summaryrefslogtreecommitdiffstats
path: root/mfbt/SHA1.cpp
blob: 432c6eee2df56c12e6a40114717ab527294e418e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "mozilla/Assertions.h"
#include "mozilla/EndianUtils.h"
#include "mozilla/SHA1.h"

#include <string.h>

using mozilla::NativeEndian;
using mozilla::SHA1Sum;

static inline uint32_t
SHA_ROTL(uint32_t aT, uint32_t aN)
{
  MOZ_ASSERT(aN < 32);
  return (aT << aN) | (aT >> (32 - aN));
}

static void
shaCompress(volatile unsigned* aX, const uint32_t* aBuf);

#define SHA_F1(X, Y, Z) ((((Y) ^ (Z)) & (X)) ^ (Z))
#define SHA_F2(X, Y, Z) ((X) ^ (Y) ^ (Z))
#define SHA_F3(X, Y, Z) (((X) & (Y)) | ((Z) & ((X) | (Y))))
#define SHA_F4(X, Y, Z) ((X) ^ (Y) ^ (Z))

#define SHA_MIX(n, a, b, c)    XW(n) = SHA_ROTL(XW(a) ^ XW(b) ^ XW(c) ^XW(n), 1)

SHA1Sum::SHA1Sum()
  : mSize(0), mDone(false)
{
  // Initialize H with constants from FIPS180-1.
  mH[0] = 0x67452301L;
  mH[1] = 0xefcdab89L;
  mH[2] = 0x98badcfeL;
  mH[3] = 0x10325476L;
  mH[4] = 0xc3d2e1f0L;
}

/*
 * Explanation of H array and index values:
 *
 * The context's H array is actually the concatenation of two arrays
 * defined by SHA1, the H array of state variables (5 elements),
 * and the W array of intermediate values, of which there are 16 elements.
 * The W array starts at H[5], that is W[0] is H[5].
 * Although these values are defined as 32-bit values, we use 64-bit
 * variables to hold them because the AMD64 stores 64 bit values in
 * memory MUCH faster than it stores any smaller values.
 *
 * Rather than passing the context structure to shaCompress, we pass
 * this combined array of H and W values.  We do not pass the address
 * of the first element of this array, but rather pass the address of an
 * element in the middle of the array, element X.  Presently X[0] is H[11].
 * So we pass the address of H[11] as the address of array X to shaCompress.
 * Then shaCompress accesses the members of the array using positive AND
 * negative indexes.
 *
 * Pictorially: (each element is 8 bytes)
 * H | H0 H1 H2 H3 H4 W0 W1 W2 W3 W4 W5 W6 W7 W8 W9 Wa Wb Wc Wd We Wf |
 * X |-11-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 X0 X1 X2 X3 X4 X5 X6 X7 X8 X9 |
 *
 * The byte offset from X[0] to any member of H and W is always
 * representable in a signed 8-bit value, which will be encoded
 * as a single byte offset in the X86-64 instruction set.
 * If we didn't pass the address of H[11], and instead passed the
 * address of H[0], the offsets to elements H[16] and above would be
 * greater than 127, not representable in a signed 8-bit value, and the
 * x86-64 instruction set would encode every such offset as a 32-bit
 * signed number in each instruction that accessed element H[16] or
 * higher.  This results in much bigger and slower code.
 */
#define H2X 11 /* X[0] is H[11], and H[0] is X[-11] */
#define W2X  6 /* X[0] is W[6],  and W[0] is X[-6]  */

/*
 *  SHA: Add data to context.
 */
void
SHA1Sum::update(const void* aData, uint32_t aLen)
{
  MOZ_ASSERT(!mDone, "SHA1Sum can only be used to compute a single hash.");

  const uint8_t* data = static_cast<const uint8_t*>(aData);

  if (aLen == 0) {
    return;
  }

  /* Accumulate the byte count. */
  unsigned int lenB = static_cast<unsigned int>(mSize) & 63U;

  mSize += aLen;

  /* Read the data into W and process blocks as they get full. */
  unsigned int togo;
  if (lenB > 0) {
    togo = 64U - lenB;
    if (aLen < togo) {
      togo = aLen;
    }
    memcpy(mU.mB + lenB, data, togo);
    aLen -= togo;
    data += togo;
    lenB = (lenB + togo) & 63U;
    if (!lenB) {
      shaCompress(&mH[H2X], mU.mW);
    }
  }

  while (aLen >= 64U) {
    aLen -= 64U;
    shaCompress(&mH[H2X], reinterpret_cast<const uint32_t*>(data));
    data += 64U;
  }

  if (aLen > 0) {
    memcpy(mU.mB, data, aLen);
  }
}


/*
 *  SHA: Generate hash value
 */
void
SHA1Sum::finish(SHA1Sum::Hash& aHashOut)
{
  MOZ_ASSERT(!mDone, "SHA1Sum can only be used to compute a single hash.");

  uint64_t size = mSize;
  uint32_t lenB = uint32_t(size) & 63;

  static const uint8_t bulk_pad[64] =
    { 0x80,0,0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 };

  /* Pad with a binary 1 (e.g. 0x80), then zeroes, then length in bits. */
  update(bulk_pad, (((55 + 64) - lenB) & 63) + 1);
  MOZ_ASSERT((uint32_t(mSize) & 63) == 56);

  /* Convert size from bytes to bits. */
  size <<= 3;
  mU.mW[14] = NativeEndian::swapToBigEndian(uint32_t(size >> 32));
  mU.mW[15] = NativeEndian::swapToBigEndian(uint32_t(size));
  shaCompress(&mH[H2X], mU.mW);

  /* Output hash. */
  mU.mW[0] = NativeEndian::swapToBigEndian(mH[0]);
  mU.mW[1] = NativeEndian::swapToBigEndian(mH[1]);
  mU.mW[2] = NativeEndian::swapToBigEndian(mH[2]);
  mU.mW[3] = NativeEndian::swapToBigEndian(mH[3]);
  mU.mW[4] = NativeEndian::swapToBigEndian(mH[4]);
  memcpy(aHashOut, mU.mW, 20);
  mDone = true;
}

/*
 *  SHA: Compression function, unrolled.
 *
 * Some operations in shaCompress are done as 5 groups of 16 operations.
 * Others are done as 4 groups of 20 operations.
 * The code below shows that structure.
 *
 * The functions that compute the new values of the 5 state variables
 * A-E are done in 4 groups of 20 operations (or you may also think
 * of them as being done in 16 groups of 5 operations).  They are
 * done by the SHA_RNDx macros below, in the right column.
 *
 * The functions that set the 16 values of the W array are done in
 * 5 groups of 16 operations.  The first group is done by the
 * LOAD macros below, the latter 4 groups are done by SHA_MIX below,
 * in the left column.
 *
 * gcc's optimizer observes that each member of the W array is assigned
 * a value 5 times in this code.  It reduces the number of store
 * operations done to the W array in the context (that is, in the X array)
 * by creating a W array on the stack, and storing the W values there for
 * the first 4 groups of operations on W, and storing the values in the
 * context's W array only in the fifth group.  This is undesirable.
 * It is MUCH bigger code than simply using the context's W array, because
 * all the offsets to the W array in the stack are 32-bit signed offsets,
 * and it is no faster than storing the values in the context's W array.
 *
 * The original code for sha_fast.c prevented this creation of a separate
 * W array in the stack by creating a W array of 80 members, each of
 * whose elements is assigned only once. It also separated the computations
 * of the W array values and the computations of the values for the 5
 * state variables into two separate passes, W's, then A-E's so that the
 * second pass could be done all in registers (except for accessing the W
 * array) on machines with fewer registers.  The method is suboptimal
 * for machines with enough registers to do it all in one pass, and it
 * necessitates using many instructions with 32-bit offsets.
 *
 * This code eliminates the separate W array on the stack by a completely
 * different means: by declaring the X array volatile.  This prevents
 * the optimizer from trying to reduce the use of the X array by the
 * creation of a MORE expensive W array on the stack. The result is
 * that all instructions use signed 8-bit offsets and not 32-bit offsets.
 *
 * The combination of this code and the -O3 optimizer flag on GCC 3.4.3
 * results in code that is 3 times faster than the previous NSS sha_fast
 * code on AMD64.
 */
static void
shaCompress(volatile unsigned* aX, const uint32_t* aBuf)
{
  unsigned A, B, C, D, E;

#define XH(n) aX[n - H2X]
#define XW(n) aX[n - W2X]

#define K0 0x5a827999L
#define K1 0x6ed9eba1L
#define K2 0x8f1bbcdcL
#define K3 0xca62c1d6L

#define SHA_RND1(a, b, c, d, e, n) \
  a = SHA_ROTL(b, 5) + SHA_F1(c, d, e) + a + XW(n) + K0; c = SHA_ROTL(c, 30)
#define SHA_RND2(a, b, c, d, e, n) \
  a = SHA_ROTL(b, 5) + SHA_F2(c, d, e) + a + XW(n) + K1; c = SHA_ROTL(c, 30)
#define SHA_RND3(a, b, c, d, e, n) \
  a = SHA_ROTL(b, 5) + SHA_F3(c, d, e) + a + XW(n) + K2; c = SHA_ROTL(c, 30)
#define SHA_RND4(a, b, c, d, e, n) \
  a = SHA_ROTL(b ,5) + SHA_F4(c, d, e) + a + XW(n) + K3; c = SHA_ROTL(c, 30)

#define LOAD(n) XW(n) = NativeEndian::swapToBigEndian(aBuf[n])

  A = XH(0);
  B = XH(1);
  C = XH(2);
  D = XH(3);
  E = XH(4);

  LOAD(0);		   SHA_RND1(E,A,B,C,D, 0);
  LOAD(1);		   SHA_RND1(D,E,A,B,C, 1);
  LOAD(2);		   SHA_RND1(C,D,E,A,B, 2);
  LOAD(3);		   SHA_RND1(B,C,D,E,A, 3);
  LOAD(4);		   SHA_RND1(A,B,C,D,E, 4);
  LOAD(5);		   SHA_RND1(E,A,B,C,D, 5);
  LOAD(6);		   SHA_RND1(D,E,A,B,C, 6);
  LOAD(7);		   SHA_RND1(C,D,E,A,B, 7);
  LOAD(8);		   SHA_RND1(B,C,D,E,A, 8);
  LOAD(9);		   SHA_RND1(A,B,C,D,E, 9);
  LOAD(10);		   SHA_RND1(E,A,B,C,D,10);
  LOAD(11);		   SHA_RND1(D,E,A,B,C,11);
  LOAD(12);		   SHA_RND1(C,D,E,A,B,12);
  LOAD(13);		   SHA_RND1(B,C,D,E,A,13);
  LOAD(14);		   SHA_RND1(A,B,C,D,E,14);
  LOAD(15);		   SHA_RND1(E,A,B,C,D,15);

  SHA_MIX( 0, 13,  8,  2); SHA_RND1(D,E,A,B,C, 0);
  SHA_MIX( 1, 14,  9,  3); SHA_RND1(C,D,E,A,B, 1);
  SHA_MIX( 2, 15, 10,  4); SHA_RND1(B,C,D,E,A, 2);
  SHA_MIX( 3,  0, 11,  5); SHA_RND1(A,B,C,D,E, 3);

  SHA_MIX( 4,  1, 12,  6); SHA_RND2(E,A,B,C,D, 4);
  SHA_MIX( 5,  2, 13,  7); SHA_RND2(D,E,A,B,C, 5);
  SHA_MIX( 6,  3, 14,  8); SHA_RND2(C,D,E,A,B, 6);
  SHA_MIX( 7,  4, 15,  9); SHA_RND2(B,C,D,E,A, 7);
  SHA_MIX( 8,  5,  0, 10); SHA_RND2(A,B,C,D,E, 8);
  SHA_MIX( 9,  6,  1, 11); SHA_RND2(E,A,B,C,D, 9);
  SHA_MIX(10,  7,  2, 12); SHA_RND2(D,E,A,B,C,10);
  SHA_MIX(11,  8,  3, 13); SHA_RND2(C,D,E,A,B,11);
  SHA_MIX(12,  9,  4, 14); SHA_RND2(B,C,D,E,A,12);
  SHA_MIX(13, 10,  5, 15); SHA_RND2(A,B,C,D,E,13);
  SHA_MIX(14, 11,  6,  0); SHA_RND2(E,A,B,C,D,14);
  SHA_MIX(15, 12,  7,  1); SHA_RND2(D,E,A,B,C,15);

  SHA_MIX( 0, 13,  8,  2); SHA_RND2(C,D,E,A,B, 0);
  SHA_MIX( 1, 14,  9,  3); SHA_RND2(B,C,D,E,A, 1);
  SHA_MIX( 2, 15, 10,  4); SHA_RND2(A,B,C,D,E, 2);
  SHA_MIX( 3,  0, 11,  5); SHA_RND2(E,A,B,C,D, 3);
  SHA_MIX( 4,  1, 12,  6); SHA_RND2(D,E,A,B,C, 4);
  SHA_MIX( 5,  2, 13,  7); SHA_RND2(C,D,E,A,B, 5);
  SHA_MIX( 6,  3, 14,  8); SHA_RND2(B,C,D,E,A, 6);
  SHA_MIX( 7,  4, 15,  9); SHA_RND2(A,B,C,D,E, 7);

  SHA_MIX( 8,  5,  0, 10); SHA_RND3(E,A,B,C,D, 8);
  SHA_MIX( 9,  6,  1, 11); SHA_RND3(D,E,A,B,C, 9);
  SHA_MIX(10,  7,  2, 12); SHA_RND3(C,D,E,A,B,10);
  SHA_MIX(11,  8,  3, 13); SHA_RND3(B,C,D,E,A,11);
  SHA_MIX(12,  9,  4, 14); SHA_RND3(A,B,C,D,E,12);
  SHA_MIX(13, 10,  5, 15); SHA_RND3(E,A,B,C,D,13);
  SHA_MIX(14, 11,  6,  0); SHA_RND3(D,E,A,B,C,14);
  SHA_MIX(15, 12,  7,  1); SHA_RND3(C,D,E,A,B,15);

  SHA_MIX( 0, 13,  8,  2); SHA_RND3(B,C,D,E,A, 0);
  SHA_MIX( 1, 14,  9,  3); SHA_RND3(A,B,C,D,E, 1);
  SHA_MIX( 2, 15, 10,  4); SHA_RND3(E,A,B,C,D, 2);
  SHA_MIX( 3,  0, 11,  5); SHA_RND3(D,E,A,B,C, 3);
  SHA_MIX( 4,  1, 12,  6); SHA_RND3(C,D,E,A,B, 4);
  SHA_MIX( 5,  2, 13,  7); SHA_RND3(B,C,D,E,A, 5);
  SHA_MIX( 6,  3, 14,  8); SHA_RND3(A,B,C,D,E, 6);
  SHA_MIX( 7,  4, 15,  9); SHA_RND3(E,A,B,C,D, 7);
  SHA_MIX( 8,  5,  0, 10); SHA_RND3(D,E,A,B,C, 8);
  SHA_MIX( 9,  6,  1, 11); SHA_RND3(C,D,E,A,B, 9);
  SHA_MIX(10,  7,  2, 12); SHA_RND3(B,C,D,E,A,10);
  SHA_MIX(11,  8,  3, 13); SHA_RND3(A,B,C,D,E,11);

  SHA_MIX(12,  9,  4, 14); SHA_RND4(E,A,B,C,D,12);
  SHA_MIX(13, 10,  5, 15); SHA_RND4(D,E,A,B,C,13);
  SHA_MIX(14, 11,  6,  0); SHA_RND4(C,D,E,A,B,14);
  SHA_MIX(15, 12,  7,  1); SHA_RND4(B,C,D,E,A,15);

  SHA_MIX( 0, 13,  8,  2); SHA_RND4(A,B,C,D,E, 0);
  SHA_MIX( 1, 14,  9,  3); SHA_RND4(E,A,B,C,D, 1);
  SHA_MIX( 2, 15, 10,  4); SHA_RND4(D,E,A,B,C, 2);
  SHA_MIX( 3,  0, 11,  5); SHA_RND4(C,D,E,A,B, 3);
  SHA_MIX( 4,  1, 12,  6); SHA_RND4(B,C,D,E,A, 4);
  SHA_MIX( 5,  2, 13,  7); SHA_RND4(A,B,C,D,E, 5);
  SHA_MIX( 6,  3, 14,  8); SHA_RND4(E,A,B,C,D, 6);
  SHA_MIX( 7,  4, 15,  9); SHA_RND4(D,E,A,B,C, 7);
  SHA_MIX( 8,  5,  0, 10); SHA_RND4(C,D,E,A,B, 8);
  SHA_MIX( 9,  6,  1, 11); SHA_RND4(B,C,D,E,A, 9);
  SHA_MIX(10,  7,  2, 12); SHA_RND4(A,B,C,D,E,10);
  SHA_MIX(11,  8,  3, 13); SHA_RND4(E,A,B,C,D,11);
  SHA_MIX(12,  9,  4, 14); SHA_RND4(D,E,A,B,C,12);
  SHA_MIX(13, 10,  5, 15); SHA_RND4(C,D,E,A,B,13);
  SHA_MIX(14, 11,  6,  0); SHA_RND4(B,C,D,E,A,14);
  SHA_MIX(15, 12,  7,  1); SHA_RND4(A,B,C,D,E,15);

  XH(0) += A;
  XH(1) += B;
  XH(2) += C;
  XH(3) += D;
  XH(4) += E;
}