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[u/mdw/catacomb] / symm / des3.h

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+/* -*-c-*-
+ *
+ * Implementation of double- and triple-DES
+ *
+ * (c) 1999 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.
+ */
+
+#ifndef CATACOMB_DES3_H
+#define CATACOMB_DES3_H
+
+#ifdef __cplusplus
+  extern "C" {
+#endif
+
+/*----- Notes on double- and triple-DES -----------------------------------*
+ *
+ * The normal recommendation for using DES now is `triple DES'.
+ * Conventionally, this involves an encrypt-decrypt-encrypt sequence,
+ * although whether the first and last operations use the same key is
+ * unfortunately not agreed upon.  This interface handles both cases (and the
+ * single-key one too, although the simple @des@ calls are quicker for that).
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <stddef.h>
+
+#include <mLib/bits.h>
+
+#ifndef CATACOMB_DES_H
+#  include "des.h"
+#endif
+
+/*----- Magical numbers ---------------------------------------------------*/
+
+#define DES3_BLKSZ 8
+#define DES3_KEYSZ 21
+#define DES3_CLASS (N, B, 64)
+
+extern const octet des3_keysz[];
+
+/*----- Data structures ---------------------------------------------------*/
+
+typedef struct des3_ctx {
+  des_ctx a, b, c;
+} des3_ctx;
+
+/*----- Functions provided ------------------------------------------------*/
+
+/* --- @des3_init@ --- *
+ *
+ * Arguments:  @des3_ctx *k@ = pointer to key block
+ *             @const void *buf@ = pointer to key buffer
+ *             @size_t sz@ = size of key material
+ *
+ * Returns:    ---
+ *
+ * Use:                Initializes a DES key buffer.  The key buffer may have length
+ *             7, 8, 14, 16, 21, or 24.  These correspond to one, two or
+ *             three DES keys, either packed or unpacked (i.e., still
+ *             containing parity bits).
+ */
+
+extern void des3_init(des3_ctx */*k*/, const void */*buf*/, size_t /*sz*/);
+
+/* --- @des3_eblk@, @des_dblk@ --- *
+ *
+ * Arguments:  @const des3_ctx *k@ = pointer to key block
+ *             @const uint32 s[2]@ = pointer to source block
+ *             @uint32 d[2]@ = pointer to destination block
+ *
+ * Returns:    ---
+ *
+ * Use:                Low-level block encryption and decryption.
+ */
+
+extern void des3_eblk(const des3_ctx */*k*/,
+                     const uint32 */*s*/, uint32 */*d*/);
+extern void des3_dblk(const des3_ctx */*k*/,
+                     const uint32 */*s*/, uint32 */*d*/);
+
+/*----- That's all, folks -------------------------------------------------*/
+
+#ifdef __cplusplus
+  }
+#endif
+
+#endif