Class DerBitString

object --+    
         |    
 DerObject --+
             |
            DerBitString

Class to model a DER BIT STRING.

An example of encoding is:

>>> from Crypto.Util.asn1 import DerBitString
>>> from binascii import hexlify, unhexlify
>>> bs_der = DerBitString(b'\xaa')
>>> bs_der.value += b'\xbb'
>>> print hexlify(bs_der.encode())

which will show 040300aabb, the DER encoding for the bit string b'\xAA\xBB'.

For decoding:

>>> s = unhexlify(b'040300aabb')
>>> try:
>>>   bs_der = DerBitString()
>>>   bs_der.decode(s)
>>>   print hexlify(bs_der.value)
>>> except (ValueError, EOFError):
>>>   print "Not a valid DER OCTET STRING"

the output will be aabb.