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 1.14 2007/02/13 09:57:12 asterix
17 *#* Add directive #if in struct EntropyPool, and remove #else in randpool_add.
19 *#* Revision 1.13 2007/02/12 18:25:34 asterix
20 *#* Fix bug in randpool_getN.
22 *#* Revision 1.12 2007/02/12 09:47:39 asterix
23 *#* Remove randpool_save. Add randpool_pool.
25 *#* Revision 1.10 2007/02/12 09:03:32 asterix
26 *#* Add CONFIG_RANDPOOL_TIMER macro to swich on or off timer support
28 *#* Revision 1.9 2007/02/09 17:58:09 asterix
29 *#* Add macro CONFIG_RANDPOOL_TIMER.
31 *#* Revision 1.6 2007/02/09 09:24:38 asterix
32 *#* Typos. Add data_len in randpool_add and n_byte in randpool_push pototypes.
34 *#* Revision 1.3 2007/02/08 14:25:29 asterix
35 *#* Write static funcion push_byte.
42 #include <stdio.h> //sprintf();
43 #include <string.h> //memset(), memcpy();
45 #include <cfg/compiler.h>
46 #include <cfg/debug.h> //ASSERT()
47 #include <cfg/macros.h> //MIN()
49 #if CONFIG_RANDPOOL_TIMER
50 #include <drv/timer.h> //timer_clock();
56 * Insert bytes in entropy pool, making a XOR of bytes present
59 static void randpool_push(EntropyPool *pool, void *_byte, size_t n_byte)
61 size_t i = pool->pos_add; // Current number of byte insert in entropy pool.
64 byte = (uint8_t *)_byte;
67 * Insert a bytes in entropy pool.
69 for(int j = 0; j < n_byte; j++)
71 pool->pool_entropy[i] = pool->pool_entropy[i] ^ byte[j];
72 i = (i++) % CONFIG_SIZE_ENTROPY_POOL;
75 pool->pos_add = i; // Update a insert bytes.
80 * This function stir entropy pool with MD2 function hash.
83 static void randpool_stir(EntropyPool *pool)
85 size_t entropy = pool->entropy; //Save current calue of entropy.
87 uint8_t tmp_buf[((sizeof(size_t) * 2) + sizeof(int)) * 2]; //Temporary buffer.
89 md2_init(&context); //Init MD2 algorithm.
91 randpool_add(pool, "", 0, 0);
93 for (int i = 0; i < NUM_STIR_LOOP; i++)
95 sprintf(tmp_buf, "%0x%0x%0x",pool->counter, i, pool->pos_add);
98 * Hash with MD2 algorithm the entropy pool.
100 md2_update(&context, pool->pool_entropy, CONFIG_SIZE_ENTROPY_POOL);
102 md2_update(&context, tmp_buf, strlen(tmp_buf));
104 /*Insert a message digest in entropy pool.*/
105 randpool_push(pool, md2_end(&context), CONFIG_MD2_BLOCK_LEN);
107 pool->counter = (pool->counter + 1) & 0xFFFFFFFF; //Clamp a counter to 4 byte.
111 /*Insert in pool the difference between a two call of this function (see above).*/
112 randpool_add(pool, "", 0, 0);
114 pool->entropy = entropy; //Restore old value of entropy. We haven't add entropy.
118 * Add n_bit of entropy in entropy pool.
120 void randpool_add(EntropyPool *pool, void *data, size_t data_len, size_t entropy)
122 uint8_t sep[] = "\xaa\xaa\xaa\xaa"; // ??
124 randpool_push(pool, data, data_len); //Insert data to entropy pool.
126 randpool_push(pool, sep, strlen(sep)); // ??
128 #if CONFIG_RANDPOOL_TIMER
130 ticks_t event = timer_clock();
133 /*Difference of time between a two accese to entropy pool.*/
134 delta = event - pool->last_counter;
137 randpool_push(pool, &delta, sizeof(delta));
139 delta = delta & 0xff;
141 randpool_push(pool, &delta, sizeof(delta));
144 * Count of number entropy bit add with delta.
152 pool->last_counter = event;
156 pool->entropy += entropy; //Update a entropy of the pool.
160 * Randpool function initialization.
161 * The entropy pool can be initialize also with
162 * a previous entropy pool.
164 void randpool_init(EntropyPool *pool, void *_data, size_t len)
168 data = (uint8_t *)_data;
170 memset(pool, 0, sizeof(EntropyPool));
171 pool->pos_get = CONFIG_MD2_BLOCK_LEN;
173 #if CONFIG_RANDPOOL_TIMER
174 pool->last_counter = timer_clock();
177 ASSERT(len < CONFIG_SIZE_ENTROPY_POOL);
182 * Initialize a entropy pool with a
183 * previous pool, and assume all pool as
186 memcpy(pool->pool_entropy, data, len);
193 * Get the actual value of entropy.
195 size_t randpool_size(EntropyPool *pool)
197 return pool->entropy;
200 void randpool_get(EntropyPool *pool, void *data, size_t n_byte)
206 * Get n_byte from entropy pool. If n_byte is larger than number
207 * byte of entropy in entropy pool, rand_pool_getN continue
208 * to generate pseudocasual value from previous state of
211 void randpool_getN(EntropyPool *pool, void *_data, size_t n_byte)
214 size_t i = pool->pos_get;
216 size_t len = MIN((size_t)CONFIG_MD2_BLOCK_LEN, n_byte);
219 data = (uint8_t *)_data;
221 /* Test if i + CONFIG_MD2_BLOCK_LEN is inside of entropy pool.*/
222 ASSERT((CONFIG_MD2_BLOCK_LEN + i) < CONFIG_SIZE_ENTROPY_POOL);
229 /*Hash previous state of pool*/
230 md2_update(&context, &pool->pool_entropy[i], CONFIG_MD2_BLOCK_LEN);
232 memcpy(data, md2_end(&context), len);
234 n -= len; //Number of byte copied in data.
236 len = MIN(n, CONFIG_MD2_BLOCK_LEN);
238 i = (i + CONFIG_MD2_BLOCK_LEN) % CONFIG_SIZE_ENTROPY_POOL;
240 /* If we haven't more entropy pool to hash, we stir it.*/
241 if(i < CONFIG_MD2_BLOCK_LEN)
248 pool->pos_get = i; //Current number of byte we get from pool.
250 pool->entropy -= n_byte; //Update a entropy.
252 /*If we get all entropy entropy is 0*/
253 if(pool->entropy < 0)
259 * Return a pointer to entropy pool.
261 uint8_t *randpool_pool(EntropyPool *pool)
263 return pool->pool_entropy;