Gem::Security::Policy#check_cert

# File tmp/rubies/ruby-3.4.1/lib/rubygems/security/policy.rb, line 86
def check_cert(signer, issuer, time)
  raise Gem::Security::Exception, "missing signing certificate" unless
    signer

  message = "certificate #{signer.subject}"

  if (not_before = signer.not_before) && not_before > time
    raise Gem::Security::Exception,
          "#{message} not valid before #{not_before}"
  end

  if (not_after = signer.not_after) && not_after < time
    raise Gem::Security::Exception, "#{message} not valid after #{not_after}"
  end

  if issuer && !signer.verify(issuer.public_key)
    raise Gem::Security::Exception,
          "#{message} was not issued by #{issuer.subject}"
  end

  true
end