Re: [netconf] ietf crypto types - permanently hidden

Kent Watsen <kent@watsen.net> Fri, 03 May 2019 16:15 UTC

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From: Kent Watsen <kent@watsen.net>
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Date: Fri, 3 May 2019 16:15:26 +0000
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Cc: rwilton@cisco.com, "netconf@ietf.org" <netconf@ietf.org>
To: Martin Bjorklund <mbj@tail-f.com>
References: <e30aa60f31ba40e8abc9cfaeffad7802@XCH-RCD-007.cisco.com> <20190503.084757.791827158808672980.mbj@tail-f.com> <3208a877354745fa85188b81a3d8aa24@XCH-RCD-007.cisco.com> <20190503.133743.1149689382943153005.mbj@tail-f.com>
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Subject: Re: [netconf] ietf crypto types - permanently hidden
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>> (ii) The ability to program a client defined key pair in a private way
>> that is not visible in the configuration.  Have we considered a
>> solution that puts these into the configuration but has them encrypted
>> with a device specific public/private key pair.
> 
> I don't think so.  I'm not sure this itself solves the problem
> though.  FWIW, we have tailf-specific types that work like this.  They
> are similar to iana-crypt-hash in syntax and semantics, but they use
> encryption rather than hashing.


Encrypting "hidden" keys is a viable option that would enable such keys to appear in standard config and hence support the "document model" (backup/restore operations using, e.g., <copy-config>).  The only catch is that the restore-operation *only* works on the same device (or, more specifically, the same crypto-processor).  Still, this would help the scenario where the device needs to be restored after having its non-volatile memory reformatted or replaced.

I was also thinking about the relation to crypt-hash, but the scenarios is different in that the crypt-hash operation is idempotent; passing in a "$0$" prefixed password will always produce the same result.  In the "best practice" scenario, no private-key data is passed in, and just asking the device to generate a random key each time will give different results each time (not idempotent).


Kent // contributor