Re: [tcpm] public-private keys for TCP-AO

Joe Touch <touch@strayalpha.com> Tue, 30 October 2018 01:13 UTC

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From: Joe Touch <touch@strayalpha.com>
In-Reply-To: <95f4b81948844b2799ecca33450bdde1@XCH-ALN-014.cisco.com>
Date: Mon, 29 Oct 2018 18:13:13 -0700
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To: "Jakob Heitz (jheitz)" <jheitz@cisco.com>
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Subject: Re: [tcpm] public-private keys for TCP-AO
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> On Oct 29, 2018, at 5:45 PM, Jakob Heitz (jheitz) <jheitz@cisco.com> wrote:
> 
> Why was there not a public-private key algorithm specified for TCP-AO? Or did I miss it?

There has not been. I doubt it would make sense (see below).

> For example ECC.
> An MKT can specify a private key for the sender and a public key for the receivers.

Yes, but the MKT is derived into public/private keys using a KDF.

I am not aware of a KDF that can take a private key and generate a derived private key that would work with a correspondingly derived public key generated from the corresponding public key.

> To use, the sender will hash the data, encrypt the hash and put the result into the MAC field.
> The receiver would decrypt the MAC field, then hash the data and verify the hash against the decrypted MAC.
> This way, the private key never needs to be exposed to anyone, simplifying key management.
> Is there any objection to getting this done?

See above; it doesn’t make sense with the way TCP-AO derives keys for each connection, AFAICT.

Joe

>  
> Regards,
> Jakob.
>  
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