diff --git a/include/psa/crypto_platform.h b/include/psa/crypto_platform.h
index aa55aea..4e2f162 100644
--- a/include/psa/crypto_platform.h
+++ b/include/psa/crypto_platform.h
@@ -44,16 +44,32 @@
 /* PSA requires several types which C99 provides in stdint.h. */
 #include <stdint.h>
 
+#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
+    !defined(inline) && !defined(__cplusplus)
+#define inline __inline
+#endif
+
 /* Integral type representing a key handle. */
 typedef uint16_t psa_key_handle_t;
 
 #if defined(MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER)
 
-#if defined(PSA_CRYPTO_SECURE)
 /* Building for the PSA Crypto service on a PSA platform. */
 /* A key owner is a PSA partition identifier. */
 typedef int32_t mbedtls_key_owner_id_t;
-#endif
+
+/** Compare two key owner identifiers.
+ *
+ * \param id1 First key owner identifier.
+ * \param id2 Second key owner identifier.
+ *
+ * \return Non-zero if the two key owner identifiers are equal, zero otherwise.
+ */
+static inline int mbedtls_key_owner_id_equal( mbedtls_key_owner_id_t id1,
+                                              mbedtls_key_owner_id_t id2 )
+{
+    return( id1 == id2 );
+}
 
 #endif /* MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER */
 
diff --git a/include/psa/crypto_types.h b/include/psa/crypto_types.h
index fb61e9a..864e937 100644
--- a/include/psa/crypto_types.h
+++ b/include/psa/crypto_types.h
@@ -240,6 +240,7 @@
 
 #define MBEDTLS_SVC_KEY_ID_INIT ( (psa_key_id_t)0 )
 #define MBEDTLS_SVC_KEY_ID_GET_KEY_ID( id ) ( id )
+#define MBEDTLS_SVC_KEY_ID_GET_OWNER_ID( id ) ( 0 )
 
 /** Utility to initialize a key identifier at runtime.
  *
@@ -254,6 +255,19 @@
     return( key_id );
 }
 
+/** Compare two key identifiers.
+ *
+ * \param id1 First key identifier.
+ * \param id2 Second key identifier.
+ *
+ * \return Non-zero if the two key identifier are equal, zero otherwise.
+ */
+static inline int mbedtls_svc_key_id_equal( mbedtls_svc_key_id_t id1,
+                                            mbedtls_svc_key_id_t id2 )
+{
+    return( id1 == id2 );
+}
+
 #else /* MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER */
 /* Implementation-specific: The Mbed Cryptography library can be built as
  * part of a multi-client service that exposes the PSA Cryptograpy API in each
@@ -268,6 +282,7 @@
 
 #define MBEDTLS_SVC_KEY_ID_INIT ( (mbedtls_svc_key_id_t){ 0, 0 } )
 #define MBEDTLS_SVC_KEY_ID_GET_KEY_ID( id ) ( ( id ).key_id )
+#define MBEDTLS_SVC_KEY_ID_GET_OWNER_ID( id ) ( ( id ).owner )
 
 /** Utility to initialize a key identifier at runtime.
  *
@@ -281,6 +296,20 @@
                                     .owner = owner_id } );
 }
 
+/** Compare two key identifiers.
+ *
+ * \param id1 First key identifier.
+ * \param id2 Second key identifier.
+ *
+ * \return Non-zero if the two key identifier are equal, zero otherwise.
+ */
+static inline int mbedtls_svc_key_id_equal( mbedtls_svc_key_id_t id1,
+                                            mbedtls_svc_key_id_t id2 )
+{
+    return( ( id1.key_id == id2.key_id ) &&
+            mbedtls_key_owner_id_equal( id1.owner, id2.owner ) );
+}
+
 #endif /* !MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER */
 
 /**@}*/