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Implement ECDH

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This commit is contained in:
Gilles Peskine
2018-09-18 12:11:27 +02:00
parent 5968559a9c
commit b7ecdf0509
2 changed files with 123 additions and 5 deletions
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54
library/psa_crypto.c
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@ -62,6 +62,7 @@
#include "mbedtls/cmac.h"
#include "mbedtls/ctr_drbg.h"
#include "mbedtls/des.h"
#include "mbedtls/ecdh.h"
#include "mbedtls/ecp.h"
#include "mbedtls/entropy.h"
#include "mbedtls/error.h"
@ -3593,6 +3594,48 @@ psa_status_t psa_key_derivation( psa_crypto_generator_t *generator,
/* Key agreement */
/****************************************************************/
static psa_status_t psa_key_agreement_ecdh( const uint8_t *peer_key,
size_t peer_key_length,
const mbedtls_ecp_keypair *our_key,
uint8_t *shared_secret,
size_t shared_secret_size,
size_t *shared_secret_length )
{
mbedtls_pk_context pk;
mbedtls_ecp_keypair *their_key = NULL;
mbedtls_ecdh_context ecdh;
int ret;
mbedtls_ecdh_init( &ecdh );
mbedtls_pk_init( &pk );
ret = mbedtls_pk_parse_public_key( &pk, peer_key, peer_key_length );
if( ret != 0 )
goto exit;
if( mbedtls_pk_get_type( &pk ) != MBEDTLS_PK_ECKEY )
{
ret = MBEDTLS_ERR_ECP_INVALID_KEY;
goto exit;
}
their_key = mbedtls_pk_ec( pk );
ret = mbedtls_ecdh_get_params( &ecdh, their_key, MBEDTLS_ECDH_THEIRS );
if( ret != 0 )
goto exit;
ret = mbedtls_ecdh_get_params( &ecdh, our_key, MBEDTLS_ECDH_OURS );
if( ret != 0 )
goto exit;
ret = mbedtls_ecdh_calc_secret( &ecdh,
shared_secret_length,
shared_secret, shared_secret_size,
mbedtls_ctr_drbg_random,
&global_data.ctr_drbg );
exit:
mbedtls_pk_free( &pk );
mbedtls_ecdh_free( &ecdh );
return( mbedtls_to_psa_error( ret ) );
}
#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,
@ -3609,6 +3652,17 @@ static psa_status_t psa_key_agreement_internal( psa_crypto_generator_t *generato
* secret. */
switch( PSA_ALG_KEY_AGREEMENT_GET_BASE( alg ) )
{
#if defined(MBEDTLS_ECDH_C)
case PSA_ALG_ECDH_BASE:
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,
shared_secret,
sizeof( shared_secret ),
&shared_secret_length );
break;
#endif /* MBEDTLS_ECDH_C */
default:
return( PSA_ERROR_NOT_SUPPORTED );
}