diff --git a/include/mbedtls/pk.h b/include/mbedtls/pk.h index 57a7005a5..862065eed 100644 --- a/include/mbedtls/pk.h +++ b/include/mbedtls/pk.h @@ -740,6 +740,31 @@ int mbedtls_pk_write_pubkey( unsigned char **p, unsigned char *start, int mbedtls_pk_load_file( const char *path, unsigned char **buf, size_t *n ); #endif +#if defined(MBEDTLS_USE_PSA_CRYPTO) +/** + * \brief Turn an EC key into an Opaque one + * + * \warning This is a temporary utility function for tests. It might + * change or be removed at any time without notice. + * + * \note Only ECDSA keys are supported so far. Signing with the + * specified hash is the only allowed use of that key. + * + * \param pk Input: the EC key to transfer to a PSA key slot. + * Output: a PK context wrapping that PSA key slot. + * \param slot Output: the chosen slot for storing the key. + * It's the caller's responsibility to destroy that slot + * after calling mbedtls_pk_free() on the PK context. + * \param hash_alg The hash algorithm to allow for use with that key. + * + * \return \c 0 if successful. + * \return An Mbed TLS error code otherwise. + */ +int mbedtls_pk_wrap_as_opaque( mbedtls_pk_context *pk, + psa_key_slot_t *slot, + psa_algorithm_t hash_alg ); +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + #ifdef __cplusplus } #endif diff --git a/library/pk.c b/library/pk.c index c34ab7e02..989ed095b 100644 --- a/library/pk.c +++ b/library/pk.c @@ -41,6 +41,10 @@ #include "mbedtls/ecdsa.h" #endif +#if defined(MBEDTLS_USE_PSA_CRYPTO) +#include "mbedtls/psa_util.h" +#endif + #include #include @@ -535,4 +539,65 @@ mbedtls_pk_type_t mbedtls_pk_get_type( const mbedtls_pk_context *ctx ) return( ctx->pk_info->type ); } +#if defined(MBEDTLS_USE_PSA_CRYPTO) +/* + * Load the key to a PSA key slot, + * then turn the PK context into a wrapper for that key slot. + * + * Currently only works for EC private keys. + */ +int mbedtls_pk_wrap_as_opaque( mbedtls_pk_context *pk, + psa_key_slot_t *slot, + psa_algorithm_t hash_alg ) +{ +#if !defined(MBEDTLS_ECP_C) + return( MBEDTLS_ERR_PK_TYPE_MISMATCH ); +#else + psa_key_slot_t key; + const mbedtls_ecp_keypair *ec; + unsigned char d[MBEDTLS_ECP_MAX_BYTES]; + size_t d_len; + psa_ecc_curve_t curve_id; + psa_key_type_t key_type; + psa_key_policy_t policy; + int ret; + + /* export the private key material in the format PSA wants */ + if( mbedtls_pk_get_type( pk ) != MBEDTLS_PK_ECKEY ) + return( MBEDTLS_ERR_PK_TYPE_MISMATCH ); + + ec = mbedtls_pk_ec( *pk ); + d_len = ( ec->grp.nbits + 7 ) / 8; + if( ( ret = mbedtls_mpi_write_binary( &ec->d, d, d_len ) ) != 0 ) + return( ret ); + + curve_id = mbedtls_ecp_curve_info_from_grp_id( ec->grp.id )->tls_id; + + /* find a free key slot */ + if( PSA_SUCCESS != mbedtls_psa_get_free_key_slot( &key ) ) + return( MBEDTLS_ERR_PK_HW_ACCEL_FAILED ); + + /* set policy */ + psa_key_policy_init( &policy ); + psa_key_policy_set_usage( &policy, PSA_KEY_USAGE_SIGN, + PSA_ALG_ECDSA(hash_alg) ); + if( PSA_SUCCESS != psa_set_key_policy( key, &policy ) ) + return( MBEDTLS_ERR_PK_HW_ACCEL_FAILED ); + + /* import private key in slot */ + key_type = PSA_KEY_TYPE_ECC_KEYPAIR(curve_id); + if( PSA_SUCCESS != psa_import_key( key, key_type, d, d_len ) ) + return( MBEDTLS_ERR_PK_HW_ACCEL_FAILED ); + + /* remember slot number to be destroyed later by caller */ + *slot = key; + + /* make PK context wrap the key slot */ + mbedtls_pk_free( pk ); + mbedtls_pk_init( pk ); + + return( mbedtls_pk_setup_opaque( pk, key ) ); +#endif /* MBEDTLS_ECP_C */ +} +#endif /* MBEDTLS_USE_PSA_CRYPTO */ #endif /* MBEDTLS_PK_C */