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: math

We are working with a security policy that treats two passwords of equivalent strength: 8 character password with two character sets represented (pick two of upper/lower/number/symbol) 6 character password with three character sets represented (pick three of upper/lower/number/symbol) The question arises, how equivalent (or not) are they? Well, it’s time to do some math. Total Possible Passwords One way to measure password strength is in the total number of passwords that one might be able to generate that meet that criteria. More would be better. There are 26 uppercase, 26 lowercase, 10 digit, and 33 ASCII-printable symbols available on the average keyboard (totaling 95 options). If we simply asked how many possible 6 character passwords are there, you can multiply 95 for[…]