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Implement psa_key_agreement_raw_shared_secret

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Refactor: split psa_key_agreement_raw_internal out of
psa_key_agreement_internal, and call it from
psa_key_agreement_raw_shared_secret as well.
This commit is contained in:
Gilles Peskine 2019-04-11 21:23:21 +02:00
parent f9ee633d33
commit 0216fe16b7
1 changed files with 76 additions and 16 deletions
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92
library/psa_crypto.c
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@ -4596,6 +4596,37 @@ exit:
#define PSA_KEY_AGREEMENT_MAX_SHARED_SECRET_SIZE MBEDTLS_ECP_MAX_BYTES
static psa_status_t psa_key_agreement_raw_internal( psa_algorithm_t alg,
psa_key_slot_t *private_key,
const uint8_t *peer_key,
size_t peer_key_length,
uint8_t *shared_secret,
size_t shared_secret_size,
size_t *shared_secret_length )
{
switch( alg )
{
#if defined(MBEDTLS_ECDH_C)
case PSA_ALG_ECDH:
if( ! PSA_KEY_TYPE_IS_ECC_KEYPAIR( private_key->type ) )
return( PSA_ERROR_INVALID_ARGUMENT );
return( psa_key_agreement_ecdh( peer_key, peer_key_length,
private_key->data.ecp,
shared_secret, shared_secret_size,
shared_secret_length ) );
break;
#endif /* MBEDTLS_ECDH_C */
default:
(void) private_key;
(void) peer_key;
(void) peer_key_length;
(void) shared_secret;
(void) shared_secret_size;
(void) shared_secret_length;
return( PSA_ERROR_NOT_SUPPORTED );
}
}
/* Note that if this function fails, you must call psa_generator_abort()
* to potentially free embedded data structures and wipe confidential data.
*/
@ -4608,28 +4639,16 @@ static psa_status_t psa_key_agreement_internal( psa_crypto_generator_t *generato
psa_status_t status;
uint8_t shared_secret[PSA_KEY_AGREEMENT_MAX_SHARED_SECRET_SIZE];
size_t shared_secret_length = 0;
psa_algorithm_t ka_alg = PSA_ALG_KEY_AGREEMENT_GET_BASE( generator->alg );
/* Step 1: run the secret agreement algorithm to generate the shared
* secret. */
switch( PSA_ALG_KEY_AGREEMENT_GET_BASE( generator->alg ) )
{
#if defined(MBEDTLS_ECDH_C)
case PSA_ALG_ECDH:
if( ! PSA_KEY_TYPE_IS_ECC_KEYPAIR( private_key->type ) )
return( PSA_ERROR_INVALID_ARGUMENT );
status = psa_key_agreement_ecdh( peer_key, peer_key_length,
private_key->data.ecp,
status = psa_key_agreement_raw_internal( ka_alg,
private_key,
peer_key, peer_key_length,
shared_secret,
sizeof( shared_secret ),
&shared_secret_length );
break;
#endif /* MBEDTLS_ECDH_C */
default:
(void) private_key;
(void) peer_key;
(void) peer_key_length;
return( PSA_ERROR_NOT_SUPPORTED );
}
if( status != PSA_SUCCESS )
goto exit;
@ -4665,6 +4684,47 @@ psa_status_t psa_key_agreement( psa_crypto_generator_t *generator,
return( status );
}
psa_status_t psa_key_agreement_raw_shared_secret( psa_algorithm_t alg,
psa_key_handle_t private_key,
const uint8_t *peer_key,
size_t peer_key_length,
uint8_t *output,
size_t output_size,
size_t *output_length )
{
psa_key_slot_t *slot;
psa_status_t status;
if( ! PSA_ALG_IS_KEY_AGREEMENT( alg ) )
{
status = PSA_ERROR_INVALID_ARGUMENT;
goto exit;
}
status = psa_get_key_from_slot( private_key, &slot,
PSA_KEY_USAGE_DERIVE, alg );
if( status != PSA_SUCCESS )
goto exit;
status = psa_key_agreement_raw_internal( alg, slot,
peer_key, peer_key_length,
output, output_size,
output_length );
exit:
if( status != PSA_SUCCESS )
{
/* If an error happens and is not handled properly, the output
* may be used as a key to protect sensitive data. Arrange for such
* a key to be random, which is likely to result in decryption or
* verification errors. This is better than filling the buffer with
* some constant data such as zeros, which would result in the data
* being protected with a reproducible, easily knowable key.
*/
psa_generate_random( output, output_size );
*output_length = output_size;
}
return( status );
}
/****************************************************************/