gcr-viewer does not recognize three OIDs (perhaps more). First is Authority Key Identifier (OID 2.5.29.35). Subject Key Identifier is displayed as expected. Second is sha256WithRSAEncryption signature algorithm (OID 1.2.840.113549.1.1.11). sha1WithRSAEncryption is displayed as expected. Third is Netscape Certificate Comment (OID 2.16.840.1.113730.1.13). Attached are the relevant screen captures. Debian 7.3, x64 (fully patched): $ uname -a Linux debian-q500 3.2.0-4-amd64 #1 SMP Debian 3.2.54-2 x86_64 GNU/Linux