diff --git a/build-aux/git-authenticate.scm b/build-aux/git-authenticate.scm
index a3d4b40ccf..a84b79dfe7 100644
--- a/build-aux/git-authenticate.scm
+++ b/build-aux/git-authenticate.scm
@@ -25,6 +25,7 @@
              (guix base16)
              (guix git)
              (guix git-authenticate)
+             (guix channels)
              (guix i18n)
              ((guix openpgp)
               #:select (openpgp-public-key-fingerprint
@@ -37,186 +38,6 @@
              (ice-9 pretty-print))
 
 
-(define %historical-committers
-  ;; List of "historical" committers---people once authorized committers
-  ;; before the '.guix-authorizations' file was created.
-  ;;
-  ;; These are the user names found on
-  ;; <https://savannah.gnu.org/project/memberlist.php?group=guix> along with
-  ;; the fingerprint of the signing (sub)key.
-  '(("andreas"
-     "AD17 A21E F8AE D8F1 CC02  DBD9 F7D5 C9BF 765C 61E3")
-    ("ajgrf"
-     "2A39 3FFF 68F4 EF7A 3D29  12AF 6F51 20A0 22FB B2D5")
-    ("alexvong1995"
-     "306F CB8F 2C01 C25D 29D3  0556 61EF 502E F602 52F2")
-    ("alezost"
-     "4FB9 9F49 2B12 A365 7997  E664 8246 0C08 2A0E E98F")
-    ("ambrevar"
-     "50F3 3E2E 5B0C 3D90 0424  ABE8 9BDC F497 A4BB CC7F")
-    ("apteryx"
-     "27D5 86A4 F890 0854 329F  F09F 1260 E464 82E6 3562")
-    ("arunisaac"
-     "7F73 0343 F2F0 9F3C 77BF  79D3 2E25 EE8B 6180 2BB3")
-    ("atheia"
-     ;; primary: "3B12 9196 AE30 0C3C 0E90  A26F A715 5567 3271 9948"
-     "9A2B 401E D001 0650 1584  BAAC 8BC4 F447 6E8A 8E00")
-    ("bandali"
-     ;; primary: "BE62 7373 8E61 6D6D 1B3A  08E8 A21A 0202 4881 6103"
-     "39B3 3C8D 9448 0D2D DCC2  A498 8B44 A0CD C7B9 56F2")
-    ("bavier"
-     ;; primary: "34FF 38BC D151 25A6 E340  A0B5 3453 2F9F AFCA 8B8E"
-     "A0C5 E352 2EF8 EF5C 64CD  B7F0 FD73 CAC7 19D3 2566")
-    ("beffa"
-     "3774 8024 880F D3FF DCA2  C9AB 5893 6E0E 2F1B 5A4C")
-    ("benwoodcroft"
-     "BCF8 F737 2CED 080A 67EB  592D 2A6A D9F4 AAC2 0DF6")
-    ("biscuolo"
-     "45CC 63B8 5258 C9D5 5F34  B239 D37D 0EA7 CECC 3912")
-    ("boskovits"
-     "7988 3B9F 7D6A 4DBF 3719  0367 2506 A96C CF63 0B21")
-    ("brettgilio"
-     "DFC0 C7F7 9EE6 0CA7 AE55  5E19 6722 43C4 A03F 0EEE")
-    ("carl"
-     ;; primary: "0401 7A2A 6D9A 0CCD C81D  8EC2 96AB 007F 1A7E D999"
-     "09CD D25B 5244 A376 78F6  EEA8 0CC5 2153 1979 91A5")
-    ("cbaines"
-     "3E89 EEE7 458E 720D 9754  E0B2 5E28 A33B 0B84 F577")
-    ("civodul"
-     "3CE4 6455 8A84 FDC6 9DB4  0CFB 090B 1199 3D9A EBB5")
-    ("cwebber"
-     "510A 8628 E2A7 7678 8F8C  709C 4BC0 2592 5FF8 F4D3")
-    ("dannym"
-     ;; primary: "295A F991 6F46 F8A1 34B0  29DA 8086 3842 F0FE D83B"
-     "76CE C6B1 7274 B465 C02D  B3D9 E71A 3554 2C30 BAA5")
-    ("davexunit"
-     "B3C0 DB4D AD73 BA5D 285E  19AE 5143 0234 CEFD 87C3")
-    ("davexunit (2nd)"                            ;FIXME: to be confirmed!
-     "8CCB A7F5 52B9 CBEA E1FB  2915 8328 C747 0FF1 D807")
-    ("daviwil"
-     "53C4 1E6E 41AA FE55 335A  CA5E 446A 2ED4 D940 BF14")
-    ("dvc"
-     "6909 6DFD D702 8BED ACC5  884B C5E0 51C7 9C0B ECDB")
-    ("dvc (old)"
-     "5F43 B681 0437 2F4B A898  A64B 33B9 E9FD E28D 2C23")
-    ("efraim"
-     "A28B F40C 3E55 1372 662D  14F7 41AA E7DC CA3D 8351")
-    ("efraim (old)"
-     "9157 41FE B22F A4E3 3B6E  8F8D F4C1 D391 7EAC EE93")
-    ("glv"
-     ;; primary: "2453 02B1 BAB1 F867 FDCA  96BC 8F3F 861F 82EB 7A9A"
-     "CBC5 9C66 EC27 B971 7940  6B3E 6BE8 208A DF21 FE3F")
-    ("hoebjo"
-     "2219 43F4 9E9F 276F 9499  3382 BF28 6CB6 593E 5FFD")
-    ("htgoebel"
-     "B943 509D 633E 80DD 27FC  4EED 634A 8DFF D3F6 31DF")
-    ("ipetkov"
-     "7440 26BA 7CA3 C668 E940  1D53 0B43 1E98 3705 6942")
-    ("iyzsong"
-     ;; primary: "66A5 6D9C 9A98 BE7F 719A  B401 2652 5665 AE72 7D37"
-     "0325 78A6 8298 94E7 2AA2  66F5 D415 BF25 3B51 5976")
-
-    ;; https://lists.gnu.org/archive/html/guix-devel/2018-04/msg00229.html
-    ("janneke (old)"
-     "DB34 CB51 D25C 9408 156F  CDD6 A12F 8797 8D70 1B99")
-    ("janneke"
-     "1A85 8392 E331 EAFD B8C2  7FFB F3C1 A0D9 C1D6 5273")
-
-    ("jlicht"
-     ;; primary: "1BA4 08C5 8BF2 0EA7 3179  635A 865D C0A3 DED9 B5D0"
-     "E31D 9DDE EBA5 4A14 8A20  4550 DA45 97F9 47B4 1025")
-    ("jmd"
-     "8797 A26D 0854 2EAB 0285  A290 8A67 719C 2DE8 27B3")
-    ("kkebreau"
-     "83B6 703A DCCA 3B69 4BCE  2DA6 E6A5 EE3C 1946 7A0D")
-    ("leungbk"
-     "45E5 75FA 53EA 8BD6 1BCE  0B4E 3ADC 75F0 13D6 78F9")
-    ("lfam"
-     ;; primary: "4F71 6F9A 8FA2 C80E F1B5  E1BA 5E35 F231 DE1A C5E0"
-     "B051 5948 F1E7 D3C1 B980  38A0 2646 FA30 BACA 7F08")
-    ("lsl88"
-     "2AE3 1395 932B E642 FC0E  D99C 9BED 6EDA 32E5 B0BC")
-    ("marusich"
-     "CBF5 9755 CBE7 E7EF EF18  3FB1 DD40 9A15 D822 469D")
-    ("mbakke"
-     "BBB0 2DDF 2CEA F6A8 0D1D  E643 A2A0 6DF2 A33A 54FA")
-    ("mhw"
-     "D919 0965 CE03 199E AF28  B3BE 7CEF 2984 7562 C516")
-    ("mothacehe"
-     "4008 6A7E 0252 9B60 31FB  8607 8354 7635 3176 9CA6")
-    ("mthl"
-     "F2A3 8D7E EB2B 6640 5761  070D 0ADE E100 9460 4D37")
-    ("nckx"
-     ;; primary: "F5BC 5534 C36F 0087 B39D  36EF 1C9D C4FE B9DB 7C4B"
-     "F5DA 2032 4B87 3D0B 7A38  7672 0DB0 FF88 4F55 6D79")
-    ("nckx (revoked; not compromised)"
-     ;; primary: "F5BC 5534 C36F 0087 B39D  36EF 1C9D C4FE B9DB 7C4B"
-     "7E8F AED0 0944 78EF 72E6  4D16 D889 B0F0 18C5 493C")
-    ("niedzejkob"
-     "E576 BFB2 CF6E B13D F571  33B9 E315 A758 4613 1564")
-    ("ngz"
-     "ED0E F1C8 E126 BA83 1B48  5FE9 DA00 B4F0 48E9 2F2D")
-    ("pelzflorian"
-     "CEF4 CB91 4856 BA38 0A20  A7E2 3008 88CB 39C6 3817")
-    ("pgarlick"
-     ;; primary: "B68B DF22 73F9 DA0E 63C1  8A32 515B F416 9242 D600"
-     "C699 ED09 E51B CE89 FD1D  A078 AAC7 E891 896B 568A")
-    ("phant0mas"
-     "3A86 380E 58A8 B942 8D39  60E1 327C 1EF3 8DF5 4C32")
-    ("reepca"
-     "74D6 A930 F44B 9B84 9EA5  5606 C166 AA49 5F7F 189C")
-    ("rekado"
-     "BCA6 89B6 3655 3801 C3C6  2150 197A 5888 235F ACAC")
-    ("rhelling"
-     "0154 E1B9 1CC9 D9EF 7764  8DE7 F3A7 27DB 44FC CA36")
-    ("roelj (old)"
-     "17CB 2812 EB63 3DFF 2C7F  0452 C3EC 1DCA 8430 72E1")
-    ("roelj"
-     ;; From commit cc51c03ff867d4633505354819c6d88af88bf919 (March 2020).
-     ;; See <https://lists.gnu.org/archive/html/guix-devel/2020-03/msg00070.html>.
-     "F556 FD94 FB8F 8B87 79E3  6832 CBD0 CD51 38C1 9AFC")
-    ("roptat (old)"
-     "B5FA E628 5B41 3728 B2A0  FAED 4311 1F45 2008 6A0C")
-    ("roptat"
-     ;; From commit 2cbede5935eb6a40173bbdf30a9ad22bf7574c22 (Jan. 2020).  See
-     ;; <https://lists.gnu.org/archive/html/guix-devel/2020-01/msg00499.html>.
-     "1EFB 0909 1F17 D28C CBF9  B13A 53D4 57B2 D636 EE82")
-    ("samplet"
-     ;; primary: "D6B0 C593 DA8C 5EDC A44C  7A58 C336 91F7 1188 B004"
-     "A02C 2D82 0EF4 B25B A6B5  1D90 2AC6 A5EC 1C35 7C59")
-    ("sleep_walker"
-     "77DD AD2D 97F5 31BB C0F3  C7FD DFB5 EB09 AA62 5423")
-    ("snape"
-     "F494 72F4 7A59 00D5 C235  F212 89F9 6D48 08F3 59C7")
-    ("steap"
-     "4E26 CCE9 578E 0828 9855  BDD4 1C79 95D2 D5A3 8336")
-    ("taylanub"
-     "9ADE 9ECF 2B19 C180 9C99  5CEA A1F4 CFCC 5283 6BAC")
-
-    ;; https://lists.gnu.org/archive/html/guix-devel/2017-03/msg00826.html
-    ("thomasd"
-     ;; primary: "1DD1 681F E285 E07F 11DC  0C59 2E15 A6BC D77D 54FD"
-     "3D2C DA58 819C 08C2 A649  D43D 5C3B 064C 724A 5726")
-    ("thomasd (old)"
-     "A5C5 92EA 606E 7106 A6A3  BC08 98B2 1575 91E1 2B08")
-
-    ("toothbrush"
-     "D712 1D73 A40A 7264 9E43  ED7D F284 6B1A 0D32 C442")
-    ("vagrantc"
-     "6580 7361 3BFC C5C7 E2E4  5D45 DC51 8FC8 7F97 16AA")
-    ("wigust"
-     ;; primary: "C955 CC5D C048 7FB1 7966  40A9 199A F6A3 67E9 4ABB"
-     "7238 7123 8EAC EB63 4548  5857 167F 8EA5 001A FA9C")
-    ("wingo"
-     "FF47 8FB2 64DE 32EC 2967  25A3 DDC0 F535 8812 F8F2")))
-
-(define %historical-authorized-signing-keys
-  ;; Fingerprint of historically authorized signing keys.
-  (map (match-lambda
-         ((name fingerprint)
-          (base16-string->bytevector
-           (string-downcase (string-filter char-set:graphic fingerprint)))))
-       %historical-committers))
 
 (define %commits-with-bad-signature
   ;; Commits with a known-bad signature.
@@ -226,73 +47,25 @@
   ;; Commits lacking a signature.
   '())
 
-(define commit-short-id
-  (compose (cut string-take <> 7) oid->string commit-id))
-
 
 ;;;
 ;;; Entry point.
 ;;;
 
 (define (git-authenticate args)
-  (define repository
-    (repository-open "."))
-
   (let loop ((args args))
     (match args
       ((_ start end)
-       (define start-commit
-         (commit-lookup repository (string->oid start)))
-       (define end-commit
-         (commit-lookup repository (string->oid end)))
-
-       (define authenticated-commits
-         ;; Previously-authenticated commits that don't need to be checked
-         ;; again.
-         (filter-map (lambda (id)
-                       (false-if-exception
-                        (commit-lookup repository (string->oid id))))
-                     (previously-authenticated-commits "channels/guix")))
-
-       (define commits
-         ;; Commits to authenticate, excluding the closure of
-         ;; AUTHENTICATED-COMMITS.
-         (commit-difference end-commit start-commit
-                            authenticated-commits))
-
-       (define reporter
-         (progress-reporter/bar (length commits)))
-
-       (format #t (G_ "Authenticating ~a to ~a (~a commits)...~%")
-               (commit-short-id start-commit)
-               (commit-short-id end-commit)
-               (length commits))
-
-       (let ((stats (call-with-progress-reporter reporter
-                      (lambda (report)
-                        (authenticate-commits repository commits
-                                              #:default-authorizations
-                                              %historical-authorized-signing-keys
-                                              #:report-progress report)))))
-         (cache-authenticated-commit "channels/guix"
-                                     (oid->string (commit-id end-commit)))
-
-         (unless (null? stats)
-           (format #t (G_ "Signing statistics:~%"))
-           (for-each (match-lambda
-                       ((signer . count)
-                        (format #t "  ~a ~10d~%"
-                                (openpgp-format-fingerprint
-                                 (openpgp-public-key-fingerprint signer))
-                                count)))
-                     (sort stats
-                           (match-lambda*
-                             (((_ . count1) (_ . count2))
-                              (> count1 count2))))))))
+       (authenticate-channel (car %default-channels) "." end
+                             ;; Require users to have a local 'keyring'
+                             ;; branch.
+                             #:keyring-reference-prefix ""))
       ((command start)
-       (let* ((head (repository-head repository))
-              (end  (reference-target head)))
-         (loop (list command start (oid->string end)))))
+       (let* ((repository (repository-open "."))
+              (head       (repository-head repository))
+              (end        (oid->string (reference-target head))))
+         (repository-close! repository)
+         (loop (list command start end))))
       (_
        (format (current-error-port)
                (G_ "Usage: git-authenticate START [END]
diff --git a/guix/channels.scm b/guix/channels.scm
index 9e6adda5e9..b9983c6a43 100644
--- a/guix/channels.scm
+++ b/guix/channels.scm
@@ -126,26 +126,211 @@
 ;; as its signer's fingerprint.  The pair must be signed by the signer of that
 ;; commit so that only them may emit this introduction.  Introductions are
 ;; used to bootstrap trust in a channel.
+;;
+;; For the 'guix' channel, the introduction can also list "prehistorical
+;; authorizations": the list of fingerprints of authorized committers before
+;; the '.guix-authorizations' file was introduced.  Currently this feature is
+;; only available for the 'guix' channel because otherwise we would need and
+;; out-of-band mechanism to authenticate those prehistorical authorizations.
 (define-record-type <channel-introduction>
   (make-channel-introduction first-signed-commit first-commit-signer
-                             signature)
+                             prehistorical-authorizations signature)
   channel-introduction?
   (first-signed-commit  channel-introduction-first-signed-commit) ;hex string
   (first-commit-signer  channel-introduction-first-commit-signer) ;bytevector
+  (prehistorical-authorizations
+   channel-introduction-prehistorical-authorizations)    ;list of bytevectors
   (signature            channel-introduction-signature))          ;string
 
+(define %guix-historical-committers
+  ;; List of "historical" Guix committers---people once authorized committers
+  ;; before the '.guix-authorizations' file was created.
+  ;;
+  ;; These are the user names found on
+  ;; <https://savannah.gnu.org/project/memberlist.php?group=guix> along with
+  ;; the fingerprint of the signing (sub)key.
+  '(("andreas"
+     "AD17 A21E F8AE D8F1 CC02  DBD9 F7D5 C9BF 765C 61E3")
+    ("ajgrf"
+     "2A39 3FFF 68F4 EF7A 3D29  12AF 6F51 20A0 22FB B2D5")
+    ("alexvong1995"
+     "306F CB8F 2C01 C25D 29D3  0556 61EF 502E F602 52F2")
+    ("alezost"
+     "4FB9 9F49 2B12 A365 7997  E664 8246 0C08 2A0E E98F")
+    ("ambrevar"
+     "50F3 3E2E 5B0C 3D90 0424  ABE8 9BDC F497 A4BB CC7F")
+    ("apteryx"
+     "27D5 86A4 F890 0854 329F  F09F 1260 E464 82E6 3562")
+    ("arunisaac"
+     "7F73 0343 F2F0 9F3C 77BF  79D3 2E25 EE8B 6180 2BB3")
+    ("atheia"
+     ;; primary: "3B12 9196 AE30 0C3C 0E90  A26F A715 5567 3271 9948"
+     "9A2B 401E D001 0650 1584  BAAC 8BC4 F447 6E8A 8E00")
+    ("bandali"
+     ;; primary: "BE62 7373 8E61 6D6D 1B3A  08E8 A21A 0202 4881 6103"
+     "39B3 3C8D 9448 0D2D DCC2  A498 8B44 A0CD C7B9 56F2")
+    ("bavier"
+     ;; primary: "34FF 38BC D151 25A6 E340  A0B5 3453 2F9F AFCA 8B8E"
+     "A0C5 E352 2EF8 EF5C 64CD  B7F0 FD73 CAC7 19D3 2566")
+    ("beffa"
+     "3774 8024 880F D3FF DCA2  C9AB 5893 6E0E 2F1B 5A4C")
+    ("benwoodcroft"
+     "BCF8 F737 2CED 080A 67EB  592D 2A6A D9F4 AAC2 0DF6")
+    ("biscuolo"
+     "45CC 63B8 5258 C9D5 5F34  B239 D37D 0EA7 CECC 3912")
+    ("boskovits"
+     "7988 3B9F 7D6A 4DBF 3719  0367 2506 A96C CF63 0B21")
+    ("brettgilio"
+     "DFC0 C7F7 9EE6 0CA7 AE55  5E19 6722 43C4 A03F 0EEE")
+    ("carl"
+     ;; primary: "0401 7A2A 6D9A 0CCD C81D  8EC2 96AB 007F 1A7E D999"
+     "09CD D25B 5244 A376 78F6  EEA8 0CC5 2153 1979 91A5")
+    ("cbaines"
+     "3E89 EEE7 458E 720D 9754  E0B2 5E28 A33B 0B84 F577")
+    ("civodul"
+     "3CE4 6455 8A84 FDC6 9DB4  0CFB 090B 1199 3D9A EBB5")
+    ("cwebber"
+     "510A 8628 E2A7 7678 8F8C  709C 4BC0 2592 5FF8 F4D3")
+    ("dannym"
+     ;; primary: "295A F991 6F46 F8A1 34B0  29DA 8086 3842 F0FE D83B"
+     "76CE C6B1 7274 B465 C02D  B3D9 E71A 3554 2C30 BAA5")
+    ("davexunit"
+     "B3C0 DB4D AD73 BA5D 285E  19AE 5143 0234 CEFD 87C3")
+    ("davexunit (2nd)"                            ;FIXME: to be confirmed!
+     "8CCB A7F5 52B9 CBEA E1FB  2915 8328 C747 0FF1 D807")
+    ("daviwil"
+     "53C4 1E6E 41AA FE55 335A  CA5E 446A 2ED4 D940 BF14")
+    ("dvc"
+     "6909 6DFD D702 8BED ACC5  884B C5E0 51C7 9C0B ECDB")
+    ("dvc (old)"
+     "5F43 B681 0437 2F4B A898  A64B 33B9 E9FD E28D 2C23")
+    ("efraim"
+     "A28B F40C 3E55 1372 662D  14F7 41AA E7DC CA3D 8351")
+    ("efraim (old)"
+     "9157 41FE B22F A4E3 3B6E  8F8D F4C1 D391 7EAC EE93")
+    ("glv"
+     ;; primary: "2453 02B1 BAB1 F867 FDCA  96BC 8F3F 861F 82EB 7A9A"
+     "CBC5 9C66 EC27 B971 7940  6B3E 6BE8 208A DF21 FE3F")
+    ("hoebjo"
+     "2219 43F4 9E9F 276F 9499  3382 BF28 6CB6 593E 5FFD")
+    ("htgoebel"
+     "B943 509D 633E 80DD 27FC  4EED 634A 8DFF D3F6 31DF")
+    ("ipetkov"
+     "7440 26BA 7CA3 C668 E940  1D53 0B43 1E98 3705 6942")
+    ("iyzsong"
+     ;; primary: "66A5 6D9C 9A98 BE7F 719A  B401 2652 5665 AE72 7D37"
+     "0325 78A6 8298 94E7 2AA2  66F5 D415 BF25 3B51 5976")
+
+    ;; https://lists.gnu.org/archive/html/guix-devel/2018-04/msg00229.html
+    ("janneke (old)"
+     "DB34 CB51 D25C 9408 156F  CDD6 A12F 8797 8D70 1B99")
+    ("janneke"
+     "1A85 8392 E331 EAFD B8C2  7FFB F3C1 A0D9 C1D6 5273")
+
+    ("jlicht"
+     ;; primary: "1BA4 08C5 8BF2 0EA7 3179  635A 865D C0A3 DED9 B5D0"
+     "E31D 9DDE EBA5 4A14 8A20  4550 DA45 97F9 47B4 1025")
+    ("jmd"
+     "8797 A26D 0854 2EAB 0285  A290 8A67 719C 2DE8 27B3")
+    ("kkebreau"
+     "83B6 703A DCCA 3B69 4BCE  2DA6 E6A5 EE3C 1946 7A0D")
+    ("leungbk"
+     "45E5 75FA 53EA 8BD6 1BCE  0B4E 3ADC 75F0 13D6 78F9")
+    ("lfam"
+     ;; primary: "4F71 6F9A 8FA2 C80E F1B5  E1BA 5E35 F231 DE1A C5E0"
+     "B051 5948 F1E7 D3C1 B980  38A0 2646 FA30 BACA 7F08")
+    ("lsl88"
+     "2AE3 1395 932B E642 FC0E  D99C 9BED 6EDA 32E5 B0BC")
+    ("marusich"
+     "CBF5 9755 CBE7 E7EF EF18  3FB1 DD40 9A15 D822 469D")
+    ("mbakke"
+     "BBB0 2DDF 2CEA F6A8 0D1D  E643 A2A0 6DF2 A33A 54FA")
+    ("mhw"
+     "D919 0965 CE03 199E AF28  B3BE 7CEF 2984 7562 C516")
+    ("mothacehe"
+     "4008 6A7E 0252 9B60 31FB  8607 8354 7635 3176 9CA6")
+    ("mthl"
+     "F2A3 8D7E EB2B 6640 5761  070D 0ADE E100 9460 4D37")
+    ("nckx"
+     ;; primary: "F5BC 5534 C36F 0087 B39D  36EF 1C9D C4FE B9DB 7C4B"
+     "F5DA 2032 4B87 3D0B 7A38  7672 0DB0 FF88 4F55 6D79")
+    ("nckx (revoked; not compromised)"
+     ;; primary: "F5BC 5534 C36F 0087 B39D  36EF 1C9D C4FE B9DB 7C4B"
+     "7E8F AED0 0944 78EF 72E6  4D16 D889 B0F0 18C5 493C")
+    ("niedzejkob"
+     "E576 BFB2 CF6E B13D F571  33B9 E315 A758 4613 1564")
+    ("ngz"
+     "ED0E F1C8 E126 BA83 1B48  5FE9 DA00 B4F0 48E9 2F2D")
+    ("pelzflorian"
+     "CEF4 CB91 4856 BA38 0A20  A7E2 3008 88CB 39C6 3817")
+    ("pgarlick"
+     ;; primary: "B68B DF22 73F9 DA0E 63C1  8A32 515B F416 9242 D600"
+     "C699 ED09 E51B CE89 FD1D  A078 AAC7 E891 896B 568A")
+    ("phant0mas"
+     "3A86 380E 58A8 B942 8D39  60E1 327C 1EF3 8DF5 4C32")
+    ("reepca"
+     "74D6 A930 F44B 9B84 9EA5  5606 C166 AA49 5F7F 189C")
+    ("rekado"
+     "BCA6 89B6 3655 3801 C3C6  2150 197A 5888 235F ACAC")
+    ("rhelling"
+     "0154 E1B9 1CC9 D9EF 7764  8DE7 F3A7 27DB 44FC CA36")
+    ("roelj (old)"
+     "17CB 2812 EB63 3DFF 2C7F  0452 C3EC 1DCA 8430 72E1")
+    ("roelj"
+     ;; From commit cc51c03ff867d4633505354819c6d88af88bf919 (March 2020).
+     ;; See <https://lists.gnu.org/archive/html/guix-devel/2020-03/msg00070.html>.
+     "F556 FD94 FB8F 8B87 79E3  6832 CBD0 CD51 38C1 9AFC")
+    ("roptat (old)"
+     "B5FA E628 5B41 3728 B2A0  FAED 4311 1F45 2008 6A0C")
+    ("roptat"
+     ;; From commit 2cbede5935eb6a40173bbdf30a9ad22bf7574c22 (Jan. 2020).  See
+     ;; <https://lists.gnu.org/archive/html/guix-devel/2020-01/msg00499.html>.
+     "1EFB 0909 1F17 D28C CBF9  B13A 53D4 57B2 D636 EE82")
+    ("samplet"
+     ;; primary: "D6B0 C593 DA8C 5EDC A44C  7A58 C336 91F7 1188 B004"
+     "A02C 2D82 0EF4 B25B A6B5  1D90 2AC6 A5EC 1C35 7C59")
+    ("sleep_walker"
+     "77DD AD2D 97F5 31BB C0F3  C7FD DFB5 EB09 AA62 5423")
+    ("snape"
+     "F494 72F4 7A59 00D5 C235  F212 89F9 6D48 08F3 59C7")
+    ("steap"
+     "4E26 CCE9 578E 0828 9855  BDD4 1C79 95D2 D5A3 8336")
+    ("taylanub"
+     "9ADE 9ECF 2B19 C180 9C99  5CEA A1F4 CFCC 5283 6BAC")
+
+    ;; https://lists.gnu.org/archive/html/guix-devel/2017-03/msg00826.html
+    ("thomasd"
+     ;; primary: "1DD1 681F E285 E07F 11DC  0C59 2E15 A6BC D77D 54FD"
+     "3D2C DA58 819C 08C2 A649  D43D 5C3B 064C 724A 5726")
+    ("thomasd (old)"
+     "A5C5 92EA 606E 7106 A6A3  BC08 98B2 1575 91E1 2B08")
+
+    ("toothbrush"
+     "D712 1D73 A40A 7264 9E43  ED7D F284 6B1A 0D32 C442")
+    ("vagrantc"
+     "6580 7361 3BFC C5C7 E2E4  5D45 DC51 8FC8 7F97 16AA")
+    ("wigust"
+     ;; primary: "C955 CC5D C048 7FB1 7966  40A9 199A F6A3 67E9 4ABB"
+     "7238 7123 8EAC EB63 4548  5857 167F 8EA5 001A FA9C")
+    ("wingo"
+     "FF47 8FB2 64DE 32EC 2967  25A3 DDC0 F535 8812 F8F2")))
+
+(define (openpgp-fingerprint->bytevector str)
+  (base16-string->bytevector
+   (string-downcase (string-filter char-set:hex-digit str))))
+
 (define %guix-channel-introduction
-  ;; Introduction of the official 'guix channel.  The chosen commit is the
-  ;; first one that introduces '.guix-authorizations' on the 'core-updates'
-  ;; branch that was eventually merged in 'master'.  Any branch starting
-  ;; before that commit cannot be merged or it will be rejected by 'guix pull'
-  ;; & co.
+  ;; Introduction of the official 'guix channel.
   (make-channel-introduction
-   "87a40d7203a813921b3ef0805c2b46c0026d6c31"
-   (base16-string->bytevector
-    (string-downcase
-     (string-filter char-set:hex-digit            ;mbakke
-                    "BBB0 2DDF 2CEA F6A8 0D1D  E643 A2A0 6DF2 A33A 54FA")))
+   "6298c3ffd9654d3231a6f25390b056483e8f407c"     ;v1.0.0
+   (openpgp-fingerprint->bytevector
+    "3CE4 6455 8A84 FDC6 9DB4  0CFB 090B 1199 3D9A EBB5") ;civodul
+
+   ;; The "prehistorical authorizations" lists authorized committers between
+   ;; v1.0.0 and the commit where '.guix-authorizations' was introduced.
+   (match %guix-historical-committers
+     (((_ fingerprints) ...)
+      (map openpgp-fingerprint->bytevector fingerprints)))
    #f))                   ;TODO: Add an intro signature so it can be exported.
 
 (define %default-channel-url
@@ -331,6 +516,10 @@ fails."
                                    (string-append keyring-reference-prefix
                                                   keyring-reference)))
 
+    (define prehistorical-authorizations
+      (channel-introduction-prehistorical-authorizations
+       (channel-introduction channel)))
+
     (define authenticated-commits
       ;; Previously-authenticated commits that don't need to be checked again.
       (filter-map (lambda (id)
@@ -381,6 +570,8 @@ commits ~a to ~a (~h new commits)...~%")
             (lambda (report)
               (authenticate-commits repository commits
                                     #:keyring keyring
+                                    #:default-authorizations
+                                    prehistorical-authorizations
                                     #:report-progress report)))
 
           (unless (null? commits)
diff --git a/tests/channels.scm b/tests/channels.scm
index 5f13a48ec1..8c64d7a7c7 100644
--- a/tests/channels.scm
+++ b/tests/channels.scm
@@ -430,6 +430,7 @@
                          (openpgp-public-key-fingerprint
                           (read-openpgp-packet
                            %ed25519bis-public-key-file)) ;different key
+                         '()
                          #f))                     ;no signature
                (channel (channel (name 'example)
                                  (url (string-append "file://" directory))
@@ -486,6 +487,7 @@
                          (openpgp-public-key-fingerprint
                           (read-openpgp-packet
                            %ed25519-public-key-file))
+                         '()
                          #f))                     ;no signature
                (channel (channel (name 'example)
                                  (url (string-append "file://" directory))
