> -----Original Message----- > From: linux-crypto-owner@xxxxxxxxxxxxxxx <linux-crypto-owner@xxxxxxxxxxxxxxx> On Behalf Of > Jarkko Sakkinen > Sent: Wednesday, October 9, 2019 1:54 AM > To: Ken Goldman <kgold@xxxxxxxxxxxxx> > Cc: Safford, David (GE Global Research, US) <david.safford@xxxxxx>; Mimi Zohar > <zohar@xxxxxxxxxxxxx>; linux-integrity@xxxxxxxxxxxxxxx; stable@xxxxxxxxxxxxxxx; open > list:ASYMMETRIC KEYS <keyrings@xxxxxxxxxxxxxxx>; open list:CRYPTO API <linux- > crypto@xxxxxxxxxxxxxxx>; open list <linux-kernel@xxxxxxxxxxxxxxx> > Subject: Re: [PATCH] KEYS: asym_tpm: Switch to get_random_bytes() > > On Wed, Oct 09, 2019 at 02:49:35AM +0300, Jarkko Sakkinen wrote: > > On Mon, Oct 07, 2019 at 06:13:01PM -0400, Ken Goldman wrote: > > > The TPM library specification states that the TPM must comply with NIST > > > SP800-90 A. > > > > > > https://trustedcomputinggroup.org/membership/certification/tpm-certified-products/ > > > > > > shows that the TPMs get third party certification, Common Criteria EAL 4+. > > > > > > While it's theoretically possible that an attacker could compromise > > > both the TPM vendors and the evaluation agencies, we do have EAL 4+ > > > assurance against both 1 and 2. > > > > Certifications do not equal to trust. > So having an implementation reviewed by a capable third party of your choosing (as that's how certification usually works) is less trustworthy than having random individuals hacking away at it? (and trust me, _most_ people are not going to review that by themselves - very few people on this planet are capable to do so) > And for trusted keys the least trust solution is to do generation > with the kernel assets and sealing with TPM. With TEE the least > trust solution is equivalent. > > Are you proposing that the kernel random number generation should > be removed? That would be my conclusion of this discussion if I > would agree any of this (I don't). > Life is not that black and white. If certification is _not_ a requirement you can use the kernel random number generator, especially if you don't trust, say, the TPM one. If you _do_ require certification - and in many industries this is _mandatory_, you simply _must_ follow the certification rules (which may impose restrictions how the random number generation is done), and this should not be made impossible for such _existing_ use cases. Having said all that, generating _true_ entropy (and, importantly, ensuring it cannot be manipulated) is a very complicated subject and considering how all encryption security ultimately depends on the quality of the random numbers used for key material, I would not trust any implementation that has not been certified or otherwise carefully scrutinized by people _proven_ to have the expertise. Regards, Pascal van Leeuwen Silicon IP Architect, Multi-Protocol Engines @ Verimatrix www.insidesecure.com
