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Re: [TLS] Using RSA PSS in TLS

Geoffrey Keating <geoffk@geoffk.org> Thu, 15 January 2015 02:11 UTC

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From: Geoffrey Keating <geoffk@geoffk.org>
Date: Wed, 14 Jan 2015 18:11:18 -0800
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Subject: Re: [TLS] Using RSA PSS in TLS
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mrex@sap.com (Martin Rex) writes:

> If the spec was tightened to prohibit *all* kinds of parsing
> of the RSA-decrypted BT01 padding signature plaintext,
> and instead required rebuilding of the BT01 padding from the input hash
> value and input hash oid, and comparison of the newly composed result
> with what the RSA decryption returned, then none of the parser problems
> for RSA PKCS#1 v1.5 signatures would have existed.
> 
> That approach to RSA signature verification is actually the one
> recommended by PKCS#1 v2.1 for the RSASSA-PKCS1-V1_5-VERIFY operation.
> 
>   https://tools.ietf.org/html/rfc3447#section-8.2.2

Would this actually work?  I suspect implementations use slightly
inconsistent padding generation...

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