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 1.13 2007/02/12 18:25:34 asterix
17 *#* Fix bug in randpool_getN.
19 *#* Revision 1.12 2007/02/12 09:47:39 asterix
20 *#* Remove randpool_save. Add randpool_pool.
22 *#* Revision 1.10 2007/02/12 09:03:32 asterix
23 *#* Add CONFIG_RANDPOOL_TIMER macro to swich on or off timer support
25 *#* Revision 1.9 2007/02/09 17:58:09 asterix
26 *#* Add macro CONFIG_RANDPOOL_TIMER.
28 *#* Revision 1.6 2007/02/09 09:24:38 asterix
29 *#* Typos. Add data_len in randpool_add and n_byte in randpool_push pototypes.
31 *#* Revision 1.3 2007/02/08 14:25:29 asterix
32 *#* Write static funcion push_byte.
39 #include <stdio.h> //sprintf();
40 #include <string.h> //memset(), memcpy();
42 #include <cfg/compiler.h>
43 #include <cfg/debug.h> //ASSERT()
44 #include <cfg/macros.h> //MIN()
46 #if CONFIG_RANDPOOL_TIMER
47 #include <drv/timer.h> //timer_clock();
53 * Insert bytes in entropy pool, making a XOR of bytes present
56 static void randpool_push(EntropyPool *pool, void *_byte, size_t n_byte)
58 size_t i = pool->pos_add; // Current number of byte insert in entropy pool.
61 byte = (uint8_t *)_byte;
64 * Insert a bytes in entropy pool.
66 for(int j = 0; j < n_byte; j++)
68 pool->pool_entropy[i] = pool->pool_entropy[i] ^ byte[j];
69 i = (i++) % CONFIG_SIZE_ENTROPY_POOL;
72 pool->pos_add = i; // Update a insert bytes.
77 * This function stir entropy pool with MD2 function hash.
80 static void randpool_stir(EntropyPool *pool)
82 size_t entropy = pool->entropy; //Save current calue of entropy.
84 uint8_t tmp_buf[((sizeof(size_t) * 2) + sizeof(int)) * 2]; //Temporary buffer.
86 md2_init(&context); //Init MD2 algorithm.
88 randpool_add(pool, "", 0, 0);
90 for (int i = 0; i < NUM_STIR_LOOP; i++)
92 sprintf(tmp_buf, "%0x%0x%0x",pool->counter, i, pool->pos_add);
95 * Hash with MD2 algorithm the entropy pool.
97 md2_update(&context, pool->pool_entropy, CONFIG_SIZE_ENTROPY_POOL);
99 md2_update(&context, tmp_buf, strlen(tmp_buf));
101 /*Insert a message digest in entropy pool.*/
102 randpool_push(pool, md2_end(&context), CONFIG_MD2_BLOCK_LEN);
104 pool->counter = (pool->counter + 1) & 0xFFFFFFFF; //Clamp a counter to 4 byte.
108 /*Insert in pool the difference between a two call of this function (see above).*/
109 randpool_add(pool, "", 0, 0);
111 pool->entropy = entropy; //Restore old value of entropy. We haven't add entropy.
115 * Add n_bit of entropy in entropy pool.
117 void randpool_add(EntropyPool *pool, void *data, size_t data_len, size_t entropy)
119 uint8_t sep[] = "\xaa\xaa\xaa\xaa"; // ??
121 randpool_push(pool, data, data_len); //Insert data to entropy pool.
123 randpool_push(pool, sep, strlen(sep)); // ??
125 #if CONFIG_RANDPOOL_TIMER
127 ticks_t event = timer_clock();
130 /*Difference of time between a two accese to entropy pool.*/
131 delta = event - pool->last_counter;
134 randpool_push(pool, &delta, sizeof(delta));
136 delta = delta & 0xff;
138 randpool_push(pool, &delta, sizeof(delta));
141 * Count of number entropy bit add with delta.
152 /*Difference of time between a two accese to entropy pool.*/
153 event = pool->last_counter++;
157 pool->entropy += entropy; //Update a entropy of the pool.
158 pool->last_counter = event;
162 * Randpool function initialization.
163 * The entropy pool can be initialize also with
164 * a previous entropy pool.
166 void randpool_init(EntropyPool *pool, void *_data, size_t len)
170 data = (uint8_t *)_data;
172 memset(pool, 0, sizeof(EntropyPool));
173 pool->pos_get = CONFIG_MD2_BLOCK_LEN;
175 #if CONFIG_RANDPOOL_TIMER
176 pool->last_counter = timer_clock();
179 ASSERT(len < CONFIG_SIZE_ENTROPY_POOL);
184 * Initialize a entropy pool with a
185 * previous pool, and assume all pool as
188 memcpy(pool->pool_entropy, data, len);
195 * Get the actual value of entropy.
197 size_t randpool_size(EntropyPool *pool)
199 return pool->entropy;
202 void randpool_get(EntropyPool *pool, void *data, size_t n_byte)
208 * Get n_byte from entropy pool. If n_byte is larger than number
209 * byte of entropy in entropy pool, rand_pool_getN continue
210 * to generate pseudocasual value from previous state of
213 void randpool_getN(EntropyPool *pool, void *_data, size_t n_byte)
216 size_t i = pool->pos_get;
218 size_t len = MIN((size_t)CONFIG_MD2_BLOCK_LEN, n_byte);
221 data = (uint8_t *)_data;
223 /* Test if i + CONFIG_MD2_BLOCK_LEN is inside of entropy pool.*/
224 ASSERT((CONFIG_MD2_BLOCK_LEN + i) < CONFIG_SIZE_ENTROPY_POOL);
231 /*Hash previous state of pool*/
232 md2_update(&context, &pool->pool_entropy[i], CONFIG_MD2_BLOCK_LEN);
234 memcpy(data, md2_end(&context), len);
236 n -= len; //Number of byte copied in data.
238 len = MIN(n, CONFIG_MD2_BLOCK_LEN);
240 i = (i + CONFIG_MD2_BLOCK_LEN) % CONFIG_SIZE_ENTROPY_POOL;
242 /* If we haven't more entropy pool to hash, we stir it.*/
243 if(i < CONFIG_MD2_BLOCK_LEN)
250 pool->pos_get = i; //Current number of byte we get from pool.
252 pool->entropy -= n_byte; //Update a entropy.
254 /*If we get all entropy entropy is 0*/
255 if(pool->entropy < 0)
261 * Return a pointer to entropy pool.
263 uint8_t *randpool_pool(EntropyPool *pool)
265 return pool->pool_entropy;