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commented
5 months ago @Knogle Hi, can you confirm I am running the latest version of AES, thanks.
Extract from prng.c
/* EXPERIMENTAL implementation of AES-128 in counter mode to provide high-quality random numbers */
int nwipe_aes_ctr_prng_init( NWIPE_PRNG_INIT_SIGNATURE )
{
nwipe_log( NWIPE_LOG_NOTICE, "Initialising AES CTR PRNG" );
if( *state == NULL )
{
/* This is the first time that we have been called. */
*state = malloc( sizeof( aes_ctr_state_t ) );
}
aes_ctr_prng_init(
(aes_ctr_state_t*) *state, (unsigned long*) ( seed->s ), seed->length / sizeof( unsigned long ) );
return 0;
}
int nwipe_aes_ctr_prng_read( NWIPE_PRNG_READ_SIGNATURE )
{
u8* restrict bufpos = buffer;
size_t words = count / SIZE_OF_AES_CTR_PRNG;
/* Loop to fill the buffer with 128-bit blocks directly */
for( size_t ii = 0; ii < words; ++ii )
{
aes_ctr_prng_genrand_uint128_to_buf( (aes_ctr_state_t*) *state, bufpos );
bufpos += 16; // Move to the next block
}
/* Handle remaining bytes if count is not a multiple of SIZE_OF_AES_CTR_PRNG */
const size_t remain = count % SIZE_OF_AES_CTR_PRNG;
if( remain > 0 )
{
unsigned char temp_output[16]; // Temporary buffer for the last block
aes_ctr_prng_genrand_uint128_to_buf( (aes_ctr_state_t*) *state, temp_output );
// Copy the remaining bytes
memcpy( bufpos, temp_output, remain );
}
return 0; // Success
}aes/aes_ctr_prng.c
/*
* AES CTR PRNG Implementation
* Author: Fabian Druschke
* Date: 2024-03-13
*
* This is an AES (Advanced Encryption Standard) implementation in CTR (Counter) mode
* for pseudorandom number generation, utilizing OpenSSL for cryptographic functions.
*
* As the author of this implementation, I, Fabian Druschke, hereby release this work into
* the public domain. I dedicate any and all copyright interest in this work to the public
* domain, making it free to use for anyone for any purpose without any conditions, unless
* such conditions are required by law.
*
* This software is provided "as is", without warranty of any kind, express or implied,
* including but not limited to the warranties of merchantability, fitness for a particular
* purpose and noninfringement. In no event shall the authors be liable for any claim,
* damages or other liability, whether in an action of contract, tort or otherwise, arising
* from, out of or in connection with the software or the use or other dealings in the software.
*
* USAGE OF OPENSSL IN THIS SOFTWARE:
* This software uses OpenSSL for cryptographic operations. Users are responsible for
* ensuring compliance with OpenSSL's licensing terms.
*/
#include "aes_ctr_prng.h"
#include <openssl/rand.h>
#include <string.h>
#include <openssl/aes.h>
#include <openssl/modes.h>
#include <openssl/sha.h> // Include for SHA256
void aes_ctr_prng_init( aes_ctr_state_t* state, unsigned long init_key[], unsigned long key_length )
{
unsigned char key[32]; // Size for 256 bits
SHA256_CTX sha256;
SHA256_Init( &sha256 );
SHA256_Update( &sha256, (unsigned char*) init_key, key_length * sizeof( unsigned long ) ); // Add the init_key
// Optional: Add a salt to increase uniqueness
// const unsigned char salt[] = "optional salt value";
// SHA256_Update(&sha256, salt, sizeof(salt));
SHA256_Final( key, &sha256 ); // Generate the final key
AES_set_encrypt_key( key, 256, &state->aes_key ); // Use the 256-bit key
memset( state->ivec, 0, AES_BLOCK_SIZE ); // Initialize the IV with zeros
state->num = 0;
memset( state->ecount, 0, AES_BLOCK_SIZE );
}
static void next_state( aes_ctr_state_t* state )
{
for( int i = 0; i < AES_BLOCK_SIZE; ++i )
{
if( ++state->ivec[i] )
break;
}
}
void aes_ctr_prng_genrand_uint128_to_buf( aes_ctr_state_t* state, unsigned char* bufpos )
{
// Initialize bufpos directly with random numbers, avoiding the use of a separate output buffer
CRYPTO_ctr128_encrypt(
bufpos, bufpos, 16, &state->aes_key, state->ivec, state->ecount, &state->num, (block128_f) AES_encrypt );
// Ensure that next_state is called correctly without causing errors
next_state( state );
}
Knogle
Key Features:
Implementation Details:
This PRNG implementation stands as a robust and efficient tool for generating high-quality pseudo-random numbers, crucial for cryptographic operations, secure communications, and randomized algorithms. The combination of AES-CTR mode, OpenSSL's reliability, and the performance benefits of AES-NI hardware acceleration results in a superior random number generator.
I have ensured that the implementation is well-documented with clear comments, making it accessible for review, understanding, and maintenance, following best practices in both software development and cryptographic standards.
I look forward to receiving feedback on this pull request to further improve and ensure the effectiveness of the PRNG implementation.
Test of randomness: