What is Bcrypt?
Bcrypt is a widely used password hashing algorithm designed to enhance the security of user passwords. It is specifically designed to resist various types of attacks, including brute-force attacks and rainbow table attacks, making it a strong choice for storing passwords securely.
When using Bcrypt for password hashing, the process involves several steps:
- Hashing Process: When a user creates or updates their password, the plaintext password is passed through the Bcrypt algorithm. Bcrypt generates a hash value based on the password and a randomly generated salt.
- Salting: A salt is a random value that is combined with the password before hashing. The salt is unique for each user and is stored alongside the hash. Salting helps prevent attacks like rainbow table attacks, where attackers try to match hashes with precomputed tables.
- Key Stretching: Bcrypt employs a technique called key stretching. It involves iterating the hashing process multiple times, making it computationally intensive and time-consuming. This slows down attackers attempting to crack the password through brute force.
- Cost Factor: Bcrypt allows you to specify a cost factor (number of rounds) that determines the computational intensity of the hashing process. A higher cost factor makes the algorithm more resource-intensive and consequently more secure.
- Storing Hash and Salt: The generated hash and salt are then stored in the database. When a user attempts to log in, the entered password is hashed with the stored salt, and the resulting hash is compared with the stored hash. If they match, the password is correct.
Significance for Password Security
Bcrypt's effectiveness comes from its computational intensity, salting, and key stretching features. These properties make it significantly more difficult for attackers to crack passwords even if they obtain the hash and salt from the database.
Because Bcrypt is slow and resource-intensive, it hinders automated brute-force attacks. Additionally, the unique salt for each user prevents the use of precomputed tables, and the key stretching ensures that each hash calculation takes a substantial amount of time.
As a result, even if an attacker gains access to the database, obtaining plaintext passwords from Bcrypt hashes is a formidable challenge. Bcrypt has become an industry-standard for securely hashing passwords, and its usage is recommended in applications where password security is a priority.