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3a0d900a DM |
1 | /* These are the four functions used in the four steps of the MD5 algorithm |
2 | and defined in the RFC 1321. The first function is a little bit optimized | |
3 | (as found in Colin Plumbs public domain implementation). */ | |
4 | /* #define FF(b, c, d) ((b & c) | (~b & d)) */ | |
5 | #define FF(b, c, d) (d ^ (b & (c ^ d))) | |
6 | #define FG(b, c, d) FF (d, b, c) | |
7 | #define FH(b, c, d) (b ^ c ^ d) | |
8 | #define FI(b, c, d) (c ^ (b | ~d)) | |
9 | ||
10 | /* Process LEN bytes of BUFFER, accumulating context into CTX. | |
11 | It is assumed that LEN % 64 == 0. */ | |
12 | ||
13 | void | |
14 | __md5_process_block (const void *buffer, size_t len, struct md5_ctx *ctx) | |
15 | { | |
16 | md5_uint32 correct_words[16]; | |
17 | const md5_uint32 *words = buffer; | |
18 | size_t nwords = len / sizeof (md5_uint32); | |
19 | const md5_uint32 *endp = words + nwords; | |
20 | md5_uint32 A = ctx->A; | |
21 | md5_uint32 B = ctx->B; | |
22 | md5_uint32 C = ctx->C; | |
23 | md5_uint32 D = ctx->D; | |
24 | md5_uint32 lolen = len; | |
25 | ||
26 | /* First increment the byte count. RFC 1321 specifies the possible | |
27 | length of the file up to 2^64 bits. Here we only compute the | |
28 | number of bytes. Do a double word increment. */ | |
29 | ctx->total[0] += lolen; | |
30 | ctx->total[1] += (len >> 31 >> 1) + (ctx->total[0] < lolen); | |
31 | ||
32 | /* Process all bytes in the buffer with 64 bytes in each round of | |
33 | the loop. */ | |
34 | while (words < endp) | |
35 | { | |
36 | md5_uint32 *cwp = correct_words; | |
37 | md5_uint32 A_save = A; | |
38 | md5_uint32 B_save = B; | |
39 | md5_uint32 C_save = C; | |
40 | md5_uint32 D_save = D; | |
41 | ||
42 | /* First round: using the given function, the context and a constant | |
43 | the next context is computed. Because the algorithms processing | |
44 | unit is a 32-bit word and it is determined to work on words in | |
45 | little endian byte order we perhaps have to change the byte order | |
46 | before the computation. To reduce the work for the next steps | |
47 | we store the swapped words in the array CORRECT_WORDS. */ | |
48 | ||
49 | #define OP(a, b, c, d, s, T) \ | |
50 | do \ | |
51 | { \ | |
52 | a += FF (b, c, d) + (*cwp++ = SWAP (*words)) + T; \ | |
53 | ++words; \ | |
54 | CYCLIC (a, s); \ | |
55 | a += b; \ | |
56 | } \ | |
57 | while (0) | |
58 | ||
59 | /* It is unfortunate that C does not provide an operator for | |
60 | cyclic rotation. Hope the C compiler is smart enough. */ | |
61 | #define CYCLIC(w, s) (w = (w << s) | (w >> (32 - s))) | |
62 | ||
63 | /* Before we start, one word to the strange constants. | |
64 | They are defined in RFC 1321 as | |
65 | ||
66 | T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64 | |
67 | */ | |
68 | ||
69 | /* Round 1. */ | |
70 | OP (A, B, C, D, 7, 0xd76aa478); | |
71 | OP (D, A, B, C, 12, 0xe8c7b756); | |
72 | OP (C, D, A, B, 17, 0x242070db); | |
73 | OP (B, C, D, A, 22, 0xc1bdceee); | |
74 | OP (A, B, C, D, 7, 0xf57c0faf); | |
75 | OP (D, A, B, C, 12, 0x4787c62a); | |
76 | OP (C, D, A, B, 17, 0xa8304613); | |
77 | OP (B, C, D, A, 22, 0xfd469501); | |
78 | OP (A, B, C, D, 7, 0x698098d8); | |
79 | OP (D, A, B, C, 12, 0x8b44f7af); | |
80 | OP (C, D, A, B, 17, 0xffff5bb1); | |
81 | OP (B, C, D, A, 22, 0x895cd7be); | |
82 | OP (A, B, C, D, 7, 0x6b901122); | |
83 | OP (D, A, B, C, 12, 0xfd987193); | |
84 | OP (C, D, A, B, 17, 0xa679438e); | |
85 | OP (B, C, D, A, 22, 0x49b40821); | |
86 | ||
87 | /* For the second to fourth round we have the possibly swapped words | |
88 | in CORRECT_WORDS. Redefine the macro to take an additional first | |
89 | argument specifying the function to use. */ | |
90 | #undef OP | |
91 | #define OP(f, a, b, c, d, k, s, T) \ | |
92 | do \ | |
93 | { \ | |
94 | a += f (b, c, d) + correct_words[k] + T; \ | |
95 | CYCLIC (a, s); \ | |
96 | a += b; \ | |
97 | } \ | |
98 | while (0) | |
99 | ||
100 | /* Round 2. */ | |
101 | OP (FG, A, B, C, D, 1, 5, 0xf61e2562); | |
102 | OP (FG, D, A, B, C, 6, 9, 0xc040b340); | |
103 | OP (FG, C, D, A, B, 11, 14, 0x265e5a51); | |
104 | OP (FG, B, C, D, A, 0, 20, 0xe9b6c7aa); | |
105 | OP (FG, A, B, C, D, 5, 5, 0xd62f105d); | |
106 | OP (FG, D, A, B, C, 10, 9, 0x02441453); | |
107 | OP (FG, C, D, A, B, 15, 14, 0xd8a1e681); | |
108 | OP (FG, B, C, D, A, 4, 20, 0xe7d3fbc8); | |
109 | OP (FG, A, B, C, D, 9, 5, 0x21e1cde6); | |
110 | OP (FG, D, A, B, C, 14, 9, 0xc33707d6); | |
111 | OP (FG, C, D, A, B, 3, 14, 0xf4d50d87); | |
112 | OP (FG, B, C, D, A, 8, 20, 0x455a14ed); | |
113 | OP (FG, A, B, C, D, 13, 5, 0xa9e3e905); | |
114 | OP (FG, D, A, B, C, 2, 9, 0xfcefa3f8); | |
115 | OP (FG, C, D, A, B, 7, 14, 0x676f02d9); | |
116 | OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a); | |
117 | ||
118 | /* Round 3. */ | |
119 | OP (FH, A, B, C, D, 5, 4, 0xfffa3942); | |
120 | OP (FH, D, A, B, C, 8, 11, 0x8771f681); | |
121 | OP (FH, C, D, A, B, 11, 16, 0x6d9d6122); | |
122 | OP (FH, B, C, D, A, 14, 23, 0xfde5380c); | |
123 | OP (FH, A, B, C, D, 1, 4, 0xa4beea44); | |
124 | OP (FH, D, A, B, C, 4, 11, 0x4bdecfa9); | |
125 | OP (FH, C, D, A, B, 7, 16, 0xf6bb4b60); | |
126 | OP (FH, B, C, D, A, 10, 23, 0xbebfbc70); | |
127 | OP (FH, A, B, C, D, 13, 4, 0x289b7ec6); | |
128 | OP (FH, D, A, B, C, 0, 11, 0xeaa127fa); | |
129 | OP (FH, C, D, A, B, 3, 16, 0xd4ef3085); | |
130 | OP (FH, B, C, D, A, 6, 23, 0x04881d05); | |
131 | OP (FH, A, B, C, D, 9, 4, 0xd9d4d039); | |
132 | OP (FH, D, A, B, C, 12, 11, 0xe6db99e5); | |
133 | OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8); | |
134 | OP (FH, B, C, D, A, 2, 23, 0xc4ac5665); | |
135 | ||
136 | /* Round 4. */ | |
137 | OP (FI, A, B, C, D, 0, 6, 0xf4292244); | |
138 | OP (FI, D, A, B, C, 7, 10, 0x432aff97); | |
139 | OP (FI, C, D, A, B, 14, 15, 0xab9423a7); | |
140 | OP (FI, B, C, D, A, 5, 21, 0xfc93a039); | |
141 | OP (FI, A, B, C, D, 12, 6, 0x655b59c3); | |
142 | OP (FI, D, A, B, C, 3, 10, 0x8f0ccc92); | |
143 | OP (FI, C, D, A, B, 10, 15, 0xffeff47d); | |
144 | OP (FI, B, C, D, A, 1, 21, 0x85845dd1); | |
145 | OP (FI, A, B, C, D, 8, 6, 0x6fa87e4f); | |
146 | OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0); | |
147 | OP (FI, C, D, A, B, 6, 15, 0xa3014314); | |
148 | OP (FI, B, C, D, A, 13, 21, 0x4e0811a1); | |
149 | OP (FI, A, B, C, D, 4, 6, 0xf7537e82); | |
150 | OP (FI, D, A, B, C, 11, 10, 0xbd3af235); | |
151 | OP (FI, C, D, A, B, 2, 15, 0x2ad7d2bb); | |
152 | OP (FI, B, C, D, A, 9, 21, 0xeb86d391); | |
153 | ||
154 | /* Add the starting values of the context. */ | |
155 | A += A_save; | |
156 | B += B_save; | |
157 | C += C_save; | |
158 | D += D_save; | |
159 | } | |
160 | ||
161 | /* Put checksum in context given as argument. */ | |
162 | ctx->A = A; | |
163 | ctx->B = B; | |
164 | ctx->C = C; | |
165 | ctx->D = D; | |
166 | } |