CRL request over HTTP - packet analysis

One of the ways a CRL can be retrieved is HTTP. Whole transaction consists of an HTTP GET and an OK 200 response packets. The response is a PKIX-CRL MIME type encoded CRL. PKIX-CRL is an IETF standard defined in RFC 2585 - http://www.ietf.org/rfc/rfc2585.txt

1. CRL requester generates an HTTP query using an HTTP GET verb

HTTP header:

GET /pki/IssuingCA-DC1.crl HTTP/1.1

Cache-Control: no-cache

Connection: Keep-Alive

Pragma: no-cache

Accept: */*

User-Agent: Microsoft-CryptoAPI/6.2

Host: dc1.kp.local

2. Server responds with CRL encoded in PKIX-CRL MIME type

HTTP header:

HTTP/1.1 200 OK

Content-Type: application/pkix-crl

Last-Modified: Mon, 22 Apr 2013 08:29:51 GMT

Accept-Ranges: bytes

ETag: "d06e258f333fce1:0"

Server: Microsoft-IIS/8.0

X-Powered-By: ASP.NET

Date: Sun, 21 Apr 2013 08:46:23 GMT

Content-Length: 820

WireShark decodes the PKIX-CRL. We can see all CRL extensions directly in the packet.

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#SecureSenses --verbose

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