psa: Move RSA/ECP export code to RSA/ECP specific C file

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/library/psa_crypto_rsa.c b/library/psa_crypto_rsa.c
index b4ea86a..3e5d1b4 100644
--- a/library/psa_crypto_rsa.c
+++ b/library/psa_crypto_rsa.c
@@ -117,7 +117,6 @@
     mbedtls_pk_free( &ctx );
     return( status );
 }
-
 #endif /* defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_CRYPT) ||
         * defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_SIGN) ||
         * defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_OAEP) ||
@@ -125,4 +124,89 @@
         * defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR) ||
         * defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_PUBLIC_KEY) */
 
+#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR) || \
+    defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_PUBLIC_KEY)
+psa_status_t mbedtls_psa_rsa_export_key( psa_key_type_t type,
+                                         mbedtls_rsa_context *rsa,
+                                         uint8_t *data,
+                                         size_t data_size,
+                                         size_t *data_length )
+{
+#if defined(MBEDTLS_PK_WRITE_C)
+    int ret;
+    mbedtls_pk_context pk;
+    uint8_t *pos = data + data_size;
+
+    mbedtls_pk_init( &pk );
+    pk.pk_info = &mbedtls_rsa_info;
+    pk.pk_ctx = rsa;
+
+    /* PSA Crypto API defines the format of an RSA key as a DER-encoded
+     * representation of the non-encrypted PKCS#1 RSAPrivateKey for a
+     * private key and of the RFC3279 RSAPublicKey for a public key. */
+    if( PSA_KEY_TYPE_IS_KEY_PAIR( type ) )
+        ret = mbedtls_pk_write_key_der( &pk, data, data_size );
+    else
+        ret = mbedtls_pk_write_pubkey( &pos, data, &pk );
+
+    if( ret < 0 )
+    {
+        /* Clean up in case pk_write failed halfway through. */
+        memset( data, 0, data_size );
+        return( mbedtls_to_psa_error( ret ) );
+    }
+
+    /* The mbedtls_pk_xxx functions write to the end of the buffer.
+     * Move the data to the beginning and erase remaining data
+     * at the original location. */
+    if( 2 * (size_t) ret <= data_size )
+    {
+        memcpy( data, data + data_size - ret, ret );
+        memset( data + data_size - ret, 0, ret );
+    }
+    else if( (size_t) ret < data_size )
+    {
+        memmove( data, data + data_size - ret, ret );
+        memset( data + ret, 0, data_size - ret );
+    }
+
+    *data_length = ret;
+    return( PSA_SUCCESS );
+#else
+    (void) type;
+    (void) rsa;
+    (void) data;
+    (void) data_size;
+    (void) data_length;
+    return( PSA_ERROR_NOT_SUPPORTED );
+#endif /* MBEDTLS_PK_WRITE_C */
+}
+
+psa_status_t mbedtls_psa_rsa_export_public_key(
+    const psa_key_attributes_t *attributes,
+    const uint8_t *key_buffer, size_t key_buffer_size,
+    uint8_t *data, size_t data_size, size_t *data_length )
+{
+    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
+    mbedtls_rsa_context *rsa = NULL;
+
+    status = mbedtls_psa_rsa_load_representation(
+                 attributes->core.type, key_buffer, key_buffer_size, &rsa );
+    if( status != PSA_SUCCESS )
+        return( status );
+
+    status = mbedtls_psa_rsa_export_key( PSA_KEY_TYPE_RSA_PUBLIC_KEY,
+                                         rsa,
+                                         data,
+                                         data_size,
+                                         data_length );
+
+    mbedtls_rsa_free( rsa );
+    mbedtls_free( rsa );
+
+    return( status );
+}
+#endif /* defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR) ||
+        * defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_PUBLIC_KEY) */
+
 #endif /* MBEDTLS_PSA_CRYPTO_C */