What is Bcrypt?

Bcrypt is a method for turning a password into a scrambled string that’s hard for computers to reverse. It adds extra random data and repeats the scrambling many times to make cracking very slow.

Let's break it down

  • Method: a specific algorithm designed to protect passwords.
  • Turning a password into a scrambled string: converting the original text into a “hash” that looks like random characters.
  • Hard for computers to reverse: even powerful machines can’t easily figure out the original password from the hash.
  • Adds extra random data: includes a “salt” - random bits that make each hash unique, even if two users have the same password.
  • Repeats the scrambling many times: runs the algorithm many rounds (called “cost factor”) so each guess takes longer, slowing down attackers.

Why does it matter?

Because passwords are the most common way we prove who we are online, protecting them stops hackers from stealing accounts, personal data, and money. Using a strong hash like bcrypt makes it far harder for attackers to guess or crack passwords even if they obtain the stored data.

Where is it used?

  • Websites and web apps that store user login credentials (e.g., social media, e-commerce sites).
  • Mobile applications that need to keep local passwords safe (e.g., banking apps).
  • Server-side authentication services and APIs that manage user accounts.
  • Open-source platforms and frameworks (e.g., Django, Ruby on Rails) that include bcrypt as a default password-hashing option.

Good things about it

  • Built-in salt: automatically adds unique random data, preventing reuse attacks.
  • Adjustable cost factor: you can increase the number of rounds as computers get faster, keeping security up-to-date.
  • Resistant to GPU attacks: its design makes parallel cracking on graphics cards less effective than with simpler hashes.
  • Widely supported: available in most programming languages and frameworks.
  • Proven security track record: has been vetted by cryptographers for many years.

Not-so-good things

  • Slower than simpler hashes: the intentional delay can impact performance on high-traffic sites if not tuned properly.
  • Memory usage grows with cost: higher cost factors require more CPU time, which can strain limited resources.
  • Not suitable for non-password data: bcrypt is designed for passwords; using it for general data encryption is inefficient.
  • Fixed output size: the hash length is always the same, which may not fit systems expecting variable-length hashes.