Alloy Computer Products Network Device BWS-136 - Manual (Page 18)

BWS-136 User Manual_amend.doc - 35 -
although impractical.
************************************************/
//#include "xtea.h"
void encipher(unsigned long *const v,unsigned long *const w,
const unsigned long *const k)
{
register unsigned long y=v[0],z=v[1],sum=0,delta=0x9E3779B9,n=32;
while(n-->0)
{ y+= (z<<4 ^ z>>5) + z ^ sum + k[sum&3];
sum += delta;
z+= (y<<4 ^ y>>5) + y ^ sum + k[sum>>11 & 3];
}
w[0]=y; w[1]=z;
}
void decipher(unsigned long *const v,unsigned long *const w,
const unsigned long *const k)
{
register unsigned long y=v[0],z=v[1],sum=0xC6EF3720,
delta=0x9E3779B9,n=32;
/* sum = delta<<5, in general sum = delta * n */
while(n-->0)
{
z-= (y<<4 ^ y>>5) + y ^ sum + k[sum>>11 & 3];
sum -= delta;
y-= (z<<4 ^ z>>5) + z ^ sum + k[sum&3];
}
w[0]=y; w[1]=z;
BWS-136 User Manual_amend.doc - 36 -
}
2. The TEA.H
#ifndef __XTEA_H__
#define __XTEA_H__
void encipher(unsigned long *const v,unsigned long *const w,
const unsigned long *const k);
void decipher(unsigned long *const v,unsigned long *const w,
const unsigned long *const k);
#endif