Does Truecrypt's hash function weaken the security of a chosen cipher cascade?
Considering I want to choose a cipher cascade of 3 ciphers for long term security (50+ years) for my archived data on blu-ray disk. Truecrypt allows me to choose only 1 hash algorithm, but up to 3 cipher algorithms.
Doesn't that make the hash function the ultimate weakest link? If SHA2, Whirlpool and RIPEMD160 were all "broken" - would that result in a broken truecrypt container?
Unlike the ciphers, the hash algorithm is not used directly to protect your data. Its only purpose is to take your ASCII passphrase and mix it up, shrinking or expanding it to the size required by the underlying ciphers. In order to make brute force attacks more infeasible, this process is repeated thousands of times in an algorithm called PBKDF2-HMAC so that each password attempt takes time. Because they are not used to directly protect your data, it would not be a major problem if the hash function were found to be weaker than believed. In fact, if your password was strong, even using the infamously broken MD4 algorithm would be technically acceptable, although it would be a rather nasty cryptography faux pas.