X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/ba6e6b64033b1f9de49feccb5c9cd438354481f7..0f00dc4c8eb47e67bc0f148c2dd109f73a451e0a:/symm/tea.h

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+/* -*-c-*-
+ *
+ * The Tiny Encryption Algorithm
+ *
+ * (c) 2000 Straylight/Edgeware
+ */
+
+/*----- Licensing notice --------------------------------------------------*
+ *
+ * This file is part of Catacomb.
+ *
+ * Catacomb is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Library General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * Catacomb is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with Catacomb; if not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+/*----- Notes on the Tiny Encryption Algorithm ----------------------------*
+ *
+ * TEA is an amazingly simple 64-round Feistel network.  It's tiny, fairly
+ * quick and surprisingly strong.  It was invented by David Wheeler and Roger
+ * Needham.  It's unpatented.  The keyspace is has only 126 effective bits,
+ * and there are related-key attacks.  If you want these fixed, use XTEA.
+ *
+ * This implementation uses big-endian byte order, following SCAN.
+ */
+
+#ifndef CATACOMB_TEA_H
+#define CATACOMB_TEA_H
+
+#ifdef __cplusplus
+  extern "C" {
+#endif
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <stddef.h>
+
+#include <mLib/bits.h>
+
+/*----- Magical numbers ---------------------------------------------------*/
+
+#define TEA_BLKSZ 8
+#define TEA_KEYSZ 16
+#define TEA_CLASS (N, B, 64)
+
+extern const octet tea_keysz[];
+
+/*----- Data structures ---------------------------------------------------*/
+
+typedef struct tea_ctx {
+  unsigned r;
+  uint32 ka, kb, kc, kd;
+} tea_ctx;
+
+/*----- Functions provided ------------------------------------------------*/
+
+/* --- @tea_init@ --- *
+ *
+ * Arguments:	@tea_ctx *k@ = pointer to key block
+ *		@const void *buf@ = pointer to key buffer
+ *		@size_t sz@ = size of key material
+ *
+ * Returns:	---
+ *
+ * Use:		Initializes a TEA key buffer.  The key buffer may be up to 16
+ *		bytes long.
+ */
+
+extern void tea_init(tea_ctx */*k*/, const void */*buf*/, size_t /*sz*/);
+
+/* --- @tea_eblk@, @tea_dblk@ --- *
+ *
+ * Arguments:	@const tea_ctx *k@ = pointer to key block
+ *		@const uint32 s[2]@ = pointer to source block
+ *		@uint32 d[2]@ = pointer to teatination block
+ *
+ * Returns:	---
+ *
+ * Use:		Low-level block encryption and decryption.
+ */
+
+extern void tea_eblk(const tea_ctx */*k*/,
+		     const uint32 */*s*/, uint32 */*d*/);
+extern void tea_dblk(const tea_ctx */*k*/,
+		     const uint32 */*s*/, uint32 */*d*/);
+
+/*----- That's all, folks -------------------------------------------------*/
+
+#ifdef __cplusplus
+  }
+#endif
+
+#endif