Esempio n. 1
0
 def __init__(self, key, element=None):
     self.value = None
     self.encrypted_value = EncryptedValue(key.pskc.encryption)
     self.value_mac = ValueMAC(key.pskc.mac)
     self.parse(element)
Esempio n. 2
0
class DataType(object):
    """Provide access to possibly encrypted, MAC'ed information.

    This class is meant to be subclassed to provide typed access to stored
    values. Instances of this class provide the following attributes:

      value: unencrypted value if present
      encrypted_value: reference to an EncryptedValue instance
      value_mac: reference to a ValueMAC instance
    """

    def __init__(self, key, element=None):
        self.value = None
        self.encrypted_value = EncryptedValue(key.pskc.encryption)
        self.value_mac = ValueMAC(key.pskc.mac)
        self.parse(element)

    def parse(self, element):
        """Read information from the provided element.

        The element is expected to contain <PlainValue>, <EncryptedValue>
        and/or ValueMAC elements that contain information on the actual
        value."""
        from pskc.xml import find, findtext

        if element is None:
            return
        value = findtext(element, "pskc:PlainValue")
        if value is not None:
            self.value = self.from_text(value)
        self.encrypted_value.parse(find(element, "pskc:EncryptedValue"))
        self.value_mac.parse(find(element, "pskc:ValueMAC"))

    def make_xml(self, key, tag):
        from pskc.xml import find, mk_elem

        # skip empty values
        value = self.get_value()
        if value is None:
            return
        # find the data tag and create our tag under it
        data = find(key, "pskc:Data")
        if data is None:
            data = mk_elem(key, "pskc:Data", empty=True)
        element = mk_elem(data, tag, empty=True)
        mk_elem(element, "pskc:PlainValue", self.to_text(self.value))

    def get_value(self):
        """Provide the raw binary value."""
        if self.value is not None:
            return self.value
        if self.encrypted_value.cipher_value:
            # check MAC and decrypt
            self.check()
            return self.from_bin(self.encrypted_value.decrypt())

    def set_value(self, value):
        """Set the unencrypted value."""
        self.value = value
        self.encrypted_value.cipher_value = None

    def check(self):
        """Check whether the embedded MAC is correct."""
        # this checks the encrypted value
        return self.value_mac.check(self.encrypted_value.cipher_value)