--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/rc6.c	Mon May 31 18:25:41 2004 +0000
@@ -0,0 +1,298 @@
+/* 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
+ */
+
+/* RC6 code by Tom St Denis */
+#include "mycrypt.h"
+
+#ifdef RC6
+
+const struct _cipher_descriptor rc6_desc =
+{
+    "rc6",
+    3,
+    8, 128, 16, 20,
+    &rc6_setup,
+    &rc6_ecb_encrypt,
+    &rc6_ecb_decrypt,
+    &rc6_test,
+    &rc6_keysize
+};
+
+static const ulong32 stab[44] = {
+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 };
+
+#ifdef CLEAN_STACK
+static int _rc6_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
+#else
+int rc6_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
+#endif
+{
+    ulong32 L[64], S[50], A, B, i, j, v, s, l;
+
+    _ARGCHK(key != NULL);
+    _ARGCHK(skey != NULL);
+
+    /* test parameters */
+    if (num_rounds != 0 && num_rounds != 20) { 
+       return CRYPT_INVALID_ROUNDS;
+    }
+
+    /* key must be between 64 and 1024 bits */
+    if (keylen < 8 || keylen > 128) {
+       return CRYPT_INVALID_KEYSIZE;
+    }
+
+    /* 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)) {
+           L[j++] = BSWAP(A);
+           A = 0;
+        }
+    }
+
+    /* handle odd sized keys */
+    if (keylen & 3) { 
+       A <<= (8 * (4 - (keylen&3))); 
+       L[j++] = BSWAP(A); 
+    }
+
+    /* setup the S array */
+    memcpy(S, stab, 44 * sizeof(stab[0]));
+
+    /* mix buffer */
+    s = 3 * MAX(44, 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 == 44) { i = 0; }
+        if (++j == l)  { j = 0; }
+    }
+    
+    /* copy to key */
+    for (i = 0; i < 44; i++) { 
+        skey->rc6.K[i] = S[i];
+    }
+    return CRYPT_OK;
+}
+
+#ifdef CLEAN_STACK
+int rc6_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
+{
+   int x;
+   x = _rc6_setup(key, keylen, num_rounds, skey);
+   burn_stack(sizeof(ulong32) * 122);
+   return x;
+}
+#endif
+
+#ifdef CLEAN_STACK
+static void _rc6_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key)
+#else
+void rc6_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key)
+#endif
+{
+   ulong32 a,b,c,d,t,u, *K;
+   int r;
+   
+   _ARGCHK(key != NULL);
+   _ARGCHK(pt != NULL);
+   _ARGCHK(ct != NULL);
+   LOAD32L(a,&pt[0]);LOAD32L(b,&pt[4]);LOAD32L(c,&pt[8]);LOAD32L(d,&pt[12]);
+
+   b += key->rc6.K[0];
+   d += key->rc6.K[1];
+
+#define RND(a,b,c,d) \
+       t = (b * (b + b + 1)); t = ROL(t, 5); \
+       u = (d * (d + d + 1)); u = ROL(u, 5); \
+       a = ROL(a^t,u) + K[0];                \
+       c = ROL(c^u,t) + K[1]; K += 2;   
+    
+   K = key->rc6.K + 2;
+   for (r = 0; r < 20; r += 4) {
+       RND(a,b,c,d);
+       RND(b,c,d,a);
+       RND(c,d,a,b);
+       RND(d,a,b,c);
+   }
+   
+#undef RND
+
+   a += key->rc6.K[42];
+   c += key->rc6.K[43];
+   STORE32L(a,&ct[0]);STORE32L(b,&ct[4]);STORE32L(c,&ct[8]);STORE32L(d,&ct[12]);
+}
+
+#ifdef CLEAN_STACK
+void rc6_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key)
+{
+   _rc6_ecb_encrypt(pt, ct, key);
+   burn_stack(sizeof(ulong32) * 6 + sizeof(int));
+}
+#endif
+
+#ifdef CLEAN_STACK
+static void _rc6_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key)
+#else
+void rc6_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key)
+#endif
+{
+   ulong32 a,b,c,d,t,u, *K;
+   int r;
+
+   _ARGCHK(key != NULL);
+   _ARGCHK(pt != NULL);
+   _ARGCHK(ct != NULL);
+   
+   LOAD32L(a,&ct[0]);LOAD32L(b,&ct[4]);LOAD32L(c,&ct[8]);LOAD32L(d,&ct[12]);
+   a -= key->rc6.K[42];
+   c -= key->rc6.K[43];
+   
+#define RND(a,b,c,d) \
+       t = (b * (b + b + 1)); t = ROL(t, 5); \
+       u = (d * (d + d + 1)); u = ROL(u, 5); \
+       c = ROR(c - K[1], t) ^ u; \
+       a = ROR(a - K[0], u) ^ t; K -= 2;
+   
+   K = key->rc6.K + 40;
+   
+   for (r = 0; r < 20; r += 4) {
+       RND(d,a,b,c);
+       RND(c,d,a,b);
+       RND(b,c,d,a);
+       RND(a,b,c,d);
+   }
+   
+#undef RND
+
+   b -= key->rc6.K[0];
+   d -= key->rc6.K[1];
+   STORE32L(a,&pt[0]);STORE32L(b,&pt[4]);STORE32L(c,&pt[8]);STORE32L(d,&pt[12]);
+}
+
+#ifdef CLEAN_STACK
+void rc6_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key)
+{
+   _rc6_ecb_decrypt(ct, pt, key);
+   burn_stack(sizeof(ulong32) * 6 + sizeof(int));
+}
+#endif
+
+int rc6_test(void)
+{
+ #ifndef LTC_TEST
+    return CRYPT_NOP;
+ #else    
+   static const struct {
+       int keylen;
+       unsigned char key[32], pt[16], ct[16];
+   } tests[] = {
+   {
+       16,
+       { 0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef,
+         0x01, 0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78,
+         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
+       { 0x02, 0x13, 0x24, 0x35, 0x46, 0x57, 0x68, 0x79,
+         0x8a, 0x9b, 0xac, 0xbd, 0xce, 0xdf, 0xe0, 0xf1 },
+       { 0x52, 0x4e, 0x19, 0x2f, 0x47, 0x15, 0xc6, 0x23,
+         0x1f, 0x51, 0xf6, 0x36, 0x7e, 0xa4, 0x3f, 0x18 }
+   },
+   {
+       24,
+       { 0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef,
+         0x01, 0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78,
+         0x89, 0x9a, 0xab, 0xbc, 0xcd, 0xde, 0xef, 0xf0,
+         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
+       { 0x02, 0x13, 0x24, 0x35, 0x46, 0x57, 0x68, 0x79,
+         0x8a, 0x9b, 0xac, 0xbd, 0xce, 0xdf, 0xe0, 0xf1 },
+       { 0x68, 0x83, 0x29, 0xd0, 0x19, 0xe5, 0x05, 0x04,
+         0x1e, 0x52, 0xe9, 0x2a, 0xf9, 0x52, 0x91, 0xd4 }
+   },
+   {
+       32,
+       { 0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef,
+         0x01, 0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78,
+         0x89, 0x9a, 0xab, 0xbc, 0xcd, 0xde, 0xef, 0xf0,
+         0x10, 0x32, 0x54, 0x76, 0x98, 0xba, 0xdc, 0xfe },
+       { 0x02, 0x13, 0x24, 0x35, 0x46, 0x57, 0x68, 0x79,
+         0x8a, 0x9b, 0xac, 0xbd, 0xce, 0xdf, 0xe0, 0xf1 },
+       { 0xc8, 0x24, 0x18, 0x16, 0xf0, 0xd7, 0xe4, 0x89,
+         0x20, 0xad, 0x16, 0xa1, 0x67, 0x4e, 0x5d, 0x48 }
+   }
+   };
+   unsigned char tmp[2][16];
+   int x, y, err;
+   symmetric_key key;
+
+   for (x  = 0; x < (int)(sizeof(tests) / sizeof(tests[0])); x++) {
+      /* setup key */
+      if ((err = rc6_setup(tests[x].key, tests[x].keylen, 0, &key)) != CRYPT_OK) {
+         return err;
+      }
+
+      /* encrypt and decrypt */
+      rc6_ecb_encrypt(tests[x].pt, tmp[0], &key);
+      rc6_ecb_decrypt(tmp[0], tmp[1], &key);
+
+      /* compare */
+      if (memcmp(tmp[0], tests[x].ct, 16) || memcmp(tmp[1], tests[x].pt, 16)) {
+#if 0
+         printf("\n\nFailed test %d\n", x);
+         if (memcmp(tmp[0], tests[x].ct, 16)) {
+            printf("Ciphertext:  ");
+            for (y = 0; y < 16; y++) printf("%02x ", tmp[0][y]);
+            printf("\nExpected  :  ");
+            for (y = 0; y < 16; y++) printf("%02x ", tests[x].ct[y]);
+            printf("\n");
+         }
+         if (memcmp(tmp[1], tests[x].pt, 16)) {
+            printf("Plaintext:  ");
+            for (y = 0; y < 16; y++) printf("%02x ", tmp[0][y]);
+            printf("\nExpected :  ");
+            for (y = 0; y < 16; y++) printf("%02x ", tests[x].pt[y]);
+            printf("\n");
+         }
+#endif
+         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 < 16; y++) tmp[0][y] = 0;
+      for (y = 0; y < 1000; y++) rc6_ecb_encrypt(tmp[0], tmp[0], &key);
+      for (y = 0; y < 1000; y++) rc6_ecb_decrypt(tmp[0], tmp[0], &key);
+      for (y = 0; y < 16; y++) if (tmp[0][y] != 0) return CRYPT_FAIL_TESTVECTOR;
+   }
+   return CRYPT_OK;
+  #endif
+}
+
+int rc6_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 /*RC6*/
+
+