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Simplify psa_generator_tls12_prf_generate_next_block()

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This commit is contained in:
Hanno Becker 2018-11-13 20:56:14 +00:00
parent 580fba1431
commit 3b339e2342
1 changed files with 26 additions and 40 deletions
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66
library/psa_crypto.c
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@ -3372,6 +3372,9 @@ static psa_status_t psa_generator_tls12_prf_generate_next_block(
psa_hmac_internal_data hmac; psa_hmac_internal_data hmac;
psa_status_t status, cleanup_status; psa_status_t status, cleanup_status;
unsigned char *Ai;
size_t Ai_len;
/* We can't be wanting more output after block 0xff, otherwise /* We can't be wanting more output after block 0xff, otherwise
* the capacity check in psa_generator_read() would have * the capacity check in psa_generator_read() would have
* prevented this call. It could happen only if the generator * prevented this call. It could happen only if the generator
@ -3415,51 +3418,34 @@ static psa_status_t psa_generator_tls12_prf_generate_next_block(
* length than the other A(i). */ * length than the other A(i). */
if( tls12_prf->block_number == 1 ) if( tls12_prf->block_number == 1 )
{ {
/* Compute A(1) = HMAC_hash(secret, label + seed) */ Ai = tls12_prf->Ai_with_seed + hash_length;
status = psa_hmac_setup_internal( &hmac, Ai_len = tls12_prf->Ai_with_seed_len - hash_length;
tls12_prf->key,
tls12_prf->key_len,
hash_alg );
if( status != PSA_SUCCESS )
goto cleanup;
status = psa_hash_update( &hmac.hash_ctx,
/* This omits the (so far undefined)
* first hash_length bytes. */
tls12_prf->Ai_with_seed + hash_length,
tls12_prf->Ai_with_seed_len - hash_length );
if( status != PSA_SUCCESS )
goto cleanup;
status = psa_hmac_finish_internal( &hmac,
tls12_prf->Ai_with_seed,
hash_length );
if( status != PSA_SUCCESS )
goto cleanup;
} }
else else
{ {
/* Compute A(i+1) = HMAC_hash(secret, A(i)) */ Ai = tls12_prf->Ai_with_seed;
status = psa_hmac_setup_internal( &hmac, Ai_len = hash_length;
tls12_prf->key,
tls12_prf->key_len,
hash_alg );
if( status != PSA_SUCCESS )
goto cleanup;
status = psa_hash_update( &hmac.hash_ctx,
tls12_prf->Ai_with_seed,
/* This omits the seed part of A(i) */
hash_length );
if( status != PSA_SUCCESS )
goto cleanup;
status = psa_hmac_finish_internal( &hmac,
tls12_prf->Ai_with_seed,
hash_length );
if( status != PSA_SUCCESS )
goto cleanup;
} }
/* Compute A(i+1) = HMAC_hash(secret, A(i)) */
status = psa_hmac_setup_internal( &hmac,
tls12_prf->key,
tls12_prf->key_len,
hash_alg );
if( status != PSA_SUCCESS )
goto cleanup;
status = psa_hash_update( &hmac.hash_ctx,
Ai, Ai_len );
if( status != PSA_SUCCESS )
goto cleanup;
status = psa_hmac_finish_internal( &hmac,
tls12_prf->Ai_with_seed,
hash_length );
if( status != PSA_SUCCESS )
goto cleanup;
/* Compute the next block `HMAC_hash(secret, A(i+1) + seed)`. */ /* Compute the next block `HMAC_hash(secret, A(i+1) + seed)`. */
status = psa_hmac_setup_internal( &hmac, status = psa_hmac_setup_internal( &hmac,
tls12_prf->key, tls12_prf->key,