I was recently recommended a specific smartcard over on HardwareRecs.SE. As part of this, the answerer (our ursine overlord) stated that the cards in question don't offer a means to securely backup keys but however accept plaintext keys to be imported. It was suggested to run my own key ceremony to generate those keys.

Now for the preparation of this I had to ask myself:
Is there any way to ensure / verify that I actually burnt the correct and intended ISO onto the disc I'll use for the ceremony?

The threat model: I'd like to minimize trust in every single hardware and software component which came in-touch with this ISO and get an as strong as possible assertion that the ISO is indeed valid and the disc content equals the ISO.

Possible attack vectors include, but are not limited to:

  • A malicious browser (used to retrieve the ISO)
  • A malicious software on the OS (used to store the ISO until download is completed and burn process is initiated)
  • A malicious burning software (which will report fake hashes to me or make malicious changes)
  • A malicious hardware drive (used to store the ISO until it's burnt)
  • A malicious DVD burner
  • All of the attack vectors you list seem to be targetet precisely at your key generation ceremony. The thing is: if someone wants to undermine your ceremony, the surely will be able to do so. CAs rightly put a hell of an effort into protecting their ceremonies. You wont be able to afford protection against specifically targeted attacks by yourself. – marstato Apr 23 '16 at 14:16

I assume that your ISOs a provided with a hash in order to verify their integrity right?

Just grab the hash along with the ISO, write that sucker down on a piece of paper (yes it's long, just do it). When you've burned your DVD, pop it into another system and generate an ISO based off the DVD using the dd command (unlikely anyone would compromise dd in this particular senario). Then just run the hash against the generated ISO to compare.

If you can't trust the hash listed with the ISO when you're grabbing it, then I suggest contacting the originator of the ISO out of band (yes, we still have phones) to get the hash.

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