age-plugin-yubikey VS homebrew-core

_o/ hi all, age author here!

The OP link is the spec, here's a few other things you might find interesting

- the Go reference implementation https://age-encryption.org

- the Go library docs https://pkg.go.dev/filippo.io/age

- the CLI man page https://filippo.io/age/age.1

- an interoperable Rust implementation by @str4d https://github.com/str4d/rage

- a YubiKey plugin by @str4d https://github.com/str4d/age-plugin-yubikey

- the draft plugin protocol specification (which we should really merge) https://github.com/C2SP/C2SP/pull/5/files?short_path=07bf8cc...

- a Windows GUI by @spieglt https://github.com/spieglt/winage

- a discussion of the authentication properties of age https://words.filippo.io/dispatches/age-authentication/

- a discussion of a potential post-quantum plugin https://words.filippo.io/dispatches/post-quantum-age/

- a password-store fork that uses age instead of gpg https://github.com/FiloSottile/passage (see also: how I use it with a YubiKey https://words.filippo.io/dispatches/passage/)

I am using the yubikey plug-in for age (https://github.com/str4d/age-plugin-yubikey). It creates a private key and writes it to one of the retired PIV slot. What I want to do is to write the same private key to two different Yubikeys.

So with age I can also just use my ssh public key to encrypt and my ssh private key to decrypt my files. If I want to get fancy, I can use something like https://github.com/str4d/age-plugin-yubikey to provide the key material for my age operations (which should compose with age.el quite well also, i.e. you can have every decrypt operation have a touch requirement in Emacs that way).

> A good feature of PIV applet of Yubikey 5 is that it stores 24 keys.

Note that not all 24 of those keys are suitable for age usage. The 4 main keys have specific usage definitions in the PIV specification that mean hardware tokens alter how those key slots behave. Only one of them (the KeyManagement slot) has a definition that allows encryption, and even that I was somewhat suspicious of overlapping with, as I couldn't predict how those existing keys were being used, and didn't want to support every possible key type that might be in that slot (which users likely wouldn't be able to alter).

age-plugin-yubikey avoids this complexity by only interacting with the 20 "retired" slots, which have no constraining definitions. (I am considering adding restricted support for the KeyManagement slot specifically for CAC card users who aren't allowed to add new keys to their cards [0], but this would be behind a default-off feature flag to keep the primary UX simple.)

[0] https://github.com/str4d/age-plugin-yubikey/issues/62

We designed the plugin protocol (https://hackmd.io/@str4d/age-plugin-spec) and generally the age recipient/identity structure specifically to enable the use of hardware or remote keys!

For example, https://github.com/str4d/age-plugin-yubikey makes it very easy to use PIV tokens, including YubiKeys, with age. (Well, for now with rage, since plugin support is coming in age v1.1.0.)

I argue against password-protecting keys by default because, unlike using hardware tokens, it doesn't protect against many threat models.

Hardware? I assume if someone was concerned about key access they wouldn't want keys on their filesystem at all but move them into an HSM instead. Since age identities can come from standard input I assume it'd be feasible to put together a workflow there coming from one of the various cli utilities for interacting with keys. There is already a YubiKey specific age plugin [0] getting worked on as well. Currently in beta but looks interesting. Hopefully that will continue to expand to cover other common options. HSM support is pretty important for a modern encryption utility IMO but unfortunately the landscape is pretty all over the place too, so makes sense to just leave it to plugins or as part of a unix flow.

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0: https://github.com/str4d/age-plugin-yubikey

age also has a notion of plugins, one of which is age-plugin-yubikey (written in Rust, there is also yubage written in Go) which allows you to create an age identity whose private key is stored via PIV.

Is disabling the compromised repo the typical GitHub policy? My concern is there are monorepos used by package managers, like brew, that are a collection of thousands of projects [1]. These monorepos seem like a prime target for attack and if GitHub disables one because a malicious commit was merged then you've taken down an entire ecosystem.

[1] https://github.com/Homebrew/homebrew-core

> Correct. Though we do not appear to be affected, this revert was done out of an abundance of caution.

[1] https://github.com/Homebrew/homebrew-core/pull/167512

> right, but now you know even less about your setup when you some roadblock

This is the same with a binary though. And with homebrew, you can't follow patches or flags used or if they change.

- https://github.com/Homebrew/homebrew-core/blob/c964ad7fa53ad...

definitely be careful about using fortune in a corporate environment or public space if you don't know what dat files you are using or you might just get an extremely unwelcome surprise.

I was practicing a presentation and used to use "fortune" all the time. I forget exactly what it output but I remember being absolutely mortified about what could have happened if that had popped up during an internal company tech talk.

Kudos to brew for keeping unsuspecting people safe

https://github.com/Homebrew/homebrew-core/commit/3fb3c4c3e55...

I'm sorry to be asking this as I find it a bit silly, but it's blocking my PR [3], so could a few of you star the project on Github [1] to get my PR to run?

[1] https://github.com/laktak/chkbit-py

[2] https://brew.sh

[3] https://github.com/Homebrew/homebrew-core/pull/160018