Re: [TLS] TLS 1.3: Deterministic RSA-PSS and ECDSA

mrex@sap.com (Martin Rex) Wed, 10 August 2016 17:57 UTC

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To: Tony Arcieri <bascule@gmail.com>
Date: Wed, 10 Aug 2016 19:57:06 +0200 (CEST)
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From: mrex@sap.com (Martin Rex)
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Subject: Re: [TLS] TLS 1.3: Deterministic RSA-PSS and ECDSA
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Tony Arcieri wrote:
>
> It's also worth noting that BERserk is one of many such incidents of this
> coming up in practice:
> https://cryptosense.com/why-pkcs1v1-5-signature-should-also-be-put-out-of-our-misery/

With the PKCS#1 v1.5 signature verification operation,
as described in PKCS#1 v2.0 (rfc2437, Oct-1998, Section 8.1.2)

https://tools.ietf.org/html/rfc2437#section-8.1.2

it is *IMPOSSIBLE* to create an implementation with a bug such
as BERserk, because there is (on purpose) *NO* ASN.1 decoding step
defined for this signature verification.


A useful specification that is almost 2 decades old does not
protect from clueless implementors, however.

Heartbleed is also not part of the underlying specification.
Anyhow some very seriously broken code, for a completely useless
feature (within TLS, not DTLS), was created and shipped into
large parts of the installed base...


-Martin