def get_signature(signature_data):
    """Decode the signature data and returns the signature.

    :param siganture_data: the base64-encoded signature data
    :returns: the decoded signature
    :raises: SignatureVerificationError if the signature data is malformatted
    """
    try:
        signature = base64.decode_as_bytes(signature_data)
    except (__HOLE__, binascii.Error):
        raise exception.SignatureVerificationError(
            reason=_('The signature data was not properly '
                     'encoded using base64'))

    return signature
dataset/ETHPy150Open BU-NU-CLOUD-SP16/Trusted-Platform-Module-nova/nova/signature_utils.py/get_signature