--- /dev/null
+#ifndef CONFIG_CRYPTO_H
+#define CONFIG_CRYPTO_H
+
+/** @file
+ *
+ * Cryptographic configuration
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+/** Margin of error (in seconds) allowed in signed timestamps
+ *
+ * We default to allowing a reasonable margin of error: 12 hours to
+ * allow for the local time zone being non-GMT, plus 30 minutes to
+ * allow for general clock drift.
+ */
+#define TIMESTAMP_ERROR_MARGIN ( ( 12 * 60 + 30 ) * 60 )
+
+#include <config/named.h>
+#include NAMED_CONFIG(crypto.h)
+#include <config/local/crypto.h>
+#include LOCAL_NAMED_CONFIG(crypto.h)
+
+#endif /* CONFIG_CRYPTO_H */