GCR is a library for displaying certificates, and crypto UI, accessing key stores. It also provides the viewer for crypto files on the GNOME desktop. GCK is a library for accessing PKCS#11 modules like smart cards, in a (G)object oriented way. DEBUG TRACING ============== The Gcr and Gck libraries contain statements which help debug flow and logic. In many cases these help you track down problems. Use the environment variable GCR_DEBUG='all' or GCR_HELP='xxx' to display either all messages or a specific category of debug messages. To figure out what you can use in place of the 'xxx' category above, use GCR_DEBUG='help' and you'll see a list of all the messages. Example to display all debug messages: $ GCR_DEBUG=all gcr-viewer /path/to/certificate.crt (gcr-viewer:9418): Gcr-DEBUG: gcr_pkcs11_initialize_async: starting initialize of registered modules ... Example to display the various debug categories: $ GCR_DEBUG=help gcr-viewer /path/to/certificate.crt Supported debug values: library certificate-chain parse gnupg trust import key prompt all help Example to display debug messages for a specific category: $ GCR_DEBUG=library gcr-viewer /path/to/certificate.crt (gcr-viewer:9503): Gcr-DEBUG: gcr_pkcs11_initialize_async: starting initialize of registered modules ... If you wish to permanently enable certain debug messages, include compiler directives like this when configuring this library: $ CFLAGS='-DGCR_DEBUG=library' ./configure ... For the Gck debug messages simply replace 'GCR_DEBUG' with 'GCK_DEBUG' in the above examples.