--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/rc5.c	Mon May 31 18:21:40 2004 +0000
@@ -0,0 +1,269 @@
+/* LibTomCrypt, modular cryptographic library -- Tom St Denis
+ *
+ * LibTomCrypt is a library that provides various cryptographic
+ * algorithms in a highly modular and flexible manner.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ *
+ * Tom St Denis, [email protected], http://libtomcrypt.org
+ */
+
+/* RC5 code by Tom St Denis */
+
+#include "mycrypt.h"
+
+#ifdef RC5
+
+const struct _cipher_descriptor rc5_desc =
+{
+    "rc5",
+    2,
+    8, 128, 8, 12,
+    &rc5_setup,
+    &rc5_ecb_encrypt,
+    &rc5_ecb_decrypt,
+    &rc5_test,
+    &rc5_keysize
+};
+
+static const ulong32 stab[50] = {
+0xb7e15163UL, 0x5618cb1cUL, 0xf45044d5UL, 0x9287be8eUL, 0x30bf3847UL, 0xcef6b200UL, 0x6d2e2bb9UL, 0x0b65a572UL,
+0xa99d1f2bUL, 0x47d498e4UL, 0xe60c129dUL, 0x84438c56UL, 0x227b060fUL, 0xc0b27fc8UL, 0x5ee9f981UL, 0xfd21733aUL,
+0x9b58ecf3UL, 0x399066acUL, 0xd7c7e065UL, 0x75ff5a1eUL, 0x1436d3d7UL, 0xb26e4d90UL, 0x50a5c749UL, 0xeedd4102UL,
+0x8d14babbUL, 0x2b4c3474UL, 0xc983ae2dUL, 0x67bb27e6UL, 0x05f2a19fUL, 0xa42a1b58UL, 0x42619511UL, 0xe0990ecaUL,
+0x7ed08883UL, 0x1d08023cUL, 0xbb3f7bf5UL, 0x5976f5aeUL, 0xf7ae6f67UL, 0x95e5e920UL, 0x341d62d9UL, 0xd254dc92UL,
+0x708c564bUL, 0x0ec3d004UL, 0xacfb49bdUL, 0x4b32c376UL, 0xe96a3d2fUL, 0x87a1b6e8UL, 0x25d930a1UL, 0xc410aa5aUL,
+0x62482413UL, 0x007f9dccUL
+};
+
+#ifdef CLEAN_STACK
+static int _rc5_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
+#else
+int rc5_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
+#endif
+{
+    ulong32 L[64], *S, A, B, i, j, v, s, t, l;
+
+    _ARGCHK(skey != NULL);
+    _ARGCHK(key  != NULL);
+    
+    /* test parameters */
+    if (num_rounds == 0) { 
+       num_rounds = rc5_desc.default_rounds;
+    }
+
+    if (num_rounds < 12 || num_rounds > 24) { 
+       return CRYPT_INVALID_ROUNDS;
+    }
+
+    /* key must be between 64 and 1024 bits */
+    if (keylen < 8 || keylen > 128) {
+       return CRYPT_INVALID_KEYSIZE;
+    }
+    
+    skey->rc5.rounds = num_rounds;
+    S = skey->rc5.K;
+
+    /* copy the key into the L array */
+    for (A = i = j = 0; i < (ulong32)keylen; ) { 
+        A = (A << 8) | ((ulong32)(key[i++] & 255));
+        if ((i & 3) == 0) {
+           L[j++] = BSWAP(A);
+           A = 0;
+        }
+    }
+
+    if ((keylen & 3) != 0) { 
+       A <<= (ulong32)((8 * (4 - (keylen&3)))); 
+       L[j++] = BSWAP(A);
+    }
+
+    /* setup the S array */
+    t = (ulong32)(2 * (num_rounds + 1));
+    memcpy(S, stab, t * sizeof(*S));
+
+    /* mix buffer */
+    s = 3 * MAX(t, j);
+    l = j;
+    for (A = B = i = j = v = 0; v < s; v++) { 
+        A = S[i] = ROL(S[i] + A + B, 3);
+        B = L[j] = ROL(L[j] + A + B, (A+B));
+        if (++i == t) { i = 0; }
+        if (++j == l) { j = 0; }
+    }
+    return CRYPT_OK;
+}
+
+#ifdef CLEAN_STACK
+int rc5_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
+{
+   int x;
+   x = _rc5_setup(key, keylen, num_rounds, skey);
+   burn_stack(sizeof(ulong32) * 122 + sizeof(int));
+   return x;
+}
+#endif
+
+#ifdef CLEAN_STACK
+static void _rc5_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key)
+#else
+void rc5_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key)
+#endif
+{
+   ulong32 A, B, *K;
+   int r;
+   _ARGCHK(key != NULL);
+   _ARGCHK(pt != NULL);
+   _ARGCHK(ct != NULL);
+
+   LOAD32L(A, &pt[0]);
+   LOAD32L(B, &pt[4]);
+   A += key->rc5.K[0];
+   B += key->rc5.K[1];
+   K  = key->rc5.K + 2;
+   
+   if ((key->rc5.rounds & 1) == 0) {
+      for (r = 0; r < key->rc5.rounds; r += 2) {
+          A = ROL(A ^ B, B) + K[0];
+          B = ROL(B ^ A, A) + K[1];
+          A = ROL(A ^ B, B) + K[2];
+          B = ROL(B ^ A, A) + K[3];
+          K += 4;
+      }
+   } else {
+      for (r = 0; r < key->rc5.rounds; r++) {
+          A = ROL(A ^ B, B) + K[0];
+          B = ROL(B ^ A, A) + K[1];
+          K += 2;
+      }
+   }
+   STORE32L(A, &ct[0]);
+   STORE32L(B, &ct[4]);
+}
+
+#ifdef CLEAN_STACK
+void rc5_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key)
+{
+   _rc5_ecb_encrypt(pt, ct, key);
+   burn_stack(sizeof(ulong32) * 2 + sizeof(int));
+}
+#endif
+
+#ifdef CLEAN_STACK
+static void _rc5_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key)
+#else
+void rc5_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key)
+#endif
+{
+   ulong32 A, B, *K;
+   int r;
+   _ARGCHK(key != NULL);
+   _ARGCHK(pt != NULL);
+   _ARGCHK(ct != NULL);
+
+   LOAD32L(A, &ct[0]);
+   LOAD32L(B, &ct[4]);
+   K = key->rc5.K + (key->rc5.rounds << 1);
+   
+   if ((key->rc5.rounds & 1) == 0) {
+       K -= 2;
+       for (r = key->rc5.rounds - 1; r >= 0; r -= 2) {
+          B = ROR(B - K[3], A) ^ A;
+          A = ROR(A - K[2], B) ^ B;
+          B = ROR(B - K[1], A) ^ A;
+          A = ROR(A - K[0], B) ^ B;
+          K -= 4;
+        }
+   } else {
+      for (r = key->rc5.rounds - 1; r >= 0; r--) {
+          B = ROR(B - K[1], A) ^ A;
+          A = ROR(A - K[0], B) ^ B;
+          K -= 2;
+      }
+   }
+   A -= key->rc5.K[0];
+   B -= key->rc5.K[1];
+   STORE32L(A, &pt[0]);
+   STORE32L(B, &pt[4]);
+}
+
+#ifdef CLEAN_STACK
+void rc5_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key)
+{
+   _rc5_ecb_decrypt(ct, pt, key);
+   burn_stack(sizeof(ulong32) * 2 + sizeof(int));
+}
+#endif
+
+int rc5_test(void)
+{
+ #ifndef LTC_TEST
+    return CRYPT_NOP;
+ #else    
+   static const struct {
+       unsigned char key[16], pt[8], ct[8];
+   } tests[] = {
+   {
+       { 0x91, 0x5f, 0x46, 0x19, 0xbe, 0x41, 0xb2, 0x51,
+         0x63, 0x55, 0xa5, 0x01, 0x10, 0xa9, 0xce, 0x91 },
+       { 0x21, 0xa5, 0xdb, 0xee, 0x15, 0x4b, 0x8f, 0x6d },
+       { 0xf7, 0xc0, 0x13, 0xac, 0x5b, 0x2b, 0x89, 0x52 }
+   },
+   {
+       { 0x78, 0x33, 0x48, 0xe7, 0x5a, 0xeb, 0x0f, 0x2f,
+         0xd7, 0xb1, 0x69, 0xbb, 0x8d, 0xc1, 0x67, 0x87 },
+       { 0xF7, 0xC0, 0x13, 0xAC, 0x5B, 0x2B, 0x89, 0x52 },
+       { 0x2F, 0x42, 0xB3, 0xB7, 0x03, 0x69, 0xFC, 0x92 }
+   },
+   {
+       { 0xDC, 0x49, 0xdb, 0x13, 0x75, 0xa5, 0x58, 0x4f,
+         0x64, 0x85, 0xb4, 0x13, 0xb5, 0xf1, 0x2b, 0xaf },
+       { 0x2F, 0x42, 0xB3, 0xB7, 0x03, 0x69, 0xFC, 0x92 },
+       { 0x65, 0xc1, 0x78, 0xb2, 0x84, 0xd1, 0x97, 0xcc }
+   }
+   };
+   unsigned char tmp[2][8];
+   int x, y, err;
+   symmetric_key key;
+
+   for (x = 0; x < (int)(sizeof(tests) / sizeof(tests[0])); x++) {
+      /* setup key */
+      if ((err = rc5_setup(tests[x].key, 16, 12, &key)) != CRYPT_OK) {
+         return err;
+      }
+
+      /* encrypt and decrypt */
+      rc5_ecb_encrypt(tests[x].pt, tmp[0], &key);
+      rc5_ecb_decrypt(tmp[0], tmp[1], &key);
+
+      /* compare */
+      if (memcmp(tmp[0], tests[x].ct, 8) != 0 || memcmp(tmp[1], tests[x].pt, 8) != 0) {
+         return CRYPT_FAIL_TESTVECTOR;
+      }
+
+      /* now see if we can encrypt all zero bytes 1000 times, decrypt and come back where we started */
+      for (y = 0; y < 8; y++) tmp[0][y] = 0;
+      for (y = 0; y < 1000; y++) rc5_ecb_encrypt(tmp[0], tmp[0], &key);
+      for (y = 0; y < 1000; y++) rc5_ecb_decrypt(tmp[0], tmp[0], &key);
+      for (y = 0; y < 8; y++) if (tmp[0][y] != 0) return CRYPT_FAIL_TESTVECTOR;
+   }
+   return CRYPT_OK;
+  #endif
+}
+
+int rc5_keysize(int *desired_keysize)
+{
+   _ARGCHK(desired_keysize != NULL);
+   if (*desired_keysize < 8) {
+      return CRYPT_INVALID_KEYSIZE;
+   } else if (*desired_keysize > 128) {
+      *desired_keysize = 128;
+   }
+   return CRYPT_OK;
+}
+
+#endif
+
+
+