challenge-response

A binary gap within a positive integer N is any maximal sequence of consecutive zeros that is surrounded by ones at both ends in the binary representation of N. For example, number 9 has binary representation 1001 and contains a binary gap of length 2. The number 529 has binary representation 1000010001 and contains two binary gaps: one of length 4 and one of length 3. The number 20 has binary representation 10100 and contains one binary gap of length 1. The number 15 has binary representation 1111 and has no binary gaps. Write a function: int solution(int N); that, given a positive integer N,

I would like to know if jCryption + Challenge Response Authentication Mechanism are a good alternative to SSL. I know that SSL is very much better, but I'm making a project where the owner don't want to buy a SSL certificate and, I would like to find a solution to give the best security approach that could be acquired without the use of SSL. Any ideas? No, it's not. Just off the top of my head, I can think of many reasons: HTTP headers are still unencrypted, the key exchange is vulnerable to man-in-the-middle attacks, and you're putting a high degree of trust in client-side code. Just use a

Ok guys just a small game: I have some specifications for a project. At some point they ask for the following to encrypt a password over the net, saying that it is a challenge response protocol: CLIENT ----------------------------- SERVER (1)ask for challenge --------------> (2) <---------------------------- send SHA1 taken from the time (this is the challenge) (3) make SHA1 xor PASSWORD --------> if it's equal to SHA1 xor stored password (4) <---------------------------- Grant access For those who don't know it SHA stands for Secure Hashing Algorithm, a standard algorithm for cryptography. I

Suppose you want to add an extra layer of credentials on top of a SSL-encrypted login/password, but you don't want to increase complexity to the user. Is there a way to add the requirement of the possession of a dongle to web-server authentication schemes with existing cross-platform browser capabilities? In other words, to get access to the web-site, you would need a username, password, and a USB dongle that has been plugged into the client computer. The dongle would presumably do some sort of challenge/response. It'd be ideal if this dongle solution worked with Firefox automatically or with