-static int decode_key(const char *key_file, const char *header_str,
- const char *footer_str, unsigned char **result)
+/** Private keys start with this header. */
+#define PRIVATE_KEY_HEADER "-----BEGIN RSA PRIVATE KEY-----"
+/** Private keys end with this footer. */
+#define PRIVATE_KEY_FOOTER "-----END RSA PRIVATE KEY-----"
+
+static int decode_key(const char *key_file, unsigned char **result)