Hi, Hope you're doing well. I just wanted to give you heads up about a broken link I found on your page here: https://docs.python.org/2.6/library/sha.html You've mentioned Cryptographic Toolkit (csrc.nist.gov/CryptoToolkit/) which is unfortunately no longer available. It used to be such a helpful website... If you're looking to replace the broken link, we recently put together a comprehensive introduction/guide on cryptography here: https://thebestvpn.com/cryptography/ It's pretty in-depth and we've put to lot of work on it. Cheers and let me know if it's worth mentioning on your page :) Carol B.