I'd prefer to use the crypt function and use blowfish encryption, but the current implementation of this module uses the hash function, which doesn't offer this encryption method. So, what is the safest algorithm in Kohana's auth module? Would SHA-512 be a good option or am I better off modifying the module to use crypt and blowfish?
From an answer to this stackoverflow question: SHA512 vs. Blowfish and Bcrypt
It should suffice to say whether bcrypt or SHA-512 is good enough. And the answer is yes, either algorithm is secure enough that a breach will occur through an implementation flaw, not cryptanalysis.
In other words, it seems wiser to use the somewhat hardened implementation already in Kohana vs. trying to modify the module and potentially introduce new implementation errors.