Rearrange the file tree.

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

diff --git a/symm/xtea.c b/symm/xtea.c
new file mode 100644 (file)
index 0000000..7f95981
--- /dev/null
+++ b/symm/xtea.c
@@ -0,0 +1,120 @@
+/* -*-c-*-
+ *
+ * The Extended 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.
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <mLib/bits.h>
+
+#include "blkc.h"
+#include "gcipher.h"
+#include "paranoia.h"
+#include "xtea.h"
+
+/*----- Global variables --------------------------------------------------*/
+
+const octet xtea_keysz[] = { KSZ_RANGE, XTEA_KEYSZ, 0, 16, 1 };
+
+/*----- Main code ---------------------------------------------------------*/
+
+/* --- @xtea_init@ --- *
+ *
+ * Arguments:  @xtea_ctx *k@ = pointer to key block
+ *             @const void *buf@ = pointer to key buffer
+ *             @size_t sz@ = size of key material
+ *
+ * Returns:    ---
+ *
+ * Use:                Initializes an XTEA key buffer.  The key buffer must be 16
+ *             bytes long.
+ */
+
+void xtea_init(xtea_ctx *k, const void *buf, size_t sz)
+{
+  octet kb[16];
+  const octet *p;
+
+  KSZ_ASSERT(xtea, sz);
+  if (sz >= sizeof(kb))
+    p = buf;
+  else {
+    memcpy(kb, buf, sz);
+    memset(kb + sz, 0, sizeof(kb) - sz);
+    p = kb;
+  }
+
+  k->k[0] = LOAD32(p + 0); k->k[1] = LOAD32(p +  4);
+  k->k[2] = LOAD32(p + 8); k->k[3] = LOAD32(p + 12);
+  k->r = 32;
+
+  if (p == kb)
+    BURN(kb);
+}
+
+/* --- @xtea_eblk@, @xtea_dblk@ --- *
+ *
+ * Arguments:  @const xtea_ctx *k@ = pointer to key block
+ *             @const uint32 s[2]@ = pointer to source block
+ *             @uint32 d[2]@ = pointer to xteatination block
+ *
+ * Returns:    ---
+ *
+ * Use:                Low-level block encryption and decryption.
+ */
+
+#define DELTA 0x9e3779b9
+
+void xtea_eblk(const xtea_ctx *k, const uint32 *s, uint32 *d)
+{
+  uint32 y = s[0], z = s[1];
+  uint32 n = 0;
+  unsigned i;
+
+  for (i = 0; i < k->r; i++) {
+    y = U32(y + ((((z << 4) ^ (z >> 5)) + z) ^ (n + k->k[n & 3])));
+    n += DELTA;
+    z = U32(z + ((((y << 4) ^ (y >> 5)) + y) ^ (n + k->k[(n >> 11) & 3])));
+  }
+  d[0] = y; d[1] = z;
+}
+
+void xtea_dblk(const xtea_ctx *k, const uint32 *s, uint32 *d)
+{
+  uint32 y = s[0], z = s[1];
+  uint32 n = DELTA * k->r;
+  unsigned i;
+
+  for (i = 0; i < k->r; i++) {
+    z = U32(z - ((((y << 4) ^ (y >> 5)) + y) ^ (n + k->k[(n >> 11) & 3])));
+    n -= DELTA;
+    y = U32(y - ((((z << 4) ^ (z >> 5)) + z) ^ (n + k->k[n & 3])));
+  }
+  d[0] = y; d[1] = z;
+}
+
+BLKC_TEST(XTEA, xtea)
+
+/*----- That's all, folks -------------------------------------------------*/