sha1_portable.cc revision 5821806d5e7f356e8fa4b058a389a808ea183019 
1// Copyright (c) 2011 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "base/sha1.h"
6
7#include <string.h>
8
9#include "base/basictypes.h"
10
11namespace base {
12
13// Implementation of SHA-1. Only handles data in byte-sized blocks,
14// which simplifies the code a fair bit.
15
16// Identifier names follow notation in FIPS PUB 180-3, where you'll
17// also find a description of the algorithm:
18// http://csrc.nist.gov/publications/fips/fips180-3/fips180-3_final.pdf
19
20// Usage example:
21//
22// SecureHashAlgorithm sha;
23// while(there is data to hash)
24//   sha.Update(moredata, size of data);
25// sha.Final();
26// memcpy(somewhere, sha.Digest(), 20);
27//
28// to reuse the instance of sha, call sha.Init();
29
30// TODO(jhawkins): Replace this implementation with a per-platform
31// implementation using each platform's crypto library.  See
32// http://crbug.com/47218
33
34class SecureHashAlgorithm {
35 public:
36  SecureHashAlgorithm() { Init(); }
37
38  static const int kDigestSizeBytes;
39
40  void Init();
41  void Update(const void* data, size_t nbytes);
42  void Final();
43
44  // 20 bytes of message digest.
45  const unsigned char* Digest() const {
46    return reinterpret_cast<const unsigned char*>(H);
47  }
48
49 private:
50  void Pad();
51  void Process();
52
53  uint32 A, B, C, D, E;
54
55  uint32 H[5];
56
57  union {
58    uint32 W[80];
59    uint8 M[64];
60  };
61
62  uint32 cursor;
63  uint32 l;
64};
65
66static inline uint32 f(uint32 t, uint32 B, uint32 C, uint32 D) {
67  if (t < 20) {
68    return (B & C) | ((~B) & D);
69  } else if (t < 40) {
70    return B ^ C ^ D;
71  } else if (t < 60) {
72    return (B & C) | (B & D) | (C & D);
73  } else {
74    return B ^ C ^ D;
75  }
76}
77
78static inline uint32 S(uint32 n, uint32 X) {
79  return (X << n) | (X >> (32-n));
80}
81
82static inline uint32 K(uint32 t) {
83  if (t < 20) {
84    return 0x5a827999;
85  } else if (t < 40) {
86    return 0x6ed9eba1;
87  } else if (t < 60) {
88    return 0x8f1bbcdc;
89  } else {
90    return 0xca62c1d6;
91  }
92}
93
94static inline void swapends(uint32* t) {
95  *t = ((*t & 0xff000000) >> 24) |
96       ((*t & 0xff0000) >> 8) |
97       ((*t & 0xff00) << 8) |
98       ((*t & 0xff) << 24);
99}
100
101const int SecureHashAlgorithm::kDigestSizeBytes = 20;
102
103void SecureHashAlgorithm::Init() {
104  A = 0;
105  B = 0;
106  C = 0;
107  D = 0;
108  E = 0;
109  cursor = 0;
110  l = 0;
111  H[0] = 0x67452301;
112  H[1] = 0xefcdab89;
113  H[2] = 0x98badcfe;
114  H[3] = 0x10325476;
115  H[4] = 0xc3d2e1f0;
116}
117
118void SecureHashAlgorithm::Final() {
119  Pad();
120  Process();
121
122  for (int t = 0; t < 5; ++t)
123    swapends(&H[t]);
124}
125
126void SecureHashAlgorithm::Update(const void* data, size_t nbytes) {
127  const uint8* d = reinterpret_cast<const uint8*>(data);
128  while (nbytes--) {
129    M[cursor++] = *d++;
130    if (cursor >= 64)
131      Process();
132    l += 8;
133  }
134}
135
136void SecureHashAlgorithm::Pad() {
137  M[cursor++] = 0x80;
138
139  if (cursor > 64-8) {
140    // pad out to next block
141    while (cursor < 64)
142      M[cursor++] = 0;
143
144    Process();
145  }
146
147  while (cursor < 64-4)
148    M[cursor++] = 0;
149
150  M[64-4] = (l & 0xff000000) >> 24;
151  M[64-3] = (l & 0xff0000) >> 16;
152  M[64-2] = (l & 0xff00) >> 8;
153  M[64-1] = (l & 0xff);
154}
155
156void SecureHashAlgorithm::Process() {
157  uint32 t;
158
159  // Each a...e corresponds to a section in the FIPS 180-3 algorithm.
160
161  // a.
162  //
163  // W and M are in a union, so no need to memcpy.
164  // memcpy(W, M, sizeof(M));
165  for (t = 0; t < 16; ++t)
166    swapends(&W[t]);
167
168  // b.
169  for (t = 16; t < 80; ++t)
170    W[t] = S(1, W[t - 3] ^ W[t - 8] ^ W[t - 14] ^ W[t - 16]);
171
172  // c.
173  A = H[0];
174  B = H[1];
175  C = H[2];
176  D = H[3];
177  E = H[4];
178
179  // d.
180  for (t = 0; t < 80; ++t) {
181    uint32 TEMP = S(5, A) + f(t, B, C, D) + E + W[t] + K(t);
182    E = D;
183    D = C;
184    C = S(30, B);
185    B = A;
186    A = TEMP;
187  }
188
189  // e.
190  H[0] += A;
191  H[1] += B;
192  H[2] += C;
193  H[3] += D;
194  H[4] += E;
195
196  cursor = 0;
197}
198
199std::string SHA1HashString(const std::string& str) {
200  char hash[SecureHashAlgorithm::kDigestSizeBytes];
201  SHA1HashBytes(reinterpret_cast<const unsigned char*>(str.c_str()),
202                str.length(), reinterpret_cast<unsigned char*>(hash));
203  return std::string(hash, SecureHashAlgorithm::kDigestSizeBytes);
204}
205
206void SHA1HashBytes(const unsigned char* data, size_t len,
207                   unsigned char* hash) {
208  SecureHashAlgorithm sha;
209  sha.Update(data, len);
210  sha.Final();
211
212  memcpy(hash, sha.Digest(), SecureHashAlgorithm::kDigestSizeBytes);
213}
214
215}  // namespace base
216