Salting is a fundamental technique in cryptography that enhances password security by adding randomness to passwords before hashing. Let's delve into its significance and address your specific questions.
How Does Salting Protect Against Precomputed Hash Attacks (Like Rainbow Tables)?
A rainbow table is a precomputed database of hash values for common passwords. Attackers use these tables to quickly match a stolen hash to its original password without performing the computational work of hashing each guess. Salting mitigates this threat by appending a unique, random value—known as a salt—to each password before hashing. This process ensures that even if two users have the same password, their hashed outputs will differ due to distinct salts. Consequently, attackers cannot use precomputed tables effectively, as they'd need to generate a separate rainbow table for each possible salt, which is computationally infeasible.
Does Salting Alone Make Passwords Safer Against Brute Force Attacks, or Is It Just a Partial Solution?
While salting is crucial, it primarily defends against precomputed attacks like rainbow tables. Against brute force attacks—where attackers systematically try every possible password combination—salting alone offers limited protection. To bolster security against brute force attacks, it's essential to use key stretching techniques. Algorithms like bcrypt, PBKDF2, or Argon2 are designed to be computationally intensive, deliberately slowing down the hashing process. This deliberate slowness makes it more time-consuming and resource-intensive for attackers to guess passwords, thereby enhancing security.
If an Attacker Has Access to the Hashed and Salted Passwords, What Additional Steps Do They Need to Take to Break Them?
If an attacker obtains both the hashed passwords and their associated salts, they cannot leverage precomputed tables due to the uniqueness introduced by the salts. Instead, they must perform a brute force attack for each password individually. This involves guessing a password, appending the known salt, hashing the combination, and comparing the result to the stored hash. The computational effort required depends on the strength of the hashing algorithm and the complexity of the password. Employing algorithms like bcrypt or Argon2, which are designed to be resource-intensive, further increases the difficulty for attackers, making the cracking process significantly more challenging and time-consuming.
