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Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
diff --git a/ChangeLog.d/support-ecdh-kdf-with-ecdh-key.txt b/ChangeLog.d/support-ecdh-kdf-with-ecdh-key.txt
index 842d5ff..6660dc3 100644
--- a/ChangeLog.d/support-ecdh-kdf-with-ecdh-key.txt
+++ b/ChangeLog.d/support-ecdh-kdf-with-ecdh-key.txt
@@ -2,3 +2,5 @@
* In PSA, allow using a key declared with a base key agreement algorithm
in combined key agreement and derivation operations, as long as the key
agreement algorithm in use matches the algorithm the key was declared with.
+ This is currently non-standard behaviour, but expected to make it into a
+ future revision of the PSA Crypto standard.
diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index 69852fa..ad6f052 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -1085,7 +1085,8 @@
( requested_alg & ~PSA_ALG_HASH_MASK ) );
}
/* If policy_alg is a generic key agreement operation, then using it for
- * a key derivation with that key agreement is also compliant. */
+ * a key derivation with that key agreement should also be allowed. This
+ * behaviour is expected to be defined in a future specification version. */
if( PSA_ALG_IS_RAW_KEY_AGREEMENT( policy_alg ) &&
PSA_ALG_IS_KEY_AGREEMENT( requested_alg ) )
{
@@ -5876,12 +5877,6 @@
PSA_KEY_TYPE_DERIVE,
shared_secret,
shared_secret_length );
-
- /* If a private key has been added as SECRET, we allow the derived
- * key material to be used as a key in PSA Crypto. */
- if( step == PSA_KEY_DERIVATION_INPUT_SECRET )
- operation->can_output_key = 1;
-
exit:
mbedtls_platform_zeroize( shared_secret, shared_secret_length );
return( status );
@@ -5906,6 +5901,13 @@
peer_key, peer_key_length );
if( status != PSA_SUCCESS )
psa_key_derivation_abort( operation );
+ else
+ {
+ /* If a private key has been added as SECRET, we allow the derived
+ * key material to be used as a key in PSA Crypto. */
+ if( step == PSA_KEY_DERIVATION_INPUT_SECRET )
+ operation->can_output_key = 1;
+ }
return( status );
}
diff --git a/tests/suites/test_suite_psa_crypto.function b/tests/suites/test_suite_psa_crypto.function
index 328508d..fc563cb 100644
--- a/tests/suites/test_suite_psa_crypto.function
+++ b/tests/suites/test_suite_psa_crypto.function
@@ -5233,7 +5233,7 @@
{
psa_key_handle_t our_key = 0;
psa_algorithm_t alg = alg_arg;
- psa_algorithm_t key_alg = our_key_alg_arg;
+ psa_algorithm_t our_key_alg = our_key_alg_arg;
psa_key_type_t our_key_type = our_key_type_arg;
psa_key_derivation_operation_t operation = PSA_KEY_DERIVATION_OPERATION_INIT;
psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
@@ -5243,7 +5243,7 @@
PSA_ASSERT( psa_crypto_init( ) );
psa_set_key_usage_flags( &attributes, PSA_KEY_USAGE_DERIVE );
- psa_set_key_algorithm( &attributes, key_alg );
+ psa_set_key_algorithm( &attributes, our_key_alg );
psa_set_key_type( &attributes, our_key_type );
PSA_ASSERT( psa_import_key( &attributes,
our_key_data->x, our_key_data->len,