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What is bcrypt and how does it work?

When it comes to securing sensitive information, such as user passwords, proper encryption is crucial. One popular method for password hashing is bcrypt. In this article, we will explore what bcrypt is, how it works, why it is preferred for password hashing, and how it compares to other algorithms like SHA256. We will also discuss the safety of bcrypt for password hashing.

What is bcrypt?

Bcrypt is a cryptographic algorithm specifically designed for password hashing. It was developed by Niels Provos and David Mazières, intended to address certain vulnerabilities and weaknesses found in other hash functions. Bcrypt is widely recognized as a secure and reliable choice for password hashing.

How does bcrypt work?

Bcrypt incorporates several unique features to enhance password security:

Salt: Bcrypt uses a technique called salting, which involves adding a random value called a salt to each password before hashing. The salt is stored alongside the hash, making it unique to every password. Salting prevents precomputed table attacks and ensures that even identical passwords have different hashes.

Key stretching: Bcrypt uses a configurable work factor that determines the computational cost of hashing. The work factor controls how many iterations the algorithm performs, making the hashing process deliberately slow. This intentional slowdown helps to protect against brute-force and dictionary attacks.

Variable-length password support: Bcrypt can handle passwords up to 72 bytes in length. If a password exceeds this limit, it is truncated, ensuring compatibility across different systems.

Why you should use bcrypt to hash stored passwords Using bcrypt for password hashing offers several key benefits:

Strong security: Bcrypt is designed to be resistant to various password cracking techniques, including brute-force, rainbow table, and dictionary attacks. The combination of salting, key stretching, and variable-length password support greatly enhances the security of stored passwords.

Future-proofing: Bcrypt's adjustable work factor allows you to adapt the algorithm's computational cost over time. As technology advances, you can increase the work factor to compensate for increased computational power, ensuring the longevity of your password hashes.

Easy implementation: Bcrypt has become widely supported across different programming languages and frameworks, making it relatively easy to implement in your applications. Many popular password hashing libraries and frameworks already provide built-in support for bcrypt.

Bcrypt vs. SHA256

SHA256 is another commonly used cryptographic algorithm for password hashing. While SHA256 is a secure hash function, it lacks some of the features that make bcrypt an ideal choice for password storage.

Speed: SHA256 is designed to be fast, making it more susceptible to brute-force attacks. Bcrypt's deliberate slowdown through key stretching makes it much more time-consuming to compute hashes, significantly increasing the time required for each attempted password guess.

Salting: While SHA256 can incorporate salt for password hashing, bcrypt's salting mechanism is more advanced and inherently built into the algorithm. Bcrypt ensures that every password has a unique salt, preventing the effectiveness of precomputed tables.

Is bcrypt safe for password hashing?

Yes, bcrypt is considered safe for password hashing. Its design focuses on protecting against common attack vectors, and its slow computational process effectively mitigates brute-force and dictionary attacks. However, it is essential to use bcrypt correctly and keep up with best practices, such as choosing an appropriate work factor and properly managing the storage of salts and hashes.


Bcrypt is a reliable and secure algorithm for password hashing, widely preferred for storing sensitive information like user passwords. With its unique features such as salting, key stretching, and variable-length password support, bcrypt provides enhanced protection against various password cracking techniques. When compared to SHA256, bcrypt's intentional slowdown and stronger salting mechanism make it a better choice for securing passwords. By using bcrypt correctly and keeping up with best practices, you can ensure the safety of your stored passwords and provide a robust defense against potential security breaches.

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