From 8208d167daf4e9b0e506adc9f9687cc2969bd261 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Manuel=20P=C3=A9gouri=C3=A9-Gonnard?= Date: Thu, 30 Jan 2014 12:19:26 +0100 Subject: [PATCH] Add hmac_random_with_add() --- include/polarssl/hmac_drbg.h | 26 ++++++++++++++++++++++++-- library/hmac_drbg.c | 36 ++++++++++++++++++++++++++++++------ 2 files changed, 54 insertions(+), 8 deletions(-) diff --git a/include/polarssl/hmac_drbg.h b/include/polarssl/hmac_drbg.h index f86c13665..b35d62b3d 100644 --- a/include/polarssl/hmac_drbg.h +++ b/include/polarssl/hmac_drbg.h @@ -75,16 +75,38 @@ int hmac_drbg_init( hmac_drbg_context *ctx, void hmac_drbg_update( hmac_drbg_context *ctx, const unsigned char *additional, size_t add_len ); +/** + * \brief HMAC_DRBG generate random with additional update input + * + * Note: Automatically reseeds if reseed_counter is reached. + * + * \param p_rng HMAC_DRBG context + * \param output Buffer to fill + * \param output_len Length of the buffer + * \param additional Additional data to update with (can be NULL) + * \param add_len Length of additional data (can be 0) + * + * \return 0 if successful, or + * TODO: POLARSSL_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED, or + * TODO: POLARSSL_ERR_HMAC_DRBG_REQUEST_TOO_BIG + */ +int hmac_drbg_random_with_add( void *p_rng, + unsigned char *output, size_t output_len, + const unsigned char *additional, + size_t add_len ); + /** * \brief HMAC_DRBG generate random * - * Note: Automatically reseeds if reseed_counter is reached. (TODO) + * Note: Automatically reseeds if reseed_counter is reached. * * \param p_rng HMAC_DRBG context * \param output Buffer to fill * \param output_len Length of the buffer * - * \return 0 if successful. + * \return 0 if successful, or + * TODO: POLARSSL_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED, or + * TODO: POLARSSL_ERR_HMAC_DRBG_REQUEST_TOO_BIG */ int hmac_drbg_random( void *p_rng, unsigned char *output, size_t out_len ); diff --git a/library/hmac_drbg.c b/library/hmac_drbg.c index 6aa1ba565..bc5b90816 100644 --- a/library/hmac_drbg.c +++ b/library/hmac_drbg.c @@ -24,8 +24,9 @@ */ /* - * The NIST SP 800-90 DRBGs are described in the following publication. + * The NIST SP 800-90A DRBGs are described in the following publication. * http://csrc.nist.gov/publications/nistpubs/800-90A/SP800-90A.pdf + * References below are based on rev. 1 (January 2012). */ #include "polarssl/config.h" @@ -35,7 +36,7 @@ #include "polarssl/hmac_drbg.h" /* - * HMAC_DRBG update, using optional additional data + * HMAC_DRBG update, using optional additional data (10.1.2.2) */ void hmac_drbg_update( hmac_drbg_context *ctx, const unsigned char *additional, size_t add_len ) @@ -46,6 +47,7 @@ void hmac_drbg_update( hmac_drbg_context *ctx, for( sep[0] = 0; sep[0] < rounds; sep[0]++ ) { + /* Step 1 or 4 */ md_hmac_starts( &ctx->md_ctx, ctx->K, md_len ); md_hmac_update( &ctx->md_ctx, ctx->V, md_len ); md_hmac_update( &ctx->md_ctx, sep, 1 ); @@ -53,6 +55,7 @@ void hmac_drbg_update( hmac_drbg_context *ctx, md_hmac_update( &ctx->md_ctx, additional, add_len ); md_hmac_finish( &ctx->md_ctx, ctx->K ); + /* Step 2 or 5 */ md_hmac_starts( &ctx->md_ctx, ctx->K, md_len ); md_hmac_update( &ctx->md_ctx, ctx->V, md_len ); md_hmac_finish( &ctx->md_ctx, ctx->V ); @@ -82,15 +85,24 @@ int hmac_drbg_init( hmac_drbg_context *ctx, } /* - * Simplified HMAC_DRBG random function + * HMAC_DRBG random function with optional additional data (10.1.2.5) */ -int hmac_drbg_random( void *p_rng, unsigned char *output, size_t out_len ) +int hmac_drbg_random_with_add( void *p_rng, + unsigned char *output, size_t out_len, + const unsigned char *additional, size_t add_len ) { hmac_drbg_context *ctx = (hmac_drbg_context *) p_rng; - size_t md_len = ctx->md_ctx.md_info->size; + size_t md_len = md_get_size( ctx->md_ctx.md_info ); size_t left = out_len; unsigned char *out = output; + /* 1. Check reseed counter (TODO) */ + + /* 2. Use additional data if any */ + if( additional != NULL && add_len != 0 ) + hmac_drbg_update( ctx, additional, add_len ); + + /* 3, 4, 5. Generate bytes */ while( left != 0 ) { size_t use_len = left > md_len ? md_len : left; @@ -104,11 +116,23 @@ int hmac_drbg_random( void *p_rng, unsigned char *output, size_t out_len ) left -= use_len; } - hmac_drbg_update( ctx, NULL, 0 ); + /* 6. Update */ + hmac_drbg_update( ctx, additional, add_len ); + /* 7. Update reseed counter (TODO) */ + + /* 8. Done */ return( 0 ); } +/* + * HMAC_DRBG random function + */ +int hmac_drbg_random( void *p_rng, unsigned char *output, size_t out_len ) +{ + return( hmac_drbg_random_with_add( p_rng, output, out_len, NULL, 0 ) ); +} + /* * Free an HMAC_DRBG context */