The website was posted here to show your 8 year olds. Although I think it would be just as effective to just tell your kids "You scramble your messages with a

The website was posted here to show your 8 year olds. Although I think it would be just as effective to just tell your kids "You scramble your messages with a key and only a person with the key can unscramble your messages." And then proceed to explain to them the conjugate DH exchange, the number field seive algorithm, and common block ciphers.