> It is in the context of building a larger > cryptographic protocol. But they aren't > building a cryptographic protocol in this > case, so none of that

> It is in the context of building a larger > cryptographic protocol. But they aren't > building a cryptographic protocol in this > case, so none of that applies here at all, > even a tiny bit. "Crypto" in the context of "don't roll your own crypto" does not mean "cryptographic protocol", it means "crypto system". The Wikipedia page uses protocols as examples of crypto systems. > "Encryption" has a very specific meaning that is > hundreds of years old, "crypto" is just a shorthand > way of writing encryption You're wrong. As I said before, in the case of "rolling one's own crypto" it refers to "crypto systems". Not every word containing "crypto" refers strictly to encryption. E.g., MD5 is a "cryptographic hash function". > or cryptographic, and neither term is a synonym for > authentication. > ... > I cannot tell if this confusion originates from > people not understanding what the words "encryption" > or "cryptographic" mean, or from them not > understanding the difference between authentication > as a broader topic and encryption/hashing as a > singular component within it. Cryptography encompasses more than just encryption. Authentication is included in the definition of "cryptography" here: https://en.wikipedia.org/wiki/Cryptography https://en.wikipedia.org/wiki/Cryptography. An authentication system is totally a crypto system and totally falls under the definition of "cryptography"! MD5 is a bunch of XORs and MODs. Bcrypt has a bit of that, but mostly it uses Blowfish. Scrypt is used for more or less the same purposes as bcrypt, and is built on top of PBKDF2_HMAC_SHA256. Do you see the difference? Bcrypt and scrypt are built out of things at MD5's level. Once again, from Wikipedia, https://en.wikipedia.org/wiki/Cryptosystem https://en.wikipedia.org/wiki/Cryptosystem: Typically, a cryptosystem consists of three algorithms: one for key generation, one for encryption, and one for decryption. That sounds like bcrypt and scrypt qualify. I don't know, but they are clearly much closer to it than MD5. Anyway, the distinction is not always black and white. The point is to use as high-level and complete an implementation you can find for any crypto-related things you need to do. Including password hashing. MD5 was too low-level, and look at how badly they messed it up. They tried to achieve what bcrypt and scrypt were designed for by using a much lower-level construct in MD5. They rolled their own crypto. > Do you really think an authentication scheme > is a cryptographic protocol? Is AES an authentication > scheme? Is Kerberos a cryptographic protocol? No No I don't. But an authentication scheme is a crypto system. Kerberos is a crypto system. Hence the term "don't roll your own crypto" would apply to both.