137 lines
2.9 KiB
C
137 lines
2.9 KiB
C
/* simple XXTEA en/decrypt utility
|
|
*
|
|
* BSD Licence
|
|
*
|
|
* btea function is from
|
|
* <https://secure.wikimedia.org/wikipedia/en/wiki/XXTEA#Reference_code>
|
|
*
|
|
* (c) by Sec <sec@42.org> 6/2011
|
|
*/
|
|
|
|
#include <stdint.h>
|
|
|
|
#define DELTA 0x9e3779b9
|
|
#define MX (((z>>5^y<<2) + (y>>3^z<<4)) ^ ((sum^y) + (k[(p&3)^e] ^ z)))
|
|
#include "xxtea.h"
|
|
|
|
uint32_t charp2uint32(uint8_t *data, uint8_t bytes)
|
|
{
|
|
uint32_t r = 0;
|
|
if( bytes ){
|
|
r |= *data++;
|
|
}
|
|
if( bytes > 1){
|
|
r<<=8;
|
|
r |= *data++;
|
|
}
|
|
if( bytes > 2){
|
|
r<<=8;
|
|
r |= *data++;
|
|
}
|
|
if( bytes > 3){
|
|
r<<=8;
|
|
r |= *data++;
|
|
}
|
|
return r;
|
|
}
|
|
|
|
void charp2uint32p(uint8_t* data, uint8_t n, uint32_t *v)
|
|
{
|
|
int i,j=0;
|
|
int fullwords = n/4;
|
|
for(i=0; i<fullwords*4; i+=4){
|
|
v[j++] = charp2uint32(data+i,4);
|
|
}
|
|
|
|
uint8_t extrabytes = n - i;
|
|
v[j] = charp2uint32(data+i,extrabytes);
|
|
}
|
|
|
|
void uint322charp(uint32_t data, uint8_t *buf, uint8_t bytes)
|
|
{
|
|
if( bytes )
|
|
buf[0] = data>>24;
|
|
if( bytes > 1)
|
|
buf[1] = (data>>16)&0xFF;
|
|
if( bytes > 2)
|
|
buf[2] = (data>>8)&0xFF;
|
|
if( bytes > 3)
|
|
buf[3] = (data>>0)&0xFF;
|
|
}
|
|
|
|
void uint32p2charp(uint8_t* data, uint8_t n, uint32_t *v)
|
|
{
|
|
int i;
|
|
int fullwords = n/4;
|
|
|
|
for(i=0; i<fullwords; i++){
|
|
uint322charp(v[i],data+i*4,4);
|
|
}
|
|
|
|
uint8_t extrabytes = n - fullwords*4;
|
|
uint322charp(v[i],data+i*4,extrabytes);
|
|
}
|
|
|
|
void xxtea_encode(uint8_t *data, int n, uint32_t const k[4])
|
|
{
|
|
uint32_t v[8]; //maximum 32 bytes
|
|
int words = (n+3)/4;
|
|
if( words > 8 )
|
|
return;
|
|
charp2uint32p(data, n, v);
|
|
xxtea_encode_words(v, words, k);
|
|
uint32p2charp(data, n, v);
|
|
}
|
|
|
|
void xxtea_decode(uint8_t *data, int n, uint32_t const k[4])
|
|
{
|
|
uint32_t v[8]; //maximum 32 bytes
|
|
int words = (n+3)/4;
|
|
if( words > 8 )
|
|
return;
|
|
charp2uint32p(data, n, v);
|
|
xxtea_decode_words(v, words, k);
|
|
uint32p2charp(data, n, v);
|
|
}
|
|
|
|
void xxtea_encode_words(uint32_t *v, int n, uint32_t const k[4])
|
|
{
|
|
if(k[0] == 0 && k[1] == 0 && k[2] == 0 && k[3] == 0) return;
|
|
uint32_t y, z, sum;
|
|
unsigned p, rounds, e;
|
|
rounds = 6 + 52/n;
|
|
sum = 0;
|
|
z = v[n-1];
|
|
do {
|
|
sum += DELTA;
|
|
e = (sum >> 2) & 3;
|
|
for (p=0; p<n-1; p++) {
|
|
y = v[p+1];
|
|
z = v[p] += MX;
|
|
}
|
|
y = v[0];
|
|
z = v[n-1] += MX;
|
|
} while (--rounds);
|
|
}
|
|
|
|
void xxtea_decode_words(uint32_t *v, int n, uint32_t const k[4])
|
|
{
|
|
if(k[0] == 0 && k[1] == 0 && k[2] == 0 && k[3] == 0) return;
|
|
uint32_t y, z, sum;
|
|
unsigned p, rounds, e;
|
|
|
|
rounds = 6 + 52/n;
|
|
sum = rounds*DELTA;
|
|
y = v[0];
|
|
do {
|
|
e = (sum >> 2) & 3;
|
|
for (p=n-1; p>0; p--) {
|
|
z = v[p-1];
|
|
y = v[p] -= MX;
|
|
}
|
|
z = v[n-1];
|
|
y = v[0] -= MX;
|
|
} while ((sum -= DELTA) != 0);
|
|
}
|
|
|