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New API function: psa_key_agreement

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Set up a generator from a key agreement.
This commit is contained in:
Gilles Peskine 2018-09-18 12:01:02 +02:00
parent 8feb3a886d
commit 01d718cee8
4 changed files with 256 additions and 0 deletions
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60
library/psa_crypto.c
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@ -3589,6 +3589,66 @@ psa_status_t psa_key_derivation( psa_crypto_generator_t *generator,
/****************************************************************/
/* Key agreement */
/****************************************************************/
#define PSA_KEY_AGREEMENT_MAX_SHARED_SECRET_SIZE MBEDTLS_ECP_MAX_BYTES
static psa_status_t psa_key_agreement_internal( psa_crypto_generator_t *generator,
key_slot_t *private_key,
const uint8_t *peer_key,
size_t peer_key_length,
psa_algorithm_t alg )
{
psa_status_t status;
uint8_t shared_secret[PSA_KEY_AGREEMENT_MAX_SHARED_SECRET_SIZE];
size_t shared_secret_length = 0;
/* Step 1: run the secret agreement algorithm to generate the shared
* secret. */
switch( PSA_ALG_KEY_AGREEMENT_GET_BASE( alg ) )
{
default:
return( PSA_ERROR_NOT_SUPPORTED );
}
if( status != PSA_SUCCESS )
goto exit;
/* Step 2: set up the key derivation to generate key material from
* the shared secret. */
status = psa_key_derivation_internal( generator,
shared_secret, shared_secret_length,
PSA_ALG_KEY_AGREEMENT_GET_KDF( alg ),
NULL, 0, NULL, 0,
PSA_GENERATOR_UNBRIDLED_CAPACITY );
exit:
mbedtls_zeroize( shared_secret, shared_secret_length );
return( status );
}
psa_status_t psa_key_agreement( psa_crypto_generator_t *generator,
psa_key_slot_t private_key,
const uint8_t *peer_key,
size_t peer_key_length,
psa_algorithm_t alg )
{
key_slot_t *slot;
psa_status_t status;
if( ! PSA_ALG_IS_KEY_AGREEMENT( alg ) )
return( PSA_ERROR_INVALID_ARGUMENT );
status = psa_get_key_from_slot( private_key, &slot,
PSA_KEY_USAGE_DERIVE, alg );
if( status != PSA_SUCCESS )
return( status );
return( psa_key_agreement_internal( generator,
slot,
peer_key, peer_key_length,
alg ) );
}
/****************************************************************/
/* Random generation */
/****************************************************************/