forgotten file (a lot of them)

[arm-crypto-lib.git] / entropium / entropium.c

diff --git a/entropium/entropium.c b/entropium/entropium.c
new file mode 100644 (file)
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+++ b/entropium/entropium.c
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+/* entropium.c */
+/*
+    This file is part of the ARM-Crypto-Lib.
+    Copyright (C) 2006-2010  Daniel Otte (daniel.otte@rub.de)
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+/**
+ * \file    entropium.c
+ * \author  Daniel Otte
+ * \email   daniel.otte@rub.de
+ * \date    2006-05-17
+ * \license    GPLv3 or later
+ * \brief      This file contains an implementaition of a pseudo-random-number generator.
+ * 
+ * Extension 1:
+ *     rndCore is expanded to 512 bits for more security.
+ *
+  \verbatim
+                       ################################################################################################
+                       #                                                                                              #
+                       #         +---------------------------+                                                        #
+                       #         |                           |                                                        #
+                       #         V                           |                                                        #
+                       #      (concat)                       |                                                        #
+   +---------------+   #    o---------o             (xor)+---------+      o---------o        o----o     o---------o   #    +--------------+
+   | entropy Block | -----> | sha-256 | --(offset)-<     | rndCore | ---> | sha-256 | --+----| +1 |---> | sha-256 | -----> | random Block |
+   +---------------+   #    o---------o             (xor)+---------+      o---------o   |    o----o     o---------o   #    +--------------+
+                       #                                 (xor) (xor)                    |                             #
+                       #                                   ^     ^                      |                             #
+                       #                                    \   /                       |                             #
+                       #                                   (offset)---------------------+                             #
+                       #                                                                                              #
+                       ################################################################################################
+  \endverbatim
+ */
+
+#include <inttypes.h>
+#include <string.h>
+#include "sha256.h"
+#include "entropium.h"
+
+#include <stdio.h>
+
+/**
+ * \brief secret entropy pool. 
+ * This is the core of the random which is generated
+ */
+static
+uint32_t rndCore[16]; 
+
+/*************************************************************************/
+
+/* idea is: hash the message and add it via xor to rndCore
+ *
+ * length in bits 
+ * 
+ * we simply first "hash" rndCore, then entropy.
+ */
+void entropium_addEntropy(unsigned length_b, const void* data){
+       sha256_ctx_t s;
+       static uint8_t offset=0; /* selects if higher or lower half gets updated */
+       sha256_init(&s);
+       sha256_nextBlock(&s, rndCore);
+       while (length_b>=512){
+               sha256_nextBlock(&s, data);
+               data = (uint8_t*)data+ 512/8;
+               length_b -= 512;        
+       }
+       sha256_lastBlock(&s, data, length_b);
+       uint8_t i;
+       for (i=0; i<8; ++i){
+               rndCore[i+offset] ^= s.h[i];
+       }
+       offset ^= 8; /* hehe */
+}
+
+/*************************************************************************/
+
+void entropium_getRandomBlock(void *b){
+       sha256_ctx_t s;
+       uint8_t offset=8;
+       
+       sha256_init(&s);
+       sha256_lastBlock(&s, rndCore, 512); /* remember the byte order! */
+       uint8_t i;
+       for (i=0; i<8; ++i){
+               rndCore[i+offset] ^= s.h[i];
+       }
+       offset ^= 8; /* hehe */
+       memcpy(b, s.h, 32); /* back up first hash in b */
+       ((uint8_t*)b)[*((uint8_t*)b)&31]++;     /* the important increment step */
+       sha256_init(&s);
+       sha256_lastBlock(&s, b, 256);
+       memcpy(b, s.h, 32);
+}
+
+/*************************************************************************/
+
+
+uint8_t entropium_getRandomByte(void){
+    static uint8_t block[32];
+    static uint8_t i = 0;
+
+       if(i == 0){
+               entropium_getRandomBlock((void*)block);
+               i = 32;
+       }       
+       return block[--i];
+}
+
+void entropium_fillBlockRandom(void* block, unsigned length_B){
+       while(length_B>ENTROPIUM_RANDOMBLOCK_SIZE){
+               entropium_getRandomBlock(block);
+               block = (uint8_t*)block + ENTROPIUM_RANDOMBLOCK_SIZE;
+               length_B -= ENTROPIUM_RANDOMBLOCK_SIZE;
+       }
+       while(length_B){
+               *((uint8_t*)block) = entropium_getRandomByte();
+               block= (uint8_t*)block +1; --length_B;
+       }
+}
+ 
+