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 1.10 2007/02/12 09:03:32 asterix
17 *#* Add CONFIG_RANDPOOL_TIMER macro to swich on or off timer support
19 *#* Revision 1.9 2007/02/09 17:58:09 asterix
20 *#* Add macro CONFIG_RANDPOOL_TIMER.
22 *#* Revision 1.6 2007/02/09 09:24:38 asterix
23 *#* Typos. Add data_len in randpool_add and n_byte in randpool_push pototypes.
25 *#* Revision 1.3 2007/02/08 14:25:29 asterix
26 *#* Write static funcion push_byte.
33 #include <stdio.h> //sprintf();
34 #include <string.h> //memset(), memcpy();
36 #include <cfg/compiler.h>
37 #include <cfg/debug.h> //ASSERT()
38 #include <cfg/macros.h> //MIN()
40 #if CONFIG_RANDPOOL_TIMER
41 #include <drv/timer.h> //timer_clock();
47 * Insert bytes in entropy pool, making a XOR of bytes present
50 static void randpool_push(EntropyPool *pool, void *_byte, size_t n_byte)
52 size_t i = pool->pos_add; // Current number of byte insert in entropy pool.
55 byte = (uint8_t *)_byte;
58 * Insert a bytes in entropy pool.
60 for(int j = 0; j < n_byte; j++)
62 pool->pool_entropy[i] = pool->pool_entropy[i] ^ byte[j];
63 i = (i++) % CONFIG_SIZE_ENTROPY_POOL;
66 pool->pos_add = i; // Update a insert bytes.
71 * This function stir entropy pool with MD2 function hash.
74 static void randpool_stir(EntropyPool *pool)
76 size_t entropy = pool->entropy; //Save current calue of entropy.
78 uint8_t tmp_buf[((sizeof(size_t) * 2) + sizeof(int)) * 2]; //Temporary buffer.
80 md2_init(&context); //Init MD2 algorithm.
82 randpool_add(pool, "", 0, 0);
84 for (int i = 0; i < NUM_STIR_LOOP; i++)
86 sprintf(tmp_buf, "%0x%0x%0x",pool->counter, i, pool->pos_add);
89 * Hash with MD2 algorithm the entropy pool.
91 md2_update(&context, pool->pool_entropy, CONFIG_SIZE_ENTROPY_POOL);
93 md2_update(&context, tmp_buf, strlen(tmp_buf));
95 /*Insert a message digest in entropy pool.*/
96 randpool_push(pool, md2_end(&context), CONFIG_MD2_BLOCK_LEN);
98 pool->counter = (pool->counter + 1) & 0xFFFFFFFF; //Clamp a counter to 4 byte.
102 /*Insert in pool the difference between a two call of this function (see above).*/
103 randpool_add(pool, "", 0, 0);
105 pool->entropy = entropy; //Restore old value of entropy. We haven't add entropy.
109 * Add n_bit of entropy in entropy pool.
111 void randpool_add(EntropyPool *pool, void *data, size_t data_len, size_t entropy)
113 uint8_t sep[] = "\xaa\xaa\xaa\xaa"; // ??
115 randpool_push(pool, data, data_len); //Insert data to entropy pool.
117 randpool_push(pool, sep, strlen(sep)); // ??
119 #if CONFIG_RANDPOOL_TIMER
121 ticks_t event = timer_clock();
124 /*Difference of time between a two accese to entropy pool.*/
125 delta = event - pool->last_counter;
128 randpool_push(pool, &delta, sizeof(delta));
130 delta = delta & 0xff;
132 randpool_push(pool, &delta, sizeof(delta));
135 * Count of number entropy bit add with delta.
146 /*Difference of time between a two accese to entropy pool.*/
147 event = pool->last_counter++;
151 pool->entropy += entropy; //Update a entropy of the pool.
152 pool->last_counter = event;
156 void randpool_init(EntropyPool *pool)
159 memset(pool, 0, sizeof(EntropyPool));
160 pool->pos_get = CONFIG_MD2_BLOCK_LEN;
162 #if CONFIG_RANDPOOL_TIMER
163 pool->last_counter = timer_clock();
170 * Get the actual value of entropy.
172 size_t randpool_size(EntropyPool *pool)
174 return pool->entropy;
177 void randpool_get(EntropyPool *pool, void *data, size_t n_byte)
183 * Get n_byte from entropy pool. If n_byte is larger than number
184 * byte of entropy in entropy pool, rand_pool_getN continue
185 * to generate pseudocasual value from previous state of
188 void randpool_getN(EntropyPool *pool, void *data, size_t n_byte)
191 size_t i = pool->pos_get;
193 size_t len = MIN((size_t)CONFIG_MD2_BLOCK_LEN, n_byte);
195 /* Test if i + CONFIG_MD2_BLOCK_LEN is inside of entropy pool.*/
196 ASSERT((CONFIG_MD2_BLOCK_LEN + i) < CONFIG_SIZE_ENTROPY_POOL);
202 /*Hash previous state of pool*/
203 md2_update(&context, &pool->pool_entropy[i], CONFIG_MD2_BLOCK_LEN);
205 memcpy(data, md2_end(&context), len);
207 n -= len; //Number of byte copied in data.
209 len = MIN(n, CONFIG_MD2_BLOCK_LEN);
211 i = (i + CONFIG_MD2_BLOCK_LEN) % CONFIG_SIZE_ENTROPY_POOL;
213 /* If we haven't more entropy pool to hash, we stir it.*/
214 if(i < CONFIG_MD2_BLOCK_LEN)
221 pool->pos_get = i; //Current number of byte we get from pool.
223 pool->entropy -= n_byte; //Update a entropy.
225 /*If we get all entropy entropy is 0*/
226 if(pool->entropy < 0)
230 bool randpool_save(void *data)
234 uint8_t *randpool_load(void)