--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/ciphers/twofish/twofish.c	Sun May 08 06:36:47 2005 +0000
@@ -0,0 +1,704 @@
+/* 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
+ */
+
+ /** 
+   @file twofish.c
+   Implementation of Twofish by Tom St Denis 
+ */
+#include "tomcrypt.h"
+
+#ifdef TWOFISH
+
+/* first TWOFISH_ALL_TABLES must ensure TWOFISH_TABLES is defined */
+#ifdef TWOFISH_ALL_TABLES
+#ifndef TWOFISH_TABLES
+#define TWOFISH_TABLES
+#endif
+#endif
+
+const struct ltc_cipher_descriptor twofish_desc =
+{
+    "twofish",
+    7,
+    16, 32, 16, 16,
+    &twofish_setup,
+    &twofish_ecb_encrypt,
+    &twofish_ecb_decrypt,
+    &twofish_test,
+    &twofish_done,
+    &twofish_keysize,
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL
+};
+
+/* the two polynomials */
+#define MDS_POLY          0x169
+#define RS_POLY           0x14D
+
+/* The 4x4 MDS Linear Transform */
+#if 0
+static const unsigned char MDS[4][4] = {
+    { 0x01, 0xEF, 0x5B, 0x5B },
+    { 0x5B, 0xEF, 0xEF, 0x01 },
+    { 0xEF, 0x5B, 0x01, 0xEF },
+    { 0xEF, 0x01, 0xEF, 0x5B }
+};
+#endif
+
+/* The 4x8 RS Linear Transform */
+static const unsigned char RS[4][8] = {
+    { 0x01, 0xA4, 0x55, 0x87, 0x5A, 0x58, 0xDB, 0x9E },
+    { 0xA4, 0x56, 0x82, 0xF3, 0X1E, 0XC6, 0X68, 0XE5 },
+    { 0X02, 0XA1, 0XFC, 0XC1, 0X47, 0XAE, 0X3D, 0X19 },
+    { 0XA4, 0X55, 0X87, 0X5A, 0X58, 0XDB, 0X9E, 0X03 }
+};
+
+/* sbox usage orderings */
+static const unsigned char qord[4][5] = {
+   { 1, 1, 0, 0, 1 },
+   { 0, 1, 1, 0, 0 },
+   { 0, 0, 0, 1, 1 },
+   { 1, 0, 1, 1, 0 }
+};
+
+#ifdef TWOFISH_TABLES
+
+#include "twofish_tab.c"
+
+#define sbox(i, x) ((ulong32)SBOX[i][(x)&255])
+
+#else
+
+/* The Q-box tables */
+static const unsigned char qbox[2][4][16] = {
+{
+   { 0x8, 0x1, 0x7, 0xD, 0x6, 0xF, 0x3, 0x2, 0x0, 0xB, 0x5, 0x9, 0xE, 0xC, 0xA, 0x4 },
+   { 0xE, 0XC, 0XB, 0X8, 0X1, 0X2, 0X3, 0X5, 0XF, 0X4, 0XA, 0X6, 0X7, 0X0, 0X9, 0XD },
+   { 0XB, 0XA, 0X5, 0XE, 0X6, 0XD, 0X9, 0X0, 0XC, 0X8, 0XF, 0X3, 0X2, 0X4, 0X7, 0X1 },
+   { 0XD, 0X7, 0XF, 0X4, 0X1, 0X2, 0X6, 0XE, 0X9, 0XB, 0X3, 0X0, 0X8, 0X5, 0XC, 0XA }
+},
+{
+   { 0X2, 0X8, 0XB, 0XD, 0XF, 0X7, 0X6, 0XE, 0X3, 0X1, 0X9, 0X4, 0X0, 0XA, 0XC, 0X5 },
+   { 0X1, 0XE, 0X2, 0XB, 0X4, 0XC, 0X3, 0X7, 0X6, 0XD, 0XA, 0X5, 0XF, 0X9, 0X0, 0X8 },
+   { 0X4, 0XC, 0X7, 0X5, 0X1, 0X6, 0X9, 0XA, 0X0, 0XE, 0XD, 0X8, 0X2, 0XB, 0X3, 0XF },
+   { 0xB, 0X9, 0X5, 0X1, 0XC, 0X3, 0XD, 0XE, 0X6, 0X4, 0X7, 0XF, 0X2, 0X0, 0X8, 0XA }
+}
+};
+
+/* computes S_i[x] */
+#ifdef LTC_CLEAN_STACK
+static ulong32 _sbox(int i, ulong32 x)
+#else
+static ulong32 sbox(int i, ulong32 x)
+#endif
+{
+   unsigned char a0,b0,a1,b1,a2,b2,a3,b3,a4,b4,y;
+
+   /* a0,b0 = [x/16], x mod 16 */
+   a0 = (unsigned char)((x>>4)&15);
+   b0 = (unsigned char)((x)&15);
+
+   /* a1 = a0 ^ b0 */
+   a1 = a0 ^ b0;
+
+   /* b1 = a0 ^ ROR(b0, 1) ^ 8a0 */
+   b1 = (a0 ^ ((b0<<3)|(b0>>1)) ^ (a0<<3)) & 15;
+
+   /* a2,b2 = t0[a1], t1[b1] */
+   a2 = qbox[i][0][(int)a1];
+   b2 = qbox[i][1][(int)b1];
+
+   /* a3 = a2 ^ b2 */
+   a3 = a2 ^ b2;
+
+   /* b3 = a2 ^ ROR(b2, 1) ^ 8a2 */
+   b3 = (a2 ^ ((b2<<3)|(b2>>1)) ^ (a2<<3)) & 15;
+
+   /* a4,b4 = t2[a3], t3[b3] */
+   a4 = qbox[i][2][(int)a3];
+   b4 = qbox[i][3][(int)b3];
+
+   /* y = 16b4 + a4 */
+   y = (b4 << 4) + a4;
+
+   /* return result */
+   return (ulong32)y;
+}
+
+#ifdef LTC_CLEAN_STACK
+static ulong32 sbox(int i, ulong32 x)
+{
+   ulong32 y;
+   y = _sbox(i, x);
+   burn_stack(sizeof(unsigned char) * 11);
+   return y;
+}
+#endif /* LTC_CLEAN_STACK */
+
+#endif /* TWOFISH_TABLES */
+
+/* computes ab mod p */
+static ulong32 gf_mult(ulong32 a, ulong32 b, ulong32 p)
+{
+   ulong32 result, B[2], P[2];
+
+   P[1] = p;
+   B[1] = b;
+   result = P[0] = B[0] = 0;
+
+   /* unrolled branchless GF multiplier */
+   result ^= B[a&1]; a >>= 1;  B[1] = P[B[1]>>7] ^ (B[1] << 1); 
+   result ^= B[a&1]; a >>= 1;  B[1] = P[B[1]>>7] ^ (B[1] << 1); 
+   result ^= B[a&1]; a >>= 1;  B[1] = P[B[1]>>7] ^ (B[1] << 1); 
+   result ^= B[a&1]; a >>= 1;  B[1] = P[B[1]>>7] ^ (B[1] << 1); 
+   result ^= B[a&1]; a >>= 1;  B[1] = P[B[1]>>7] ^ (B[1] << 1); 
+   result ^= B[a&1]; a >>= 1;  B[1] = P[B[1]>>7] ^ (B[1] << 1); 
+   result ^= B[a&1]; a >>= 1;  B[1] = P[B[1]>>7] ^ (B[1] << 1); 
+   result ^= B[a&1]; 
+
+   return result;
+}
+
+/* computes [y0 y1 y2 y3] = MDS . [x0] */
+#ifndef TWOFISH_TABLES
+static ulong32 mds_column_mult(unsigned char in, int col)
+{
+   ulong32 x01, x5B, xEF;
+
+   x01 = in;
+   x5B = gf_mult(in, 0x5B, MDS_POLY);
+   xEF = gf_mult(in, 0xEF, MDS_POLY);
+
+   switch (col) {
+       case 0:
+          return (x01 << 0 ) |
+                 (x5B << 8 ) |
+                 (xEF << 16) |
+                 (xEF << 24);
+       case 1:
+          return (xEF << 0 ) |
+                 (xEF << 8 ) |
+                 (x5B << 16) |
+                 (x01 << 24);
+       case 2:
+          return (x5B << 0 ) |
+                 (xEF << 8 ) |
+                 (x01 << 16) |
+                 (xEF << 24);
+       case 3:
+          return (x5B << 0 ) |
+                 (x01 << 8 ) |
+                 (xEF << 16) |
+                 (x5B << 24);
+   }
+   /* avoid warnings, we'd never get here normally but just to calm compiler warnings... */
+   return 0;
+}
+
+#else /* !TWOFISH_TABLES */
+
+#define mds_column_mult(x, i) mds_tab[i][x]
+
+#endif /* TWOFISH_TABLES */
+
+/* Computes [y0 y1 y2 y3] = MDS . [x0 x1 x2 x3] */
+static void mds_mult(const unsigned char *in, unsigned char *out)
+{
+  int x;
+  ulong32 tmp;
+  for (tmp = x = 0; x < 4; x++) {
+      tmp ^= mds_column_mult(in[x], x);
+  }
+  STORE32L(tmp, out);
+}
+
+#ifdef TWOFISH_ALL_TABLES
+/* computes [y0 y1 y2 y3] = RS . [x0 x1 x2 x3 x4 x5 x6 x7] */
+static void rs_mult(const unsigned char *in, unsigned char *out)
+{
+   ulong32 tmp;
+   tmp = rs_tab0[in[0]] ^ rs_tab1[in[1]] ^ rs_tab2[in[2]] ^ rs_tab3[in[3]] ^
+         rs_tab4[in[4]] ^ rs_tab5[in[5]] ^ rs_tab6[in[6]] ^ rs_tab7[in[7]];
+   STORE32L(tmp, out);
+}
+
+#else /* !TWOFISH_ALL_TABLES */
+
+/* computes [y0 y1 y2 y3] = RS . [x0 x1 x2 x3 x4 x5 x6 x7] */
+static void rs_mult(const unsigned char *in, unsigned char *out)
+{
+  int x, y;
+  for (x = 0; x < 4; x++) {
+      out[x] = 0;
+      for (y = 0; y < 8; y++) {
+          out[x] ^= gf_mult(in[y], RS[x][y], RS_POLY);
+      }
+  }
+}
+
+#endif
+
+/* computes h(x) */
+static void h_func(const unsigned char *in, unsigned char *out, unsigned char *M, int k, int offset)
+{
+  int x;
+  unsigned char y[4];
+  for (x = 0; x < 4; x++) {
+      y[x] = in[x];
+ }
+  switch (k) {
+     case 4:
+            y[0] = (unsigned char)(sbox(1, (ulong32)y[0]) ^ M[4 * (6 + offset) + 0]);
+            y[1] = (unsigned char)(sbox(0, (ulong32)y[1]) ^ M[4 * (6 + offset) + 1]);
+            y[2] = (unsigned char)(sbox(0, (ulong32)y[2]) ^ M[4 * (6 + offset) + 2]);
+            y[3] = (unsigned char)(sbox(1, (ulong32)y[3]) ^ M[4 * (6 + offset) + 3]);
+     case 3:
+            y[0] = (unsigned char)(sbox(1, (ulong32)y[0]) ^ M[4 * (4 + offset) + 0]);
+            y[1] = (unsigned char)(sbox(1, (ulong32)y[1]) ^ M[4 * (4 + offset) + 1]);
+            y[2] = (unsigned char)(sbox(0, (ulong32)y[2]) ^ M[4 * (4 + offset) + 2]);
+            y[3] = (unsigned char)(sbox(0, (ulong32)y[3]) ^ M[4 * (4 + offset) + 3]);
+     case 2:
+            y[0] = (unsigned char)(sbox(1, sbox(0, sbox(0, (ulong32)y[0]) ^ M[4 * (2 + offset) + 0]) ^ M[4 * (0 + offset) + 0]));
+            y[1] = (unsigned char)(sbox(0, sbox(0, sbox(1, (ulong32)y[1]) ^ M[4 * (2 + offset) + 1]) ^ M[4 * (0 + offset) + 1]));
+            y[2] = (unsigned char)(sbox(1, sbox(1, sbox(0, (ulong32)y[2]) ^ M[4 * (2 + offset) + 2]) ^ M[4 * (0 + offset) + 2]));
+            y[3] = (unsigned char)(sbox(0, sbox(1, sbox(1, (ulong32)y[3]) ^ M[4 * (2 + offset) + 3]) ^ M[4 * (0 + offset) + 3]));
+  }
+  mds_mult(y, out);
+}
+
+#ifndef TWOFISH_SMALL
+
+/* for GCC we don't use pointer aliases */
+#if defined(__GNUC__)
+    #define S1 skey->twofish.S[0]
+    #define S2 skey->twofish.S[1]
+    #define S3 skey->twofish.S[2]
+    #define S4 skey->twofish.S[3]
+#endif
+
+/* the G function */
+#define g_func(x, dum)  (S1[byte(x,0)] ^ S2[byte(x,1)] ^ S3[byte(x,2)] ^ S4[byte(x,3)])
+#define g1_func(x, dum) (S2[byte(x,0)] ^ S3[byte(x,1)] ^ S4[byte(x,2)] ^ S1[byte(x,3)])
+
+#else
+
+#ifdef LTC_CLEAN_STACK
+static ulong32 _g_func(ulong32 x, symmetric_key *key)
+#else
+static ulong32 g_func(ulong32 x, symmetric_key *key)
+#endif
+{
+   unsigned char g, i, y, z;
+   ulong32 res;
+
+   res = 0;
+   for (y = 0; y < 4; y++) {
+       z = key->twofish.start;
+
+       /* do unkeyed substitution */
+       g = sbox(qord[y][z++], (x >> (8*y)) & 255);
+
+       /* first subkey */
+       i = 0;
+
+       /* do key mixing+sbox until z==5 */
+       while (z != 5) {
+          g = g ^ key->twofish.S[4*i++ + y];
+          g = sbox(qord[y][z++], g);
+       }
+
+       /* multiply g by a column of the MDS */
+       res ^= mds_column_mult(g, y);
+   }
+   return res;
+}
+
+#define g1_func(x, key) g_func(ROLc(x, 8), key)
+
+#ifdef LTC_CLEAN_STACK
+static ulong32 g_func(ulong32 x, symmetric_key *key)
+{
+    ulong32 y;
+    y = _g_func(x, key);
+    burn_stack(sizeof(unsigned char) * 4 + sizeof(ulong32));
+    return y;
+}
+#endif /* LTC_CLEAN_STACK */
+
+#endif /* TWOFISH_SMALL */
+
+ /**
+    Initialize the Twofish block cipher
+    @param key The symmetric key you wish to pass
+    @param keylen The key length in bytes
+    @param num_rounds The number of rounds desired (0 for default)
+    @param skey The key in as scheduled by this function.
+    @return CRYPT_OK if successful
+ */
+#ifdef LTC_CLEAN_STACK
+static int _twofish_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
+#else
+int twofish_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
+#endif
+{
+#ifndef TWOFISH_SMALL
+   unsigned char S[4*4], tmpx0, tmpx1;
+#endif
+   int k, x, y;
+   unsigned char tmp[4], tmp2[4], M[8*4];
+   ulong32 A, B;
+
+   LTC_ARGCHK(key  != NULL);
+   LTC_ARGCHK(skey != NULL);
+
+   /* invalid arguments? */
+   if (num_rounds != 16 && num_rounds != 0) {
+      return CRYPT_INVALID_ROUNDS;
+   }
+
+   if (keylen != 16 && keylen != 24 && keylen != 32) {
+      return CRYPT_INVALID_KEYSIZE;
+   }
+
+   /* k = keysize/64 [but since our keysize is in bytes...] */
+   k = keylen / 8;
+
+   /* copy the key into M */
+   for (x = 0; x < keylen; x++) {
+       M[x] = key[x] & 255;
+   }
+
+   /* create the S[..] words */
+#ifndef TWOFISH_SMALL
+   for (x = 0; x < k; x++) {
+       rs_mult(M+(x*8), S+(x*4));
+   }
+#else
+   for (x = 0; x < k; x++) {
+       rs_mult(M+(x*8), skey->twofish.S+(x*4));
+   }
+#endif
+
+   /* make subkeys */
+   for (x = 0; x < 20; x++) {
+       /* A = h(p * 2x, Me) */
+       for (y = 0; y < 4; y++) {
+           tmp[y] = x+x;
+       }
+       h_func(tmp, tmp2, M, k, 0);
+       LOAD32L(A, tmp2);
+
+       /* B = ROL(h(p * (2x + 1), Mo), 8) */
+       for (y = 0; y < 4; y++) {
+           tmp[y] = (unsigned char)(x+x+1);
+       }
+       h_func(tmp, tmp2, M, k, 1);
+       LOAD32L(B, tmp2);
+       B = ROLc(B, 8);
+
+       /* K[2i]   = A + B */
+       skey->twofish.K[x+x] = (A + B) & 0xFFFFFFFFUL;
+
+       /* K[2i+1] = (A + 2B) <<< 9 */
+       skey->twofish.K[x+x+1] = ROLc(B + B + A, 9);
+   }
+
+#ifndef TWOFISH_SMALL
+   /* make the sboxes (large ram variant) */
+   if (k == 2) {
+        for (x = 0; x < 256; x++) {
+           tmpx0 = sbox(0, x);
+           tmpx1 = sbox(1, x);
+           skey->twofish.S[0][x] = mds_column_mult(sbox(1, (sbox(0, tmpx0 ^ S[0]) ^ S[4])),0);
+           skey->twofish.S[1][x] = mds_column_mult(sbox(0, (sbox(0, tmpx1 ^ S[1]) ^ S[5])),1);
+           skey->twofish.S[2][x] = mds_column_mult(sbox(1, (sbox(1, tmpx0 ^ S[2]) ^ S[6])),2);
+           skey->twofish.S[3][x] = mds_column_mult(sbox(0, (sbox(1, tmpx1 ^ S[3]) ^ S[7])),3);
+        }
+   } else if (k == 3) {
+        for (x = 0; x < 256; x++) {
+           tmpx0 = sbox(0, x);
+           tmpx1 = sbox(1, x);
+           skey->twofish.S[0][x] = mds_column_mult(sbox(1, (sbox(0, sbox(0, tmpx1 ^ S[0]) ^ S[4]) ^ S[8])),0);
+           skey->twofish.S[1][x] = mds_column_mult(sbox(0, (sbox(0, sbox(1, tmpx1 ^ S[1]) ^ S[5]) ^ S[9])),1);
+           skey->twofish.S[2][x] = mds_column_mult(sbox(1, (sbox(1, sbox(0, tmpx0 ^ S[2]) ^ S[6]) ^ S[10])),2);
+           skey->twofish.S[3][x] = mds_column_mult(sbox(0, (sbox(1, sbox(1, tmpx0 ^ S[3]) ^ S[7]) ^ S[11])),3);
+        }
+   } else {
+        for (x = 0; x < 256; x++) {
+           tmpx0 = sbox(0, x);
+           tmpx1 = sbox(1, x);
+           skey->twofish.S[0][x] = mds_column_mult(sbox(1, (sbox(0, sbox(0, sbox(1, tmpx1 ^ S[0]) ^ S[4]) ^ S[8]) ^ S[12])),0);
+           skey->twofish.S[1][x] = mds_column_mult(sbox(0, (sbox(0, sbox(1, sbox(1, tmpx0 ^ S[1]) ^ S[5]) ^ S[9]) ^ S[13])),1);
+           skey->twofish.S[2][x] = mds_column_mult(sbox(1, (sbox(1, sbox(0, sbox(0, tmpx0 ^ S[2]) ^ S[6]) ^ S[10]) ^ S[14])),2);
+           skey->twofish.S[3][x] = mds_column_mult(sbox(0, (sbox(1, sbox(1, sbox(0, tmpx1 ^ S[3]) ^ S[7]) ^ S[11]) ^ S[15])),3);
+        }
+   }
+#else
+   /* where to start in the sbox layers */
+   /* small ram variant */
+   switch (k) {
+         case 4 : skey->twofish.start = 0; break;
+         case 3 : skey->twofish.start = 1; break; 
+         default: skey->twofish.start = 2; break;
+   }
+#endif
+   return CRYPT_OK;
+}
+
+#ifdef LTC_CLEAN_STACK
+int twofish_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
+{
+   int x;
+   x = _twofish_setup(key, keylen, num_rounds, skey);
+   burn_stack(sizeof(int) * 7 + sizeof(unsigned char) * 56 + sizeof(ulong32) * 2);
+   return x;
+}
+#endif
+
+/**
+  Encrypts a block of text with Twofish
+  @param pt The input plaintext (16 bytes)
+  @param ct The output ciphertext (16 bytes)
+  @param skey The key as scheduled
+*/
+#ifdef LTC_CLEAN_STACK
+static void _twofish_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *skey)
+#else
+void twofish_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *skey)
+#endif
+{
+    ulong32 a,b,c,d,ta,tb,tc,td,t1,t2, *k;
+    int r;
+#if !defined(TWOFISH_SMALL) && !defined(__GNUC__)
+    ulong32 *S1, *S2, *S3, *S4;
+#endif    
+
+    LTC_ARGCHK(pt   != NULL);
+    LTC_ARGCHK(ct   != NULL);
+    LTC_ARGCHK(skey != NULL);
+    
+#if !defined(TWOFISH_SMALL) && !defined(__GNUC__)
+    S1 = skey->twofish.S[0];
+    S2 = skey->twofish.S[1];
+    S3 = skey->twofish.S[2];
+    S4 = skey->twofish.S[3];
+#endif    
+
+    LOAD32L(a,&pt[0]); LOAD32L(b,&pt[4]);
+    LOAD32L(c,&pt[8]); LOAD32L(d,&pt[12]);
+    a ^= skey->twofish.K[0];
+    b ^= skey->twofish.K[1];
+    c ^= skey->twofish.K[2];
+    d ^= skey->twofish.K[3];
+    
+    k  = skey->twofish.K + 8;
+    for (r = 8; r != 0; --r) {
+        t2 = g1_func(b, skey);
+        t1 = g_func(a, skey) + t2;
+        c  = RORc(c ^ (t1 + k[0]), 1);
+        d  = ROLc(d, 1) ^ (t2 + t1 + k[1]);
+        
+        t2 = g1_func(d, skey);
+        t1 = g_func(c, skey) + t2;
+        a  = RORc(a ^ (t1 + k[2]), 1);
+        b  = ROLc(b, 1) ^ (t2 + t1 + k[3]);
+        k += 4;
+   }
+
+    /* output with "undo last swap" */
+    ta = c ^ skey->twofish.K[4];
+    tb = d ^ skey->twofish.K[5];
+    tc = a ^ skey->twofish.K[6];
+    td = b ^ skey->twofish.K[7];
+
+    /* store output */
+    STORE32L(ta,&ct[0]); STORE32L(tb,&ct[4]);
+    STORE32L(tc,&ct[8]); STORE32L(td,&ct[12]);
+}
+
+#ifdef LTC_CLEAN_STACK
+void twofish_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *skey)
+{
+   _twofish_ecb_encrypt(pt, ct, skey);
+   burn_stack(sizeof(ulong32) * 10 + sizeof(int));
+}
+#endif
+
+/**
+  Decrypts a block of text with Twofish
+  @param ct The input ciphertext (16 bytes)
+  @param pt The output plaintext (16 bytes)
+  @param skey The key as scheduled 
+*/
+#ifdef LTC_CLEAN_STACK
+static void _twofish_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *skey)
+#else
+void twofish_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *skey)
+#endif
+{
+    ulong32 a,b,c,d,ta,tb,tc,td,t1,t2, *k;
+    int r;
+#if !defined(TWOFISH_SMALL) && !defined(__GNUC__)
+    ulong32 *S1, *S2, *S3, *S4;
+#endif    
+
+    LTC_ARGCHK(pt   != NULL);
+    LTC_ARGCHK(ct   != NULL);
+    LTC_ARGCHK(skey != NULL);
+    
+#if !defined(TWOFISH_SMALL) && !defined(__GNUC__)
+    S1 = skey->twofish.S[0];
+    S2 = skey->twofish.S[1];
+    S3 = skey->twofish.S[2];
+    S4 = skey->twofish.S[3];
+#endif    
+
+    /* load input */
+    LOAD32L(ta,&ct[0]); LOAD32L(tb,&ct[4]);
+    LOAD32L(tc,&ct[8]); LOAD32L(td,&ct[12]);
+
+    /* undo undo final swap */
+    a = tc ^ skey->twofish.K[6];
+    b = td ^ skey->twofish.K[7];
+    c = ta ^ skey->twofish.K[4];
+    d = tb ^ skey->twofish.K[5];
+
+    k = skey->twofish.K + 36;
+    for (r = 8; r != 0; --r) {
+        t2 = g1_func(d, skey);
+        t1 = g_func(c, skey) + t2;
+        a = ROLc(a, 1) ^ (t1 + k[2]);
+        b = RORc(b ^ (t2 + t1 + k[3]), 1);
+
+        t2 = g1_func(b, skey);
+        t1 = g_func(a, key) + t2;
+        c = ROLc(c, 1) ^ (t1 + k[0]);
+        d = RORc(d ^ (t2 +  t1 + k[1]), 1);
+        k -= 4;
+    }
+
+    /* pre-white */
+    a ^= skey->twofish.K[0];
+    b ^= skey->twofish.K[1];
+    c ^= skey->twofish.K[2];
+    d ^= skey->twofish.K[3];
+    
+    /* store */
+    STORE32L(a, &pt[0]); STORE32L(b, &pt[4]);
+    STORE32L(c, &pt[8]); STORE32L(d, &pt[12]);
+}
+
+#ifdef LTC_CLEAN_STACK
+void twofish_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *skey)
+{
+   _twofish_ecb_decrypt(ct, pt, skey);
+   burn_stack(sizeof(ulong32) * 10 + sizeof(int));
+}
+#endif
+
+/**
+  Performs a self-test of the Twofish block cipher
+  @return CRYPT_OK if functional, CRYPT_NOP if self-test has been disabled
+*/
+int twofish_test(void)
+{
+ #ifndef LTC_TEST
+    return CRYPT_NOP;
+ #else    
+ static const struct { 
+     int keylen;
+     unsigned char key[32], pt[16], ct[16];
+ } tests[] = {
+   { 16,
+     { 0x9F, 0x58, 0x9F, 0x5C, 0xF6, 0x12, 0x2C, 0x32,
+       0xB6, 0xBF, 0xEC, 0x2F, 0x2A, 0xE8, 0xC3, 0x5A },
+     { 0xD4, 0x91, 0xDB, 0x16, 0xE7, 0xB1, 0xC3, 0x9E,
+       0x86, 0xCB, 0x08, 0x6B, 0x78, 0x9F, 0x54, 0x19 },
+     { 0x01, 0x9F, 0x98, 0x09, 0xDE, 0x17, 0x11, 0x85,
+       0x8F, 0xAA, 0xC3, 0xA3, 0xBA, 0x20, 0xFB, 0xC3 }
+   }, {
+     24,
+     { 0x88, 0xB2, 0xB2, 0x70, 0x6B, 0x10, 0x5E, 0x36,
+       0xB4, 0x46, 0xBB, 0x6D, 0x73, 0x1A, 0x1E, 0x88,
+       0xEF, 0xA7, 0x1F, 0x78, 0x89, 0x65, 0xBD, 0x44 },
+     { 0x39, 0xDA, 0x69, 0xD6, 0xBA, 0x49, 0x97, 0xD5,
+       0x85, 0xB6, 0xDC, 0x07, 0x3C, 0xA3, 0x41, 0xB2 },
+     { 0x18, 0x2B, 0x02, 0xD8, 0x14, 0x97, 0xEA, 0x45,
+       0xF9, 0xDA, 0xAC, 0xDC, 0x29, 0x19, 0x3A, 0x65 }
+   }, { 
+     32,
+     { 0xD4, 0x3B, 0xB7, 0x55, 0x6E, 0xA3, 0x2E, 0x46,
+       0xF2, 0xA2, 0x82, 0xB7, 0xD4, 0x5B, 0x4E, 0x0D,
+       0x57, 0xFF, 0x73, 0x9D, 0x4D, 0xC9, 0x2C, 0x1B,
+       0xD7, 0xFC, 0x01, 0x70, 0x0C, 0xC8, 0x21, 0x6F },
+     { 0x90, 0xAF, 0xE9, 0x1B, 0xB2, 0x88, 0x54, 0x4F,
+       0x2C, 0x32, 0xDC, 0x23, 0x9B, 0x26, 0x35, 0xE6 },
+     { 0x6C, 0xB4, 0x56, 0x1C, 0x40, 0xBF, 0x0A, 0x97,
+       0x05, 0x93, 0x1C, 0xB6, 0xD4, 0x08, 0xE7, 0xFA }
+   }
+};
+
+
+ symmetric_key key;
+ unsigned char tmp[2][16];
+ int err, i, y;
+ 
+ for (i = 0; i < (int)(sizeof(tests)/sizeof(tests[0])); i++) {
+    if ((err = twofish_setup(tests[i].key, tests[i].keylen, 0, &key)) != CRYPT_OK) {
+       return err;
+    }
+    twofish_ecb_encrypt(tests[i].pt, tmp[0], &key);
+    twofish_ecb_decrypt(tmp[0], tmp[1], &key);
+    if (memcmp(tmp[0], tests[i].ct, 16) != 0 || memcmp(tmp[1], tests[i].pt, 16) != 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 < 16; y++) tmp[0][y] = 0;
+      for (y = 0; y < 1000; y++) twofish_ecb_encrypt(tmp[0], tmp[0], &key);
+      for (y = 0; y < 1000; y++) twofish_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 
+}
+
+/** Terminate the context 
+   @param skey    The scheduled key
+*/
+void twofish_done(symmetric_key *skey)
+{
+}
+
+/**
+  Gets suitable key size
+  @param keysize [in/out] The length of the recommended key (in bytes).  This function will store the suitable size back in this variable.
+  @return CRYPT_OK if the input key size is acceptable.
+*/
+int twofish_keysize(int *keysize)
+{
+   LTC_ARGCHK(keysize);
+   if (*keysize < 16)
+      return CRYPT_INVALID_KEYSIZE;
+   if (*keysize < 24) {
+      *keysize = 16;
+      return CRYPT_OK;
+   } else if (*keysize < 32) {
+      *keysize = 24;
+      return CRYPT_OK;
+   } else {
+      *keysize = 32;
+      return CRYPT_OK;
+   }
+}
+
+#endif
+
+
+