I am definitely not an expert, but the really short answer is that “salting” a line of text means to stick a few extra characters on the end of it. You could salt “salt” with “abcdefg” to get “saltabcdefg”. This might be useful if “salt” happens to be a password that you’d like to make … Read more
A new salt should be randomly generated for each user and each time they change their password as a minimum. Don’t just rely on a site wide salt for example, as that defeats the point of using a salt in the first place. Using a unique salt for each user is so that if two … Read more
It’s been a while since I asked this question, and I’m much more familiar with the cryptographic theory now, so here is the more modern approach: Reasoning Don’t use md5. Don’t use a single cycle of sha-family quick hashes. Quick hashes help attackers, so you don’t want that. Use a resource-intensive hash, like bcrypt, instead. … Read more
Inspired from this post and that post, I use this code to generate and verify hashed salted passwords. It only uses JDK provided classes, no external dependency. The process is: you create a salt with getNextSalt you ask the user his password and use the hash method to generate a salted and hashed password. The … Read more
After some experimentation, I have come to the conclusion that this is due to the way the salt is treated. The salt is not considered to be literal text, but rather to be a base64 encoded string, such that 22 bytes of salt data would actually represent a 16 byte string (floor(22 * 24 / … Read more
In your case, breaking the hash algorithm is equivalent to finding a collision in the hash algorithm. That means you don’t need to find the password itself (which would be a preimage attack), you just need to find an output of the hash function that is equal to the hash of a valid password (thus … Read more
It doesn’t stop dictionary attacks. What it does is stop someone who manages to get a copy of your password file from using a rainbow table to figure out what the passwords are from the hashes. Eventually, it can be brute-forced, though. The answer to that part is to force your users to not use … Read more
Have a good look at the values you’re dealing with. The random salt generated will be, say: abcdefg… What is fed into crypt looks like this: crypt($password, ‘$2y$10$abcdefg…’) | | | | | +- the salt | +- the cost parameter +- the algorithm type The result looks like: $2y$10$abcdefg…123456789… | | | | | … Read more
The salt is incorporated into the hash (encoded in a base64-style format). For example, in traditional Unix passwords the salt was stored as the first two characters of the password. The remaining characters represented the hash value. The checker function knows this, and pulls the hash apart to get the salt back out.
Ok. Seeing as I need to write about this over and over, I’ll do one last canonical answer on pepper alone. The Apparent Upside Of Peppers It seems quite obvious that peppers should make hash functions more secure. I mean, if the attacker only gets your database, then your users passwords should be secure, right? … Read more