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/*
* Copyright © 2002 Vita Nuova Holdings Limited. All rights reserved.
*/
#include <lib9.h>
#include <bio.h>
/* CBC, ECB, integrate, SSL */
#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]);
}
}
static void
decerr(char *s)
{
fprint(2, "decrypt error: %s (wrong password ?)\n", s);
exits("decrypt");
}
void
main(int argc, char **argv)
{
/*
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 };
uchar tmp[8];
*/
ushort edkey[2*KEYLEN];
uchar obuf[8], buf[8], key[16];
long i, m, n, om;
int dec, stdin = 0, stdout = 1;
Biobuf *bin, *bout;
/*
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("");
}
*/
if((argc != 3 && argc != 4) || (strcmp(argv[1], "-e") != 0 && strcmp(argv[1], "-d") != 0) || strlen(argv[2]) != 16){
fprint(2, "usage: idea -[e | d] <16 char key> [inputfile]\n");
exits("usage");
}
dec = strcmp(argv[1], "-d") == 0;
if(argc == 4){
char s[128];
stdin = open(argv[3], OREAD);
if(stdin < 0){
fprint(2, "cannot open %s\n", argv[3]);
exits("");
}
strcpy(s, argv[3]);
if(dec){
if(strcmp(s+strlen(s)-3, ".id") != 0){
fprint(2, "input file not a .id file\n");
exits("");
}
s[strlen(s)-3] = '\0';
}
else
strcat(s, ".id");
stdout = create(s, OWRITE, 0666);
if(stdout < 0){
fprint(2, "cannot create %s\n", s);
exits("");
}
}
for(i = 0; i < 16; i++)
key[i] = argv[2][i];
idea_key_setup(key, edkey);
m = om = 0;
bin = (Biobuf*)malloc(sizeof(Biobuf));
bout = (Biobuf*)malloc(sizeof(Biobuf));
Binit(bin, stdin, OREAD);
Binit(bout, stdout, OWRITE);
for(;;){
n = Bread(bin, &buf[m], 8-m);
if(n <= 0)
break;
m += n;
if(m == 8){
idea_cipher(edkey, buf, dec);
if(dec){ /* leave last block around */
if(om > 0)
Bwrite(bout, obuf, 8);
memcpy(obuf, buf, 8);
om = 8;
}
else
Bwrite(bout, buf, 8);
m = 0;
}
}
if(dec){
if(om != 8)
decerr("no last block");
if(m != 0)
decerr("last block not 8 bytes long");
m = obuf[7];
if(m < 0 || m > 7)
decerr("bad modulus");
for(i = m; i < 8-1; i++)
if(obuf[i] != 0)
decerr("byte not 0");
Bwrite(bout, obuf, m);
}
else{
for(i = m; i < 8; i++)
buf[i] = 0;
buf[7] = m;
idea_cipher(edkey, buf, dec);
Bwrite(bout, buf, 8);
}
Bflush(bout);
Bterm(bin);
Bterm(bout);
}
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