I happened to notice what seems to be an output glitch in the textual output of a certificate. I received a copy of the QuoVadis Root CA 2 certificate as a file. When I examined the certificate via openssl x509 -text -in /tmp/QV.cer (using OpenSSL 1.0.1 14 Mar 2012 as installed in Ubuntu 14.04) I noticed an extra first zero byte of the Modulus was shown, as compared to the display of that certificate in Firefox. > Certificate: > Data: > Version: 3 (0x2) > Serial Number: 1289 (0x509) > Signature Algorithm: sha1WithRSAEncryption > Issuer: C=BM, O=QuoVadis Limited, CN=QuoVadis Root CA 2 > ... > Subject Public Key Info: > Public Key Algorithm: rsaEncryption > Public-Key: (4096 bit) > Modulus: > 00:9a:18:ca:4b:94:0d:00:2d:af:03:29:8a:f0:0f: > ... > 09:62:04:92:16:10:d8:9e:27:47:fb:3b:21:e3:f8: > eb:1d:5b I believe there should be 4096/8 = 512 bytes in that modulus. There are 15 bytes shown per line. 512/15 = 34 with a remainder of 2. This output shows 513 bytes (34 lines plus a remainder of 3).