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anon7000 a day ago

The signing key for Firefox stored on a single hardware yubikey available to a single person?

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pamcake a day ago | parent | next [-]

Could be multiple individuals, each with a different key.

https://eprint.iacr.org/2020/540

https://en.wikipedia.org/wiki/Shamir%27s_Secret_Sharing

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kevincox a day ago | parent [-]

SSS doesn't support signing AFAIK. When I last looked into it GPG/PGP doesn't support shared signing.

You can use SSS to encrypt the signing key, but then you need to fully materialize the signing key to actually sign the release. Which makes the exact situation that occurred here possible.

The only way to do multi-signer PGP is outside of the PGP protocol, you just need to sign the artifact multiple times then have the verifier assert that a sufficient number of signatures are present. But again, this isn't supported by the regular PGP tools.

	▲	pamcake 15 hours ago \| parent [-]
		You are right that SSS requires temporarily rematerializing the raw key at the moment of signing. Even so it would be a huge improvement: > Which makes the exact situation that occurred here possible. Not so. The situation here was operator errror and someone mistakenly committing signing key in cleartext to repo. So this exact situation would not be possible. They could also have a process of signing on a dedicated instance (possibly with its own shard) which would remove key exposure completely from operator machines. This is all achivable with existing tooling and without changing implementations on verifier side. The first link shows how an actual threshold signature scheme for PGP could be constructed.

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computerfriend a day ago | parent | prev [-]

Multiple hardware devices can have the same key.

	▲	_bernd a day ago \| parent [-]
		Yes but then you have to take extra care of this one special system which generates the key on this local system and which transfers the key material to the HSM. Sure it's a valid use case but depending on your requirements this could be a no go. But sharing key files with developers comes also with a price tag.