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 1.7 2007/02/09 15:49:54 asterix
17 *#* Fix bug in randpool_stir and randpool_add. Typos.
19 *#* Revision 1.6 2007/02/09 09:24:38 asterix
20 *#* Typos. Add data_len in randpool_add and n_byte in randpool_push pototypes.
22 *#* Revision 1.3 2007/02/08 14:25:29 asterix
23 *#* Write static funcion push_byte.
30 #include <string.h> //memset(), memcpy();
31 #include <cfg/compiler.h>
32 #include <cfg/debug.h> //ASSERT()
33 #include <drv/timer.h> //timer_clock();
35 #include <stdio.h> //sprintf();
40 * Insert bytes in entropy pool, making a XOR of bytes present
43 static void randpool_push(EntropyPool *pool, void *_byte, size_t n_byte)
45 size_t i = pool->pos_add; // Current number of byte insert in entropy pool.
48 byte = (uint8_t *)_byte;
51 * Insert a bytes in entropy pool.
53 for(int j = 0; j < n_byte; j++)
55 pool->pool_entropy[i] = pool->pool_entropy[i] ^ byte[j];
56 i = (i++) % CONFIG_SIZE_ENTROPY_POOL;
59 pool->pos_add = i; // Update a insert bytes.
64 * Add n_bit of entropy in entropy pool.
66 void randpool_add(EntropyPool *pool, void *data, size_t data_len, size_t entropy)
68 ticks_t event = timer_clock();
70 uint8_t sep[] = "\xaa\xaa\xaa\xaa"; // ??
72 randpool_push(pool, data, data_len); //Insert data to entropy pool.
74 randpool_push(pool, sep, strlen(sep)); // ??
76 /*Difference of time between a two accese to entropy pool.*/
77 delta = event - pool->last_counter;
79 randpool_push(pool, &delta, sizeof(delta));
83 randpool_push(pool, &delta, sizeof(delta));
86 * Count of number entropy bit add with delta.
94 pool->entropy += entropy; //Update a entropy of the pool.
95 pool->last_counter = event;
99 * This function stir entropy pool with MD2 function hash.
102 static void randpool_stir(EntropyPool *pool)
104 size_t entropy = pool->entropy; //Save current calue of entropy.
106 uint8_t tmp_buf[((sizeof(size_t) * 2) + sizeof(int)) * 2]; //Temporary buffer.
108 md2_init(&context); //Init MD2 algorithm.
110 randpool_add(pool, "", 0, 0);
112 for (int i = 0; i < NUM_STIR_LOOP; i++)
114 sprintf(tmp_buf, "%0x%0x%0x",pool->counter, i, pool->pos_add);
117 * Hash with MD2 algorithm the entropy pool.
119 md2_update(&context, pool->pool_entropy, CONFIG_SIZE_ENTROPY_POOL);
121 md2_update(&context, tmp_buf, strlen(tmp_buf));
123 /*Insert a message digest in entropy pool.*/
124 randpool_push(pool, md2_end(&context), CONFIG_MD2_BLOCK_LEN);
126 pool->counter = (pool->counter + 1) & 0xFFFFFFFF; //Clamp a counter to 4 byte.
130 /*Insert in pool the difference between a two call of this function (see above).*/
131 randpool_add(pool, "", 0, 0);
133 pool->entropy = entropy; //Restore old value of entropy. We haven't add entropy.
137 void randpool_init(EntropyPool *pool)
140 memset(pool, 0, sizeof(EntropyPool));
141 pool->pos_get = CONFIG_MD2_BLOCK_LEN;
142 pool->last_counter = timer_clock();
144 //TODO: inizializzazione del timer di sistema.
149 * Get the actual value of entropy.
151 size_t randpool_size(EntropyPool *pool)
153 return pool->entropy;
156 void randpool_get(EntropyPool *pool, void *data, size_t n_byte)
161 void randpool_getN(EntropyPool *pool, void *data, size_t n_byte)
165 bool randpool_save(void *data)
169 uint8_t *randpool_load(void)