mbedtls_ecp_write_key: document and test larger output buffer
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/suites/test_suite_ecp.function b/tests/suites/test_suite_ecp.function
index 443bc08..aff5ba4 100644
--- a/tests/suites/test_suite_ecp.function
+++ b/tests/suites/test_suite_ecp.function
@@ -1383,6 +1383,53 @@
}
/* END_CASE */
+/* BEGIN_CASE */
+void ecp_write_key(int grp_id, data_t *in_key,
+ int exported_size, int expected_ret)
+{
+ mbedtls_ecp_keypair key;
+ mbedtls_ecp_keypair_init(&key);
+ unsigned char *exported = NULL;
+
+ TEST_EQUAL(mbedtls_ecp_read_key(grp_id, &key, in_key->x, in_key->len), 0);
+
+ TEST_CALLOC(exported, exported_size);
+ TEST_EQUAL(mbedtls_ecp_write_key(&key, exported, exported_size),
+ expected_ret);
+
+ if (expected_ret == 0) {
+ size_t length = (key.grp.nbits + 7) / 8;
+ TEST_LE_U(length, exported_size);
+
+ const unsigned char *key_start = NULL;
+ const unsigned char *zeros_start = NULL;
+ switch (mbedtls_ecp_get_type(&key.grp)) {
+ case MBEDTLS_ECP_TYPE_SHORT_WEIERSTRASS:
+ key_start = exported + exported_size - length;
+ zeros_start = exported;
+ break;
+ case MBEDTLS_ECP_TYPE_MONTGOMERY:
+ key_start = exported;
+ zeros_start = exported + length;
+ break;
+ default:
+ TEST_FAIL("Unknown ECP curve type");
+ break;
+ }
+ TEST_MEMORY_COMPARE(in_key->x, in_key->len,
+ key_start, length);
+ for (size_t i = 0; i < exported_size - length; i++) {
+ mbedtls_test_set_step(i);
+ TEST_EQUAL(zeros_start[i], 0);
+ }
+ }
+
+exit:
+ mbedtls_ecp_keypair_free(&key);
+ mbedtls_free(exported);
+}
+/* END_CASE */
+
/* BEGIN_CASE depends_on:HAVE_FIX_NEGATIVE */
void fix_negative(data_t *N_bin, int c, int bits)
{