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twofish.c
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/* This is an independent implementation of the encryption algorithm: */
/* */
/* Twofish by Bruce Schneier and colleagues */
/* */
/* which is a candidate algorithm in the Advanced Encryption Standard */
/* programme of the US National Institute of Standards and Technology. */
/* */
/* Copyright in this implementation is held by Dr B R Gladman but I */
/* hereby give permission for its free direct or derivative use subject */
/* to acknowledgment of its origin and compliance with any conditions */
/* that the originators of t he algorithm place on its exploitation. */
/* */
/* My thanks to Doug Whiting and Niels Ferguson for comments that led */
/* to improvements in this implementation. */
/* */
/* Dr Brian Gladman ([email protected]) 14th January 1999 */
/* Timing data for Twofish (twofish.c)
128 bit key:
Key Setup: 8414 cycles
Encrypt: 376 cycles = 68.1 mbits/sec
Decrypt: 374 cycles = 68.4 mbits/sec
Mean: 375 cycles = 68.3 mbits/sec
192 bit key:
Key Setup: 11628 cycles
Encrypt: 376 cycles = 68.1 mbits/sec
Decrypt: 374 cycles = 68.4 mbits/sec
Mean: 375 cycles = 68.3 mbits/sec
256 bit key:
Key Setup: 15457 cycles
Encrypt: 381 cycles = 67.2 mbits/sec
Decrypt: 374 cycles = 68.4 mbits/sec
Mean: 378 cycles = 67.8 mbits/sec
*/
#include "twofish.h"
#define Q_TABLES
#define M_TABLE
#define MK_TABLE
#define ONE_STEP
static char *alg_name[] = { "twofish", "twofish.c", "twofish" };
char **cipher_name()
{
return alg_name;
}
u4byte k_len;
u4byte l_key[40]
#if 1
= {
0x4f1a3415, 0xbf541f51,
0x86fdce14, 0xe354f4a1,
0x616aadf9, 0xf310ee3f,
0xac74403f, 0xc562a030,
0xb76ff9f8, 0xe9b06896,
0x70c408a2, 0xfe3aedac,
0x5fa06e5e, 0x61fee97a,
0xa15cba01, 0x3583fafa,
0xcdb4985a, 0xe7172864,
0x7c003d57, 0xbf9f1b71,
0xcff1f4ab, 0xbdff4376,
0x57bc905d, 0xe3131a0e,
0x1007c7ea, 0x4d054e0e,
0x76baa279, 0x35aeb6c0,
0x398f5e03, 0x3a2c1d70,
0xd6dfbcf8, 0xcaf94cf4,
0xf67c3460, 0xc808ecd0,
0xd4360d82, 0x5168cf37,
0xf7a02dbf, 0xdf8968af,
0x27135ef4, 0x41234d48,
}
#endif
;
u4byte s_key[4];
/* 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
u1byte tab_5b[4] = { 0, G_M >> 2, G_M >> 1, (G_M >> 1) ^ (G_M >> 2) };
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])
u1byte ror4[16] = { 0, 8, 1, 9, 2, 10, 3, 11, 4, 12, 5, 13, 6, 14, 7, 15 };
u1byte ashx[16] = { 0, 9, 2, 11, 4, 13, 6, 15, 8, 1, 10, 3, 12, 5, 14, 7 };
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 }
};
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 }
};
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 }
};
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 }
};
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
u4byte qt_gen = 0;
u1byte q_tab[2][256];
#define q(n,x) q_tab[n][x]
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
u4byte mt_gen = 0;
u4byte m_tab[4][256];
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
u4byte h_fun(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 = byte(x, 0); b1 = byte(x, 1); b2 = byte(x, 2); b3 = byte(x, 3);
switch(k_len)
{
case 4: b0 = q(1, b0) ^ byte(key[3],0);
b1 = q(0, b1) ^ byte(key[3],1);
b2 = q(0, b2) ^ byte(key[3],2);
b3 = q(1, b3) ^ byte(key[3],3);
case 3: b0 = q(1, b0) ^ byte(key[2],0);
b1 = q(1, b1) ^ byte(key[2],1);
b2 = q(0, b2) ^ byte(key[2],2);
b3 = q(0, b3) ^ byte(key[2],3);
case 2: b0 = q(0,q(0,b0) ^ byte(key[1],0)) ^ byte(key[0],0);
b1 = q(0,q(1,b1) ^ byte(key[1],1)) ^ byte(key[0],1);
b2 = q(1,q(0,b2) ^ byte(key[1],2)) ^ byte(key[0],2);
b3 = q(1,q(1,b3) ^ byte(key[1],3)) ^ byte(key[0],3);
}
#ifdef M_TABLE
return mds(0, b0) ^ mds(1, b1) ^ mds(2, b2) ^ mds(3, b3);
#else
b0 = q(1, b0); b1 = q(0, b1); b2 = q(1, b2); b3 = q(0, 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
u1byte sb[4][256];
#endif
#define q20(x) q(0,q(0,x) ^ byte(key[1],0)) ^ byte(key[0],0)
#define q21(x) q(0,q(1,x) ^ byte(key[1],1)) ^ byte(key[0],1)
#define q22(x) q(1,q(0,x) ^ byte(key[1],2)) ^ byte(key[0],2)
#define q23(x) q(1,q(1,x) ^ byte(key[1],3)) ^ byte(key[0],3)
#define q30(x) q(0,q(0,q(1, x) ^ byte(key[2],0)) ^ byte(key[1],0)) ^ byte(key[0],0)
#define q31(x) q(0,q(1,q(1, x) ^ byte(key[2],1)) ^ byte(key[1],1)) ^ byte(key[0],1)
#define q32(x) q(1,q(0,q(0, x) ^ byte(key[2],2)) ^ byte(key[1],2)) ^ byte(key[0],2)
#define q33(x) q(1,q(1,q(0, x) ^ byte(key[2],3)) ^ byte(key[1],3)) ^ byte(key[0],3)
#define q40(x) q(0,q(0,q(1, q(1, x) ^ byte(key[3],0)) ^ byte(key[2],0)) ^ byte(key[1],0)) ^ byte(key[0],0)
#define q41(x) q(0,q(1,q(1, q(0, x) ^ byte(key[3],1)) ^ byte(key[2],1)) ^ byte(key[1],1)) ^ byte(key[0],1)
#define q42(x) q(1,q(0,q(0, q(0, x) ^ byte(key[3],2)) ^ byte(key[2],2)) ^ byte(key[1],2)) ^ byte(key[0],2)
#define q43(x) q(1,q(1,q(0, q(1, x) ^ byte(key[3],3)) ^ byte(key[2],3)) ^ byte(key[1],3)) ^ byte(key[0],3)
void
gen_mk_tab(u4byte key[])
{ u4byte i;
u1byte by;
switch(k_len)
{
case 2: for(i = 0; i < 256; ++i)
{
by = (u1byte)i;
#ifdef ONE_STEP
mk_tab[0][i] = mds(0, q20(by)); mk_tab[1][i] = mds(1, q21(by));
mk_tab[2][i] = mds(2, q22(by)); mk_tab[3][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][i] = mds(0, q30(by)); mk_tab[1][i] = mds(1, q31(by));
mk_tab[2][i] = mds(2, q32(by)); mk_tab[3][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][i] = mds(0, q40(by)); mk_tab[1][i] = mds(1, q41(by));
mk_tab[2][i] = mds(2, q42(by)); mk_tab[3][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][byte(x,0)] ^ mk_tab[1][byte(x,1)] \
^ mk_tab[2][byte(x,2)] ^ mk_tab[3][byte(x,3)] )
# define g1_fun(x) ( mk_tab[0][byte(x,3)] ^ mk_tab[1][byte(x,0)] \
^ mk_tab[2][byte(x,1)] ^ mk_tab[3][byte(x,2)] )
# else
# define g0_fun(x) ( mds(0, sb[0][byte(x,0)]) ^ mds(1, sb[1][byte(x,1)]) \
^ mds(2, sb[2][byte(x,2)]) ^ mds(3, sb[3][byte(x,3)]) )
# define g1_fun(x) ( mds(0, sb[0][byte(x,3)]) ^ mds(1, sb[1][byte(x,0)]) \
^ mds(2, sb[2][byte(x,1)]) ^ mds(3, sb[3][byte(x,2)]) )
# endif
#else
#define g0_fun(x) h_fun(x,s_key)
#define g1_fun(x) h_fun(rotl(x,8),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
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 *tf_init(const u4byte in_key[], const u4byte key_len)
{ u4byte i, a, b, me_key[4], mo_key[4];
#ifdef Q_TABLES
if(!qt_gen)
{
gen_qtab(); qt_gen = 1;
}
#endif
#ifdef M_TABLE
if(!mt_gen)
{
gen_mtab(); mt_gen = 1;
}
#endif
k_len = key_len / 64; /* 2, 3 or 4 */
for(i = 0; i < k_len; ++i)
{
a = in_key[i + i]; me_key[i] = a;
b = in_key[i + i + 1]; mo_key[i] = b;
s_key[k_len - i - 1] = mds_rem(a, b);
}
//printf("s_key: %08x %08x %08x %08x\n", s_key[0], s_key[1], s_key[2], s_key[3]);
#if 0
printf("l_key:\n");
for(i = 0; i < 40; i += 2)
{
a = 0x01010101 * i; b = a + 0x01010101;
a = h_fun(a, me_key);
b = rotl(h_fun(b, mo_key), 8);
l_key[i] = a + b;
l_key[i + 1] = rotl(a + 2 * b, 9);
printf("%08x %08x\n", l_key[i], l_key[i+1]);
}
#endif
#ifdef MK_TABLE
gen_mk_tab(s_key);
#endif
return l_key;
};
/* encrypt a block of text */
#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 tf_encrypt(const u4byte in_blk[4], u4byte out_blk[])
{ u4byte t0, t1, blk[4];
blk[0] = in_blk[0] ^ l_key[0];
blk[1] = in_blk[1] ^ l_key[1];
blk[2] = in_blk[2] ^ l_key[2];
blk[3] = 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] = blk[2] ^ l_key[4];
out_blk[1] = blk[3] ^ l_key[5];
out_blk[2] = blk[0] ^ l_key[6];
out_blk[3] = blk[1] ^ l_key[7];
};
/* decrypt a block of text */
#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 tf_decrypt(const u4byte in_blk[4], u4byte out_blk[4])
{ u4byte t0, t1, blk[4];
blk[0] = in_blk[0] ^ l_key[4];
blk[1] = in_blk[1] ^ l_key[5];
blk[2] = in_blk[2] ^ l_key[6];
blk[3] = 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] = blk[2] ^ l_key[0];
out_blk[1] = blk[3] ^ l_key[1];
out_blk[2] = blk[0] ^ l_key[2];
out_blk[3] = blk[1] ^ l_key[3];
}