X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/165c059ff958e6a98cdaf42d5d4ffd96f7646366..ea937a0ebd081c146194a848ff3ca3829265a341:/tea.c

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+/* -*-c-*-
+ *
+ * $Id: tea.c,v 1.1 2000/07/15 13:44:31 mdw Exp $
+ *
+ * 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.
+ */
+
+/*----- Revision history --------------------------------------------------* 
+ *
+ * $Log: tea.c,v $
+ * Revision 1.1  2000/07/15 13:44:31  mdw
+ * New ciphers.
+ *
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <mLib/bits.h>
+
+#include "blkc.h"
+#include "gcipher.h"
+#include "paranoia.h"
+#include "tea.h"
+
+/*----- Global variables --------------------------------------------------*/
+
+const octet tea_keysz[] = { KSZ_RANGE, TEA_KEYSZ, 0, 16, 1 };
+
+/*----- Main code ---------------------------------------------------------*/
+
+/* --- @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 must be 16
+ *		bytes long.
+ */
+
+void tea_init(tea_ctx *k, const void *buf, size_t sz)
+{
+  octet kb[16];
+  const octet *p;
+
+  KSZ_ASSERT(tea, sz);
+  if (sz >= sizeof(kb))
+    p = buf;
+  else {
+    memcpy(kb, buf, sz);
+    memset(kb + sz, 0, sizeof(kb) - sz);
+    p = kb;
+  }
+
+  k->ka = LOAD32(p +  0);   k->kb = LOAD32(p +  4);
+  k->kc = LOAD32(p +  8);   k->kd = LOAD32(p + 12);
+
+  if (p == kb)
+    BURN(kb);
+}
+
+/* --- @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.
+ */
+
+#define DELTA 0x9e3779b9
+
+void tea_eblk(const tea_ctx *k, const uint32 *s, uint32 *d)
+{
+  uint32 y = s[0], z = s[1];
+  uint32 ka = k->ka, kb = k->kb, kc = k->kc, kd = k->kd;
+  uint32 n = 0;
+  unsigned i;
+
+  for (i = 0; i < 32; i++) {
+    n += DELTA;
+    y = U32(y + (((z << 4) + ka) ^ (z + n) ^ ((z >> 5) + kb)));
+    z = U32(z + (((y << 4) + kc) ^ (y + n) ^ ((y >> 5) + kd)));
+  }
+  d[0] = y; d[1] = z;
+}
+
+void tea_dblk(const tea_ctx *k, const uint32 *s, uint32 *d)
+{
+  uint32 y = s[0], z = s[1];
+  uint32 ka = k->ka, kb = k->kb, kc = k->kc, kd = k->kd;
+  uint32 n = DELTA << 5;
+  unsigned i;
+
+  for (i = 0; i < 32; i++) {
+    z = U32(z - (((y << 4) + kc) ^ (y + n) ^ ((y >> 5) + kd)));
+    y = U32(y - (((z << 4) + ka) ^ (z + n) ^ ((z >> 5) + kb)));
+    n -= DELTA;
+  }
+  d[0] = y; d[1] = z;
+}
+
+BLKC_TEST(TEA, tea)
+
+/*----- That's all, folks -------------------------------------------------*/