What Database Column Type and Length Are Best for Storing Bcrypt Hashed Passwords?

Determining Database Column Requirements for Bcrypt Hashed Passwords

Storing Bcrypt hashed passwords in a database requires careful consideration of the column type and length. Bcrypt, a popular password hashing algorithm, generates fixed-length character sequences when hashing passwords.

Password Hash Length in Bcrypt

Bcrypt always produces hashed passwords of the same length. As discovered by the user through examples, Bcrypt typically generates 60-character hashes in the form of a string. This means that the database column used to store the hashed password must have sufficient length to accommodate this fixed size.

Database Column Type

The column type used to store Bcrypt hashes should be capable of holding character sequences. In MySQL, appropriate types include CHAR(60) BINARY or BINARY(60). CHAR provides fixed-length strings, suitable for storing character data of specific size. BINARY indicates that the data is binary, ensuring that it's treated as raw data and not interpreted by the database.

Additional Considerations

• Encryption Considerations: It's important to note that Bcrypt hashes are not encrypted but rather one-way hashed. This ensures that even if the database is compromised, the original passwords cannot be recovered from the hashes.
• Storage Efficiency: CHAR(n) allocates exactly n bytes for each column value, regardless of whether the stored data is shorter. If most of the stored hashes are shorter than 60 characters, using a type like VARCHAR(n) may be more space-efficient.
• Database Constraints: Depending on the database system used, additional constraints may be imposed to ensure data integrity and consistency, such as uniqueness constraints to prevent duplicate hashes.

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