ed2kHash class for python

ed2kHash.py

# by fcicq (fcicq at fcicq dot net) @ 2012.5.12, Released under GPLv2
import hashlib
from cStringIO import StringIO

class ed2kHash():
  CHUNK_SIZE = 9728000
  BLOCK_SIZE = 65536
  chunkmd4_list = ''
  chunkmd4 = None
  chunkpos = 0

  def __init__(self, string=''):
    self.chunkmd4 = hashlib.new('md4') # I know it will raise ImportError... :D
    self.update(string)

  def _md4(self, string=''):
    return hashlib.new('md4', string)

  def _tohex(self, string=''):
    return ''.join(["%02x"%ord(x) for x in string])

  def update(self, string=''):
    l = len(string)
    s = StringIO(string)
    pos = 0
    if not l: return
    while pos < l:
      blocksize = min(self.CHUNK_SIZE - self.chunkpos, l - pos, self.BLOCK_SIZE)
      self.chunkmd4.update(s.read(blocksize))
      pos += blocksize
      self.chunkpos += blocksize
      if self.CHUNK_SIZE == self.chunkpos: # filled just now
        self.chunkmd4_list += self.chunkmd4.digest()
        self.chunkmd4 = self._md4()
        self.chunkpos = 0
    s.close()

  def digest(self):
    if self.chunkmd4_list: # If the first block is not completed, just return the md4 result.
      return self._md4(self.chunkmd4_list + self.chunkmd4.digest()).digest()
    else:
      return self.chunkmd4.digest()
  
  def hexdigest(self):
    return self._tohex(self.digest())
    
  def copy(self):
    raise NotImplementedError