def _decodeLen(self, idx, der):
"""Given a (part of a) DER element, and an index to the first byte of
a DER length tag (L), return a tuple with the payload size,
and the index of the first byte of the such payload (V).
Raises a ValueError exception if the DER length is invalid.
Raises an IndexError exception if the DER element is too short.
"""
length = bord(der[idx])
if length <= 127:
return (length, idx + 1)
payloadLength = bytes_to_long(der[idx + 1 : idx + 1 + (length & 0x7F)])
if payloadLength <= 127:
raise ValueError("Not a DER length tag.")
return (payloadLength, idx + 1 + (length & 0x7F))
def _decodeLen(self, idx, der):
"""Given a (part of a) DER element, and an index to the first byte of
a DER length tag (L), return a tuple with the payload size,
and the index of the first byte of the such payload (V).
Raises a ValueError exception if the DER length is invalid.
Raises an IndexError exception if the DER element is too short.
"""
length = bord(der[idx])
if length <= 127:
return (length, idx + 1)
payloadLength = bytes_to_long(der[idx + 1:idx + 1 + (length & 0x7F)])
if payloadLength <= 127:
raise ValueError("Not a DER length tag.")
return (payloadLength, idx + 1 + (length & 0x7F))
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
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
