verifier.py 文件源码

def _prepare_auth_attributes_to_digest(auth_attributes_instance):
    """
    Prepares autheticated attributes field to digesting process.
    Replaces implicit tag with SET tag.
    """
    implicit_tag = chr(0xa0)    # implicit tag of the set of authAtt
    set_tag = chr(0x31)         # tag of the ASN type "set"

    # encode authentcatdAttributes instance into DER
    attrs = encoder.encode(auth_attributes_instance)
    # remove implicit tag
    if (attrs[0] == implicit_tag):
        attrs = attrs.lstrip(implicit_tag)
        attrs = str(set_tag) + attrs

    return attrs