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Diffstat (limited to 'src/Crypto/Twofish.c')
| -rw-r--r-- | src/Crypto/Twofish.c | 548 |
1 files changed, 548 insertions, 0 deletions
diff --git a/src/Crypto/Twofish.c b/src/Crypto/Twofish.c new file mode 100644 index 00000000..7e438d1a --- /dev/null +++ b/src/Crypto/Twofish.c @@ -0,0 +1,548 @@ +/*
+ ---------------------------------------------------------------------------
+ Copyright (c) 1999, Dr Brian Gladman, Worcester, UK. All rights reserved.
+
+ LICENSE TERMS
+
+ The free distribution and use of this software is allowed (with or without
+ changes) provided that:
+
+ 1. source code distributions include the above copyright notice, this
+ list of conditions and the following disclaimer;
+
+ 2. binary distributions include the above copyright notice, this list
+ of conditions and the following disclaimer in their documentation;
+
+ 3. the name of the copyright holder is not used to endorse products
+ built using this software without specific written permission.
+
+ DISCLAIMER
+
+ This software is provided 'as is' with no explicit or implied warranties
+ in respect of its properties, including, but not limited to, correctness
+ and/or fitness for purpose.
+ ---------------------------------------------------------------------------
+
+ My thanks to Doug Whiting and Niels Ferguson for comments that led
+ to improvements in this implementation.
+
+ Issue Date: 14th January 1999
+*/
+
+/* Adapted for TrueCrypt */
+
+
+#ifdef TC_WINDOWS_BOOT
+#pragma optimize ("tl", on)
+#endif
+
+#include "Twofish.h"
+#include "Common/Endian.h"
+
+#define Q_TABLES
+#define M_TABLE
+
+#if !defined (TC_MINIMIZE_CODE_SIZE) || defined (TC_WINDOWS_BOOT_TWOFISH)
+# define MK_TABLE
+# define ONE_STEP
+#endif
+
+/* finite field arithmetic for GF(2**8) with the modular */
+/* polynomial x^8 + x^6 + x^5 + x^3 + 1 (0x169) */
+
+#define G_M 0x0169
+
+static u1byte tab_5b[4] = { 0, G_M >> 2, G_M >> 1, (G_M >> 1) ^ (G_M >> 2) };
+static u1byte tab_ef[4] = { 0, (G_M >> 1) ^ (G_M >> 2), G_M >> 1, G_M >> 2 };
+
+#define ffm_01(x) (x)
+#define ffm_5b(x) ((x) ^ ((x) >> 2) ^ tab_5b[(x) & 3])
+#define ffm_ef(x) ((x) ^ ((x) >> 1) ^ ((x) >> 2) ^ tab_ef[(x) & 3])
+
+static u1byte ror4[16] = { 0, 8, 1, 9, 2, 10, 3, 11, 4, 12, 5, 13, 6, 14, 7, 15 };
+static u1byte ashx[16] = { 0, 9, 2, 11, 4, 13, 6, 15, 8, 1, 10, 3, 12, 5, 14, 7 };
+
+static u1byte qt0[2][16] =
+{ { 8, 1, 7, 13, 6, 15, 3, 2, 0, 11, 5, 9, 14, 12, 10, 4 },
+ { 2, 8, 11, 13, 15, 7, 6, 14, 3, 1, 9, 4, 0, 10, 12, 5 }
+};
+
+static u1byte qt1[2][16] =
+{ { 14, 12, 11, 8, 1, 2, 3, 5, 15, 4, 10, 6, 7, 0, 9, 13 },
+ { 1, 14, 2, 11, 4, 12, 3, 7, 6, 13, 10, 5, 15, 9, 0, 8 }
+};
+
+static u1byte qt2[2][16] =
+{ { 11, 10, 5, 14, 6, 13, 9, 0, 12, 8, 15, 3, 2, 4, 7, 1 },
+ { 4, 12, 7, 5, 1, 6, 9, 10, 0, 14, 13, 8, 2, 11, 3, 15 }
+};
+
+static u1byte qt3[2][16] =
+{ { 13, 7, 15, 4, 1, 2, 6, 14, 9, 11, 3, 0, 8, 5, 12, 10 },
+ { 11, 9, 5, 1, 12, 3, 13, 14, 6, 4, 7, 15, 2, 0, 8, 10 }
+};
+
+static u1byte qp(const u4byte n, const u1byte x)
+{ u1byte a0, a1, a2, a3, a4, b0, b1, b2, b3, b4;
+
+ a0 = x >> 4; b0 = x & 15;
+ a1 = a0 ^ b0; b1 = ror4[b0] ^ ashx[a0];
+ a2 = qt0[n][a1]; b2 = qt1[n][b1];
+ a3 = a2 ^ b2; b3 = ror4[b2] ^ ashx[a2];
+ a4 = qt2[n][a3]; b4 = qt3[n][b3];
+ return (b4 << 4) | a4;
+};
+
+#ifdef Q_TABLES
+
+static u4byte qt_gen = 0;
+static u1byte q_tab[2][256];
+
+#define q(n,x) q_tab[n][x]
+
+static void gen_qtab(void)
+{ u4byte i;
+
+ for(i = 0; i < 256; ++i)
+ {
+ q(0,i) = qp(0, (u1byte)i);
+ q(1,i) = qp(1, (u1byte)i);
+ }
+};
+
+#else
+
+#define q(n,x) qp(n, x)
+
+#endif
+
+#ifdef M_TABLE
+
+static u4byte mt_gen = 0;
+static u4byte m_tab[4][256];
+
+static void gen_mtab(void)
+{ u4byte i, f01, f5b, fef;
+
+ for(i = 0; i < 256; ++i)
+ {
+ f01 = q(1,i); f5b = ffm_5b(f01); fef = ffm_ef(f01);
+ m_tab[0][i] = f01 + (f5b << 8) + (fef << 16) + (fef << 24);
+ m_tab[2][i] = f5b + (fef << 8) + (f01 << 16) + (fef << 24);
+
+ f01 = q(0,i); f5b = ffm_5b(f01); fef = ffm_ef(f01);
+ m_tab[1][i] = fef + (fef << 8) + (f5b << 16) + (f01 << 24);
+ m_tab[3][i] = f5b + (f01 << 8) + (fef << 16) + (f5b << 24);
+ }
+};
+
+#define mds(n,x) m_tab[n][x]
+
+#else
+
+#define fm_00 ffm_01
+#define fm_10 ffm_5b
+#define fm_20 ffm_ef
+#define fm_30 ffm_ef
+#define q_0(x) q(1,x)
+
+#define fm_01 ffm_ef
+#define fm_11 ffm_ef
+#define fm_21 ffm_5b
+#define fm_31 ffm_01
+#define q_1(x) q(0,x)
+
+#define fm_02 ffm_5b
+#define fm_12 ffm_ef
+#define fm_22 ffm_01
+#define fm_32 ffm_ef
+#define q_2(x) q(1,x)
+
+#define fm_03 ffm_5b
+#define fm_13 ffm_01
+#define fm_23 ffm_ef
+#define fm_33 ffm_5b
+#define q_3(x) q(0,x)
+
+#define f_0(n,x) ((u4byte)fm_0##n(x))
+#define f_1(n,x) ((u4byte)fm_1##n(x) << 8)
+#define f_2(n,x) ((u4byte)fm_2##n(x) << 16)
+#define f_3(n,x) ((u4byte)fm_3##n(x) << 24)
+
+#define mds(n,x) f_0(n,q_##n(x)) ^ f_1(n,q_##n(x)) ^ f_2(n,q_##n(x)) ^ f_3(n,q_##n(x))
+
+#endif
+
+static u4byte h_fun(TwofishInstance *instance, const u4byte x, const u4byte key[])
+{ u4byte b0, b1, b2, b3;
+
+#ifndef M_TABLE
+ u4byte m5b_b0, m5b_b1, m5b_b2, m5b_b3;
+ u4byte mef_b0, mef_b1, mef_b2, mef_b3;
+#endif
+
+ b0 = extract_byte(x, 0); b1 = extract_byte(x, 1); b2 = extract_byte(x, 2); b3 = extract_byte(x, 3);
+
+ switch(instance->k_len)
+ {
+ case 4: b0 = q(1, (u1byte) b0) ^ extract_byte(key[3],0);
+ b1 = q(0, (u1byte) b1) ^ extract_byte(key[3],1);
+ b2 = q(0, (u1byte) b2) ^ extract_byte(key[3],2);
+ b3 = q(1, (u1byte) b3) ^ extract_byte(key[3],3);
+ case 3: b0 = q(1, (u1byte) b0) ^ extract_byte(key[2],0);
+ b1 = q(1, (u1byte) b1) ^ extract_byte(key[2],1);
+ b2 = q(0, (u1byte) b2) ^ extract_byte(key[2],2);
+ b3 = q(0, (u1byte) b3) ^ extract_byte(key[2],3);
+ case 2: b0 = q(0, (u1byte) (q(0, (u1byte) b0) ^ extract_byte(key[1],0))) ^ extract_byte(key[0],0);
+ b1 = q(0, (u1byte) (q(1, (u1byte) b1) ^ extract_byte(key[1],1))) ^ extract_byte(key[0],1);
+ b2 = q(1, (u1byte) (q(0, (u1byte) b2) ^ extract_byte(key[1],2))) ^ extract_byte(key[0],2);
+ b3 = q(1, (u1byte) (q(1, (u1byte) b3) ^ extract_byte(key[1],3))) ^ extract_byte(key[0],3);
+ }
+#ifdef M_TABLE
+
+ return mds(0, b0) ^ mds(1, b1) ^ mds(2, b2) ^ mds(3, b3);
+
+#else
+
+ b0 = q(1, (u1byte) b0); b1 = q(0, (u1byte) b1); b2 = q(1, (u1byte) b2); b3 = q(0, (u1byte) b3);
+ m5b_b0 = ffm_5b(b0); m5b_b1 = ffm_5b(b1); m5b_b2 = ffm_5b(b2); m5b_b3 = ffm_5b(b3);
+ mef_b0 = ffm_ef(b0); mef_b1 = ffm_ef(b1); mef_b2 = ffm_ef(b2); mef_b3 = ffm_ef(b3);
+ b0 ^= mef_b1 ^ m5b_b2 ^ m5b_b3; b3 ^= m5b_b0 ^ mef_b1 ^ mef_b2;
+ b2 ^= mef_b0 ^ m5b_b1 ^ mef_b3; b1 ^= mef_b0 ^ mef_b2 ^ m5b_b3;
+
+ return b0 | (b3 << 8) | (b2 << 16) | (b1 << 24);
+
+#endif
+};
+
+#ifdef MK_TABLE
+
+#ifdef ONE_STEP
+//u4byte mk_tab[4][256];
+#else
+static u1byte sb[4][256];
+#endif
+
+#define q20(x) q(0,q(0,x) ^ extract_byte(key[1],0)) ^ extract_byte(key[0],0)
+#define q21(x) q(0,q(1,x) ^ extract_byte(key[1],1)) ^ extract_byte(key[0],1)
+#define q22(x) q(1,q(0,x) ^ extract_byte(key[1],2)) ^ extract_byte(key[0],2)
+#define q23(x) q(1,q(1,x) ^ extract_byte(key[1],3)) ^ extract_byte(key[0],3)
+
+#define q30(x) q(0,q(0,q(1, x) ^ extract_byte(key[2],0)) ^ extract_byte(key[1],0)) ^ extract_byte(key[0],0)
+#define q31(x) q(0,q(1,q(1, x) ^ extract_byte(key[2],1)) ^ extract_byte(key[1],1)) ^ extract_byte(key[0],1)
+#define q32(x) q(1,q(0,q(0, x) ^ extract_byte(key[2],2)) ^ extract_byte(key[1],2)) ^ extract_byte(key[0],2)
+#define q33(x) q(1,q(1,q(0, x) ^ extract_byte(key[2],3)) ^ extract_byte(key[1],3)) ^ extract_byte(key[0],3)
+
+#define q40(x) q(0,q(0,q(1, q(1, x) ^ extract_byte(key[3],0)) ^ extract_byte(key[2],0)) ^ extract_byte(key[1],0)) ^ extract_byte(key[0],0)
+#define q41(x) q(0,q(1,q(1, q(0, x) ^ extract_byte(key[3],1)) ^ extract_byte(key[2],1)) ^ extract_byte(key[1],1)) ^ extract_byte(key[0],1)
+#define q42(x) q(1,q(0,q(0, q(0, x) ^ extract_byte(key[3],2)) ^ extract_byte(key[2],2)) ^ extract_byte(key[1],2)) ^ extract_byte(key[0],2)
+#define q43(x) q(1,q(1,q(0, q(1, x) ^ extract_byte(key[3],3)) ^ extract_byte(key[2],3)) ^ extract_byte(key[1],3)) ^ extract_byte(key[0],3)
+
+static void gen_mk_tab(TwofishInstance *instance, u4byte key[])
+{ u4byte i;
+ u1byte by;
+
+ u4byte *mk_tab = instance->mk_tab;
+
+ switch(instance->k_len)
+ {
+ case 2: for(i = 0; i < 256; ++i)
+ {
+ by = (u1byte)i;
+#ifdef ONE_STEP
+ mk_tab[0 + 4*i] = mds(0, q20(by)); mk_tab[1 + 4*i] = mds(1, q21(by));
+ mk_tab[2 + 4*i] = mds(2, q22(by)); mk_tab[3 + 4*i] = mds(3, q23(by));
+#else
+ sb[0][i] = q20(by); sb[1][i] = q21(by);
+ sb[2][i] = q22(by); sb[3][i] = q23(by);
+#endif
+ }
+ break;
+
+ case 3: for(i = 0; i < 256; ++i)
+ {
+ by = (u1byte)i;
+#ifdef ONE_STEP
+ mk_tab[0 + 4*i] = mds(0, q30(by)); mk_tab[1 + 4*i] = mds(1, q31(by));
+ mk_tab[2 + 4*i] = mds(2, q32(by)); mk_tab[3 + 4*i] = mds(3, q33(by));
+#else
+ sb[0][i] = q30(by); sb[1][i] = q31(by);
+ sb[2][i] = q32(by); sb[3][i] = q33(by);
+#endif
+ }
+ break;
+
+ case 4: for(i = 0; i < 256; ++i)
+ {
+ by = (u1byte)i;
+#ifdef ONE_STEP
+ mk_tab[0 + 4*i] = mds(0, q40(by)); mk_tab[1 + 4*i] = mds(1, q41(by));
+ mk_tab[2 + 4*i] = mds(2, q42(by)); mk_tab[3 + 4*i] = mds(3, q43(by));
+#else
+ sb[0][i] = q40(by); sb[1][i] = q41(by);
+ sb[2][i] = q42(by); sb[3][i] = q43(by);
+#endif
+ }
+ }
+};
+
+# ifdef ONE_STEP
+# define g0_fun(x) ( mk_tab[0 + 4*extract_byte(x,0)] ^ mk_tab[1 + 4*extract_byte(x,1)] \
+ ^ mk_tab[2 + 4*extract_byte(x,2)] ^ mk_tab[3 + 4*extract_byte(x,3)] )
+# define g1_fun(x) ( mk_tab[0 + 4*extract_byte(x,3)] ^ mk_tab[1 + 4*extract_byte(x,0)] \
+ ^ mk_tab[2 + 4*extract_byte(x,1)] ^ mk_tab[3 + 4*extract_byte(x,2)] )
+
+
+# else
+# define g0_fun(x) ( mds(0, sb[0][extract_byte(x,0)]) ^ mds(1, sb[1][extract_byte(x,1)]) \
+ ^ mds(2, sb[2][extract_byte(x,2)]) ^ mds(3, sb[3][extract_byte(x,3)]) )
+# define g1_fun(x) ( mds(0, sb[0][extract_byte(x,3)]) ^ mds(1, sb[1][extract_byte(x,0)]) \
+ ^ mds(2, sb[2][extract_byte(x,1)]) ^ mds(3, sb[3][extract_byte(x,2)]) )
+# endif
+
+#else
+
+#define g0_fun(x) h_fun(instance, x, instance->s_key)
+#define g1_fun(x) h_fun(instance, rotl(x,8), instance->s_key)
+
+#endif
+
+/* The (12,8) Reed Soloman code has the generator polynomial
+
+ g(x) = x^4 + (a + 1/a) * x^3 + a * x^2 + (a + 1/a) * x + 1
+
+where the coefficients are in the finite field GF(2^8) with a
+modular polynomial a^8 + a^6 + a^3 + a^2 + 1. To generate the
+remainder we have to start with a 12th order polynomial with our
+eight input bytes as the coefficients of the 4th to 11th terms.
+That is:
+
+ m[7] * x^11 + m[6] * x^10 ... + m[0] * x^4 + 0 * x^3 +... + 0
+
+We then multiply the generator polynomial by m[7] * x^7 and subtract
+it - xor in GF(2^8) - from the above to eliminate the x^7 term (the
+artihmetic on the coefficients is done in GF(2^8). We then multiply
+the generator polynomial by x^6 * coeff(x^10) and use this to remove
+the x^10 term. We carry on in this way until the x^4 term is removed
+so that we are left with:
+
+ r[3] * x^3 + r[2] * x^2 + r[1] 8 x^1 + r[0]
+
+which give the resulting 4 bytes of the remainder. This is equivalent
+to the matrix multiplication in the Twofish description but much faster
+to implement.
+
+*/
+
+#define G_MOD 0x0000014d
+
+static u4byte mds_rem(u4byte p0, u4byte p1)
+{ u4byte i, t, u;
+
+ for(i = 0; i < 8; ++i)
+ {
+ t = p1 >> 24; // get most significant coefficient
+
+ p1 = (p1 << 8) | (p0 >> 24); p0 <<= 8; // shift others up
+
+ // multiply t by a (the primitive element - i.e. left shift)
+
+ u = (t << 1);
+
+ if(t & 0x80) // subtract modular polynomial on overflow
+
+ u ^= G_MOD;
+
+ p1 ^= t ^ (u << 16); // remove t * (a * x^2 + 1)
+
+ u ^= (t >> 1); // form u = a * t + t / a = t * (a + 1 / a);
+
+ if(t & 0x01) // add the modular polynomial on underflow
+
+ u ^= G_MOD >> 1;
+
+ p1 ^= (u << 24) | (u << 8); // remove t * (a + 1/a) * (x^3 + x)
+ }
+
+ return p1;
+};
+
+/* initialise the key schedule from the user supplied key */
+
+u4byte *twofish_set_key(TwofishInstance *instance, const u4byte in_key[], const u4byte key_len)
+{ u4byte i, a, b, me_key[4], mo_key[4];
+ u4byte *l_key, *s_key;
+
+ l_key = instance->l_key;
+ s_key = instance->s_key;
+
+#ifdef Q_TABLES
+ if(!qt_gen)
+ {
+ gen_qtab(); qt_gen = 1;
+ }
+#endif
+
+#ifdef M_TABLE
+ if(!mt_gen)
+ {
+ gen_mtab(); mt_gen = 1;
+ }
+#endif
+
+ instance->k_len = key_len / 64; /* 2, 3 or 4 */
+
+ for(i = 0; i < instance->k_len; ++i)
+ {
+ a = LE32(in_key[i + i]); me_key[i] = a;
+ b = LE32(in_key[i + i + 1]); mo_key[i] = b;
+ s_key[instance->k_len - i - 1] = mds_rem(a, b);
+ }
+
+ for(i = 0; i < 40; i += 2)
+ {
+ a = 0x01010101 * i; b = a + 0x01010101;
+ a = h_fun(instance, a, me_key);
+ b = rotl(h_fun(instance, b, mo_key), 8);
+ l_key[i] = a + b;
+ l_key[i + 1] = rotl(a + 2 * b, 9);
+ }
+
+#ifdef MK_TABLE
+ gen_mk_tab(instance, s_key);
+#endif
+
+ return l_key;
+};
+
+/* encrypt a block of text */
+
+#ifndef TC_MINIMIZE_CODE_SIZE
+
+#define f_rnd(i) \
+ t1 = g1_fun(blk[1]); t0 = g0_fun(blk[0]); \
+ blk[2] = rotr(blk[2] ^ (t0 + t1 + l_key[4 * (i) + 8]), 1); \
+ blk[3] = rotl(blk[3], 1) ^ (t0 + 2 * t1 + l_key[4 * (i) + 9]); \
+ t1 = g1_fun(blk[3]); t0 = g0_fun(blk[2]); \
+ blk[0] = rotr(blk[0] ^ (t0 + t1 + l_key[4 * (i) + 10]), 1); \
+ blk[1] = rotl(blk[1], 1) ^ (t0 + 2 * t1 + l_key[4 * (i) + 11])
+
+void twofish_encrypt(TwofishInstance *instance, const u4byte in_blk[4], u4byte out_blk[])
+{ u4byte t0, t1, blk[4];
+
+ u4byte *l_key = instance->l_key;
+ u4byte *mk_tab = instance->mk_tab;
+
+ blk[0] = LE32(in_blk[0]) ^ l_key[0];
+ blk[1] = LE32(in_blk[1]) ^ l_key[1];
+ blk[2] = LE32(in_blk[2]) ^ l_key[2];
+ blk[3] = LE32(in_blk[3]) ^ l_key[3];
+
+ f_rnd(0); f_rnd(1); f_rnd(2); f_rnd(3);
+ f_rnd(4); f_rnd(5); f_rnd(6); f_rnd(7);
+
+ out_blk[0] = LE32(blk[2] ^ l_key[4]);
+ out_blk[1] = LE32(blk[3] ^ l_key[5]);
+ out_blk[2] = LE32(blk[0] ^ l_key[6]);
+ out_blk[3] = LE32(blk[1] ^ l_key[7]);
+};
+
+#else // TC_MINIMIZE_CODE_SIZE
+
+void twofish_encrypt(TwofishInstance *instance, const u4byte in_blk[4], u4byte out_blk[])
+{ u4byte t0, t1, blk[4];
+
+ u4byte *l_key = instance->l_key;
+#ifdef TC_WINDOWS_BOOT_TWOFISH
+ u4byte *mk_tab = instance->mk_tab;
+#endif
+ int i;
+
+ blk[0] = LE32(in_blk[0]) ^ l_key[0];
+ blk[1] = LE32(in_blk[1]) ^ l_key[1];
+ blk[2] = LE32(in_blk[2]) ^ l_key[2];
+ blk[3] = LE32(in_blk[3]) ^ l_key[3];
+
+ for (i = 0; i <= 7; ++i)
+ {
+ t1 = g1_fun(blk[1]); t0 = g0_fun(blk[0]);
+ blk[2] = rotr(blk[2] ^ (t0 + t1 + l_key[4 * (i) + 8]), 1);
+ blk[3] = rotl(blk[3], 1) ^ (t0 + 2 * t1 + l_key[4 * (i) + 9]);
+ t1 = g1_fun(blk[3]); t0 = g0_fun(blk[2]);
+ blk[0] = rotr(blk[0] ^ (t0 + t1 + l_key[4 * (i) + 10]), 1);
+ blk[1] = rotl(blk[1], 1) ^ (t0 + 2 * t1 + l_key[4 * (i) + 11]);
+ }
+
+ out_blk[0] = LE32(blk[2] ^ l_key[4]);
+ out_blk[1] = LE32(blk[3] ^ l_key[5]);
+ out_blk[2] = LE32(blk[0] ^ l_key[6]);
+ out_blk[3] = LE32(blk[1] ^ l_key[7]);
+};
+
+#endif // TC_MINIMIZE_CODE_SIZE
+
+/* decrypt a block of text */
+
+#ifndef TC_MINIMIZE_CODE_SIZE
+
+#define i_rnd(i) \
+ t1 = g1_fun(blk[1]); t0 = g0_fun(blk[0]); \
+ blk[2] = rotl(blk[2], 1) ^ (t0 + t1 + l_key[4 * (i) + 10]); \
+ blk[3] = rotr(blk[3] ^ (t0 + 2 * t1 + l_key[4 * (i) + 11]), 1); \
+ t1 = g1_fun(blk[3]); t0 = g0_fun(blk[2]); \
+ blk[0] = rotl(blk[0], 1) ^ (t0 + t1 + l_key[4 * (i) + 8]); \
+ blk[1] = rotr(blk[1] ^ (t0 + 2 * t1 + l_key[4 * (i) + 9]), 1)
+
+void twofish_decrypt(TwofishInstance *instance, const u4byte in_blk[4], u4byte out_blk[4])
+{ u4byte t0, t1, blk[4];
+
+ u4byte *l_key = instance->l_key;
+ u4byte *mk_tab = instance->mk_tab;
+
+ blk[0] = LE32(in_blk[0]) ^ l_key[4];
+ blk[1] = LE32(in_blk[1]) ^ l_key[5];
+ blk[2] = LE32(in_blk[2]) ^ l_key[6];
+ blk[3] = LE32(in_blk[3]) ^ l_key[7];
+
+ i_rnd(7); i_rnd(6); i_rnd(5); i_rnd(4);
+ i_rnd(3); i_rnd(2); i_rnd(1); i_rnd(0);
+
+ out_blk[0] = LE32(blk[2] ^ l_key[0]);
+ out_blk[1] = LE32(blk[3] ^ l_key[1]);
+ out_blk[2] = LE32(blk[0] ^ l_key[2]);
+ out_blk[3] = LE32(blk[1] ^ l_key[3]);
+};
+
+#else // TC_MINIMIZE_CODE_SIZE
+
+void twofish_decrypt(TwofishInstance *instance, const u4byte in_blk[4], u4byte out_blk[4])
+{ u4byte t0, t1, blk[4];
+
+ u4byte *l_key = instance->l_key;
+#ifdef TC_WINDOWS_BOOT_TWOFISH
+ u4byte *mk_tab = instance->mk_tab;
+#endif
+ int i;
+
+ blk[0] = LE32(in_blk[0]) ^ l_key[4];
+ blk[1] = LE32(in_blk[1]) ^ l_key[5];
+ blk[2] = LE32(in_blk[2]) ^ l_key[6];
+ blk[3] = LE32(in_blk[3]) ^ l_key[7];
+
+ for (i = 7; i >= 0; --i)
+ {
+ t1 = g1_fun(blk[1]); t0 = g0_fun(blk[0]);
+ blk[2] = rotl(blk[2], 1) ^ (t0 + t1 + l_key[4 * (i) + 10]);
+ blk[3] = rotr(blk[3] ^ (t0 + 2 * t1 + l_key[4 * (i) + 11]), 1);
+ t1 = g1_fun(blk[3]); t0 = g0_fun(blk[2]);
+ blk[0] = rotl(blk[0], 1) ^ (t0 + t1 + l_key[4 * (i) + 8]);
+ blk[1] = rotr(blk[1] ^ (t0 + 2 * t1 + l_key[4 * (i) + 9]), 1);
+ }
+
+ out_blk[0] = LE32(blk[2] ^ l_key[0]);
+ out_blk[1] = LE32(blk[3] ^ l_key[1]);
+ out_blk[2] = LE32(blk[0] ^ l_key[2]);
+ out_blk[3] = LE32(blk[1] ^ l_key[3]);
+};
+
+#endif // TC_MINIMIZE_CODE_SIZE
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