Password Storage Cheat Sheet

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This article is focused on providing guidance to storing a passwords in order to help prevent password theft.

Password Storage Rules

It is crucial that passwords are stored in a way that they can be *verified* but not *exposed* in any way, even by insiders or administrations. To accomplish this, store the salted hashed value of the password. Preferably use a different random salt for each password hash instead of a constant long salt. It is recommended that you avoid storing the clear text password or an encrypted version of the password.

  1. Use a modern hash
    1. SHA
    2. bcrypt
  2. Use a long cryptographically random salt
    1. Isolate the salt from the hash
  3. Iterate the hash


Cryptographic framework for password hashing is described in PKCS #5 v2.1: Password-Based Cryptography Standard. Specific secure password hashing algorithms exist such as bcrypt, scrypt. Implementations of secure password hashing exist for PHP (phpass), ASP.NET (ASP.NET 2.0 Security Practices), Java (OWASP Hashing Java).

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