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1 : /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2 : /* vim: set ts=8 sts=2 et sw=2 tw=80: */
3 : /* This Source Code Form is subject to the terms of the Mozilla Public
4 : * License, v. 2.0. If a copy of the MPL was not distributed with this
5 : * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6 :
7 : #include "mozilla/Assertions.h"
8 : #include "mozilla/EndianUtils.h"
9 : #include "mozilla/SHA1.h"
10 :
11 : #include <string.h>
12 :
13 : using mozilla::NativeEndian;
14 : using mozilla::SHA1Sum;
15 :
16 : static inline uint32_t
17 5376 : SHA_ROTL(uint32_t aT, uint32_t aN)
18 : {
19 5376 : MOZ_ASSERT(aN < 32);
20 5376 : return (aT << aN) | (aT >> (32 - aN));
21 : }
22 :
23 : static void
24 : shaCompress(volatile unsigned* aX, const uint32_t* aBuf);
25 :
26 : #define SHA_F1(X, Y, Z) ((((Y) ^ (Z)) & (X)) ^ (Z))
27 : #define SHA_F2(X, Y, Z) ((X) ^ (Y) ^ (Z))
28 : #define SHA_F3(X, Y, Z) (((X) & (Y)) | ((Z) & ((X) | (Y))))
29 : #define SHA_F4(X, Y, Z) ((X) ^ (Y) ^ (Z))
30 :
31 : #define SHA_MIX(n, a, b, c) XW(n) = SHA_ROTL(XW(a) ^ XW(b) ^ XW(c) ^XW(n), 1)
32 :
33 22 : SHA1Sum::SHA1Sum()
34 22 : : mSize(0), mDone(false)
35 : {
36 : // Initialize H with constants from FIPS180-1.
37 22 : mH[0] = 0x67452301L;
38 22 : mH[1] = 0xefcdab89L;
39 22 : mH[2] = 0x98badcfeL;
40 22 : mH[3] = 0x10325476L;
41 22 : mH[4] = 0xc3d2e1f0L;
42 22 : }
43 :
44 : /*
45 : * Explanation of H array and index values:
46 : *
47 : * The context's H array is actually the concatenation of two arrays
48 : * defined by SHA1, the H array of state variables (5 elements),
49 : * and the W array of intermediate values, of which there are 16 elements.
50 : * The W array starts at H[5], that is W[0] is H[5].
51 : * Although these values are defined as 32-bit values, we use 64-bit
52 : * variables to hold them because the AMD64 stores 64 bit values in
53 : * memory MUCH faster than it stores any smaller values.
54 : *
55 : * Rather than passing the context structure to shaCompress, we pass
56 : * this combined array of H and W values. We do not pass the address
57 : * of the first element of this array, but rather pass the address of an
58 : * element in the middle of the array, element X. Presently X[0] is H[11].
59 : * So we pass the address of H[11] as the address of array X to shaCompress.
60 : * Then shaCompress accesses the members of the array using positive AND
61 : * negative indexes.
62 : *
63 : * Pictorially: (each element is 8 bytes)
64 : * H | H0 H1 H2 H3 H4 W0 W1 W2 W3 W4 W5 W6 W7 W8 W9 Wa Wb Wc Wd We Wf |
65 : * X |-11-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 X0 X1 X2 X3 X4 X5 X6 X7 X8 X9 |
66 : *
67 : * The byte offset from X[0] to any member of H and W is always
68 : * representable in a signed 8-bit value, which will be encoded
69 : * as a single byte offset in the X86-64 instruction set.
70 : * If we didn't pass the address of H[11], and instead passed the
71 : * address of H[0], the offsets to elements H[16] and above would be
72 : * greater than 127, not representable in a signed 8-bit value, and the
73 : * x86-64 instruction set would encode every such offset as a 32-bit
74 : * signed number in each instruction that accessed element H[16] or
75 : * higher. This results in much bigger and slower code.
76 : */
77 : #define H2X 11 /* X[0] is H[11], and H[0] is X[-11] */
78 : #define W2X 6 /* X[0] is W[6], and W[0] is X[-6] */
79 :
80 : /*
81 : * SHA: Add data to context.
82 : */
83 : void
84 44 : SHA1Sum::update(const void* aData, uint32_t aLen)
85 : {
86 44 : MOZ_ASSERT(!mDone, "SHA1Sum can only be used to compute a single hash.");
87 :
88 44 : const uint8_t* data = static_cast<const uint8_t*>(aData);
89 :
90 44 : if (aLen == 0) {
91 5 : return;
92 : }
93 :
94 : /* Accumulate the byte count. */
95 39 : unsigned int lenB = static_cast<unsigned int>(mSize) & 63U;
96 :
97 39 : mSize += aLen;
98 :
99 : /* Read the data into W and process blocks as they get full. */
100 : unsigned int togo;
101 39 : if (lenB > 0) {
102 17 : togo = 64U - lenB;
103 17 : if (aLen < togo) {
104 16 : togo = aLen;
105 : }
106 17 : memcpy(mU.mB + lenB, data, togo);
107 17 : aLen -= togo;
108 17 : data += togo;
109 17 : lenB = (lenB + togo) & 63U;
110 17 : if (!lenB) {
111 1 : shaCompress(&mH[H2X], mU.mW);
112 : }
113 : }
114 :
115 41 : while (aLen >= 64U) {
116 1 : aLen -= 64U;
117 1 : shaCompress(&mH[H2X], reinterpret_cast<const uint32_t*>(data));
118 1 : data += 64U;
119 : }
120 :
121 39 : if (aLen > 0) {
122 23 : memcpy(mU.mB, data, aLen);
123 : }
124 : }
125 :
126 :
127 : /*
128 : * SHA: Generate hash value
129 : */
130 : void
131 22 : SHA1Sum::finish(SHA1Sum::Hash& aHashOut)
132 : {
133 22 : MOZ_ASSERT(!mDone, "SHA1Sum can only be used to compute a single hash.");
134 :
135 22 : uint64_t size = mSize;
136 22 : uint32_t lenB = uint32_t(size) & 63;
137 :
138 : static const uint8_t bulk_pad[64] =
139 : { 0x80,0,0,0,0,0,0,0,0,0,
140 : 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,
141 : 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 };
142 :
143 : /* Pad with a binary 1 (e.g. 0x80), then zeroes, then length in bits. */
144 22 : update(bulk_pad, (((55 + 64) - lenB) & 63) + 1);
145 22 : MOZ_ASSERT((uint32_t(mSize) & 63) == 56);
146 :
147 : /* Convert size from bytes to bits. */
148 22 : size <<= 3;
149 22 : mU.mW[14] = NativeEndian::swapToBigEndian(uint32_t(size >> 32));
150 22 : mU.mW[15] = NativeEndian::swapToBigEndian(uint32_t(size));
151 22 : shaCompress(&mH[H2X], mU.mW);
152 :
153 : /* Output hash. */
154 22 : mU.mW[0] = NativeEndian::swapToBigEndian(mH[0]);
155 22 : mU.mW[1] = NativeEndian::swapToBigEndian(mH[1]);
156 22 : mU.mW[2] = NativeEndian::swapToBigEndian(mH[2]);
157 22 : mU.mW[3] = NativeEndian::swapToBigEndian(mH[3]);
158 22 : mU.mW[4] = NativeEndian::swapToBigEndian(mH[4]);
159 22 : memcpy(aHashOut, mU.mW, 20);
160 22 : mDone = true;
161 22 : }
162 :
163 : /*
164 : * SHA: Compression function, unrolled.
165 : *
166 : * Some operations in shaCompress are done as 5 groups of 16 operations.
167 : * Others are done as 4 groups of 20 operations.
168 : * The code below shows that structure.
169 : *
170 : * The functions that compute the new values of the 5 state variables
171 : * A-E are done in 4 groups of 20 operations (or you may also think
172 : * of them as being done in 16 groups of 5 operations). They are
173 : * done by the SHA_RNDx macros below, in the right column.
174 : *
175 : * The functions that set the 16 values of the W array are done in
176 : * 5 groups of 16 operations. The first group is done by the
177 : * LOAD macros below, the latter 4 groups are done by SHA_MIX below,
178 : * in the left column.
179 : *
180 : * gcc's optimizer observes that each member of the W array is assigned
181 : * a value 5 times in this code. It reduces the number of store
182 : * operations done to the W array in the context (that is, in the X array)
183 : * by creating a W array on the stack, and storing the W values there for
184 : * the first 4 groups of operations on W, and storing the values in the
185 : * context's W array only in the fifth group. This is undesirable.
186 : * It is MUCH bigger code than simply using the context's W array, because
187 : * all the offsets to the W array in the stack are 32-bit signed offsets,
188 : * and it is no faster than storing the values in the context's W array.
189 : *
190 : * The original code for sha_fast.c prevented this creation of a separate
191 : * W array in the stack by creating a W array of 80 members, each of
192 : * whose elements is assigned only once. It also separated the computations
193 : * of the W array values and the computations of the values for the 5
194 : * state variables into two separate passes, W's, then A-E's so that the
195 : * second pass could be done all in registers (except for accessing the W
196 : * array) on machines with fewer registers. The method is suboptimal
197 : * for machines with enough registers to do it all in one pass, and it
198 : * necessitates using many instructions with 32-bit offsets.
199 : *
200 : * This code eliminates the separate W array on the stack by a completely
201 : * different means: by declaring the X array volatile. This prevents
202 : * the optimizer from trying to reduce the use of the X array by the
203 : * creation of a MORE expensive W array on the stack. The result is
204 : * that all instructions use signed 8-bit offsets and not 32-bit offsets.
205 : *
206 : * The combination of this code and the -O3 optimizer flag on GCC 3.4.3
207 : * results in code that is 3 times faster than the previous NSS sha_fast
208 : * code on AMD64.
209 : */
210 : static void
211 24 : shaCompress(volatile unsigned* aX, const uint32_t* aBuf)
212 : {
213 : unsigned A, B, C, D, E;
214 :
215 : #define XH(n) aX[n - H2X]
216 : #define XW(n) aX[n - W2X]
217 :
218 : #define K0 0x5a827999L
219 : #define K1 0x6ed9eba1L
220 : #define K2 0x8f1bbcdcL
221 : #define K3 0xca62c1d6L
222 :
223 : #define SHA_RND1(a, b, c, d, e, n) \
224 : a = SHA_ROTL(b, 5) + SHA_F1(c, d, e) + a + XW(n) + K0; c = SHA_ROTL(c, 30)
225 : #define SHA_RND2(a, b, c, d, e, n) \
226 : a = SHA_ROTL(b, 5) + SHA_F2(c, d, e) + a + XW(n) + K1; c = SHA_ROTL(c, 30)
227 : #define SHA_RND3(a, b, c, d, e, n) \
228 : a = SHA_ROTL(b, 5) + SHA_F3(c, d, e) + a + XW(n) + K2; c = SHA_ROTL(c, 30)
229 : #define SHA_RND4(a, b, c, d, e, n) \
230 : a = SHA_ROTL(b ,5) + SHA_F4(c, d, e) + a + XW(n) + K3; c = SHA_ROTL(c, 30)
231 :
232 : #define LOAD(n) XW(n) = NativeEndian::swapToBigEndian(aBuf[n])
233 :
234 24 : A = XH(0);
235 24 : B = XH(1);
236 24 : C = XH(2);
237 24 : D = XH(3);
238 24 : E = XH(4);
239 :
240 24 : LOAD(0); SHA_RND1(E,A,B,C,D, 0);
241 24 : LOAD(1); SHA_RND1(D,E,A,B,C, 1);
242 24 : LOAD(2); SHA_RND1(C,D,E,A,B, 2);
243 24 : LOAD(3); SHA_RND1(B,C,D,E,A, 3);
244 24 : LOAD(4); SHA_RND1(A,B,C,D,E, 4);
245 24 : LOAD(5); SHA_RND1(E,A,B,C,D, 5);
246 24 : LOAD(6); SHA_RND1(D,E,A,B,C, 6);
247 24 : LOAD(7); SHA_RND1(C,D,E,A,B, 7);
248 24 : LOAD(8); SHA_RND1(B,C,D,E,A, 8);
249 24 : LOAD(9); SHA_RND1(A,B,C,D,E, 9);
250 24 : LOAD(10); SHA_RND1(E,A,B,C,D,10);
251 24 : LOAD(11); SHA_RND1(D,E,A,B,C,11);
252 24 : LOAD(12); SHA_RND1(C,D,E,A,B,12);
253 24 : LOAD(13); SHA_RND1(B,C,D,E,A,13);
254 24 : LOAD(14); SHA_RND1(A,B,C,D,E,14);
255 24 : LOAD(15); SHA_RND1(E,A,B,C,D,15);
256 :
257 24 : SHA_MIX( 0, 13, 8, 2); SHA_RND1(D,E,A,B,C, 0);
258 24 : SHA_MIX( 1, 14, 9, 3); SHA_RND1(C,D,E,A,B, 1);
259 24 : SHA_MIX( 2, 15, 10, 4); SHA_RND1(B,C,D,E,A, 2);
260 24 : SHA_MIX( 3, 0, 11, 5); SHA_RND1(A,B,C,D,E, 3);
261 :
262 24 : SHA_MIX( 4, 1, 12, 6); SHA_RND2(E,A,B,C,D, 4);
263 24 : SHA_MIX( 5, 2, 13, 7); SHA_RND2(D,E,A,B,C, 5);
264 24 : SHA_MIX( 6, 3, 14, 8); SHA_RND2(C,D,E,A,B, 6);
265 24 : SHA_MIX( 7, 4, 15, 9); SHA_RND2(B,C,D,E,A, 7);
266 24 : SHA_MIX( 8, 5, 0, 10); SHA_RND2(A,B,C,D,E, 8);
267 24 : SHA_MIX( 9, 6, 1, 11); SHA_RND2(E,A,B,C,D, 9);
268 24 : SHA_MIX(10, 7, 2, 12); SHA_RND2(D,E,A,B,C,10);
269 24 : SHA_MIX(11, 8, 3, 13); SHA_RND2(C,D,E,A,B,11);
270 24 : SHA_MIX(12, 9, 4, 14); SHA_RND2(B,C,D,E,A,12);
271 24 : SHA_MIX(13, 10, 5, 15); SHA_RND2(A,B,C,D,E,13);
272 24 : SHA_MIX(14, 11, 6, 0); SHA_RND2(E,A,B,C,D,14);
273 24 : SHA_MIX(15, 12, 7, 1); SHA_RND2(D,E,A,B,C,15);
274 :
275 24 : SHA_MIX( 0, 13, 8, 2); SHA_RND2(C,D,E,A,B, 0);
276 24 : SHA_MIX( 1, 14, 9, 3); SHA_RND2(B,C,D,E,A, 1);
277 24 : SHA_MIX( 2, 15, 10, 4); SHA_RND2(A,B,C,D,E, 2);
278 24 : SHA_MIX( 3, 0, 11, 5); SHA_RND2(E,A,B,C,D, 3);
279 24 : SHA_MIX( 4, 1, 12, 6); SHA_RND2(D,E,A,B,C, 4);
280 24 : SHA_MIX( 5, 2, 13, 7); SHA_RND2(C,D,E,A,B, 5);
281 24 : SHA_MIX( 6, 3, 14, 8); SHA_RND2(B,C,D,E,A, 6);
282 24 : SHA_MIX( 7, 4, 15, 9); SHA_RND2(A,B,C,D,E, 7);
283 :
284 24 : SHA_MIX( 8, 5, 0, 10); SHA_RND3(E,A,B,C,D, 8);
285 24 : SHA_MIX( 9, 6, 1, 11); SHA_RND3(D,E,A,B,C, 9);
286 24 : SHA_MIX(10, 7, 2, 12); SHA_RND3(C,D,E,A,B,10);
287 24 : SHA_MIX(11, 8, 3, 13); SHA_RND3(B,C,D,E,A,11);
288 24 : SHA_MIX(12, 9, 4, 14); SHA_RND3(A,B,C,D,E,12);
289 24 : SHA_MIX(13, 10, 5, 15); SHA_RND3(E,A,B,C,D,13);
290 24 : SHA_MIX(14, 11, 6, 0); SHA_RND3(D,E,A,B,C,14);
291 24 : SHA_MIX(15, 12, 7, 1); SHA_RND3(C,D,E,A,B,15);
292 :
293 24 : SHA_MIX( 0, 13, 8, 2); SHA_RND3(B,C,D,E,A, 0);
294 24 : SHA_MIX( 1, 14, 9, 3); SHA_RND3(A,B,C,D,E, 1);
295 24 : SHA_MIX( 2, 15, 10, 4); SHA_RND3(E,A,B,C,D, 2);
296 24 : SHA_MIX( 3, 0, 11, 5); SHA_RND3(D,E,A,B,C, 3);
297 24 : SHA_MIX( 4, 1, 12, 6); SHA_RND3(C,D,E,A,B, 4);
298 24 : SHA_MIX( 5, 2, 13, 7); SHA_RND3(B,C,D,E,A, 5);
299 24 : SHA_MIX( 6, 3, 14, 8); SHA_RND3(A,B,C,D,E, 6);
300 24 : SHA_MIX( 7, 4, 15, 9); SHA_RND3(E,A,B,C,D, 7);
301 24 : SHA_MIX( 8, 5, 0, 10); SHA_RND3(D,E,A,B,C, 8);
302 24 : SHA_MIX( 9, 6, 1, 11); SHA_RND3(C,D,E,A,B, 9);
303 24 : SHA_MIX(10, 7, 2, 12); SHA_RND3(B,C,D,E,A,10);
304 24 : SHA_MIX(11, 8, 3, 13); SHA_RND3(A,B,C,D,E,11);
305 :
306 24 : SHA_MIX(12, 9, 4, 14); SHA_RND4(E,A,B,C,D,12);
307 24 : SHA_MIX(13, 10, 5, 15); SHA_RND4(D,E,A,B,C,13);
308 24 : SHA_MIX(14, 11, 6, 0); SHA_RND4(C,D,E,A,B,14);
309 24 : SHA_MIX(15, 12, 7, 1); SHA_RND4(B,C,D,E,A,15);
310 :
311 24 : SHA_MIX( 0, 13, 8, 2); SHA_RND4(A,B,C,D,E, 0);
312 24 : SHA_MIX( 1, 14, 9, 3); SHA_RND4(E,A,B,C,D, 1);
313 24 : SHA_MIX( 2, 15, 10, 4); SHA_RND4(D,E,A,B,C, 2);
314 24 : SHA_MIX( 3, 0, 11, 5); SHA_RND4(C,D,E,A,B, 3);
315 24 : SHA_MIX( 4, 1, 12, 6); SHA_RND4(B,C,D,E,A, 4);
316 24 : SHA_MIX( 5, 2, 13, 7); SHA_RND4(A,B,C,D,E, 5);
317 24 : SHA_MIX( 6, 3, 14, 8); SHA_RND4(E,A,B,C,D, 6);
318 24 : SHA_MIX( 7, 4, 15, 9); SHA_RND4(D,E,A,B,C, 7);
319 24 : SHA_MIX( 8, 5, 0, 10); SHA_RND4(C,D,E,A,B, 8);
320 24 : SHA_MIX( 9, 6, 1, 11); SHA_RND4(B,C,D,E,A, 9);
321 24 : SHA_MIX(10, 7, 2, 12); SHA_RND4(A,B,C,D,E,10);
322 24 : SHA_MIX(11, 8, 3, 13); SHA_RND4(E,A,B,C,D,11);
323 24 : SHA_MIX(12, 9, 4, 14); SHA_RND4(D,E,A,B,C,12);
324 24 : SHA_MIX(13, 10, 5, 15); SHA_RND4(C,D,E,A,B,13);
325 24 : SHA_MIX(14, 11, 6, 0); SHA_RND4(B,C,D,E,A,14);
326 24 : SHA_MIX(15, 12, 7, 1); SHA_RND4(A,B,C,D,E,15);
327 :
328 24 : XH(0) += A;
329 24 : XH(1) += B;
330 24 : XH(2) += C;
331 24 : XH(3) += D;
332 24 : XH(4) += E;
333 24 : }
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