gnupg: Accept revoked keys.

I (nckx) have revoked all RSA subkeys, in favour of my older and
freshly-refreshed ECDSA ones.  This was merely a precaution: to my
knowledge all my RSA private keys have been carefully destroyed and
were never compromised.  This commit keeps ‘make authenticate’ happy.

* guix/gnupg.scm (revkeysig-rx): New variable for revoked keys.
(gnupg-verify): Parse it.
(gnupg-status-good-signature?): Accept it as ‘good’ for our purposes.
* build-aux/git-authenticate.scm (%committers): Clarify nckx's subkeys.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

1 files changed, 10 insertions, 1 deletions

diff --git a/guix/gnupg.scm b/guix/gnupg.scm
index bf0283f8fe..5fae24b325 100644
--- a/guix/gnupg.scm
+++ b/guix/gnupg.scm
@@ -1,6 +1,7 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2010, 2011, 2013, 2014, 2016, 2018, 2019 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2013 Nikita Karetnikov <nikita@karetnikov.org>
+;;; Copyright © 2020 Tobias Geerinckx-Rice <me@tobias.gr>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -71,6 +72,8 @@
    "^\\[GNUPG:\\] VALIDSIG ([[:xdigit:]]+) ([[:digit:]]{4}-[[:digit:]]{2}-[[:digit:]]{2}) ([[:digit:]]+) .*$"))
 (define expkeysig-rx                    ; good signature, but expired key
   (make-regexp "^\\[GNUPG:\\] EXPKEYSIG ([[:xdigit:]]+) (.*)$"))
+(define revkeysig-rx                    ; good signature, but revoked key
+  (make-regexp "^\\[GNUPG:\\] REVKEYSIG ([[:xdigit:]]+) (.*)$"))
 (define errsig-rx
   ;; Note: The fingeprint part (the last element of the line) appeared in
   ;; GnuPG 2.2.7 according to 'doc/DETAILS', and it may be missing.
@@ -114,6 +117,11 @@ revoked.  Return a status s-exp if GnuPG failed."
            (lambda (match)
              `(expired-key-signature ,(match:substring match 1) ; fingerprint
                                      ,(match:substring match 2)))) ; user name
+          ((regexp-exec revkeysig-rx line)
+           =>
+           (lambda (match)
+             `(revoked-key-signature ,(match:substring match 1) ; fingerprint
+                                     ,(match:substring match 2)))) ; user name
           ((regexp-exec errsig-rx line)
            =>
            (lambda (match)
@@ -157,7 +165,8 @@ a fingerprint/user pair; return #f otherwise."
   (match (assq 'valid-signature status)
     (('valid-signature fingerprint date timestamp)
      (match (or (assq 'good-signature status)
-                (assq 'expired-key-signature status))
+                (assq 'expired-key-signature status)
+                (assq 'revoked-key-signature status))
        ((_ key-id user) (cons fingerprint user))
        (_ #f)))
     (_