bug#45613: U2F does not work in IceCat

[John Doe]

I've been trying to get U2F to work in IceCat without success with the Nitrokey 
FIDO2 and FIDO U2F devices. To test 2 websites were used: vault.bitwarden.com 
and u2f.bin.coffee .

For vault.bitwarden.com, after entering the password, the following error popup 
appears repeatedly:
"An error has occurred. U2F Error: 1"

For u2f.bin.coffee, when clicking the U2F Register button, the following error 
appears:
"
Sending request with appId: https://u2f.bin.coffee
{
  "version": "U2F_V2",
  "challenge": "pyvBtAPUygH0mZg4_thmdo_Ltnk"
}

Got response:
{
  "errorCode": 1
}

[FAIL] Imported credential public key
Failures: 1 TODOs: 0
"
A similar error appears for the U2F Sign button.

The same websites work without trouble in ungoogled-chromium as well as Firefox 
installed in Flatpak and run with the options "flatpak run --user --device=all 
org.mozilla.firefox".

I have installed the pam-u2f package which includes the libu2f-server and 
libu2f-host packages.

In /etc/config.scm I have the following configuration to add udev rules for the 
Nitrokey device:

"
(use-modules (guix download)
             (guix packages)
(use-service-modules security-token)
;; ...
(define %nitrokey-udev-rule
  (file->udev-rule
   "41-nitrokey.rules"
   (let ((version "2019"))
     (origin
      (method url-fetch)
      (uri 
"https://raw.githubusercontent.com/Nitrokey/libnitrokey/master/data/41-nitrokey.rules";)
      (sha256
       (base32 "1j8x9i2ypr6jadpmjbcffk7rjqd3a4x0krqx5hqk7bfgsxzima23"))))))

;; ref. https://lists.gnu.org/archive/html/help-guix/2019-07/msg00051.html
(define %updated-desktop-services
  (modify-services
   %desktop-services
   (udev-service-type config =>
                      (udev-configuration
                       (inherit config)
                       (rules (append (udev-configuration-rules config)
                                      (list %nitrokey-udev-rule)))))))

(operating-system
 ;; ...
 (services
  (append
   (list
    (service xfce-desktop-service-type)
    (set-xorg-configuration
     (xorg-configuration
      (keyboard-layout keyboard-layout))))
   (list
    ;; ...
    (service pcscd-service-type))
   %updated-desktop-services))
 ;; ...
"

Please let me know if there is any additional information I can provide.