On 04/04/2015 07:18, Jakob Bohm wrote: > On 04/04/2015 04:07, Mabry Tyson wrote: >> 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). >> >> > This is a consequence of the ASN.1 DER/BER encoding rules: > All INTEGER fields are signed, so when the most significant > bit of a 2048 bit value is set, then it needs to be encoded > and processed with an extra leading 0 byte. (And ditto for a 4096 bit value of cause) > > OpenSSL displays that leading 0 byte, while NSS (used by > Firefox) apparently hides it. > Enjoy Jakob -- Jakob Bohm, CIO, Partner, WiseMo A/S. http://www.wisemo.com Transformervej 29, 2860 S?borg, Denmark. Direct +45 31 13 16 10 This public discussion message is non-binding and may contain errors. WiseMo - Remote Service Management for PCs, Phones and Embedded
