CSCA Certificates and Master Lists

Passive Authentication verifies the integrity and authenticity of the eMRTD data based on a list of trusted country certificates. This document explains where that trust comes from: what a CSCA certificate is, how the certificate chain works, and how Master Lists are obtained and maintained.

The Certificate Chain

Every issuing country operates a Country Signing Certificate Authority (CSCA). The CSCA is the root of trust for all eMRTDs issued by that country.

• The CSCA certificate is self-signed and long-lived. It is typically valid for 13-15 years. The private key is used for about 3-5 years before a new CSCA is rolled out.
• Document Signer Certificates are issued by the CSCA and are short-lived in comparison. A Document Signer key typically signs documents for only a few months.
• The SOD on each chip contains the Document Signer Certificate and hash values of the Data Groups, signed with the Document Signer key.

During Passive Authentication, the Inspection System builds and validates the certification path from a trusted CSCA certificate to the Document Signer Certificate found in the SOD. Without the correct CSCA certificate, a genuine document cannot be verified.

What Is a Master List?

A Master List is a signed collection (CMS SignedData, see ICAO Doc9303 Part 12) of CSCA certificates that the publishing state considers authentic. Master Lists exist so that verifiers do not have to collect CSCA certificates from every country through bilateral diplomatic exchange.

Publicly available sources include:

• The German Master List published by the German Federal Office for Information Security (BSI).
• The Dutch Master List published by the Netherlands.

The ICAO Public Key Directory (PKD) is the central repository operated by ICAO. It is not a public download: access requires participation in the PKD.

Why Master Lists Must Be Kept Up to Date

Countries roll out new CSCA certificates every few years. A document signed under a CSCA that is missing from your Master List will fail Passive Authentication (document_certificate_valid: false) even though the document is genuine.

Notes:

• When a country rolls over to a new CSCA, it also issues a CSCA Link Certificate: the new CSCA public key signed with the previous CSCA private key. This allows verifiers that already trust the previous CSCA to extend their trust to the new one.
• Update the Master List regularly (for example whenever the source publishes a new version) to avoid false negatives for recently issued documents.
• A failed certificate check caused by an outdated Master List is one of the most common integration issues. See Interpreting Verification Results for how this failure appears in the results.

Master Lists in the KINEGRAM Products

• The DocVal Service ships with a built-in Master List and also supports providing your own, see DocVal Service Installation.
• The MOBILE CHIP SDK offline requires you to provide and maintain a Master List yourself, see the usage guides for Android and iOS.