Re: [TLS] TLS and hardware security modules - some issues related to PKCS11

Michael D'Errico <> Mon, 23 September 2013 18:18 UTC

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Date: Mon, 23 Sep 2013 11:18:25 -0700
From: Michael D'Errico <>
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Subject: Re: [TLS] TLS and hardware security modules - some issues related to PKCS11
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I've been trying to follow this discussion and it appears to me that the
goal is to have a HSM that protects the master secret and session keys
internally, yet also allows for extractors to ask the HSM to run the PRF
for them.  The problem is that a naive HSM might be tricked into revealing
the session keys.

Couldn't this be dealt with by having the HSM simply refuse to compute the
PRF given a label of "key expansion"?  Any other label should cause the
output to differ wildly from the session keys, right?