diff options
Diffstat (limited to 'thirdparty/mbedtls/library/hmac_drbg.c')
| -rw-r--r-- | thirdparty/mbedtls/library/hmac_drbg.c | 86 |
1 files changed, 64 insertions, 22 deletions
diff --git a/thirdparty/mbedtls/library/hmac_drbg.c b/thirdparty/mbedtls/library/hmac_drbg.c index c50330e7d8..50d88bd54b 100644 --- a/thirdparty/mbedtls/library/hmac_drbg.c +++ b/thirdparty/mbedtls/library/hmac_drbg.c @@ -149,20 +149,32 @@ int mbedtls_hmac_drbg_seed_buf( mbedtls_hmac_drbg_context *ctx, } /* - * HMAC_DRBG reseeding: 10.1.2.4 (arabic) + 9.2 (Roman) + * Internal function used both for seeding and reseeding the DRBG. + * Comments starting with arabic numbers refer to section 10.1.2.4 + * of SP800-90A, while roman numbers refer to section 9.2. */ -int mbedtls_hmac_drbg_reseed( mbedtls_hmac_drbg_context *ctx, - const unsigned char *additional, size_t len ) +static int hmac_drbg_reseed_core( mbedtls_hmac_drbg_context *ctx, + const unsigned char *additional, size_t len, + int use_nonce ) { unsigned char seed[MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT]; - size_t seedlen; + size_t seedlen = 0; int ret; - /* III. Check input length */ - if( len > MBEDTLS_HMAC_DRBG_MAX_INPUT || - ctx->entropy_len + len > MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT ) { - return( MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG ); + size_t total_entropy_len; + + if( use_nonce == 0 ) + total_entropy_len = ctx->entropy_len; + else + total_entropy_len = ctx->entropy_len * 3 / 2; + + /* III. Check input length */ + if( len > MBEDTLS_HMAC_DRBG_MAX_INPUT || + total_entropy_len + len > MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT ) + { + return( MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG ); + } } memset( seed, 0, MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT ); @@ -170,9 +182,32 @@ int mbedtls_hmac_drbg_reseed( mbedtls_hmac_drbg_context *ctx, /* IV. Gather entropy_len bytes of entropy for the seed */ if( ( ret = ctx->f_entropy( ctx->p_entropy, seed, ctx->entropy_len ) ) != 0 ) + { return( MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED ); + } + seedlen += ctx->entropy_len; + + /* For initial seeding, allow adding of nonce generated + * from the entropy source. See Sect 8.6.7 in SP800-90A. */ + if( use_nonce ) + { + /* Note: We don't merge the two calls to f_entropy() in order + * to avoid requesting too much entropy from f_entropy() + * at once. Specifically, if the underlying digest is not + * SHA-1, 3 / 2 * entropy_len is at least 36 Bytes, which + * is larger than the maximum of 32 Bytes that our own + * entropy source implementation can emit in a single + * call in configurations disabling SHA-512. */ + if( ( ret = ctx->f_entropy( ctx->p_entropy, + seed + seedlen, + ctx->entropy_len / 2 ) ) != 0 ) + { + return( MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED ); + } + + seedlen += ctx->entropy_len / 2; + } - seedlen = ctx->entropy_len; /* 1. Concatenate entropy and additional data if any */ if( additional != NULL && len != 0 ) @@ -195,7 +230,19 @@ exit: } /* + * HMAC_DRBG reseeding: 10.1.2.4 + 9.2 + */ +int mbedtls_hmac_drbg_reseed( mbedtls_hmac_drbg_context *ctx, + const unsigned char *additional, size_t len ) +{ + return( hmac_drbg_reseed_core( ctx, additional, len, 0 ) ); +} + +/* * HMAC_DRBG initialisation (10.1.2.3 + 9.1) + * + * The nonce is not passed as a separate parameter but extracted + * from the entropy source as suggested in 8.6.7. */ int mbedtls_hmac_drbg_seed( mbedtls_hmac_drbg_context *ctx, const mbedtls_md_info_t * md_info, @@ -205,7 +252,7 @@ int mbedtls_hmac_drbg_seed( mbedtls_hmac_drbg_context *ctx, size_t len ) { int ret; - size_t entropy_len, md_size; + size_t md_size; if( ( ret = mbedtls_md_setup( &ctx->md_ctx, md_info, 1 ) ) != 0 ) return( ret ); @@ -233,20 +280,15 @@ int mbedtls_hmac_drbg_seed( mbedtls_hmac_drbg_context *ctx, * * (This also matches the sizes used in the NIST test vectors.) */ - entropy_len = md_size <= 20 ? 16 : /* 160-bits hash -> 128 bits */ - md_size <= 28 ? 24 : /* 224-bits hash -> 192 bits */ - 32; /* better (256+) -> 256 bits */ - - /* - * For initialisation, use more entropy to emulate a nonce - * (Again, matches test vectors.) - */ - ctx->entropy_len = entropy_len * 3 / 2; + ctx->entropy_len = md_size <= 20 ? 16 : /* 160-bits hash -> 128 bits */ + md_size <= 28 ? 24 : /* 224-bits hash -> 192 bits */ + 32; /* better (256+) -> 256 bits */ - if( ( ret = mbedtls_hmac_drbg_reseed( ctx, custom, len ) ) != 0 ) + if( ( ret = hmac_drbg_reseed_core( ctx, custom, len, + 1 /* add nonce */ ) ) != 0 ) + { return( ret ); - - ctx->entropy_len = entropy_len; + } return( 0 ); } |