diff --git a/src/include/gpxe/crypto.h b/src/include/gpxe/crypto.h
new file mode 100644
index 00000000..e2a728fd
--- /dev/null
+++ b/src/include/gpxe/crypto.h
@@ -0,0 +1,44 @@
+#ifndef _GPXE_CRYPTO_H
+#define _GPXE_CRYPTO_H
+
+/** @file
+ *
+ * Cryptographic API
+ *
+ */
+
+#include <stdint.h>
+
+/**
+ * A message-digest algorithm
+ *
+ */
+struct digest_algorithm {
+	/** Size of a context for this algorithm */
+	size_t context_len;
+	/** Size of a message digest for this algorithm */
+	size_t digest_len;
+	/**
+	 * Initialise digest algorithm
+	 *
+	 * @v context		Context for digest operations
+	 */
+	void ( * init ) ( void *context );
+	/**
+	 * Calculate digest over data buffer
+	 *
+	 * @v context		Context for digest operations
+	 * @v data		Data buffer
+	 * @v len		Length of data buffer
+	 */
+	void ( * update ) ( void *context, const void *data, size_t len );
+	/**
+	 * Finish calculating digest
+	 *
+	 * @v context		Context for digest operations
+	 * @v digest		Buffer for message digest
+	 */
+	void ( * finish ) ( void *context, void *digest );
+};
+
+#endif /* _GPXE_CRYPTO_H */