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VeraCrypt/src/Crypto/Twofish.c

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/*
---------------------------------------------------------------------------
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[])
{ 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 = 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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