But aircrack-ng is the top encryption cracker for such type data ??
It can 100% crack any WEP based encryption and to crack WPA based encryptions will obviously require a wordlist to pass it to.
My guess is you are attempting to crack a WPA based encryption and its not working because, Either you did not log enough captured IV's while logging the cap file. In which case I would suggest looking into using de-authentication tools to speed up the capture of solid IV's in the cap file. The more IV data captured while logging the cap file will result in a easier to crack password. As this is the captured data of one system making a valid connection to that network. Also could just be that your wordlist crap and doesnt actually contain the password of the network so it cant crack it.
Point being if its a WEP encrypted password you are trying to crack aircrack-ng will crack it 100% of the time. If its a WPA based encryption then its all gonna come down to how many valid IV's you capture in the cap file and your wordlist file to brute it with.
At lest that is what I'm guessing you mean cracking a .cap file, Because a cap file is usually just a file containing captured networking data doesnt always have to be a wifi password that a cap contains a cap could also contain arp spoof logs and such so maybe want to be a little more clear in your thread.
