Rearrange the file tree.

[u/mdw/catacomb] / symm / desx.c

diff --git a/symm/desx.c b/symm/desx.c
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+/* -*-c-*-
+ *
+ * Implementation of DESX
+ *
+ * (c) 2001 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.
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <mLib/bits.h>
+
+#include "blkc.h"
+#include "des-base.h"
+#include "des.h"
+#include "desx.h"
+#include "desx-tab.h"
+#include "gcipher.h"
+
+/*----- Tables ------------------------------------------------------------*/
+
+static const octet s[256] = DESX_S;
+
+/*----- Global variables --------------------------------------------------*/
+
+const octet desx_keysz[] = { KSZ_SET, 23, 7, 8, 15, 16, 24, 0 };
+
+/*----- Main code ---------------------------------------------------------*/
+
+/* --- @desx_init@ --- *
+ *
+ * Arguments:  @desx_ctx *k@ = pointer to key block
+ *             @const void *buf@ = pointer to key buffer
+ *             @size_t sz@ = size of key material
+ *
+ * Returns:    ---
+ *
+ * Use:                Initializes a DESX key buffer.  The key buffer contains, in
+ *             order, a single-DES key (either 7 or 8 bytes), an optional
+ *             8-byte pre-whitening key, and an optional 8-byte
+ *             port-whitening key.  If no whitening keys are specified, the
+ *             algorithm becomes the same as single-DES.
+ */
+
+static void mangle(octet *b, const octet *p)
+{
+  unsigned i;
+
+  for (i = 0; i < 8; i++)
+    b[i] = *p++ ^ s[b[i] ^ b[(i + 1) & 7u]];
+}
+
+void desx_init(desx_ctx *k, const void *buf, size_t sz)
+{
+  const octet *p = buf, *kk = buf;
+  size_t n;
+
+  KSZ_ASSERT(desx, sz);
+
+  n = sz % 8 == 7 ? 7 : 8;
+  des_init(&k->k, p, n);
+  p += n;
+  sz -= n;
+  if (!sz)
+    k->prea = k->preb = k->posta = k->postb = 0;
+  else {
+    const octet *q = p;
+    k->prea = LOAD32(q + 0);
+    k->preb = LOAD32(q + 4);
+    p += 8;
+    sz -= 8;
+    if (sz) {
+      k->posta = LOAD32(p + 0);
+      k->postb = LOAD32(p + 4);
+    } else {
+      octet b[16];
+      uint32 x, y;
+
+      des_expand(kk, n, &x, &y);
+      STORE32(b + 8, x); STORE32(b + 12, y);
+      memset(b, 0, 8);
+      mangle(b, b + 8);
+      mangle(b, q);
+      k->posta = LOAD32(b + 0);
+      k->postb = LOAD32(b + 4);
+    }
+  }
+}
+
+/* --- @desx_eblk@, @desx_dblk@ --- *
+ *
+ * Arguments:  @const desx_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.
+ */
+
+void desx_eblk(const desx_ctx *k, const uint32 *s, uint32 *d)
+{
+  uint32 x = s[0], y = s[1];
+  x ^= k->prea; y ^= k->preb;
+  DES_IP(x, y);
+  DES_EBLK(k->k.k, x, y, x, y);
+  DES_IPINV(x, y);
+  x ^= k->posta; y ^= k->postb;
+  d[0] = x, d[1] = y;
+}
+
+void desx_dblk(const desx_ctx *k, const uint32 *s, uint32 *d)
+{
+  uint32 x = s[0], y = s[1];
+  x ^= k->posta; y ^= k->postb;
+  DES_IP(x, y);
+  DES_DBLK(k->k.k, x, y, x, y);
+  DES_IPINV(x, y);
+  x ^= k->prea; y ^= k->preb;
+  d[0] = x, d[1] = y;
+}
+
+BLKC_TEST(DESX, desx)
+
+/*----- That's all, folks -------------------------------------------------*/