Lightweight 8 byte hash function algorithm

Question

I need to extract an 8 byte digest from a variable length string so I\'m looking for such an algorithm that I will implement in c/c++. That will be part of a digital signatu

Answer 1

Here is a modified version of a 32 bit version I found in my old source files

static unsigned long long llhash(const char *str)
{
    unsigned long long hash = 5381;
    int c;

    while (c = *str++)
        hash = ((hash << 5) + hash) + c;

    return hash;
}

But hashing will always result in collisions. Of course some algorithms are better than others.

Edit: I found the source of the 32 bit version: http://www.cse.yorku.ca/~oz/hash.html