[cryptography] workaround for length extension attacks (was: Doubts over necessity of SHA-3 cryptography standard)

If you're using one of the pre-SHA-3 error secure hash functions which is vulnerable to length-extension attacks (e.g. SHA-256), then a good fix is the "HASH_d" technique suggested in Ferguson and Schneier's "Practical Cryptography" book (whose new edition is Ferguson, Schneier, and Kohno's "Crypto

Re: [cryptography] Doubts over necessity of SHA-3 cryptography standard

Yes, when the SHA-3 process was launched—in the exciting time when MD5 and SHA-1 had been dramatically shown to be weak—it seemed like we were in danger of waking up one day and finding out that we had no strong hash functions left. It was prudent to get started on SHA-3 ASAP in order to have an al