/*
* HMAC_DRBG random function with optional additional data:
* 10.1.2.5 (arabic) + 9.3 (Roman)
*/
int mbedtls_hmac_drbg_random_with_add( void *p_rng,
unsigned char *output, size_t out_len,
const unsigned char *additional, size_t add_len )
{
int ret;
mbedtls_hmac_drbg_context *ctx = (mbedtls_hmac_drbg_context *) p_rng;
size_t md_len = mbedtls_md_get_size( ctx->md_ctx.md_info );
size_t left = out_len;
unsigned char *out = output;
/* II. Check request length */
if( out_len > MBEDTLS_HMAC_DRBG_MAX_REQUEST )
return( MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG );
/* III. Check input length */
if( add_len > MBEDTLS_HMAC_DRBG_MAX_INPUT )
return( MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG );
/* 1. (aka VII and IX) Check reseed counter and PR */
if( ctx->f_entropy != NULL && /* For no-reseeding instances */
( ctx->prediction_resistance == MBEDTLS_HMAC_DRBG_PR_ON ||
ctx->reseed_counter > ctx->reseed_interval ) )
{
if( ( ret = mbedtls_hmac_drbg_reseed( ctx, additional, add_len ) ) != 0 )
return( ret );
add_len = 0; /* VII.4 */
}
/* 2. Use additional data if any */
if( additional != NULL && add_len != 0 )
mbedtls_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;
mbedtls_md_hmac_reset( &ctx->md_ctx );
mbedtls_md_hmac_update( &ctx->md_ctx, ctx->V, md_len );
mbedtls_md_hmac_finish( &ctx->md_ctx, ctx->V );
memcpy( out, ctx->V, use_len );
out += use_len;
left -= use_len;
}
/* 6. Update */
mbedtls_hmac_drbg_update( ctx, additional, add_len );
/* 7. Update reseed counter */
ctx->reseed_counter++;
/* 8. Done */
return( 0 );
}
int mbedtls_hmac_drbg_update_seed_file( mbedtls_hmac_drbg_context *ctx, const char *path )
{
FILE *f;
size_t n;
unsigned char buf[ MBEDTLS_HMAC_DRBG_MAX_INPUT ];
if( ( f = fopen( path, "rb" ) ) == NULL )
return( MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR );
fseek( f, 0, SEEK_END );
n = (size_t) ftell( f );
fseek( f, 0, SEEK_SET );
if( n > MBEDTLS_HMAC_DRBG_MAX_INPUT )
{
fclose( f );
return( MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG );
}
if( fread( buf, 1, n, f ) != n )
{
fclose( f );
return( MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR );
}
fclose( f );
mbedtls_hmac_drbg_update( ctx, buf, n );
return( mbedtls_hmac_drbg_write_seed_file( ctx, path ) );
}
/*
* HMAC_DRBG reseeding: 10.1.2.4 (arabic) + 9.2 (Roman)
*/
int mbedtls_hmac_drbg_reseed( mbedtls_hmac_drbg_context *ctx,
const unsigned char *additional, size_t len )
{
unsigned char seed[MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT];
size_t seedlen;
size_t entropy_len;
/* III. Check input length */
entropy_len = ctx->entropy_len;
if( len > MBEDTLS_HMAC_DRBG_MAX_INPUT ||
entropy_len + len > MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT )
//ctx->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 );
/* IV. Gather entropy_len bytes of entropy for the seed */
//if( ctx->f_entropy( ctx->p_entropy, seed, ctx->entropy_len ) != 0 )
if( get_entropy(seed, entropy_len ) != 0 )
return( MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED );
seedlen = entropy_len;
/* 1. Concatenate entropy and additional data if any */
if( additional != NULL && len != 0 )
{
memcpy( seed + seedlen, additional, len );
seedlen += len;
}
/* 2. Update state */
mbedtls_hmac_drbg_update( ctx, seed, seedlen );
/* 3. Reset reseed_counter */
ctx->reseed_counter = 1;
/* 4. Done */
return( 0 );
}
/*
* Simplified HMAC_DRBG initialisation (for use with deterministic ECDSA)
*/
int mbedtls_hmac_drbg_seed_buf( mbedtls_hmac_drbg_context *ctx,
const mbedtls_md_info_t * md_info,
const unsigned char *data, size_t data_len )
{
int ret;
if( ( ret = mbedtls_md_setup( &ctx->md_ctx, md_info, 1 ) ) != 0 )
return( ret );
/*
* Set initial working state.
* Use the V memory location, which is currently all 0, to initialize the
* MD context with an all-zero key. Then set V to its initial value.
*/
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 );
return( 0 );
}
