commit bf69f2e682cd220aede2f70eaa88acb1acf60e37
author Gilles Peskine <Gilles.Peskine@arm.com> Wed Mar 06 13:39:01 2024 +0100
committer Gilles Peskine <Gilles.Peskine@arm.com> Tue Mar 12 15:06:45 2024 +0100
tree 94115f9526833a20d5b1b15c42fcd69e294bc82c
parent d7e7f48323a0fe06e705849512c7ced2a33edf46

New function mbedtls_pk_copy_public_from_psa

Document and implement mbedtls_pk_copy_public_from_psa() to export the
public key of a PSA key into PK.

Unit-test it alongside mbedtls_pk_copy_from_psa().

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

library/pk.c

diff --git a/library/pk.c b/library/pk.c
index 4345ea2..7bc1da8 100644
--- a/library/pk.c
+++ b/library/pk.c
@@ -1379,7 +1379,9 @@
 }
 
 #if defined(MBEDTLS_PSA_CRYPTO_C)
-int mbedtls_pk_copy_from_psa(mbedtls_svc_key_id_t key_id, mbedtls_pk_context *pk)
+static int copy_from_psa(mbedtls_svc_key_id_t key_id,
+                         mbedtls_pk_context *pk,
+                         int public_only)
 {
     psa_status_t status;
     psa_key_attributes_t key_attr = PSA_KEY_ATTRIBUTES_INIT;
@@ -1400,13 +1402,20 @@
         return MBEDTLS_ERR_PK_BAD_INPUT_DATA;
     }
 
-    status = psa_export_key(key_id, exp_key, sizeof(exp_key), &exp_key_len);
+    if (public_only) {
+        status = psa_export_public_key(key_id, exp_key, sizeof(exp_key), &exp_key_len);
+    } else {
+        status = psa_export_key(key_id, exp_key, sizeof(exp_key), &exp_key_len);
+    }
     if (status != PSA_SUCCESS) {
         ret = PSA_PK_TO_MBEDTLS_ERR(status);
         goto exit;
     }
 
     key_type = psa_get_key_type(&key_attr);
+    if (public_only) {
+        key_type = PSA_KEY_TYPE_PUBLIC_KEY_OF_KEY_PAIR(key_type);
+    }
     key_bits = psa_get_key_bits(&key_attr);
     alg_type = psa_get_key_algorithm(&key_attr);
 
@@ -1485,6 +1494,19 @@
 
     return ret;
 }
+
+
+int mbedtls_pk_copy_from_psa(mbedtls_svc_key_id_t key_id,
+                             mbedtls_pk_context *pk)
+{
+    return copy_from_psa(key_id, pk, 0);
+}
+
+int mbedtls_pk_copy_public_from_psa(mbedtls_svc_key_id_t key_id,
+                                    mbedtls_pk_context *pk)
+{
+    return copy_from_psa(key_id, pk, 1);
+}
 #endif /* MBEDTLS_PSA_CRYPTO_C */
 
 #endif /* MBEDTLS_PK_C */