'Verify a signature for a file.
:param signature_filename: The pathname to the file containing the
signature.
:param data_filename: The pathname to the file containing the
signed data.
:return: True if the signature was verified, else False.'

def verify_signature(self, signature_filename, data_filename):

    if (not self.gpg):
        raise DistlibException('verification    unavailable    because    gpg    unavailable')
    cmd = self.get_verify_command(signature_filename, data_filename)
    (rc, stdout, stderr) = self.run_command(cmd)
    if (rc not in (0, 1)):
        raise DistlibException(('verify    command    failed    with    error    code    %s' % rc))
    return (rc == 0)
