asn1.py 文件源码

def decode(self, derEle, noLeftOvers=0):
                """Decode a complete INTEGER DER element, and re-initializes this
                object with it.

                @param derEle       A complete INTEGER DER element. It must start with a DER
                                    INTEGER tag.
                @param noLeftOvers  Indicate whether it is acceptable to complete the
                                    parsing of the DER element and find that not all
                                    bytes in derEle have been used.
                @return             Index of the first unused byte in the given DER element.

                Raises a ValueError exception if the DER element is not a
                valid non-negative INTEGER.
                Raises an IndexError exception if the DER element is too short.
                """
                tlvLength = DerObject.decode(self, derEle, noLeftOvers)
                if self.typeTag!=self.typeTags['INTEGER']:
                        raise ValueError ("Not a DER INTEGER.")
                if bord(self.payload[0])>127:
                        raise ValueError ("Negative INTEGER.")
                self.value = bytes_to_long(self.payload)
                return tlvLength