Hi, i would want to know how to create a hash of a data.

I've already know crypt() and how to create a md5 hash with it, but problems come when any byte is equal to zero, because de crypt function declaration is:

char * crypt(const char * key , const char *salt);

e.g:

struct data{
int x;
int y;
int z;
}

struct data var1;
var1.x = 5;
var1.y = 0;
var1.z = 5;

hash = crypt((char *) &var1, "$1$");
/*the hash is: (for example) $1$ZH$YGGYInw6oH0P29Ze6hlo.1

again, with different data, (pay attention to var2.z)

*/

struct data var2;
var2.x = 5;
var2.y = 0;
var2.z = 115;

hash = crypt((char *) &var2, "$1$");

/*the hash will be the same, since var2.z parameter which is different from first, is not passed, because var2.y is null-byte, and the string ends */

Could anybody show me another function to create a hash which i can pass null-byte data??

Thanks In Advance

Yeah, it looks like crypt() was intended for use with ASCII passwords, so a null value isn't really possible. Check out mhash. Haven't used it, but it looks something like what you want.

If you just need a simple, quick and dirty hash, you can add or xor the bytes.

Does this help?
"man 3 sha" or "man md5"