HMAC_DRBG: deprecate mbedtls_hmac_drbg_update because it ignores errors

Deprecate mbedtls_hmac_drbg_update (which returns void) in favor of a
new function mbedtls_hmac_drbg_update_ret which reports error. The old
function is not officially marked as deprecated in this branch because
this is a stable maintenance branch.
This commit is contained in:
Gilles Peskine 2018-09-13 22:19:57 +02:00
parent 9ce2972399
commit 4d23757fad
2 changed files with 74 additions and 19 deletions

View file

@ -195,11 +195,31 @@ void mbedtls_hmac_drbg_set_reseed_interval( mbedtls_hmac_drbg_context *ctx,
* \param additional Additional data to update state with, or NULL
* \param add_len Length of additional data, or 0
*
* \return \c 0 on success, or an error from the underlying
* hash calculation.
*
* \note Additional data is optional, pass NULL and 0 as second
* third argument if no additional data is being used.
*/
int mbedtls_hmac_drbg_update_ret( mbedtls_hmac_drbg_context *ctx,
const unsigned char *additional, size_t add_len );
/**
* \brief HMAC_DRBG update state
*
* \warning This function cannot report errors. You should use
* mbedtls_hmac_drbg_update_ret() instead.
*
* \param ctx HMAC_DRBG context
* \param additional Additional data to update state with, or NULL
* \param add_len Length of additional data, or 0
*
* \note Additional data is optional, pass NULL and 0 as second
* third argument if no additional data is being used.
*/
void mbedtls_hmac_drbg_update( mbedtls_hmac_drbg_context *ctx,
const unsigned char *additional, size_t add_len );
const unsigned char *additional,
size_t add_len );
/**
* \brief HMAC_DRBG reseeding (extracts data from entropy source)

View file

@ -70,31 +70,56 @@ void mbedtls_hmac_drbg_init( mbedtls_hmac_drbg_context *ctx )
/*
* HMAC_DRBG update, using optional additional data (10.1.2.2)
*/
void mbedtls_hmac_drbg_update( mbedtls_hmac_drbg_context *ctx,
const unsigned char *additional, size_t add_len )
int mbedtls_hmac_drbg_update_ret( mbedtls_hmac_drbg_context *ctx,
const unsigned char *additional,
size_t add_len )
{
size_t md_len = mbedtls_md_get_size( ctx->md_ctx.md_info );
unsigned char rounds = ( additional != NULL && add_len != 0 ) ? 2 : 1;
unsigned char sep[1];
unsigned char K[MBEDTLS_MD_MAX_SIZE];
int ret;
for( sep[0] = 0; sep[0] < rounds; sep[0]++ )
{
/* Step 1 or 4 */
mbedtls_md_hmac_reset( &ctx->md_ctx );
mbedtls_md_hmac_update( &ctx->md_ctx, ctx->V, md_len );
mbedtls_md_hmac_update( &ctx->md_ctx, sep, 1 );
if( ( ret = mbedtls_md_hmac_reset( &ctx->md_ctx ) ) != 0 )
goto exit;
if( ( ret = mbedtls_md_hmac_update( &ctx->md_ctx,
ctx->V, md_len ) ) != 0 )
goto exit;
if( ( ret = mbedtls_md_hmac_update( &ctx->md_ctx,
sep, 1 ) ) != 0 )
goto exit;
if( rounds == 2 )
mbedtls_md_hmac_update( &ctx->md_ctx, additional, add_len );
mbedtls_md_hmac_finish( &ctx->md_ctx, K );
{
if( ( ret = mbedtls_md_hmac_update( &ctx->md_ctx,
additional, add_len ) ) != 0 )
goto exit;
}
if( ( ret = mbedtls_md_hmac_finish( &ctx->md_ctx, K ) ) != 0 )
goto exit;
/* Step 2 or 5 */
mbedtls_md_hmac_starts( &ctx->md_ctx, K, md_len );
mbedtls_md_hmac_update( &ctx->md_ctx, ctx->V, md_len );
mbedtls_md_hmac_finish( &ctx->md_ctx, ctx->V );
if( ( ret = mbedtls_md_hmac_starts( &ctx->md_ctx, K, md_len ) ) != 0 )
goto exit;
if( ( ret = mbedtls_md_hmac_update( &ctx->md_ctx,
ctx->V, md_len ) ) != 0 )
goto exit;
if( ( ret = mbedtls_md_hmac_finish( &ctx->md_ctx, ctx->V ) ) != 0 )
goto exit;
}
exit:
mbedtls_zeroize( K, sizeof( K ) );
return( ret );
}
void mbedtls_hmac_drbg_update( mbedtls_hmac_drbg_context *ctx,
const unsigned char *additional,
size_t add_len )
{
(void) mbedtls_hmac_drbg_update_ret( ctx, additional, add_len );
}
/*
@ -117,7 +142,8 @@ int mbedtls_hmac_drbg_seed_buf( mbedtls_hmac_drbg_context *ctx,
mbedtls_md_hmac_starts( &ctx->md_ctx, ctx->V, mbedtls_md_get_size( md_info ) );
memset( ctx->V, 0x01, mbedtls_md_get_size( md_info ) );
mbedtls_hmac_drbg_update( ctx, data, data_len );
if( ( ret = mbedtls_hmac_drbg_update_ret( ctx, data, data_len ) ) != 0 )
return( ret );
return( 0 );
}
@ -130,6 +156,7 @@ int mbedtls_hmac_drbg_reseed( mbedtls_hmac_drbg_context *ctx,
{
unsigned char seed[MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT];
size_t seedlen;
int ret;
/* III. Check input length */
if( len > MBEDTLS_HMAC_DRBG_MAX_INPUT ||
@ -154,14 +181,16 @@ int mbedtls_hmac_drbg_reseed( mbedtls_hmac_drbg_context *ctx,
}
/* 2. Update state */
mbedtls_hmac_drbg_update( ctx, seed, seedlen );
if( ( ret = mbedtls_hmac_drbg_update_ret( ctx, seed, seedlen ) ) != 0 )
goto exit;
/* 3. Reset reseed_counter */
ctx->reseed_counter = 1;
exit:
/* 4. Done */
mbedtls_zeroize( seed, seedlen );
return( 0 );
return( ret );
}
/*
@ -280,7 +309,11 @@ int mbedtls_hmac_drbg_random_with_add( void *p_rng,
/* 2. Use additional data if any */
if( additional != NULL && add_len != 0 )
mbedtls_hmac_drbg_update( ctx, additional, add_len );
{
if( ( ret = mbedtls_hmac_drbg_update_ret( ctx,
additional, add_len ) ) != 0 )
goto exit;
}
/* 3, 4, 5. Generate bytes */
while( left != 0 )
@ -297,13 +330,16 @@ int mbedtls_hmac_drbg_random_with_add( void *p_rng,
}
/* 6. Update */
mbedtls_hmac_drbg_update( ctx, additional, add_len );
if( ( ret = mbedtls_hmac_drbg_update_ret( ctx,
additional, add_len ) ) != 0 )
goto exit;
/* 7. Update reseed counter */
ctx->reseed_counter++;
exit:
/* 8. Done */
return( 0 );
return( ret );
}
/*
@ -395,8 +431,7 @@ int mbedtls_hmac_drbg_update_seed_file( mbedtls_hmac_drbg_context *ctx, const ch
if( fread( buf, 1, n, f ) != n )
ret = MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR;
else
mbedtls_hmac_drbg_update( ctx, buf, n );
ret = mbedtls_hmac_drbg_update_ret( ctx, buf, n );
fclose( f );
mbedtls_zeroize( buf, sizeof( buf ) );