debian-mirror-gitlab/doc/security/password_storage.md
2022-11-25 23:54:43 +05:30

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Password and OAuth token storage (FREE)

GitLab administrators can configure how passwords and OAuth tokens are stored.

Password storage

PBKDF2 and SHA512 introduced in GitLab 15.2 with flags named pbkdf2_password_encryption and pbkdf2_password_encryption_write. Disabled by default.

GitLab stores user passwords in a hashed format to prevent passwords from being stored as plain text.

GitLab uses the Devise authentication library to hash user passwords. Created password hashes have these attributes:

  • Hashing:

    • BCrypt: By default, the bcrypt hashing function is used to generate the hash of the provided password. This cryptographic hashing function is strong and industry-standard.

    • PBKDF2 and SHA512: Starting in GitLab 15.2, PBKDF2 and SHA512 are supported behind the following feature flags (disabled by default):

      • pbkdf2_password_encryption - Enables reading and comparison of PBKDF2 + SHA512 hashed passwords and supports fallback for BCrypt hashed passwords.
      • pbkdf2_password_encryption_write - Enables new passwords to be saved using PBKDF2 and SHA512, and existing BCrypt passwords to be migrated when users sign in.

      FLAG: On self-managed GitLab, by default this feature is not available. To make it available, ask an administrator to enable the feature flags named pbkdf2_password_encryption and pbkdf2_password_encryption_write.

  • Stretching: Password hashes are stretched to harden against brute-force attacks. By default, GitLab uses a stretching factor of 10 for BCrypt and 20,000 for PBKDF2 + SHA512.

  • Salting: A cryptographic salt is added to each password to harden against pre-computed hash and dictionary attacks. To increase security, each salt is randomly generated for each password, with no two passwords sharing a salt.

OAuth access token storage

Depending on your version of GitLab and configuration, OAuth access tokens are stored in the database in PBKDF2+SHA512 format. For version information, see the relevant OAuth provider documentation.

As with PBKDF2+SHA512 password storage, access token values are stretched 20,000 times to harden against brute-force attacks.