Re: [TLS] RSA-PSS in TLS 1.3

mrex@sap.com (Martin Rex) Fri, 04 March 2016 14:20 UTC

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Date: Fri, 4 Mar 2016 15:20:24 +0100 (CET)
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From: mrex@sap.com (Martin Rex)
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Cc: tls@ietf.org
Subject: Re: [TLS] RSA-PSS in TLS 1.3
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Hanno Böck wrote:
> mrex@sap.com (Martin Rex) wrote:
>>
>> The *huge* advantage of PKCS#1 v1.5 signatures over RSA-PSS and ECDSA
>> signatures is that one can clearly distinguish "wrong public key"
>> from "signature does not fit plaintext" errors, and loosing this
>> capability makes certain kinds of programming goofs (plus a few
>> admin configuration goofs) much harder to distinguish from
>> data corruption during transfer.
> 
> Actually I see this as a disadvantage. Separating different error
> states has been the source of a whole number of vulnerabilities. The
> original Bleichenbacher attack (and all its variants including drown)
> is based on separating different errors, the Vaudenay attack is.

I'm sorry, but this is clueless.
Signature verification is a PUBLIC KEY operation.
You're not creating an oracle with a public key operation.

The examples you cite are about secret key and private key operations
which create oracles.  That isn't even in the same universe.

-Martin