What is a Salt and How Does It Make Password Hashing More Secure?
Definition of a Salt
In cryptography, a salt is a random piece of data added to a password before it is hashed. This process is known as "salting" and is used to enhance the security of password storage. The salt is typically a unique, random value generated for each password instance and is stored alongside the hashed password in the database[2][6].
Purpose and Benefits of Salting
Salting serves several critical purposes in securing passwords:
Prevents Rainbow Table Attacks: Rainbow tables are precomputed tables of hash values for common passwords. By adding a unique salt to each password, the resultant hash values become unique, even for identical passwords. This makes it impractical for attackers to use rainbow tables, as they would need to generate a separate table for each unique salt[1][2][3][9].
Thwarts Dictionary Attacks: Dictionary attacks involve using a list of common passwords to guess a user's password. Salting ensures that even if two users have the same password, their salted and hashed values will be different, making it harder for attackers to use precomputed dictionary hashes[3][9].
Mitigates Brute Force Attacks: Brute force attacks try every possible password combination. Salting increases the complexity and uniqueness of each password hash, thereby increasing the computational effort required to crack each password[3][9].
Protects Against SQL Injection Attacks: In the event of a database breach through SQL injection, salted hashes provide an additional layer of security. Attackers would need to know the salt and recompute the hash for each password attempt, significantly slowing down their efforts[3][4].
How Salting Works
The process of salting and hashing a password typically involves the following steps:
Generate a Salt: A unique, random salt is generated for each password. This salt can be created using a secure random number generator[2][6][10].
Combine Password and Salt: The salt is concatenated with the password. This combined string is then fed into a cryptographic hash function[2][3][6].
