Implement can_do for opaque ECC keypairs
Unfortunately the can_do wrapper does not receive the key context as an
argument, so it cannot check psa_get_key_information(). Later we might want to
change our internal structures to fix this, but for now we'll just restrict
opaque PSA keys to be ECDSA keypairs, as this is the only thing we need for
now. It also simplifies testing a bit (no need to test each key type).
diff --git a/include/mbedtls/pk.h b/include/mbedtls/pk.h
index b481e43..3f64093 100644
--- a/include/mbedtls/pk.h
+++ b/include/mbedtls/pk.h
@@ -249,7 +249,7 @@
* \brief Initialize a PK context to wrap a PSA key slot.
*
* \param ctx Context to initialize. Must be empty (type NONE).
- * \param key PSA key slot to wrap.
+ * \param key PSA key slot to wrap - must hold an ECC keypair.
*
* \note The wrapped key slot must remain valid as long as the
* wrapping PK context is in use, that is at least between
@@ -257,13 +257,19 @@
* mbedtls_pk_free() is called on this context. The wrapped
* key slot might then be independently used or destroyed.
*
- * \return 0 on success,
- * MBEDTLS_ERR_PK_BAD_INPUT_DATA on invalid input,
- * MBEDTLS_ERR_PK_ALLOC_FAILED on allocation failure.
+ * \return \c 0 on success,
+ * \return #MBEDTLS_ERR_PK_BAD_INPUT_DATA on invalid input
+ * (context already used, invalid key slot)
+ * \return #MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE if the key is not an
+ * ECC keypair,
+ * \return #MBEDTLS_ERR_PK_ALLOC_FAILED on allocation failure.
*
* \note This function replaces mbedtls_pk_setup() for contexts
* that wrap a (possibly opaque) PSA key slot instead of
* storing and manipulating the key material directly.
+ *
+ * \note This function is currently only available for ECC keypair.
+ * Support for other key types will be added later.
*/
int mbedtls_pk_setup_psa( mbedtls_pk_context *ctx, const psa_key_slot_t key );
#endif /* MBEDTLS_USE_PSA_CRYPTO */
diff --git a/library/pk.c b/library/pk.c
index 331ed6c..f65b2ee 100644
--- a/library/pk.c
+++ b/library/pk.c
@@ -147,10 +147,18 @@
{
const mbedtls_pk_info_t * const info = &mbedtls_pk_opaque_psa_info;
psa_key_slot_t *pk_ctx;
+ psa_key_type_t type;
if( ctx == NULL || ctx->pk_info != NULL )
return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );
+ if( PSA_SUCCESS != psa_get_key_information( key, &type, NULL ) )
+ return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );
+
+ /* Current implementation of can_do() relies on this. */
+ if( ! PSA_KEY_TYPE_IS_ECC_KEYPAIR( type ) )
+ return( MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE) ;
+
if( ( ctx->pk_ctx = info->ctx_alloc_func() ) == NULL )
return( MBEDTLS_ERR_PK_ALLOC_FAILED );
diff --git a/library/pk_wrap.c b/library/pk_wrap.c
index 75a49a1..d01694c 100644
--- a/library/pk_wrap.c
+++ b/library/pk_wrap.c
@@ -744,11 +744,20 @@
return( bits );
}
+static int pk_psa_can_do( mbedtls_pk_type_t type )
+{
+ /* For now opaque PSA keys can only wrap ECC keypairs,
+ * as checked by setup_psa().
+ * Also, ECKEY_DH does not really make sense with the current API. */
+ return( type == MBEDTLS_PK_ECKEY ||
+ type == MBEDTLS_PK_ECDSA );
+}
+
const mbedtls_pk_info_t mbedtls_pk_opaque_psa_info = {
MBEDTLS_PK_OPAQUE_PSA,
"Opaque (PSA)",
pk_psa_get_bitlen,
- NULL, /* coming soon: can_do */
+ pk_psa_can_do,
NULL, /* verify - will be done later */
NULL, /* coming soon: sign */
#if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
diff --git a/tests/suites/test_suite_pk.function b/tests/suites/test_suite_pk.function
index 8f6abf5..3beff38 100644
--- a/tests/suites/test_suite_pk.function
+++ b/tests/suites/test_suite_pk.function
@@ -108,6 +108,12 @@
mbedtls_pk_init( &pk );
+ TEST_ASSERT( mbedtls_pk_setup_psa( &pk, 0 ) ==
+ MBEDTLS_ERR_PK_BAD_INPUT_DATA );
+
+ mbedtls_pk_free( &pk );
+ mbedtls_pk_init( &pk );
+
key = pk_psa_genkey();
TEST_ASSERT( key != 0 );
@@ -119,6 +125,10 @@
TEST_ASSERT( mbedtls_pk_get_bitlen( &pk ) == bitlen );
TEST_ASSERT( mbedtls_pk_get_len( &pk ) == bitlen / 8 );
+ TEST_ASSERT( mbedtls_pk_can_do( &pk, MBEDTLS_PK_ECKEY ) == 1 );
+ TEST_ASSERT( mbedtls_pk_can_do( &pk, MBEDTLS_PK_ECDSA ) == 1 );
+ TEST_ASSERT( mbedtls_pk_can_do( &pk, MBEDTLS_PK_RSA ) == 0 );
+
/* test that freeing the context does not destroy the key */
mbedtls_pk_free( &pk );
TEST_ASSERT( PSA_SUCCESS == psa_destroy_key( key ) );
