commit 2a38e2477aeca86c881f04a9acc95ee4cd1171fa
author Gilles Peskine <Gilles.Peskine@arm.com> Wed May 29 14:33:00 2019 +0200
committer Janos Follath <janos.follath@arm.com> Thu Jul 04 14:41:07 2019 +0100
tree 0170e21ce4f2bf6c49547de220ea8613df475a09
parent 4e2cc5353cada4eddd6066e612bdb8e006cc0067

Slightly simplify derive_wrapping_key

No error can arise after the wrapping key is created, so remove the
corresponding cleanup code.

programs/psa/key_ladder_demo.c

diff --git a/programs/psa/key_ladder_demo.c b/programs/psa/key_ladder_demo.c
index 800896f..91e5178 100644
--- a/programs/psa/key_ladder_demo.c
+++ b/programs/psa/key_ladder_demo.c
@@ -333,11 +333,9 @@
     psa_key_derivation_operation_t operation = PSA_KEY_DERIVATION_OPERATION_INIT;
 
     *wrapping_key_handle = 0;
-    psa_set_key_usage_flags( &attributes, usage );
-    psa_set_key_algorithm( &attributes, WRAPPING_ALG );
-    psa_set_key_type( &attributes, PSA_KEY_TYPE_AES );
-    psa_set_key_bits( &attributes, WRAPPING_KEY_BITS );
 
+    /* Set up a key derivation operation from the key derived from
+     * the master key. */
     PSA_CHECK( psa_key_derivation_setup( &operation, KDF_ALG ) );
     PSA_CHECK( psa_key_derivation_input_bytes(
                    &operation, PSA_KEY_DERIVATION_INPUT_SALT,
@@ -348,16 +346,17 @@
     PSA_CHECK( psa_key_derivation_input_bytes(
                    &operation, PSA_KEY_DERIVATION_INPUT_INFO,
                    NULL, 0 ) );
+
+    /* Create the wrapping key. */
+    psa_set_key_usage_flags( &attributes, usage );
+    psa_set_key_algorithm( &attributes, WRAPPING_ALG );
+    psa_set_key_type( &attributes, PSA_KEY_TYPE_AES );
+    psa_set_key_bits( &attributes, WRAPPING_KEY_BITS );
     PSA_CHECK( psa_key_derivation_output_key( &attributes, &operation,
                                               wrapping_key_handle ) );
 
 exit:
     psa_key_derivation_abort( &operation );
-    if( status != PSA_SUCCESS )
-    {
-        psa_close_key( *wrapping_key_handle );
-        *wrapping_key_handle = 0;
-    }
     return( status );
 }