3.5.1.1
Defined Approach Requirements:
Hashes used to render PAN unreadable (per the first bullet of Requirement 3.5.1) are keyed cryptographic hashes of the entire PAN, with associated key-management processes and procedures in accordance with Requirements 3.6 and 3.7.
Customized Approach Objective:
Cleartext PAN cannot be determined from hashes of the PAN.
Applicability Notes:
All Applicability Notes for Requirement 3.5.1 also apply to this requirement.
Key-management processes and procedures (Requirements 3.6 and 3.7) do not apply to system components used to generate individual keyed hashes of a PAN for comparison to another system if:
- The system components only have access to one hash value at a time (hash values are not stored on the system) AND
- There is no other account data stored on the same system as the hashes.
This requirement is considered a best practice until 31 March 2025, after which it will be required and must be fully considered during a PCI DSS assessment. This requirement will replace the bullet in Requirement 3.5.1 for one-way hashes once its effective date is reached.
Defined Approach Testing Procedures:
- 3.5.1.1.a Examine documentation about the hashing method used to render PAN unreadable, including the vendor, type of system/process, and the encryption algorithms (as applicable) to verify that the hashing method results in keyed cryptographic hashes of the entire PAN, with associated key management processes and procedures.
- 3.5.1.1.b Examine documentation about the key management procedures and processes associated with the keyed cryptographic hashes to verify keys are managed in accordance with Requirements 3.6 and 3.7.
- 3.5.1.1.c Examine data repositories to verify the PAN is rendered unreadable.
- 3.5.1.1.d Examine audit logs, including payment application logs, to verify the PAN is rendered unreadable.
Purpose:
Rendering stored PAN unreadable is a defense in depth control designed to protect the data if an unauthorized individual gains access to stored data by taking advantage of a vulnerability or misconfiguration of an entity’s primary access control. A hashing function that incorporates a randomly generated secret key provides brute force attack resistance and secret authentication integrity.
Definitions:
Refer to Appendix G for the definition of “keyed cryptographic hash” and for information about appropriate keyed cryptographic hashing algorithms and additional resources.
Examples:
Systems which only have access to one hash value at a time and which store no other account data on the same system as the hash, are not required to meet key-management processes and procedures (Requirements 3.6 and 3.7). Examples of such systems include transaction-originating devices that generate a hash of the PAN for use in a backend system, such as pay-at-gate transit turnstiles. However, in such an implementation, the backend system will have access to more than one hash value at a time, and therefore is required to meet key-management processes and procedures at Requirements 3.6 and 3.7.
