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> - PBKDF2+SHA512 [introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/360658) in GitLab 15.2 [with flags](../administration/feature_flags.md) named `pbkdf2_password_encryption` and `pbkdf2_password_encryption_write`. Disabled by default.
> - Feature flags [removed](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/101691) in GitLab 15.6 and PBKDF2+SHA512 was made available to all GitLab instances running in [FIPS mode](../development/fips_compliance.md).
- In GitLab 15.2 to GitLab 15.5 when `pbkdf2_password_encryption` and `pbkdf2_password_encryption_write` [feature flags](../administration/feature_flags.md) are enabled.
- In GitLab 15.6 and later when [FIPS mode](../development/fips_compliance.md) is enabled (feature flags are not required).
OAuth access tokens are stored in the database in PBKDF2+SHA512 format. As with PBKDF2+SHA512 password storage, access token values are [stretched](https://en.wikipedia.org/wiki/Key_stretching) 20,000 times to harden against brute-force attacks.