PCI DSS 4.0 4.2.1: 4.2.1 Strong cryptography safeguards PAN over public networks
Wherever PAN crosses open, public networks (such as the Internet, Wi-Fi, Bluetooth, cellular and satellite links), PAN must be protected with strong cryptography and security protocols, arranged so that: only keys and certificates that are trusted are accepted; certificates guarding PAN in transit are confirmed as valid and neither revoked nor expired; the protocol permits only secure versions or configurations and cannot use or fall back to any insecure version, algorithm, key size or implementation; and encryption strength suits the encryption method chosen. Protection may be at the data level, the session level, or both. Applicability: a self-signed certificate can be acceptable when an internal CA of the organisation issued it, its author is confirmed, it is verified (for instance by hash or signature) and it has not expired. The bullet on confirming certificates are valid and neither revoked nor expired was advisory only up to 31 March 2025; the remaining bullets were already mandatory. Objective under the customized approach: nobody can read or capture cleartext PAN from traffic over open, public networks. Future-dated: treated as a best practice up to 31 March 2025 and mandatory since then.
This control maps to 67 controls across 22 other frameworks. If you already hold one of them, the evidence you collected for it is the starting point here rather than new work.
You are reading one control. How much of PCI DSS 4.0 have you already done?
PCI DSS 4.0 4.2.1 is one control. If you already hold one of the frameworks below, a reviewed crosswalk already says how much of PCI DSS 4.0 your existing evidence covers. Hold ISO 27001:2022 and 139 of 280 PCI DSS 4.0 controls already carry evidence.
Each report names every control your existing framework evidences, every one it does not, the reasoning behind each claim, and the claims that were argued against and rejected. 415 were rejected on the ISO 27001:2022 pair alone.