Re: [Trans] Angle brackets in the PRIVATE option (Ticket #1)
Rob Stradling <rob.stradling@comodo.com> Mon, 31 March 2014 10:10 UTC
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Date: Mon, 31 Mar 2014 11:10:39 +0100
From: Rob Stradling <rob.stradling@comodo.com>
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To: Peter Bowen <pzbowen@gmail.com>, Rick Andrews <Rick_Andrews@symantec.com>
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Subject: Re: [Trans] Angle brackets in the PRIVATE option (Ticket #1)
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On 29/03/14 03:24, Peter Bowen wrote: > On Fri, Mar 28, 2014 at 9:46 AM, Rick Andrews <Rick_Andrews@symantec.com> wrote: >> We see another potential issue with the proposed PRIVATE option. Rob’s >> current proposal would have us replace a domain label with the literal >> string “<PRIVATE>” (without the quotes). However, we try to encode DN >> components as PrintableString where possible, and angle brackets are not >> part of the PrintableString set (the lowercase letters 'a' through 'z', >> uppercase letters 'A' through 'Z', the digits '0' through '9', eleven >> special characters ' = ( ) + , - . / : ? and space). >> >> As a result, the type of the DN component would be PrintableString in the >> real cert but utf8String in the pre-certificate, and that would cause >> problems. I suggest using parentheses instead of angle brackets. > > Instead of having "<PRIVATE>", what about replacing the redacted > string with a prefixed checksum of the part? > > Assuming we specify CRC-32 with "+" as the prefix, > "mail.corp.example.com" would become "+6f993bb2.example.com". This > could also allow redacting only some labels: > "mail.secret.example.gov.xx" could become > "mail.+734313b7.example.gov.xx". This has the benefit of providing > privacy while allowing stronger matching of the certificate. Hi Peter. The aim of the PRIVATE option is to keep sub-domain names _completely hidden_ from the Log, so I think that revealing any information about them is problematic. How long would it take an attacker to perform a dictionary attack to discover that "6f993bb2" corresponds to "mail.corp" ? -- Rob Stradling Senior Research & Development Scientist COMODO - Creating Trust Online
- [Trans] Angle brackets in the PRIVATE option (Tic… Rick Andrews
- Re: [Trans] Angle brackets in the PRIVATE option … Peter Bowen
- Re: [Trans] Angle brackets in the PRIVATE option … Rob Stradling
- Re: [Trans] Angle brackets in the PRIVATE option … Rob Stradling
- Re: [Trans] Angle brackets in the PRIVATE option … Peter Bowen
- Re: [Trans] Angle brackets in the PRIVATE option … Rob Stradling
- Re: [Trans] Angle brackets in the PRIVATE option … Peter Bowen
- Re: [Trans] Angle brackets in the PRIVATE option … Rob Stradling
- Re: [Trans] Angle brackets in the PRIVATE option … Doug Beattie
- Re: [Trans] Angle brackets in the PRIVATE option … Rob Stradling
- Re: [Trans] Angle brackets in the PRIVATE option … Gervase Markham
- Re: [Trans] Angle brackets in the PRIVATE option … Rob Stradling
- Re: [Trans] Angle brackets in the PRIVATE option … Gervase Markham
- Re: [Trans] Angle brackets in the PRIVATE option … Rob Stradling
- Re: [Trans] Angle brackets in the PRIVATE option … Rick Andrews