Wireshark-bugs: [Wireshark-bugs] [Bug 8799] OCSP CertificateSerialNumber is wrong
Date: Tue, 18 Jun 2013 19:47:09 +0000

Comment # 3 on bug 8799 from
Created attachment 11013 [details]
OCSP Requests with varying serial number lengths.

I recreated a certificate four times, each with a different serial number
(2^8-1, 2^16-1, 2^32-1, 2^64-1) and then sent it to the Verisign OCSP
Responder. Note that this certificate was not one signed by Verisign, so it
gets rejected, making the responses useless. Focusing on the requests...

2^8-1 was encoded in ASN.1 as:
  02 02 ff ff
and interpreted as:
  255

2^16-1 was encoded in ASN.1 as:
  02 03 00 ff ff
and interpreted as:
  65535

2^32-1 was encoded in ASN.1 as:
  02 05 00 ff ff ff ff
and interpreted as:
  -1

2^64-1 was encoded in ASN.1 as:
  02 09 00 ff ff ff ff ff ff ff ff
and interpreted as:
  (blank)

This is due to the top bit of the serial number being set, but INTEGERs being
interpreted as two's complement, so an extra padding byte is necessary to
indicate that the number is not negative.


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