[cryptography] Client certificate crypto with a twist

Steven Bellovin smb at cs.columbia.edu
Wed Oct 10 11:54:22 EDT 2012

On Oct 10, 2012, at 9:09 AM, Ben Laurie <ben at links.org> wrote:

> On Wed, Oct 10, 2012 at 1:44 PM, Guido Witmond <guido at wtmnd.nl> wrote:
>> Hello Everyone,
>> I'm proposing to revitalise an old idea. With a twist.
>> The TL;DR:
>> 1. Ditch password based authentication over the net;
>> 2. Use SSL client certificates instead;
>> Here comes the twist:
>> 3. Don't use the few hundred global certificate authorities to sign
>>   the client certificates. These CA's require extensive identity
>>   validations before signing a certificate. These certificates are
>>   only useful when the real identity is needed.
>>   Currently, passwords provide better privacy but lousy security;
>> 4. Instead: install a CA-signer at every website that signs
>>   certificates that are only valid for that site. Validation
>>   requirement before signing: CN must be unique.
> http://tools.ietf.org/html/draft-balfanz-tls-obc-01

Sorry, I hit accidentally hit "Send".

The issue with any sort of client-side certs is private key availability,
and in particular moving it from client machine to client machine.  (I
personally use about 4 different computers and three phones/tablets.  I
need a secure, privacy-preserving mechanism to synchronize my key store.)

		--Steve Bellovin, https://www.cs.columbia.edu/~smb

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