From f0bf757f9cbfe719463e67b030442eea8299ee38 Mon Sep 17 00:00:00 2001 From: Gilles Peskine Date: Wed, 2 Oct 2019 20:31:54 +0200 Subject: [PATCH] CTR_DRBG: Don't use functions before they're defined Move the definitions of mbedtls_ctr_drbg_seed_entropy_len() and mbedtls_ctr_drbg_seed() to after they are used. This makes the code easier to read and to maintain. --- library/ctr_drbg.c | 124 ++++++++++++++++++++++----------------------- 1 file changed, 62 insertions(+), 62 deletions(-) diff --git a/library/ctr_drbg.c b/library/ctr_drbg.c index 069303fdc..9222f4ef7 100644 --- a/library/ctr_drbg.c +++ b/library/ctr_drbg.c @@ -62,68 +62,6 @@ void mbedtls_ctr_drbg_init( mbedtls_ctr_drbg_context *ctx ) #endif } -/* - * Non-public function wrapped by mbedtls_ctr_drbg_seed(). Necessary to allow - * NIST tests to succeed (which require known length fixed entropy) - */ -/* CTR_DRBG_Instantiate with derivation function (SP 800-90A §10.2.1.3.2) - * mbedtls_ctr_drbg_seed_entropy_len(ctx, f_entropy, p_entropy, - * custom, len, entropy_len) - * implements - * CTR_DRBG_Instantiate(entropy_input, nonce, personalization_string, - * security_strength) -> initial_working_state - * with inputs - * custom[:len] = nonce || personalization_string - * where entropy_input comes from f_entropy for entropy_len bytes - * and with outputs - * ctx = initial_working_state - */ -int mbedtls_ctr_drbg_seed_entropy_len( - mbedtls_ctr_drbg_context *ctx, - int (*f_entropy)(void *, unsigned char *, size_t), - void *p_entropy, - const unsigned char *custom, - size_t len, - size_t entropy_len ) -{ - int ret; - unsigned char key[MBEDTLS_CTR_DRBG_KEYSIZE]; - - mbedtls_platform_memset( key, 0, MBEDTLS_CTR_DRBG_KEYSIZE ); - - mbedtls_aes_init( &ctx->aes_ctx ); - - ctx->f_entropy = f_entropy; - ctx->p_entropy = p_entropy; - - ctx->entropy_len = entropy_len; - ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL; - - /* - * Initialize with an empty key - */ - if( ( ret = mbedtls_aes_setkey_enc( &ctx->aes_ctx, key, MBEDTLS_CTR_DRBG_KEYBITS ) ) != 0 ) - { - return( ret ); - } - - if( ( ret = mbedtls_ctr_drbg_reseed( ctx, custom, len ) ) != 0 ) - { - return( ret ); - } - return( 0 ); -} - -int mbedtls_ctr_drbg_seed( mbedtls_ctr_drbg_context *ctx, - int (*f_entropy)(void *, unsigned char *, size_t), - void *p_entropy, - const unsigned char *custom, - size_t len ) -{ - return( mbedtls_ctr_drbg_seed_entropy_len( ctx, f_entropy, p_entropy, custom, len, - MBEDTLS_CTR_DRBG_ENTROPY_LEN ) ); -} - void mbedtls_ctr_drbg_free( mbedtls_ctr_drbg_context *ctx ) { if( ctx == NULL ) @@ -427,6 +365,68 @@ exit: return( ret ); } +/* + * Non-public function wrapped by mbedtls_ctr_drbg_seed(). Necessary to allow + * NIST tests to succeed (which require known length fixed entropy) + */ +/* CTR_DRBG_Instantiate with derivation function (SP 800-90A §10.2.1.3.2) + * mbedtls_ctr_drbg_seed_entropy_len(ctx, f_entropy, p_entropy, + * custom, len, entropy_len) + * implements + * CTR_DRBG_Instantiate(entropy_input, nonce, personalization_string, + * security_strength) -> initial_working_state + * with inputs + * custom[:len] = nonce || personalization_string + * where entropy_input comes from f_entropy for entropy_len bytes + * and with outputs + * ctx = initial_working_state + */ +int mbedtls_ctr_drbg_seed_entropy_len( + mbedtls_ctr_drbg_context *ctx, + int (*f_entropy)(void *, unsigned char *, size_t), + void *p_entropy, + const unsigned char *custom, + size_t len, + size_t entropy_len ) +{ + int ret; + unsigned char key[MBEDTLS_CTR_DRBG_KEYSIZE]; + + memset( key, 0, MBEDTLS_CTR_DRBG_KEYSIZE ); + + mbedtls_aes_init( &ctx->aes_ctx ); + + ctx->f_entropy = f_entropy; + ctx->p_entropy = p_entropy; + + ctx->entropy_len = entropy_len; + ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL; + + /* + * Initialize with an empty key + */ + if( ( ret = mbedtls_aes_setkey_enc( &ctx->aes_ctx, key, MBEDTLS_CTR_DRBG_KEYBITS ) ) != 0 ) + { + return( ret ); + } + + if( ( ret = mbedtls_ctr_drbg_reseed( ctx, custom, len ) ) != 0 ) + { + return( ret ); + } + return( 0 ); +} + +int mbedtls_ctr_drbg_seed( mbedtls_ctr_drbg_context *ctx, + int (*f_entropy)(void *, unsigned char *, size_t), + void *p_entropy, + const unsigned char *custom, + size_t len ) +{ + return( mbedtls_ctr_drbg_seed_entropy_len( ctx, f_entropy, p_entropy, custom, len, + MBEDTLS_CTR_DRBG_ENTROPY_LEN ) ); +} + /* CTR_DRBG_Generate with derivation function (SP 800-90A §10.2.1.5.2) * mbedtls_ctr_drbg_random_with_add(ctx, output, output_len, additional, add_len) * implements