Rearrange the file tree.

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

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+/* -*-c-*-
+ *
+ * The Data Encryption Standard
+ *
+ * (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.
+ */
+
+/*----- Notes on the Data Encryption Standard -----------------------------*
+ *
+ * Almost twenty years after it was first accepted, DES is still the standard
+ * block cipher.  It's showing its age in its small key size and poor
+ * optimiziation for software implementations, but it's not really been badly
+ * dented by the intensive analysis thrown at it.
+ *
+ * This interface is here for compatibility with existing protocols, and
+ * because it's a trivial veneer over the base DES code which is used by the
+ * @des3@ interface which implements proper strong triple-DES.
+ */
+
+#ifndef CATACOMB_DES_H
+#define CATACOMB_DES_H
+
+#ifdef __cplusplus
+  extern "C" {
+#endif
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <stddef.h>
+
+#include <mLib/bits.h>
+
+/*----- Magical numbers ---------------------------------------------------*/
+
+#define DES_BLKSZ 8
+#define DES_KEYSZ 7
+#define DES_CLASS (N, B, 64)
+
+extern const octet des_keysz[];
+
+/*----- Data structures ---------------------------------------------------*/
+
+typedef struct des_ctx {
+  uint32 k[32];
+} des_ctx;
+
+/*----- Functions provided ------------------------------------------------*/
+
+/* --- @des_expand@ --- *
+ *
+ * Arguments:  @const octet *k@ = pointer to key material
+ *             @size_t n@ = number of octets of key material (7 or 8)
+ *             @uint32 *xx, *yy@ = where to put the results
+ *
+ * Returns:    ---
+ *
+ * Use:                Extracts 64 bits of key material from the given buffer,
+ *             possibly expanding it from 56 to 64 bits on the way.
+ *             Parity is set correctly if the key is expanded.
+ */
+
+extern void des_expand(const octet */*k*/, size_t /*n*/,
+                      uint32 */*xx*/, uint32 */*yy*/);
+
+/* --- @des_init@ --- *
+ *
+ * Arguments:  @des_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 be either 7
+ *             or 8 bytes long.  If it's 8 bytes, the key is assumed to be
+ *             padded with parity bits in the low order bit of each octet.
+ *             These are stripped out without checking prior to the actual
+ *             key scheduling.
+ */
+
+extern void des_init(des_ctx */*k*/, const void */*buf*/, size_t /*sz*/);
+
+/* --- @des_eblk@, @des_dblk@ --- *
+ *
+ * Arguments:  @const des_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 des_eblk(const des_ctx */*k*/,
+                    const uint32 */*s*/, uint32 */*d*/);
+extern void des_dblk(const des_ctx */*k*/,
+                    const uint32 */*s*/, uint32 */*d*/);
+
+/*----- That's all, folks -------------------------------------------------*/
+
+#ifdef __cplusplus
+  }
+#endif
+
+#endif