4 * Copyright 2007 Develer S.r.l. (http://www.develer.com/)
5 * This file is part of DevLib - See README.devlib for information.
8 * \brief MD2 Message-Digest algorithm.
11 * \author Daniele Basile <asterix@develer.com>
16 *#* Revision 1.10 2007/02/02 15:37:45 asterix
17 *#* Change md2_end prototype. Remove a unneeded memcpy in md2_end. Add comments.
19 *#* Revision 1.9 2007/02/02 13:10:01 asterix
20 *#* Fix some bugs in md2_pad and md2_update fuction.
22 *#* Revision 1.8 2007/02/01 14:45:56 asterix
23 *#* Rewrite md2_update function and fix some bug.
25 *#* Revision 1.7 2007/01/31 18:04:15 asterix
26 *#* Write md2_end function
28 *#* Revision 1.4 2007/01/31 13:51:57 asterix
29 *#* Write md2_compute function.
31 *#* Revision 1.2 2007/01/30 17:31:44 asterix
32 *#* Add function prototypes.
34 *#* Revision 1.1 2007/01/30 15:53:26 batt
35 *#* Add first md2 skel.
41 #include <string.h> //memset(), memcpy();
42 #include <cfg/compiler.h>
43 #include <cfg/debug.h> //ASSERT()
44 #include <cfg/macros.h> //MIN()
48 * Official array of 256 byte pemutation contructed from digits of pi, defined
51 static uint8_t md2_perm[256] = {
52 41, 46, 67, 201, 162, 216, 124, 1, 61, 54, 84, 161, 236, 240, 6,
53 19, 98, 167, 5, 243, 192, 199, 115, 140, 152, 147, 43, 217, 188,
54 76, 130, 202, 30, 155, 87, 60, 253, 212, 224, 22, 103, 66, 111, 24,
55 138, 23, 229, 18, 190, 78, 196, 214, 218, 158, 222, 73, 160, 251,
56 245, 142, 187, 47, 238, 122, 169, 104, 121, 145, 21, 178, 7, 63,
57 148, 194, 16, 137, 11, 34, 95, 33, 128, 127, 93, 154, 90, 144, 50,
58 39, 53, 62, 204, 231, 191, 247, 151, 3, 255, 25, 48, 179, 72, 165,
59 181, 209, 215, 94, 146, 42, 172, 86, 170, 198, 79, 184, 56, 210,
60 150, 164, 125, 182, 118, 252, 107, 226, 156, 116, 4, 241, 69, 157,
61 112, 89, 100, 113, 135, 32, 134, 91, 207, 101, 230, 45, 168, 2, 27,
62 96, 37, 173, 174, 176, 185, 246, 28, 70, 97, 105, 52, 64, 126, 15,
63 85, 71, 163, 35, 221, 81, 175, 58, 195, 92, 249, 206, 186, 197,
64 234, 38, 44, 83, 13, 110, 133, 40, 132, 9, 211, 223, 205, 244, 65,
65 129, 77, 82, 106, 220, 55, 200, 108, 193, 171, 250, 36, 225, 123,
66 8, 12, 189, 177, 74, 120, 136, 149, 139, 227, 99, 232, 109, 233,
67 203, 213, 254, 59, 0, 29, 57, 242, 239, 183, 14, 102, 88, 208, 228,
68 166, 119, 114, 248, 235, 117, 75, 10, 49, 68, 80, 180, 143, 237,
69 31, 26, 219, 153, 141, 51, 159, 17, 131, 20
73 * Pad function. Put len_pad unsigned char in
76 static void md2_pad(void *_block, size_t len_pad)
80 block = (uint8_t *)_block;
82 ASSERT(len_pad <= CONFIG_MD2_BLOCK_LEN);
85 * Fill input block with len_pad char.
87 memset(block, len_pad, len_pad);
91 static void md2_compute(void *_state, void *_checksum, void *_block)
95 uint8_t compute_array[COMPUTE_ARRAY_LEN];
100 state = (uint8_t *)_state;
101 checksum = (uint8_t *)_checksum;
102 block = (uint8_t *)_block;
105 * Copy state and checksum context in compute array.
107 memcpy(compute_array, state, CONFIG_MD2_BLOCK_LEN);
108 memcpy(compute_array + CONFIG_MD2_BLOCK_LEN, block, CONFIG_MD2_BLOCK_LEN);
111 * Fill compute array with state XOR block
113 for(i = 0; i < CONFIG_MD2_BLOCK_LEN; i++)
114 compute_array[i + (CONFIG_MD2_BLOCK_LEN * 2)] = state[i] ^ block[i];
119 for(i = 0; i < NUM_COMPUTE_ROUNDS; i++)
121 for(int j = 0; j < COMPUTE_ARRAY_LEN; j++)
123 compute_array[j] ^= md2_perm [t];
124 t = compute_array[j];
127 t = (t + i) & 0xff; //modulo 256.
132 t = checksum[CONFIG_MD2_BLOCK_LEN - 1];
134 for(i = 0; i < CONFIG_MD2_BLOCK_LEN; i++)
136 checksum[i] ^= md2_perm [block[i] ^ t];
141 * Update state and clean compute array.
143 memcpy(state, compute_array, CONFIG_MD2_BLOCK_LEN);
144 memset(compute_array, 0, sizeof(compute_array));
148 * Algorithm initialization.
150 * \param empty context.
152 void md2_init(Md2Context *context)
155 memset(context, 0, sizeof(Md2Context));
162 void md2_update(Md2Context *context, void *_block_in, size_t block_len)
168 * Choose a number of block that fill input context buffer.
170 size_t missing_len = MIN(block_len, CONFIG_MD2_BLOCK_LEN - context->counter);
172 block_in = (uint8_t *)_block_in;
177 * Copy in the buffer input block.
179 memcpy(&context->buffer[context->counter], block_in, missing_len);
182 * Update a context counter, input block length and remaning
183 * context buffer block lenght.
185 context->counter += missing_len;
186 block_len -= missing_len;
187 block_in += missing_len;
190 * If buffer is full, compute it.
192 if (context->counter >= CONFIG_MD2_BLOCK_LEN)
194 md2_compute(context->state, context->checksum, context->buffer);
195 context->counter = 0;
202 * Ends an MD2 message digest operation.
203 * This fuction take an context and return a pointer
206 * \param context in input.
207 * \return a pointer to context state (message digest).
209 uint8_t *md2_end(Md2Context *context)
212 uint8_t buf[CONFIG_MD2_BLOCK_LEN];
215 * Fill remaning empty context buffer.
217 md2_pad(buf, CONFIG_MD2_BLOCK_LEN - context->counter);
220 * Update context buffer and compute it.
222 md2_update(context, buf, CONFIG_MD2_BLOCK_LEN - context->counter);
225 * Add context checksum to message input.
227 md2_update(context, context->checksum, CONFIG_MD2_BLOCK_LEN);
230 return context->state; //return a pointer to message digest.