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GnuPG offers a set of different trust models, but the manual isn't sufficient (for me at least) to figure out which one to use.

Ideally, I would like a trust model that accepts the trust I explicitly assign to a key using GnuPG's --edit-key and trust subcommand, and also computes trust based on signatures. Is this possible? When I have tried to use GnuPG, it seems like it's ignoring the trust I assign using trust, and only trusting if I sign a key.

Jens Erat
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Robert P. Goldman
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  • Hi did you give the rfc a shot https://tools.ietf.org/html/rfc4880#page-30 . As far as I understand you talking about the trust signature? – Dirk Oct 06 '17 at 15:18
  • I would not use any trust model but rely on your judgement when you receive a message from a key you have not verified. – eckes Dec 06 '17 at 05:10

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GnuPG does not allow a trust model like you describe, unless you specify ultimate trust on those keys (which makes them introducers into your local view on the web of trust). For GnuPG (and this also applies for OpenPGP in general), signatures are for defining verified identity, trust is just about defining which key's signatures to follow.

Given your actual requirement is not getting along without any signatures on the trusted keys but with not sharing those, GnuPG's local signatures might be what you're looking for.

Additionally, the concept of "trust on first use" might be sufficient for your use case, although providing a much weaker concept of defining trust.

Jens Erat
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  • Given the available trust models, I don't understand what the operation of editing trust in GNUPG is for. I can set a key to be trusted, but if I don't sign it, I still get a warning about it being untrusted. If I sign it, then it's trusted. So what is trust editing for? I ask because I used to set the trust in keys, and Enigmail would use this (apparently) to decide whether or not to allow me to send email to someone (without a warning). MailMate uses a different interface, and now GPG claims that nothing is trusted. – Robert P. Goldman Oct 09 '17 at 13:05
  • The word "trust" in OpenPGP is used in different ways. When you edit trust in GnuPG, you issue trust on a key, and this allows you to declare "if this key is validated, consider certifications issued by this key when validating other keys". Sometimes, "trusted" is also used to speak of such validated keys or messages/files signed by such keys. – Jens Erat Oct 13 '17 at 18:09