// mars.cpp - written and placed in the public domain by Wei Dai
// includes IBM's key setup "tweak" proposed in August 1999 (http://www.research.ibm.com/security/key-setup.txt)
#include "pch.h"
#include "mars.h"
#include "misc.h"
NAMESPACE_BEGIN(CryptoPP)
void MARS::Base::UncheckedSetKey(const byte *userKey, unsigned int length, const NameValuePairs &)
{
AssertValidKeyLength(length);
// Initialize T[] with the key data
FixedSizeSecBlock<word32, 15> T;
GetUserKey(LITTLE_ENDIAN_ORDER, T.begin(), 15, userKey, length);
T[length/4] = length/4;
for (unsigned int j=0; j<4; j++) // compute 10 words of K[] in each iteration
{
unsigned int i;
// Do linear transformation
for (i=0; i<15; i++)
T[i] = T[i] ^ rotlFixed(T[(i+8)%15] ^ T[(i+13)%15], 3) ^ (4*i+j);
// Do four rounds of stirring
for (unsigned int k=0; k<4; k++)
for (i=0; i<15; i++)
T[i] = rotlFixed(T[i] + Sbox[T[(i+14)%15]%512], 9);
// Store next 10 key words into K[]
for (i=0; i<10; i++)
m_k[10*j+i] = T[4*i%15];
}
// Modify multiplication key-words
for(unsigned int i = 5; i < 37; i += 2)
{
word32 m, w = m_k[i] | 3;
m = (~w ^ (w<<1)) & (~w ^ (w>>1)) & 0x7ffffffe;
m &= m>>1; m &= m>>2; m &= m>>4;
m |= m<<1; m |= m<<2; m |= m<<4;
m &= 0x7ffffffc;
w ^= rotlMod(Sbox[265 + (m_k[i] & 3)], m_k[i-1]) & m;
m_k[i] = w;
}
}
#define S(a) Sbox[(a)&0x1ff]
#define S0(a) Sbox[(a)&0xff]
#define S1(a) Sbox[((a)&0xff) + 256]
typedef BlockGetAndPut<word32, LittleEndian> Block;
void MARS::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
unsigned int i;
word32 a, b, c, d, l, m, r, t;
const word32 *k = m_k;
Block::Get(inBlock)(a)(b)(c)(d);
a += k[0]; b += k[1]; c += k[2]; d += k[3];
for (i=0; i<8; i++)
{
b = (b ^ S0(a)) + S1(a>>8);
c += S0(a>>16);
a = rotrFixed(a, 24);
d ^= S1(a);
a += (i%4==0) ? d : 0;
a += (i%4==1) ? b : 0;
t = a; a = b; b = c; c = d; d = t;
}
for (i=0; i<16; i++)
{
t = rotlFixed(a, 13);
r = rotlFixed(t * k[2*i+5], 10);
m = a + k[2*i+4];
l = rotlMod((S(m) ^ rotrFixed(r, 5) ^ r), r);
c += rotlMod(m, rotrFixed(r, 5));
(i<8 ? b : d) += l;
(i<8 ? d : b) ^= r;
a = b; b = c; c = d; d = t;
}
for (i=0; i<8; i++)
{
a -= (i%4==2) ? d : 0;
a -= (i%4==3) ? b : 0;
b ^= S1(a);
c -= S0(a>>24);
t = rotlFixed(a, 24);
d = (d - S1(a>>16)) ^ S0(t);
a = b; b = c; c = d; d = t;
}
a -= k[36]; b -= k[37]; c -= k[38]; d -= k[39];
Block::Put(xorBlock, outBlock)(a)(b)(c)(d);
}
void MARS::Dec::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
unsigned int i;
word32 a, b, c, d, l, m, r, t;
const word32 *k = m_k;
Block::Get(inBlock)(d)(c)(b)(a);
d += k[36]; c += k[37]; b += k[38]; a += k[39];
for (i=0; i<8; i++)
{
b = (b ^ S0(a)) + S1(a>>8);
c += S0(a>>16);
a = rotrFixed(a, 24);
d ^= S1(a);
a += (i%4==0) ? d : 0;
a += (i%4==1) ? b : 0;
t = a; a = b; b = c; c = d; d = t;
}
for (i=0; i<16; i++)
{
t = rotrFixed(a, 13);
r = rotlFixed(a * k[35-2*i], 10);
m = t + k[34-2*i];
l = rotlMod((S(m) ^ rotrFixed(r, 5) ^ r), r);
c -= rotlMod(m, rotrFixed(r, 5));
(i<8 ? b : d) -= l;
(i<8 ? d : b) ^= r;
a = b; b = c; c = d; d = t;
}
for (i=0; i<8; i++)
{
a -= (i%4==2) ? d : 0;
a -= (i%4==3) ? b : 0;
b ^= S1(a);
c -= S0(a>>24);
t = rotlFixed(a, 24);
d = (d - S1(a>>16)) ^ S0(t);
a = b; b = c; c = d; d = t;
}
d -= k[0]; c -= k[1]; b -= k[2]; a -= k[3];
Block::Put(xorBlock, outBlock)(d)(c)(b)(a);
}
NAMESPACE_END
