X-Git-Url: https://git.cryptolib.org/?a=blobdiff_plain;f=prng.c;h=ad73bdda488dd690c4e26035ce26a0550e184ff8;hb=cc0d247149bad70179dff52f544381545054da44;hp=640c2ac031673b50b86efaba70a8d36249c8c05b;hpb=3c995d0a8faeb9d37927d48e20fc45d839e066ea;p=avr-crypto-lib.git

diff --git a/prng.c b/prng.c
index 640c2ac..ad73bdd 100644
--- 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;
+	}
+}