It is always possible to apply additional hashes to the MD5/SHA. First strip away the salt, then apply bcrypt or scrypt, next store both the new salt and the ol

It is always possible to apply additional hashes to the MD5/SHA. First strip away the salt, then apply bcrypt or scrypt, next store both the new salt and the old salt plus the new hash. Validating passwords will require two steps. First, hashing the entered password with old salt, then applying bcrypt one more time.