Huffman find and ruin

gistfile1.py

def CorruptHuffman(filename,chance,maxlen):
  with open(filename,"r+b") as f:
    filesize = os.path.getsize(filename)
    huffmanStart = 0
    huffmanEnd = 0
    found = 0

    for i in range(0,filesize):
      if found == 2:
        break
      f.seek(i)
      if f.read(1) == '\xFF':
        f.seek(i + 1)
        if f.read(1) == '\xC4':
          # Ok, we found a single huffman table, that's good!
          # Let's go hunt for the end of it.
          huffmanStart = i + 2
          found += 1
    
    found = False
    
    for i in range(huffmanStart + 2,filesize):
      if found == True:
        break
      f.seek(i)
      if f.read(1) == '\xFF':
        f.seek(i + 1)
        if f.read(1) != '\x00':
          huffmanEnd = i - 2
          found = True
    
    f.seek(random.randint(huffmanStart,huffmanEnd))
    f.write(hex(random.randint(1,250)))
    print 'Filesize: ' + str(filesize)
    print 'Huffman Start: ' + str(huffmanStart)
    print 'Huffman End: ' + str(huffmanEnd)

uh i'm not sure why i did f.read(1), wasn't thinking straight i guess

whatever this is just a dodgy implementation