trying to remove unintentionaly comitted files

[avr-crypto-lib.git] / prng.c

diff --git a/prng.c b/prng.c
index 640c2ac031673b50b86efaba70a8d36249c8c05b..ad73bdda488dd690c4e26035ce26a0550e184ff8 100644 (file)
--- a/prng.c
+++ b/prng.c
@@ -1,45 +1,72 @@
 /**
- * File:               prng.c
- * Author:             Daniel Otte
- * Date:               17.05.2006
- * License:            GPL
- * Description:        This file contains an implementaition of a pseudo-random-number generator.
+ * \file               prng.c
+ * \author             Daniel Otte
+ * \date               17.05.2006
+ * \par License:
+ *     GPL
+ * \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)                       |                             |   V                      #
+ *  +---------------+   #    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
+ */
 
-/*
- * 
- *                      ####################################################################################
- *                      #                                                                                                                                                     #
- *                                         #             +---------------------------+                                                                                    #
- *                                         #             |                                           |                                                                                    #
- *                                         #             V                                           |                                                                                    #
- *                      #      (concat)                                  |                                                                                        #
- *  +---------------+   #    o---------o             (xor)+---------+      o---------o       o---------o   #    +--------------+
- *  | entropy Block | -----> | sha-256 | --(offset)-<     | rndCore | ---> | sha-256 | --+-> | sha-256 | -----> | random Block |
- *  +---------------+   #    o---------o             (xor)+---------+      o---------o   |   o---------o   #    +--------------+
- *                                             #                                                     (xor)     (xor)                                    |                                 #
- *                                             #                                                           ^     ^                                              |                                 #
- *                                             #                                                            \   /                                               |                                 #
- *                                             #                                                           (offset)---------------------+                                 #
- *                                             #                                                                                                                                                      #
- *                                             ####################################################################################
- * 
+ /* \verbatim
+ *                      ################################################################################################
+ *                      #                                                                                              #
+ *                      #         +---------------------------+                                                        #
+ *                      #         |                           |                             +---+                      #
+ *                      #         V                           |                             |   |                      #
+ *                      #      (concat)                       |                             |   V                      #
+ *  +---------------+   #    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 <stdint.h>
 #include <string.h>
 #include "sha256.h"
+#include "prng.h"
 
+/**
+ * \brief secret entropy pool. 
+ * This is the core of the random which is generated
+ */
+uint32_t rndCore[16]; 
 
+/*************************************************************************/
 
-
-uint32_t rndCore[16]; /* secret */
-
-/*
- * idea is: hash the message and add it via xor to rndCore
+/**
+ * \brief This function adds entropy to the central entropy pool
+ * 
+ * @param length This ist the length of the random data in BITS. 
+ * @param data This is the random data which should be added to the entropy pool
+*/
+/* idea is: hash the message and add it via xor to rndCore
  *
  * length in bits 
  * 
@@ -52,7 +79,7 @@ void addEntropy(unsigned length, void* data){
        sha256_nextBlock(&s, rndCore);
        while (length>=512){
                sha256_nextBlock(&s, data);
-               data += 512/8;
+               data = (uint8_t*)data+ 512/8;
                length -= 512;  
        }
        sha256_lastBlock(&s, data, length);
@@ -62,7 +89,12 @@ void addEntropy(unsigned length, void* data){
        }
        offset ^= 8; /* hehe */
 }
- 
+
+/*************************************************************************/
+/**
+ * \brief This function fills a given buffer with 32 random bytes
+ * @param b Pointer to buffer wich is to fill
+ */
 void getRandomBlock(uint32_t *b){
        sha256_ctx_t s;
        uint8_t offset=8;
@@ -75,12 +107,18 @@ void getRandomBlock(uint32_t *b){
        }
        offset ^= 8; /* hehe */
        memcpy(b, s.h, 32); /* back up first hash in b */
+       ((uint8_t*)b)[*b&31]++;         /* the important increment step */
        sha256_init(&s);
        sha256_lastBlock(&s, b, 256);
        memcpy(b, s.h, 32);
 }
+
+/*************************************************************************/
  
-/* this does some simple buffering */
+/**
+ * \brief This function simply returns a random byte
+ * @return a random byte
+ */
 uint8_t getRandomByte(void){
        static uint8_t block[32];
        static uint8_t i=32;
@@ -91,5 +129,24 @@ uint8_t getRandomByte(void){
        }       
        return block[i++];
 }
+
+/*************************************************************************/
+ 
+/**
+ * \brief This function fills the given bock with length random bytes
+ * @return a random byte
+ */
+ 
+void fillBlockRandom(void* block, unsigned length){
+       while(length>RANDOMBLOCK_SIZE){
+               getRandomBlock(block);
+               block = (uint8_t*)block + RANDOMBLOCK_SIZE;
+               length -= RANDOMBLOCK_SIZE;
+       }
+       while(length){
+               *((uint8_t*)block) = getRandomByte();
+               block= (uint8_t*)block +1; --length;
+       }
+}