What Data Type and Length Should I Use for Storing Password Hashes?

Storing Password Hashes: Data Type and Length Considerations

Hashing is an essential security measure for storing passwords in a database. However, the specific data type and length required for the hashed password field vary depending on the hashing algorithm employed.

Hashing Algorithms and Their Output Lengths

Different hashing algorithms produce different length outputs. Here are the common options:

• MD5: 128 bits (32 characters in hexadecimal)
• SHA-1: 160 bits (40 characters in hexadecimal)
• SHA-224: 224 bits (56 characters in hexadecimal)
• SHA-256: 256 bits (64 characters in hexadecimal)
• SHA-384: 384 bits (96 characters in hexadecimal)
• SHA-512: 512 bits (128 characters in hexadecimal)
• BCrypt: 448 bits (56-76 characters in hexadecimal)

Recommended Data Types

Based on the above, the appropriate data type for the hashed password field depends on the algorithm used:

• CHAR(32) or BINARY(16) for MD5
• CHAR(40) or BINARY(20) for SHA-1
• CHAR(56) or BINARY(28) for SHA-224
• CHAR(64) or BINARY(32) for SHA-256
• CHAR(96) or BINARY(48) for SHA-384
• CHAR(128) or BINARY(64) for SHA-512
• CHAR(56-76) for BCrypt

Note: BCrypt's output length is implementation-dependent, so it's crucial to check the specific library or programming language documentation for the exact length.

Additional Considerations

While the above recommendations provide a general guideline, it's important to note that relying solely on hashing algorithms for password storage is insufficient due to the advancements in cracking techniques. For stronger password security, consider using key-strengthening hash functions like BCrypt or Argon2i, which generate longer and more complex hashes.

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