bcrypt vs sha256 which should you use for passwords

Introduction to Password Hashing

When it comes to securely hashing passwords, you have several options, but not all are created equal. bcrypt stands out as a preferred choice specifically for passwords, while SHA-256, although robust, serves a different purpose. Understanding the differences can significantly impact your application's security.

Should You Use SHA-256 for Passwords?

The simple answer is no. SHA-256 is designed for generating hash values that ensure data integrity, not for securely hashing passwords. It’s fast and efficient, making it suitable for applications like blockchain or data verification. However, its speed is a double-edged sword when it comes to password storage.

The Speed Factor

Passwords need to be hashed in a way that slows down potential attackers. Since SHA-256 is quick, an attacker can attempt millions of password guesses in a short time. For example, an attacker could try 10 million hashes per second using modern hardware. This makes it impractical for password security. In contrast, bcrypt intentionally slows down the hashing process. This means that even if someone tries to brute-force a password, they will face significantly higher time costs.

What is Bcrypt?

bcrypt is a password hashing function designed specifically for securely hashing and storing passwords. It incorporates a salt to protect against rainbow table attacks and is intentionally slow to enhance security. When you hash a password with bcrypt, it generates a unique salt for each password, which ensures that even identical passwords yield different hashes.

Key Features of Bcrypt

• Adaptive Cost Factor: You can set the work factor (cost) that determines how computationally intensive the hash calculation will be, making it future-proof against advances in computing power.
• Built-in Salt: Each bcrypt hash includes a salt, preventing attackers from using precomputed hash tables (rainbow tables) to crack passwords.

Comparing Bcrypt and SHA-256

Let's break down some critical differences between bcrypt and SHA-256 when it comes to password hashing:

• Purpose: SHA-256 is great for data integrity, while bcrypt is specifically designed for password hashing.
• Speed: SHA-256 is fast, making it unsuitable for password storage; bcrypt is deliberately slow, enhancing security.
• Salting: SHA-256 does not include a salt by default, whereas bcrypt does.
• Cost Factor: With bcrypt, you can adjust the workload to keep pace with advancements in hardware, which is not possible with SHA-256.

What is the Best Algorithm for Hashing Passwords?

If you're looking for the best algorithm for password hashing, both bcrypt and PBKDF2 are solid choices. However, bcrypt has become the industry standard due to its adaptive difficulty and built-in salting. It's essential to avoid outdated methods like MD5 or even plain SHA-256.

Alternatives to Consider

• Argon2: Winner of the Password Hashing Competition and an excellent modern alternative to bcrypt.
• PBKDF2: Widely supported but slower than bcrypt and less flexible in terms of computational cost.

Is Bcrypt Deprecated?

No, bcrypt is not deprecated. It remains widely used and is considered a secure and reliable method for hashing passwords. While new hashing algorithms like Argon2 are gaining traction, bcrypt is still recommended, especially if you have legacy systems relying on it.

Practical Example: Bcrypt vs SHA-256

Let's take a real-world example to illustrate the differences. Suppose a user creates a password, "P@ssw0rd123", and you want to hash it.

Step-by-Step Hashing with Bcrypt:

• Generate a unique salt (e.g., $2a$12$...) for the password.
• Combine the password with the salt and apply bcrypt's hashing algorithm.
• The resulting hash might look like this:

bcrypt(P@ssw0rd123) = $2a$12$F3nOQ...

Step-by-Step Hashing with SHA-256:

• Simply hash the password using SHA-256.
• The resulting hash will look like this:

SHA256(P@ssw0rd123) = 4d186321c1a7f0f354b297e8914ab240

Comparing the Results

• Bcrypt output: $2a$12$F3nOQ...
• SHA-256 output: 4d186321c1a7f0f354b297e8914ab240

As you can see, while both hashes are unique, bcrypt's output includes a salt and is designed to be slower, offering better protection against brute-force attacks.

Conclusion

When it comes to password hashing, always choose a method designed with security in mind. Bcrypt is the clear winner for hashing passwords due to its adaptive difficulty and built-in salting. SHA-256 has its place in verifying data integrity but should never be used for storing passwords. To hash passwords securely, go with bcrypt or consider newer alternatives like Argon2.

For hands-on practice, try out the SHA-256 Hash Generator at QuickFnd to see how different inputs yield different hashes. But remember, when it comes to passwords, stick with bcrypt!