hash Standard was published by NIST in 2002.
10 *
11 *  http://csrc.nist.gov/publications/fips/fips180-2/fips180-2.pdf
12 *
13 *   The implementation is based on nacl's sha256 implementation [0] and LLVM's
14 *  pre-exsiting SHA1 code [1].
15 *
16 *   [0] https://hyperelliptic.org/nacl/nacl-20110221.tar.bz2 (public domain
17 *       code)
18 *   [1] llvm/lib/Support/SHA1.{h,cpp}
19 */
20//===----------------------------------------------------------------------===//
21
22#ifndef LLVM_SUPPORT_SHA256_H
23#define LLVM_SUPPORT_SHA256_H
24
25#include <array>
26#include <cstdint>
27
28namespace llvm {
29
30template <typename T> class ArrayRef;
31class StringRef;
32
33class SHA256 {
34public:
35  explicit SHA256() { init(); }
36
37  /// Reinitialize the internal state
38  void init();
39
40  /// Digest more data.
41  void update(ArrayRef<uint8_t> Data);
42
43  /// Digest more data.
44  void update(StringRef Str);
45
46  /// Return the current raw 256-bits SHA256 for the digested
47  /// data since the last call to init(). This call will add data to the
48  /// internal state and as such is not suited for getting an intermediate
49  /// result (see result()).
50  std::array<uint8_t, 32> final();
51
52  /// Return the current raw 256-bits SHA256 for the digested
53  /// data since the last call to init(). This is suitable for getting the
54  /// SHA256 at any time without invalidating the internal state so that more
55  /// calls can be made into update.
56  std::array<uint8_t, 32> result();
57
58  /// Returns a raw 256-bit SHA256 hash for the given data.
59  static std::array<uint8_t, 32> hash(ArrayRef<uint8_t> Data);
60
61private:
62  /// Define some constants.
63  /// "static constexpr" would be cleaner but MSVC does not support it yet.
64  enum { BLOCK_LENGTH = 64 };
65  enum { HASH_LENGTH = 32 };
66
67  // Internal State
68  struct {
69    union {
70      uint8_t C[BLOCK_LENGTH];
71      uint32_t L[BLOCK_LENGTH / 4];
72    } Buffer;
73    uint32_t State[HASH_LENGTH / 4];
74    uint32_t ByteCount;
75    uint8_t BufferOffset;
76  } InternalState;
77
78  // Helper
79  void writebyte(uint8_t data);
80  void hashBlock();
81  void addUncounted(uint8_t data);
82  void pad();
83
84  void final(std::array<uint32_t, HASH_LENGTH / 4> &HashResult);
85};
86
87} // namespace llvm
88
89#endif // LLVM_SUPPORT_SHA256_H
90