I'll just paste the relevant stuff here:
# banner stuff
[org/gnome/login-screen]
banner-message-enable=true
banner-message-text='You
are accessing a U.S. Government (USG) Information System (IS) that is
provided for USG-authorized use only. By using this IS (which includes
any device attached to this IS), you consent to the following
conditions:\n -The USG routinely intercepts and monitors communications
on this IS for purposes including, but not limited to, penetration
testing, COMSEC monitoring, network operations and defense, personnel
misconduct (PM), law enforcement (LE), and counterintelligence (CI)
investigations.\n -At any time, the USG may inspect and seize data
stored on this IS.\n -Communications using, or data stored on, this IS
are not private, are subject to routine monitoring, interception, and
search, and may be disclosed or used for any USG-authorized purpose.\n
-This IS includes security measures (e.g., authentication and access
controls) to protect USG interests -- not for your personal benefit or
privacy.\n -Notwithstanding the above, using this IS does not constitute
consent to PM, LE or CI investigative searching or monitoring of the
content of privileged communications, or work product, related to
personal representation or services by attorneys, psychotherapists, or
clergy, and their assistants. Such communications and work product are
private and confidential. See User Agreement for details.'
# don't show lists of users on login screen
disable-user-list=true
# disable fingerprint reader
enable-fingerprint-authentication=false
By
my count it's 1311 characters, but that's probably not treating the
\n's as a single character. FWIW, this is our approved "short" version
of the banner.