Numberphile recently posted a video about the math behind RSA encryption. In the video below, a brief description of public key cryptography is given and then we are shown a simple example of the math used to perform encryption and decryption (math example @ 2:25). In the video, James skips over the method for determining the private key, so I thought I would run through the key generation steps for his example. Choose two distinct prime numbers p and q. These are the two primes that he mentioned, so p = 2 and q = 5. Compute n = pq. Simply multiply 2 and 5. n = 10. Compute the totient of n, or (p-1)(q-1). (2-1) times (5-1) is 1[…]

# Tag: cryptography

Since every time I posted my previous article people were asking questions, I wrote up the following as a Facebook comment and figured it deserved repeat posting here. Note that there’s an article in our archives which is similar but not as specific as this one. Get ready for your cryptography lesson. A hash is a one-way function. This means that given some input, it creates some seemingly random output. It is one-way in that you can’t do math on the output to get back to the input. So, “abc” -> (hash function) -> A9993E364706816ABA3E25717850C26C9CD0D89D and there’s no way to get “abc” back from that nasty string. UNLESS you have taken the time to generate what’s called a rainbow table. Hackers[…]