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// mars.cpp - modified by Sean Woods from Brian Gladman's mars6.c for Crypto++
// key setup updated by Wei Dai to reflect IBM's "tweak" proposed in August 1999
/* This is an independent implementation of the MARS encryption */
/* algorithm designed by a team at IBM as a candidate for the US */
/* NIST Advanced Encryption Standard (AES) effort. The algorithm */
/* is subject to Patent action by IBM, who intend to offer royalty */
/* free use if a Patent is granted. */
/* */
/* 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 */
/* constraints that IBM place on the use of the MARS algorithm. */
/* */
/* Dr Brian Gladman (gladman@seven77.demon.co.uk) 4th October 1998 */
#include "pch.h"
#include "mars.h"
#include "misc.h"
NAMESPACE_BEGIN(CryptoPP)
ANONYMOUS_NAMESPACE_BEGIN
static word32 gen_mask(word32 x)
{
word32 m;
m = (~x ^ (x >> 1)) & 0x7fffffff;
m &= (m >> 1) & (m >> 2); m &= (m >> 3) & (m >> 6);
if(!m)
return 0;
m <<= 1; m |= (m << 1); m |= (m << 2); m |= (m << 4);
m |= (m << 1) & ~x & 0x80000000;
return m & 0xfffffffc;
};
NAMESPACE_END
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++)
EK[10*j+i] = T[4*i%15];
}
// Modify multiplication key-words
for(unsigned int i = 5; i < 37; i += 2)
{
word32 w = EK[i] | 3;
word32 m = gen_mask(w);
if(m)
w ^= (rotlMod(Sbox[265 + (EK[i] & 3)], EK[i-1]) & m);
EK[i] = w;
}
}
#define f_mix(a,b,c,d) \
r = rotrFixed(a, 8); \
b ^= Sbox[a & 255]; \
b += Sbox[(r & 255) + 256]; \
r = rotrFixed(a, 16); \
a = rotrFixed(a, 24); \
c += Sbox[r & 255]; \
d ^= Sbox[(a & 255) + 256]
#define b_mix(a,b,c,d) \
r = rotlFixed(a, 8); \
b ^= Sbox[(a & 255) + 256]; \
c -= Sbox[r & 255]; \
r = rotlFixed(a, 16); \
a = rotlFixed(a, 24); \
d -= Sbox[(r & 255) + 256]; \
d ^= Sbox[a & 255]
#define f_ktr(a,b,c,d,i) \
m = a + EK[i]; \
a = rotlFixed(a, 13); \
r = a * EK[i + 1]; \
l = Sbox[m & 511]; \
r = rotlFixed(r, 5); \
l ^= r; \
c += rotlMod(m, r); \
r = rotlFixed(r, 5); \
l ^= r; \
d ^= r; \
b += rotlMod(l, r)
#define r_ktr(a,b,c,d,i) \
r = a * EK[i + 1]; \
a = rotrFixed(a, 13); \
m = a + EK[i]; \
l = Sbox[m & 511]; \
r = rotlFixed(r, 5); \
l ^= r; \
c -= rotlMod(m, r); \
r = rotlFixed(r, 5); \
l ^= r; \
d ^= r; \
b -= rotlMod(l, r)
typedef BlockGetAndPut<word32, LittleEndian> Block;
void MARS::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
word32 a, b, c, d, l, m, r;
Block::Get(inBlock)(a)(b)(c)(d);
a += EK[0];
b += EK[1];
c += EK[2];
d += EK[3];
int i;
for (i = 0; i < 2; i++) {
f_mix(a,b,c,d);
a += d;
f_mix(b,c,d,a);
b += c;
f_mix(c,d,a,b);
f_mix(d,a,b,c);
}
f_ktr(a,b,c,d, 4); f_ktr(b,c,d,a, 6); f_ktr(c,d,a,b, 8); f_ktr(d,a,b,c,10);
f_ktr(a,b,c,d,12); f_ktr(b,c,d,a,14); f_ktr(c,d,a,b,16); f_ktr(d,a,b,c,18);
f_ktr(a,d,c,b,20); f_ktr(b,a,d,c,22); f_ktr(c,b,a,d,24); f_ktr(d,c,b,a,26);
f_ktr(a,d,c,b,28); f_ktr(b,a,d,c,30); f_ktr(c,b,a,d,32); f_ktr(d,c,b,a,34);
for (i = 0; i < 2; i++) {
b_mix(a,b,c,d);
b_mix(b,c,d,a);
c -= b;
b_mix(c,d,a,b);
d -= a;
b_mix(d,a,b,c);
}
a -= EK[36];
b -= EK[37];
c -= EK[38];
d -= EK[39];
Block::Put(xorBlock, outBlock)(a)(b)(c)(d);
}
void MARS::Dec::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
word32 a, b, c, d, l, m, r;
Block::Get(inBlock)(d)(c)(b)(a);
d += EK[36];
c += EK[37];
b += EK[38];
a += EK[39];
int i;
for (i = 0; i < 2; i++) {
f_mix(a,b,c,d);
a += d;
f_mix(b,c,d,a);
b += c;
f_mix(c,d,a,b);
f_mix(d,a,b,c);
}
r_ktr(a,b,c,d,34); r_ktr(b,c,d,a,32); r_ktr(c,d,a,b,30); r_ktr(d,a,b,c,28);
r_ktr(a,b,c,d,26); r_ktr(b,c,d,a,24); r_ktr(c,d,a,b,22); r_ktr(d,a,b,c,20);
r_ktr(a,d,c,b,18); r_ktr(b,a,d,c,16); r_ktr(c,b,a,d,14); r_ktr(d,c,b,a,12);
r_ktr(a,d,c,b,10); r_ktr(b,a,d,c, 8); r_ktr(c,b,a,d, 6); r_ktr(d,c,b,a, 4);
for (i = 0; i < 2; i++) {
b_mix(a,b,c,d);
b_mix(b,c,d,a);
c -= b;
b_mix(c,d,a,b);
d -= a;
b_mix(d,a,b,c);
}
d -= EK[0];
c -= EK[1];
b -= EK[2];
a -= EK[3];
Block::Put(xorBlock, outBlock)(d)(c)(b)(a);
}
NAMESPACE_END
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