4 * This file is part of BeRTOS.
6 * Bertos is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
20 * As a special exception, you may use this file as part of a free software
21 * library without restriction. Specifically, if other files instantiate
22 * templates or use macros or inline functions from this file, or you compile
23 * this file and link it with other files to produce an executable, this
24 * file does not by itself cause the resulting executable to be covered by
25 * the GNU General Public License. This exception does not however
26 * invalidate any other reasons why the executable file might be covered by
27 * the GNU General Public License.
29 * Copyright 2007 Develer S.r.l. (http://www.develer.com/)
33 * \brief API function for to manage entropy pool.
36 * \author Daniele Basile <asterix@develer.com>
41 *#* Revision 1.20 2007/06/07 16:06:39 batt
42 *#* Fix some doxygen errors.
44 *#* Revision 1.19 2007/02/15 13:54:26 asterix
45 *#* Rename randpool_getN in randpool_get. Fix bug in randpool_get.
47 *#* Revision 1.17 2007/02/15 13:40:42 asterix
48 *#* Fix bug in randpool_add and randpool_strir.
50 *#* Revision 1.16 2007/02/13 15:11:37 asterix
53 *#* Revision 1.14 2007/02/13 09:57:12 asterix
54 *#* Add directive #if in struct EntropyPool, and remove #else in randpool_add.
56 *#* Revision 1.13 2007/02/12 18:25:34 asterix
57 *#* Fix bug in randpool_getN.
59 *#* Revision 1.12 2007/02/12 09:47:39 asterix
60 *#* Remove randpool_save. Add randpool_pool.
62 *#* Revision 1.10 2007/02/12 09:03:32 asterix
63 *#* Add CONFIG_RANDPOOL_TIMER macro to swich on or off timer support
65 *#* Revision 1.9 2007/02/09 17:58:09 asterix
66 *#* Add macro CONFIG_RANDPOOL_TIMER.
68 *#* Revision 1.6 2007/02/09 09:24:38 asterix
69 *#* Typos. Add data_len in randpool_add and n_byte in randpool_push pototypes.
71 *#* Revision 1.3 2007/02/08 14:25:29 asterix
72 *#* Write static funcion push_byte.
79 #include <stdio.h> //sprintf();
80 #include <string.h> //memset(), memcpy();
82 #include <cfg/compiler.h>
83 #include <cfg/debug.h> //ASSERT()
84 #include <cfg/macros.h> //MIN(), ROUND_UP();
86 #if CONFIG_RANDPOOL_TIMER
87 #include <drv/timer.h> //timer_clock();
93 * Insert bytes in entropy pool, making a XOR of bytes present
96 static void randpool_push(EntropyPool *pool, void *_byte, size_t n_byte)
98 size_t i = pool->pos_add; // Current number of byte insert in entropy pool.
101 byte = (uint8_t *)_byte;
104 * Insert a bytes in entropy pool.
106 for(int j = 0; j < n_byte; j++)
108 pool->pool_entropy[i] = pool->pool_entropy[i] ^ byte[j];
109 i = (++i) % CONFIG_SIZE_ENTROPY_POOL;
112 pool->pos_add = i; // Update a insert bytes.
117 * This function stir entropy pool with MD2 function hash.
120 static void randpool_stir(EntropyPool *pool)
122 size_t entropy = pool->entropy; //Save current calue of entropy.
124 uint8_t tmp_buf[((sizeof(size_t) * 2) + sizeof(int)) * 2 + 1]; //Temporary buffer.
126 md2_init(&context); //Init MD2 algorithm.
128 randpool_add(pool, NULL, 0);
130 for (int i = 0; i < (CONFIG_SIZE_ENTROPY_POOL / MD2_DIGEST_LEN); i++)
132 sprintf(tmp_buf, "%0x%0x%0x",pool->counter, i, pool->pos_add);
135 * Hash with MD2 algorithm the entropy pool.
137 md2_update(&context, pool->pool_entropy, CONFIG_SIZE_ENTROPY_POOL);
139 md2_update(&context, tmp_buf, sizeof(tmp_buf) - 1);
141 /*Insert a message digest in entropy pool.*/
142 randpool_push(pool, md2_end(&context), MD2_DIGEST_LEN);
144 pool->counter = pool->counter + 1;
148 /*Insert in pool the difference between a two call of this function (see above).*/
149 randpool_add(pool, NULL, 0);
151 pool->entropy = entropy; //Restore old value of entropy. We haven't add entropy.
155 * Add \param entropy bits from \param data buffer to the entropy \param pool
157 void randpool_add(EntropyPool *pool, void *data, size_t entropy)
159 uint8_t sep[] = "\xaa\xaa\xaa\xaa"; // ??
160 size_t data_len = ROUND_UP(entropy, 8) / 8; //Number of entropy byte in input.
162 randpool_push(pool, data, data_len); //Insert data to entropy pool.
164 #if CONFIG_RANDPOOL_TIMER
166 ticks_t event = timer_clock();
169 /*Difference of time between a two accese to entropy pool.*/
170 delta = event - pool->last_counter;
172 randpool_push(pool, &event, sizeof(ticks_t));
173 randpool_push(pool, sep, sizeof(sep) - 1); // ??
174 randpool_push(pool, &delta, sizeof(delta));
177 * Count of number entropy bit add with delta.
179 delta = delta & 0xff;
186 pool->last_counter = event;
190 pool->entropy += entropy; //Update a entropy of the pool.
194 * Randpool function initialization.
195 * The entropy pool can be initialize also with
196 * a previous entropy pool.
198 void randpool_init(EntropyPool *pool, void *_data, size_t len)
202 data = (uint8_t *)_data;
204 memset(pool, 0, sizeof(EntropyPool));
205 pool->pos_get = MD2_DIGEST_LEN;
207 #if CONFIG_RANDPOOL_TIMER
208 pool->last_counter = timer_clock();
214 * Initialize a entropy pool with a
215 * previous pool, and assume all pool as
218 len = MIN(len,(size_t)CONFIG_SIZE_ENTROPY_POOL);
219 memcpy(pool->pool_entropy, data, len);
226 * Get the actual value of entropy.
228 size_t randpool_size(EntropyPool *pool)
230 return pool->entropy;
234 * Get \param n_byte from entropy pool. If n_byte is larger than number
235 * byte of entropy in entropy pool, randpool_get continue
236 * to generate pseudocasual value from previous state of
238 * \param n_byte number fo bytes to read.
239 * \param pool is the pool entropy context.
240 * \param _data is the pointer to write the random data to.
242 void randpool_get(EntropyPool *pool, void *_data, size_t n_byte)
245 size_t i = pool->pos_get;
247 size_t pos_write = 0; //Number of block has been written in data.
248 size_t len = MIN((size_t)MD2_DIGEST_LEN, n_byte);
251 data = (uint8_t *)_data;
253 /* Test if i + CONFIG_MD2_BLOCK_LEN is inside of entropy pool.*/
254 ASSERT((MD2_DIGEST_LEN + i) < CONFIG_SIZE_ENTROPY_POOL);
261 /*Hash previous state of pool*/
262 md2_update(&context, &pool->pool_entropy[i], MD2_DIGEST_LEN);
264 memcpy(&data[pos_write], md2_end(&context), len);
266 pos_write += len; //Update number of block has been written in data.
267 n -= len; //Number of byte copied in data.
269 len = MIN(n,(size_t)MD2_DIGEST_LEN);
271 i = (i + MD2_DIGEST_LEN) % CONFIG_SIZE_ENTROPY_POOL;
273 /* If we haven't more entropy pool to hash, we stir it.*/
274 if(i < MD2_DIGEST_LEN)
282 pool->pos_get = i; //Current number of byte we get from pool.
283 pool->entropy -= n_byte; //Update a entropy.
285 /*If we get all entropy entropy is 0*/
286 if(pool->entropy < 0)
292 * Return a pointer to entropy pool.
294 uint8_t *randpool_pool(EntropyPool *pool)
296 return pool->pool_entropy;