Understanding bcrypt: A Deep Dive into Its Mechanics and Usage in Cryptography


The bcrypt hashing algorithm was first introduced in 1999 by Niels Provos and David Mazières. It was based on the Blowfish cipher and specifically designed for password hashing. The main goal behind bcrypt's creation was to introduce a computationally intensive algorithm that could withstand brute-force attacks, a prevalent threat in the realm of cybersecurity.


An example of a bcrypt hash might look like this:
This string encapsulates information about the bcrypt version, the cost factor, the salt, and the hashed value itself.


Bcrypt is predominantly used for password hashing, ensuring that stored passwords are not easily compromised. Its implementation is widespread in various web applications, databases, and authentication systems, providing a robust defense against unauthorized access.


Bcrypt emerged in response to the growing need for secure password storage mechanisms. Traditional hashing algorithms like MD5 and SHA-1 were becoming increasingly vulnerable to attacks. Bcrypt's introduction offered a more resilient approach, combining hashing with key derivation functionality.


The development of bcrypt focused on integrating a workload factor, also known as a cost factor, allowing the algorithm's computational intensity to be adjusted. This adaptation was crucial to maintain relevance over time, as computational capabilities evolved.

How it works

Bcrypt works by first generating a salt – a random value – and then combining this salt with the input (e.g., a password) using the Blowfish cipher. The process iterates multiple times (determined by the cost factor) to produce the final hash. This iterative approach is central to bcrypt's defense mechanism against brute-force attacks.


The use of a salt in bcrypt is critical. It ensures that each hash is unique, even if the same input is used. This uniqueness thwarts rainbow table attacks, where precomputed hash values are used to crack passwords.


While bcrypt is robust, it isn't immune to all forms of attack. It can still be vulnerable to hardware-based attacks like those using ASICs and FPGAs technologies, which can process bcrypt hashes at a faster rate.

Particularities compared to other algorithms

Compared to other hashing algorithms like SHA-256 or Argon2, bcrypt's distinctive feature is its adjustable cost factor, allowing it to remain resilient as hardware capabilities increase. Its sole focus on password hashing also sets it apart from more general-purpose algorithms.

Computational power/cost

The computational cost of bcrypt is a significant aspect of its security model. By adjusting the cost factor, organizations can balance between operational efficiency and security needs, ensuring that the hashing process is intensive enough to deter attacks without causing undue system strain.

Resistance to Attacks

Bcrypt's resistance to brute-force attacks is notable. Its slow hashing process, thanks to the adjustable cost factor, makes it time-consuming and resource-intensive for attackers to crack passwords, especially when compared to faster algorithms like MD5.


While bcrypt is currently effective, the evolution of computing power and potential new attack vectors mean it's crucial to remain vigilant and open to emerging, more secure algorithms.

Modern Alternatives

Modern alternatives like Argon2, which won the Password Hashing Competition in 2015, offer improved resistance to GPU-based attacks and are considered a strong alternative to bcrypt in certain applications.


Bcrypt is widely compatible across different platforms and programming languages, making it a versatile choice for many applications. However, its implementation must be carefully managed to maintain security efficacy.


In conclusion, bcrypt remains a robust and reliable choice for password hashing, offering significant defense against brute-force attacks. Its ability to adjust to increasing computational powers through the cost factor makes it a resilient option. However, it's essential to stay informed about new developments and be prepared to adopt more advanced algorithms like Argon2 as the cybersecurity landscape evolves.