--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/rc2.c	Mon May 31 18:25:41 2004 +0000
@@ -0,0 +1,319 @@
+/* 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
+ */
+/**********************************************************************\
+* To commemorate the 1996 RSA Data Security Conference, the following  *
+* code is released into the public domain by its author.  Prost!       *
+*                                                                      *
+* This cipher uses 16-bit words and little-endian byte ordering.       *
+* I wonder which processor it was optimized for?                       *
+*                                                                      *
+* Thanks to CodeView, SoftIce, and D86 for helping bring this code to  *
+* the public.                                                          *
+\**********************************************************************/
+
+#include <mycrypt.h>
+
+#ifdef RC2
+
+const struct _cipher_descriptor rc2_desc = {
+   "rc2",
+   12, 8, 128, 8, 16,
+   &rc2_setup,
+   &rc2_ecb_encrypt,
+   &rc2_ecb_decrypt,
+   &rc2_test,
+   &rc2_keysize
+};
+
+
+/**********************************************************************\
+* Expand a variable-length user key (between 1 and 128 bytes) to a     *
+* 64-short working rc2 key, of at most "bits" effective key bits.      *
+* The effective key bits parameter looks like an export control hack.  *
+* For normal use, it should always be set to 1024.  For convenience,   *
+* zero is accepted as an alias for 1024.                               *
+\**********************************************************************/
+
+   /* 256-entry permutation table, probably derived somehow from pi */
+    static const unsigned char permute[256] = {
+        217,120,249,196, 25,221,181,237, 40,233,253,121, 74,160,216,157,
+        198,126, 55,131, 43,118, 83,142, 98, 76,100,136, 68,139,251,162,
+         23,154, 89,245,135,179, 79, 19, 97, 69,109,141,  9,129,125, 50,
+        189,143, 64,235,134,183,123, 11,240,149, 33, 34, 92,107, 78,130,
+         84,214,101,147,206, 96,178, 28,115, 86,192, 20,167,140,241,220,
+         18,117,202, 31, 59,190,228,209, 66, 61,212, 48,163, 60,182, 38,
+        111,191, 14,218, 70,105,  7, 87, 39,242, 29,155,188,148, 67,  3,
+        248, 17,199,246,144,239, 62,231,  6,195,213, 47,200,102, 30,215,
+          8,232,234,222,128, 82,238,247,132,170,114,172, 53, 77,106, 42,
+        150, 26,210,113, 90, 21, 73,116, 75,159,208, 94,  4, 24,164,236,
+        194,224, 65,110, 15, 81,203,204, 36,145,175, 80,161,244,112, 57,
+        153,124, 58,133, 35,184,180,122,252,  2, 54, 91, 37, 85,151, 49,
+         45, 93,250,152,227,138,146,174,  5,223, 41, 16,103,108,186,201,
+        211,  0,230,207,225,158,168, 44, 99, 22,  1, 63, 88,226,137,169,
+         13, 56, 52, 27,171, 51,255,176,187, 72, 12, 95,185,177,205, 46,
+        197,243,219, 71,229,165,156,119, 10,166, 32,104,254,127,193,173
+    };
+
+int rc2_setup(const unsigned char *key, int keylen, int rounds, symmetric_key *skey)
+{
+   unsigned *xkey = skey->rc2.xkey;
+   unsigned char tmp[128];
+   unsigned T8, TM;
+   int i, bits;
+
+   _ARGCHK(key  != NULL);
+   _ARGCHK(skey != NULL);
+
+   if (keylen < 8 || keylen > 128) {
+      return CRYPT_INVALID_KEYSIZE;
+   }
+
+   if (rounds != 0 && rounds != 16) {
+      return CRYPT_INVALID_ROUNDS;
+   }
+
+   for (i = 0; i < keylen; i++) {
+       tmp[i] = key[i] & 255;
+   }
+
+    /* Phase 1: Expand input key to 128 bytes */
+    if (keylen < 128) {
+        for (i = keylen; i < 128; i++) {
+            tmp[i] = permute[(int)((tmp[i - 1] + tmp[i - keylen]) & 255)];
+        }
+    }
+    
+    /* Phase 2 - reduce effective key size to "bits" */
+    bits = keylen*8;
+    T8   = (unsigned)(bits+7)>>3;
+    TM   = (255 >> (unsigned)(7 & -bits));
+    tmp[128 - T8] = permute[(int)(tmp[128 - T8] & TM)];
+    for (i = 127 - T8; i >= 0; i--) {
+        tmp[i] = permute[(int)(tmp[i + 1] ^ tmp[i + T8])];
+    }
+
+    /* Phase 3 - copy to xkey in little-endian order */
+    i = 63;
+    do {
+        xkey[i] =  (unsigned)tmp[2*i] + ((unsigned)tmp[2*i+1] << 8);
+    } while (i-- > 0);
+
+#ifdef CLEAN_STACK
+    zeromem(tmp, sizeof(tmp));
+#endif
+    
+    return CRYPT_OK;
+}
+
+/**********************************************************************\
+* Encrypt an 8-byte block of plaintext using the given key.            *
+\**********************************************************************/
+#ifdef CLEAN_STACK
+static void _rc2_ecb_encrypt( const unsigned char *plain,
+                            unsigned char *cipher,
+                            symmetric_key *skey)
+#else
+void rc2_ecb_encrypt( const unsigned char *plain,
+                            unsigned char *cipher,
+                            symmetric_key *skey)
+#endif
+{
+    unsigned *xkey;
+    unsigned x76, x54, x32, x10, i;
+
+    _ARGCHK(plain != NULL);
+    _ARGCHK(cipher != NULL);
+    _ARGCHK(skey != NULL);
+
+    xkey = skey->rc2.xkey;
+
+    x76 = ((unsigned)plain[7] << 8) + (unsigned)plain[6];
+    x54 = ((unsigned)plain[5] << 8) + (unsigned)plain[4];
+    x32 = ((unsigned)plain[3] << 8) + (unsigned)plain[2];
+    x10 = ((unsigned)plain[1] << 8) + (unsigned)plain[0];
+
+    for (i = 0; i < 16; i++) {
+        x10 = (x10 + (x32 & ~x76) + (x54 & x76) + xkey[4*i+0]) & 0xFFFF;
+        x10 = ((x10 << 1) | (x10 >> 15)) & 0xFFFF;
+
+        x32 = (x32 + (x54 & ~x10) + (x76 & x10) + xkey[4*i+1]) & 0xFFFF;
+        x32 = ((x32 << 2) | (x32 >> 14)) & 0xFFFF;
+
+        x54 = (x54 + (x76 & ~x32) + (x10 & x32) + xkey[4*i+2]) & 0xFFFF;
+        x54 = ((x54 << 3) | (x54 >> 13)) & 0xFFFF;
+
+        x76 = (x76 + (x10 & ~x54) + (x32 & x54) + xkey[4*i+3]) & 0xFFFF;
+        x76 = ((x76 << 5) | (x76 >> 11)) & 0xFFFF;
+
+        if (i == 4 || i == 10) {
+            x10 = (x10 + xkey[x76 & 63]) & 0xFFFF;
+            x32 = (x32 + xkey[x10 & 63]) & 0xFFFF;
+            x54 = (x54 + xkey[x32 & 63]) & 0xFFFF;
+            x76 = (x76 + xkey[x54 & 63]) & 0xFFFF;
+        }
+    }
+
+    cipher[0] = (unsigned char)x10;
+    cipher[1] = (unsigned char)(x10 >> 8);
+    cipher[2] = (unsigned char)x32;
+    cipher[3] = (unsigned char)(x32 >> 8);
+    cipher[4] = (unsigned char)x54;
+    cipher[5] = (unsigned char)(x54 >> 8);
+    cipher[6] = (unsigned char)x76;
+    cipher[7] = (unsigned char)(x76 >> 8);
+}
+
+#ifdef CLEAN_STACK
+void rc2_ecb_encrypt( const unsigned char *plain,
+                            unsigned char *cipher,
+                            symmetric_key *skey)
+{
+    _rc2_ecb_encrypt(plain, cipher, skey);
+    burn_stack(sizeof(unsigned *) + sizeof(unsigned) * 5);
+}
+#endif
+
+/**********************************************************************\
+* Decrypt an 8-byte block of ciphertext using the given key.           *
+\**********************************************************************/
+
+#ifdef CLEAN_STACK
+static void _rc2_ecb_decrypt( const unsigned char *cipher,
+                            unsigned char *plain,
+                            symmetric_key *skey)
+#else
+void rc2_ecb_decrypt( const unsigned char *cipher,
+                            unsigned char *plain,
+                            symmetric_key *skey)
+#endif
+{
+    unsigned x76, x54, x32, x10;
+    unsigned *xkey;
+    int i;
+
+    _ARGCHK(plain != NULL);
+    _ARGCHK(cipher != NULL);
+    _ARGCHK(skey != NULL);
+
+    xkey = skey->rc2.xkey;
+
+    x76 = ((unsigned)cipher[7] << 8) + (unsigned)cipher[6];
+    x54 = ((unsigned)cipher[5] << 8) + (unsigned)cipher[4];
+    x32 = ((unsigned)cipher[3] << 8) + (unsigned)cipher[2];
+    x10 = ((unsigned)cipher[1] << 8) + (unsigned)cipher[0];
+
+    for (i = 15; i >= 0; i--) {
+        if (i == 4 || i == 10) {
+            x76 = (x76 - xkey[x54 & 63]) & 0xFFFF;
+            x54 = (x54 - xkey[x32 & 63]) & 0xFFFF;
+            x32 = (x32 - xkey[x10 & 63]) & 0xFFFF;
+            x10 = (x10 - xkey[x76 & 63]) & 0xFFFF;
+        }
+
+        x76 = ((x76 << 11) | (x76 >> 5)) & 0xFFFF;
+        x76 = (x76 - ((x10 & ~x54) + (x32 & x54) + xkey[4*i+3])) & 0xFFFF;
+
+        x54 = ((x54 << 13) | (x54 >> 3)) & 0xFFFF;
+        x54 = (x54 - ((x76 & ~x32) + (x10 & x32) + xkey[4*i+2])) & 0xFFFF;
+
+        x32 = ((x32 << 14) | (x32 >> 2)) & 0xFFFF;
+        x32 = (x32 - ((x54 & ~x10) + (x76 & x10) + xkey[4*i+1])) & 0xFFFF;
+
+        x10 = ((x10 << 15) | (x10 >> 1)) & 0xFFFF;
+        x10 = (x10 - ((x32 & ~x76) + (x54 & x76) + xkey[4*i+0])) & 0xFFFF;
+    }
+
+    plain[0] = (unsigned char)x10;
+    plain[1] = (unsigned char)(x10 >> 8);
+    plain[2] = (unsigned char)x32;
+    plain[3] = (unsigned char)(x32 >> 8);
+    plain[4] = (unsigned char)x54;
+    plain[5] = (unsigned char)(x54 >> 8);
+    plain[6] = (unsigned char)x76;
+    plain[7] = (unsigned char)(x76 >> 8);
+}
+
+#ifdef CLEAN_STACK
+void rc2_ecb_decrypt( const unsigned char *cipher,
+                            unsigned char *plain,
+                            symmetric_key *skey)
+{
+    _rc2_ecb_decrypt(cipher, plain, skey);
+    burn_stack(sizeof(unsigned *) + sizeof(unsigned) * 4 + sizeof(int));
+}
+#endif
+
+int rc2_test(void)
+{
+ #ifndef LTC_TEST
+    return CRYPT_NOP;
+ #else    
+   static const struct {
+        int keylen;
+        unsigned char key[16], pt[8], ct[8];
+   } tests[] = {
+
+   { 8,
+     { 0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
+     { 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 },
+     { 0x30, 0x64, 0x9e, 0xdf, 0x9b, 0xe7, 0xd2, 0xc2 }
+
+   },
+   { 16,
+     { 0x88, 0xbc, 0xa9, 0x0e, 0x90, 0x87, 0x5a, 0x7f,
+       0x0f, 0x79, 0xc3, 0x84, 0x62, 0x7b, 0xaf, 0xb2 },
+     { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
+     { 0x22, 0x69, 0x55, 0x2a, 0xb0, 0xf8, 0x5c, 0xa6 }
+   }
+  };
+    int x, y, err;
+    symmetric_key skey;
+    unsigned char tmp[2][8];
+
+    for (x = 0; x < (int)(sizeof(tests) / sizeof(tests[0])); x++) {
+        zeromem(tmp, sizeof(tmp));
+        if ((err = rc2_setup(tests[x].key, tests[x].keylen, 0, &skey)) != CRYPT_OK) {
+           return err;
+        }
+        
+        rc2_ecb_encrypt(tests[x].pt, tmp[0], &skey);
+        rc2_ecb_decrypt(tmp[0], tmp[1], &skey);
+        
+        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++) rc2_ecb_encrypt(tmp[0], tmp[0], &skey);
+      for (y = 0; y < 1000; y++) rc2_ecb_decrypt(tmp[0], tmp[0], &skey);
+      for (y = 0; y < 8; y++) if (tmp[0][y] != 0) return CRYPT_FAIL_TESTVECTOR;
+    }
+    return CRYPT_OK;
+   #endif
+}
+
+int rc2_keysize(int *keysize)
+{
+   _ARGCHK(keysize != NULL);
+   if (*keysize < 8) {
+       return CRYPT_INVALID_KEYSIZE;
+   } else if (*keysize > 128) {
+       *keysize = 128;
+   }
+   return CRYPT_OK;
+}
+
+#endif
+
+
+