[cabfpub] Pre-Ballot 164 - Certificate Serial Number Entropy

Brown, Wendy (10421) wendy.brown at protiviti.com
Sat Feb 27 01:43:39 UTC 2016


Why does the entropy have to be in the serial number vs a combination of serial number and date/time bits ?

From: public-bounces at cabforum.org [mailto:public-bounces at cabforum.org] On Behalf Of Richard Barnes
Sent: Friday, February 26, 2016 6:26 PM
To: Ryan Sleevi <sleevi at google.com>
Cc: CABFPub <public at cabforum.org>
Subject: Re: [cabfpub] Pre-Ballot 164 - Certificate Serial Number Entropy



On Fri, Feb 26, 2016 at 6:03 PM, Ryan Sleevi <sleevi at google.com<mailto:sleevi at google.com>> wrote:
Is there a reason for the change from "entropy" to "unpredictable bits"

Would you be opposed to "64 bits of random data from a cryptographically strong random number generator"?

The concern I have with the language change is that while "entropy" is arguably less ambiguous, I fear "unpredictable bits" will create a situation where a CA says "No one knows our [deterministic] algorithm, therefore it's unpredictable"

I admit, I'm not terribly thrilled with my rewrite either, because I don't think it should be required to use an RNG on an HSM, for example (that's arguably overkill), but I do want to make sure that the source of entropy is cryptographically strong (thus ruling out Microsoft's GUIDs, crappy RNGs, etc)

I would prefer this proposal.  It provides a specific thing that can be verified (whereas "entropy" and "unpredictable" are vague statistical properties).

--Richard


On Fri, Feb 26, 2016 at 1:49 PM, Ben Wilson <ben.wilson at digicert.com<mailto:ben.wilson at digicert.com>> wrote:

For discussion:

Pre-Ballot 164 - Certificate Serial Number Entropy

-- Motion Begins --

In Section 7.1 of the Baseline Requirements,

REPLACE

"CAs SHOULD generate non-sequential Certificate serial numbers that exhibit at least 20 bits of entropy"

WITH

"Effective April 1, 2016, CAs SHALL use a Certificate serialNumber greater than zero (0) that contains at least 64 unpredictable bits."

-- Motion Ends --


_______________________________________________
Public mailing list
Public at cabforum.org<mailto:Public at cabforum.org>
https://cabforum.org/mailman/listinfo/public<https://urldefense.proofpoint.com/v2/url?u=https-3A__cabforum.org_mailman_listinfo_public&d=CwMFaQ&c=19TEyCb-E0do3cLmFgm9ItTXlbGQ5gmhRAlAtE256go&r=CBPcrHveVS6JeW8_gWG0NRDQwKKDbvlAqGnuc-opZ58&m=gLfqC3w5Q3KWZIqYA3p1oVBUpJRLnT0Sn6QRxHzrcbk&s=nCLIEUA1hig93WH1Iz1Z5uXl3uOXAsav6dZCFhfAXJo&e=>


_______________________________________________
Public mailing list
Public at cabforum.org<mailto:Public at cabforum.org>
https://cabforum.org/mailman/listinfo/public<https://urldefense.proofpoint.com/v2/url?u=https-3A__cabforum.org_mailman_listinfo_public&d=CwMFaQ&c=19TEyCb-E0do3cLmFgm9ItTXlbGQ5gmhRAlAtE256go&r=CBPcrHveVS6JeW8_gWG0NRDQwKKDbvlAqGnuc-opZ58&m=gLfqC3w5Q3KWZIqYA3p1oVBUpJRLnT0Sn6QRxHzrcbk&s=nCLIEUA1hig93WH1Iz1Z5uXl3uOXAsav6dZCFhfAXJo&e=>

NOTICE: Protiviti is a global consulting and internal audit firm composed of experts specializing in risk and advisory services. Protiviti is not licensed or registered as a public accounting firm and does not issue opinions on financial statements or offer attestation services. This electronic mail message is intended exclusively for the individual or entity to which it is addressed. This message, together with any attachment, may contain confidential and privileged information. Any views, opinions or conclusions expressed in this message are those of the individual sender and do not necessarily reflect the views of Protiviti Inc. or its affiliates. Any unauthorized review, use, printing, copying, retention, disclosure or distribution is strictly prohibited. If you have received this message in error, please immediately advise the sender by reply email message to the sender and delete all copies of this message. Thank you.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.cabforum.org/pipermail/public/attachments/20160227/881c0099/attachment-0003.html>


More information about the Public mailing list