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#include "os.h"
#include "mp.h"
#include "libsec.h"
#define KEYLEN 52
#define MODA 0x10000
#define MODM 0x10001
#define MASKA (MODA-1)
#define OP1(x, y) ((x) ^ (y))
#define OP2(x, y) (((x) + (y)) & MASKA)
#define OP3(x, y) mod(x, y)
#define OP2INV(x) (-(x))
#define OP3INV(x) inv(x)
#define BIGEND(k, i) ((k[i]<<8)|k[i+1])
#define MSB(x) ((x)>>8)
#define LSB(x) ((x)&0xff)
static ushort
mod(ushort x, ushort y)
{
ushort q, r;
uint z;
if (x == 0)
return 1-y;
if (y == 0)
return 1-x;
z = (uint)x*(uint)y;
q = z >> 16;
r = z & MASKA;
return r-q+(r<q);
}
static ushort
inv(ushort x)
{
int q, r0, r1, r2, v0, v1, v2;
if (x <= 1)
return x;
r0 = MODM;
r1 = x;
v0 = 0;
v1 = 1;
while (r1 != 0) {
q = r0/r1;
r2 = r0-q*r1;
v2 = v0-q*v1;
r0 = r1;
r1 = r2;
v0 = v1;
v1 = v2;
}
if (v0 < 0)
v0 += MODM;
return v0 & MASKA;
}
static void
idea_key_setup_decrypt(ushort ek[KEYLEN], ushort dk[KEYLEN])
{
int i;
for (i = 0; i < 54; i += 6) {
dk[i] = OP3INV(ek[48-i]);
dk[i+1] = OP2INV(ek[50-i]);
dk[i+2] = OP2INV(ek[49-i]);
dk[i+3] = OP3INV(ek[51-i]);
if (i < 48) {
dk[i+4] = ek[46-i];
dk[i+5] = ek[47-i];
}
}
}
void
idea_key_setup(uchar key[16], ushort ek[2*KEYLEN])
{
int i, j;
ushort tmp, *e = ek;
for (i = 0; i < 8; i++)
ek[i] = BIGEND(key, 2*i);
for (i = 8, j = 1; i < KEYLEN; i++, j++) {
ek[i] = (e[j&7]<<9)|(e[(j+1)&7]>>7);
if (((i+1) & 7) == 0)
e += 8;
}
tmp = ek[49];
ek[49] = ek[50];
ek[50] = tmp;
idea_key_setup_decrypt(ek, &ek[KEYLEN]);
}
void
idea_cipher(ushort key[2*KEYLEN], uchar text[8], int decrypting)
{
int i;
ushort *k;
ushort x[4];
ushort tmp, yout, zout;
k = decrypting ? &key[KEYLEN] : key;
for (i = 0; i < 4; i++)
x[i] = BIGEND(text, 2*i);
for (i = 0; i < 17; i++) {
if (!(i&1)) { /* odd round */
x[0] = OP3(x[0], k[3*i]);
tmp = OP2(x[2], k[3*i+2]);
x[2] = OP2(x[1], k[3*i+1]);
x[3] = OP3(x[3], k[3*i+3]);
x[1] = tmp;
}
else {
tmp = OP3(k[3*i+1], OP1(x[0], x[1]));
yout = OP3(OP2(tmp, OP1(x[2], x[3])), k[3*i+2]);
zout = OP2(tmp, yout);
x[0] = OP1(x[0], yout);
x[1] = OP1(x[1], yout);
x[2] = OP1(x[2], zout);
x[3] = OP1(x[3], zout);
}
}
for (i = 0; i < 4; i++) {
text[2*i] = MSB(x[i]);
text[2*i+1] = LSB(x[i]);
}
}
void
setupIDEAstate(IDEAstate *s, uchar key[16], uchar *ivec)
{
memset(s, 0, sizeof(*s));
memmove(s->key, key, sizeof(s->key));
idea_key_setup(key, s->edkey);
if(ivec)
memmove(s->ivec, ivec, 8);
}
/*
void
main()
{
uchar key[] = { 0x00, 0x01, 0x00, 0x02, 0x00, 0x03, 0x00, 0x04,
0x00, 0x05, 0x00, 0x06, 0x00, 0x07, 0x00, 0x08 };
uchar plain[] = { 0x00, 0x00, 0x00, 0x01, 0x00, 0x02, 0x00, 0x03 };
uchar cipher[] = { 0x11, 0xFB, 0xED, 0x2B, 0x01, 0x98, 0x6D, 0xE5 };
ushort edkey[2*KEYLEN];
uchar tmp[8];
memcpy(tmp, plain, 8);
idea_key_setup(key, edkey);
idea_cipher(edkey, tmp, 0);
if (memcmp(tmp, cipher, 8)) {
print("encrypt wrong\n");
exits("");
}
idea_cipher(edkey, tmp, 1);
if (memcmp(tmp, plain, 8)) {
print("decrypt wrong\n");
exits("");
}
}
*/
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