Storing passwords securely is paramount in today’s digital landscape. Choosing the right database column type and length for bcrypt hashed passwords is a crucial aspect of this security. A poorly chosen setup can leave your system vulnerable, while a well-configured one provides robust protection against unauthorized access. This post will delve into the optimal strategies for storing bcrypt hashes, ensuring your user data remains safeguarded.

Choosing the Right Column Type

Bcrypt hashes are strings, so the natural choice for the column type is CHAR or VARCHAR. However, since bcrypt hashes have a fixed length for a given configuration (e.g., $2y$10$ results in a 60-character hash), using CHAR is generally recommended. This ensures consistent storage and predictable space usage.

Using VARCHAR introduces slight storage overhead due to the variable length nature, which isn’t necessary for bcrypt hashes. While the overhead is minimal, using CHAR offers slightly better performance and simplifies database management.

Other database systems might offer alternatives like TEXT or BINARY, but CHAR remains the most suitable choice for storing bcrypt hashes due to its fixed-length characteristic.

Determining the Correct Column Length

The length of a bcrypt hash depends on the bcrypt version and cost factor. For example, $2y$10$ (bcrypt version 2y, cost factor 10) produces a 60-character hash. It’s crucial to use a length that accommodates potential future increases in the cost factor. While a cost factor of 10 is currently recommended, you might need to increase it later. Therefore, choosing a length with some buffer is a wise decision.

A length of 60 characters is sufficient for common bcrypt configurations. However, to allow for flexibility and future-proofing, it’s generally recommended to use a length of 255 characters. This provides ample space even if you decide to increase the cost factor significantly in the future.

Choosing a larger length doesn’t significantly impact storage or performance and offers peace of mind knowing your database can handle future security enhancements.

Why Bcrypt is the Gold Standard

Bcrypt is widely recognized as a robust password hashing algorithm. Its adaptive hashing algorithm makes it resistant to brute-force attacks. Unlike older algorithms like MD5 or SHA1, bcrypt incorporates a “salt,” a random string unique to each password, which further strengthens the hash.

Bcrypt’s “cost factor” parameter allows you to control the computational intensity of the hashing process. A higher cost factor makes it exponentially harder to crack passwords, adding another layer of security.

“Security expert Bruce Schneier recommends bcrypt as the ‘best’ choice for password hashing,” highlighting the algorithm’s strength and reliability.

Implementing Bcrypt in Your Application

Integrating bcrypt into your application is relatively straightforward. Most programming languages offer libraries for bcrypt implementation. For instance, in PHP, you can use the password_hash() function. In Python, the bcrypt library provides the necessary tools.

Here’s a simplified example in PHP:

$hashed_password = password_hash($password, PASSWORD_BCRYPT);

This code snippet demonstrates the simplicity of hashing passwords using bcrypt in PHP. Ensure you are using a current and well-maintained library for your chosen language.

• Always use a strong cost factor for bcrypt.
• Never store passwords in plain text.

1. Choose a secure password hashing algorithm (bcrypt).
2. Generate a salt.
3. Hash the password using the salt and algorithm.
4. Store the hashed password in the database.

For more information on database design, check out this helpful resource.

External Resources:

• OWASP Password Storage Cheat Sheet
• OWASP Password Storage Cheat Sheet (Alternative Link)
• PHP password_hash() Documentation

Featured Snippet: For optimal bcrypt storage, utilize a CHAR(255) column in your database. This offers sufficient space for the hash and future-proofs against cost factor increases.

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FAQ

Q: What if my existing database uses a different column type?

A: You can migrate your data to the recommended CHAR(255) column. Ensure you back up your data before making any changes.

Protecting your user data is paramount. Selecting the right column type and length for bcrypt hashes is a small but crucial step in achieving robust security. By following the recommendations outlined in this post—using CHAR(255)—you can ensure your database is well-equipped to handle secure password storage. This proactive approach safeguards user data and strengthens your overall security posture. Now is the time to review your current password storage implementation and make the necessary updates. Learn more about data security best practices to further enhance your application’s protection. Explore topics like two-factor authentication and data encryption to build a comprehensive security strategy.

Question & Answer :
I want to store a hashed password (using BCrypt) in a database. What would be a good type for this, and which would be the correct length? Are passwords hashed with BCrypt always of same length?

EDIT

Example hash:

$2a$10$KssILxWNR6k62B7yiX0GAe2Q7wwHlrzhF3LqtVvpyvHZf0MwvNfVu 

After hashing some passwords, it seems that BCrypt always generates 60 character hashes.

EDIT 2

Sorry for not mentioning the implementation. I am using jBCrypt.

The modular crypt format for bcrypt consists of

• $2$, $2a$ or $2y$ identifying the hashing algorithm and format
• a two digit value denoting the cost parameter, followed by $
• a 53 characters long base-64-encoded value (they use the alphabet ., /, 0–9, A–Z, a–z that is different to the standard Base 64 Encoding alphabet) consisting of:
  • 22 characters of salt (effectively only 128 bits of the 132 decoded bits)
  • 31 characters of encrypted output (effectively only 184 bits of the 186 decoded bits)

Thus the total length is 59 or 60 bytes respectively.

As you use the 2a format, you’ll need 60 bytes. And thus for MySQL I’ll recommend to use the CHAR(60) BINARYor BINARY(60) (see The _bin and binary Collations for information about the difference).

CHAR is not binary safe and equality does not depend solely on the byte value but on the actual collation; in the worst case A is treated as equal to a. See The _bin and binary Collations for more information.