Security Hardening: PCI-DSS

bp pci-dss

Payment Card Industry - Data Security Standard (PCI-DSS) v3.1 provides an industry standard for data security requirements and procedures. Although keystone deals with sensitive data (primarily passwords), it has not made any attempt to provide PCI-compliant tools to deployers for fear of re-implementing more mature identity management solutions. At the same time, deployers are taking on the additional burden of either deploying those fully featured identity management solutions just to support keystone, or are re-implementing these behaviors on top of keystone without community support.

Problem Description

Keystone currently provides no means of satisfying at least the following security hardening guidelines:

  • PCI-DSS 8.1.4: Remove/disable inactive user accounts within 90 days.

  • PCI-DSS 8.1.6: Limit repeated access attempts by locking out the user ID after not more than six attempts.

  • PCI-DSS 8.1.7: Set the lockout duration to a minimum of 30 minutes or until an administrator enables the user ID.

  • PCI-DSS 8.2.3: Passwords/phrases must meet the following: 1) Require a minimum length of at least seven characters. 2) Contain both numeric and alphabetic characters. Alternatively, the passwords/phrases must have complexity and strength at least equivalent to the parameters specified above.

  • PCI-DSS 8.2.4: Change user passwords/passphrases at least once every 90 days.

  • PCI-DSS 8.2.5: Do not allow an individual to submit a new password/phrase that is the same as any of the last four passwords/phrases he or she has used.

  • PCI-DSS 8.3: Incorporate two-factor authentication for remote network access originating from outside the network by personnel (including users and administrators) and all third parties, (including vendor access for support or maintenance).


There may be additional guidelines that Keystone does not currently satisfy.

Proposed Change

Shadow users moved user passwords into their own table, which coincidentally provides a critical stepping stone to implementing all of the above behaviors.

To have the potential to achieve each standard “out of the box”, we at least need to make the following changes and associated behavior:

  • PCI-DSS 8.1.4: Store the last successful login time per user name. Disallow authentication if that date is greater than a configurable time period (default: 90 days).

  • PCI-DSS 8.1.6: Store rate limiting data of failed logins per user name. Deny logins if a configurable rate limit has been exceeded.

  • PCI-DSS 8.1.7: We can permanently disable the identity using an existing disable attribute, or implement a rate limiting algorithm for 8.1.6 that achieves this behavior by design.

  • PCI-DSS 8.2.3: Provide a configurable regular expression that passwords must match (using the pattern attribute in JSON Schema, for example).

  • PCI-DSS 8.2.4: Store an expiration date for each password, and only authenticate users against passwords that have not expired.

  • PCI-DSS 8.2.5: Store more than one password per identity. We could also provide a keystone-manage process to prune more than a configured maximum number of passwords per user, if desired.

  • PCI-DSS 8.3: This will be implemented as part of another spec.


There may be additional changes required to satisfy the specified guidelines.


Deployers either do not depend on Keystone for these behaviors, and instead back Keystone to an existing identity management solution, or implement these behaviors on top of keystone in middleware.

This spec prevents deployers from having to deploy another identity solution just for PCI compliance, and also prevents multiple operators from duplicating each other’s work any further.

Security Impact

This spec hardens password-based authentication according to PCI-DSS.

Notifications Impact


Other End User Impact

Keystone will be capable of presenting a new set of error messages for each new behavior.

Exposing password expirations and last login timestamps is not critical for PCI compliance, so there should be no API impact from this change.

Performance Impact

Authentication will require additional checks, although data from tables that are already being read from, so performance impact should be negligible unless the system is being abused.

Other Deployer Impact

Several new configuration options will be added to Keystone to customize each behavior. The default values could either reflect Keystone’s current behaviors (and we could simply document the recommended, hardened values), or reflect the recommended PCI-compliant standards in the default values.

Developer Impact




None, yet.

Work Items

Each PCI standard could be pursued independently, but it might be easier to design them all at once, write a single schema migration to add the required columns, and then write individual patches to implement each new behavior over the course of an entire release cycle.


This spec directly depends on the backend refactoring provided by shadow users.

Documentation Impact

Documentation describing the parts of keystone deployers need to pay attention to when ensuring PCI compliance would be invaluable.