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 API function for to manage entropy pool.
11 * \author Daniele Basile <asterix@develer.com>
16 *#* Revision 1.16 2007/02/13 15:11:37 asterix
19 *#* Revision 1.14 2007/02/13 09:57:12 asterix
20 *#* Add directive #if in struct EntropyPool, and remove #else in randpool_add.
22 *#* Revision 1.13 2007/02/12 18:25:34 asterix
23 *#* Fix bug in randpool_getN.
25 *#* Revision 1.12 2007/02/12 09:47:39 asterix
26 *#* Remove randpool_save. Add randpool_pool.
28 *#* Revision 1.10 2007/02/12 09:03:32 asterix
29 *#* Add CONFIG_RANDPOOL_TIMER macro to swich on or off timer support
31 *#* Revision 1.9 2007/02/09 17:58:09 asterix
32 *#* Add macro CONFIG_RANDPOOL_TIMER.
34 *#* Revision 1.6 2007/02/09 09:24:38 asterix
35 *#* Typos. Add data_len in randpool_add and n_byte in randpool_push pototypes.
37 *#* Revision 1.3 2007/02/08 14:25:29 asterix
38 *#* Write static funcion push_byte.
45 #include <stdio.h> //sprintf();
46 #include <string.h> //memset(), memcpy();
48 #include <cfg/compiler.h>
49 #include <cfg/debug.h> //ASSERT()
50 #include <cfg/macros.h> //MIN()
52 #if CONFIG_RANDPOOL_TIMER
53 #include <drv/timer.h> //timer_clock();
59 * Insert bytes in entropy pool, making a XOR of bytes present
62 static void randpool_push(EntropyPool *pool, void *_byte, size_t n_byte)
64 size_t i = pool->pos_add; // Current number of byte insert in entropy pool.
67 byte = (uint8_t *)_byte;
70 * Insert a bytes in entropy pool.
72 for(int j = 0; j < n_byte; j++)
74 pool->pool_entropy[i] = pool->pool_entropy[i] ^ byte[j];
75 i = (i++) % CONFIG_SIZE_ENTROPY_POOL;
78 pool->pos_add = i; // Update a insert bytes.
83 * This function stir entropy pool with MD2 function hash.
86 static void randpool_stir(EntropyPool *pool)
88 size_t entropy = pool->entropy; //Save current calue of entropy.
90 uint8_t tmp_buf[((sizeof(size_t) * 2) + sizeof(int)) * 2]; //Temporary buffer.
92 md2_init(&context); //Init MD2 algorithm.
94 randpool_add(pool, "", 0, 0);
96 for (int i = 0; i < NUM_STIR_LOOP; i++)
98 sprintf(tmp_buf, "%0x%0x%0x",pool->counter, i, pool->pos_add);
101 * Hash with MD2 algorithm the entropy pool.
103 md2_update(&context, pool->pool_entropy, CONFIG_SIZE_ENTROPY_POOL);
105 md2_update(&context, tmp_buf, strlen(tmp_buf));
107 /*Insert a message digest in entropy pool.*/
108 randpool_push(pool, md2_end(&context), CONFIG_MD2_BLOCK_LEN);
110 pool->counter = (pool->counter + 1) & 0xFFFFFFFF; //Clamp a counter to 4 byte.
114 /*Insert in pool the difference between a two call of this function (see above).*/
115 randpool_add(pool, "", 0, 0);
117 pool->entropy = entropy; //Restore old value of entropy. We haven't add entropy.
121 * Add n_bit of entropy in entropy pool.
123 void randpool_add(EntropyPool *pool, void *data, size_t data_len, size_t entropy)
125 uint8_t sep[] = "\xaa\xaa\xaa\xaa"; // ??
127 randpool_push(pool, data, data_len); //Insert data to entropy pool.
129 randpool_push(pool, sep, strlen(sep)); // ??
131 #if CONFIG_RANDPOOL_TIMER
133 ticks_t event = timer_clock();
136 /*Difference of time between a two accese to entropy pool.*/
137 delta = event - pool->last_counter;
140 randpool_push(pool, &delta, sizeof(delta));
142 delta = delta & 0xff;
144 randpool_push(pool, &delta, sizeof(delta));
147 * Count of number entropy bit add with delta.
155 pool->last_counter = event;
159 pool->entropy += entropy; //Update a entropy of the pool.
163 * Randpool function initialization.
164 * The entropy pool can be initialize also with
165 * a previous entropy pool.
167 void randpool_init(EntropyPool *pool, void *_data, size_t len)
171 data = (uint8_t *)_data;
173 memset(pool, 0, sizeof(EntropyPool));
174 pool->pos_get = CONFIG_MD2_BLOCK_LEN;
176 #if CONFIG_RANDPOOL_TIMER
177 pool->last_counter = timer_clock();
180 ASSERT(len < CONFIG_SIZE_ENTROPY_POOL);
185 * Initialize a entropy pool with a
186 * previous pool, and assume all pool as
189 memcpy(pool->pool_entropy, data, len);
196 * Get the actual value of entropy.
198 size_t randpool_size(EntropyPool *pool)
200 return pool->entropy;
203 void randpool_get(EntropyPool *pool, void *data, size_t n_byte)
209 * Get n_byte from entropy pool. If n_byte is larger than number
210 * byte of entropy in entropy pool, rand_pool_getN continue
211 * to generate pseudocasual value from previous state of
214 void randpool_getN(EntropyPool *pool, void *_data, size_t n_byte)
217 size_t i = pool->pos_get;
219 size_t pos_write = 0; //Number of block has been written in data.
220 size_t len = MIN((size_t)CONFIG_MD2_BLOCK_LEN, n_byte);
223 data = (uint8_t *)_data;
225 /* Test if i + CONFIG_MD2_BLOCK_LEN is inside of entropy pool.*/
226 ASSERT((CONFIG_MD2_BLOCK_LEN + i) < CONFIG_SIZE_ENTROPY_POOL);
233 /*Hash previous state of pool*/
234 md2_update(&context, &pool->pool_entropy[i], CONFIG_MD2_BLOCK_LEN);
236 memcpy(&data[pos_write], md2_end(&context), len);
238 pos_write += len; //Update number of block has been written in data.
239 n -= len; //Number of byte copied in data.
241 len = MIN(n,(size_t)CONFIG_MD2_BLOCK_LEN);
243 i = (i + CONFIG_MD2_BLOCK_LEN) % CONFIG_SIZE_ENTROPY_POOL;
245 /* If we haven't more entropy pool to hash, we stir it.*/
246 if(i < CONFIG_MD2_BLOCK_LEN)
255 pool->pos_get = i; //Current number of byte we get from pool.
257 pool->entropy -= n_byte; //Update a entropy.
259 /*If we get all entropy entropy is 0*/
260 if(pool->entropy < 0)
266 * Return a pointer to entropy pool.
268 uint8_t *randpool_pool(EntropyPool *pool)
270 return pool->pool_entropy;