gistfile1.txt

// Return the MAC address of this host, obfuscated for privacy.
// The result may be used as an ID which is unique to this host.
+ (NSString *)obfuscatedMACAddress 
{
    NSString *address = [NSString MACAddress];
    
    if (!address) return nil;
    
    const char *s = [address UTF8String];
    
    MD5_CTX c;
    MD5_Init(&c);
    MD5_Update(&c, s, strlen(s) );
    
    unsigned char hash[16];
    MD5_Final(hash, &c);
    
    UInt32 *hash32 = (UInt32*)hash;
    
    NSString *result = [NSString stringWithFormat:@"%04x%04x%04x%04x",
                        hash32[0], hash32[1], hash32[2], hash32[3] ];
    
    return result;
}