def decrypt_ecb_cts(self, data):
    """
    Return an iterator that decrypts `data` using the Electronic Codebook with
    Ciphertext Stealing (ECB-CTS) mode of operation.
    
    ECB-CTS mode can only operate on `data` that is greater than 8 bytes in
    length.
    
    Each iteration, except the last, always returns a block-sized :obj:`bytes`
    object (i.e. 8 bytes). The last iteration may return a :obj:`bytes` object
    with a length less than the block-size, if `data` is not a multiple of the
    block-size in length.
    
    `data` should be a :obj:`bytes`-like object that is greater than 8 bytes in
    length.
    If it is not, a :exc:`ValueError` exception is raised.
    """
    data_len = len(data)
    if data_len <= 8:
      raise ValueError("data is not greater than 8 bytes in length")
      
    S1, S2, S3, S4 = self.S
    P = self.P
    
    u4_1_pack = self._u4_1_pack
    u1_4_unpack = self._u1_4_unpack
    u4_2_pack = self._u4_2_pack
    u4_2_unpack = self._u4_2_unpack
    decrypt = self._decrypt
    
    extra_bytes = data_len % 8
    last_block_stop_i = data_len - extra_bytes
        
    cipher_L, cipher_R = u4_2_unpack(data[0:8])
    plain_block = u4_2_pack(
      *decrypt(cipher_L, cipher_R, P, S1, S2, S3, S4, u4_1_pack, u1_4_unpack)
    )
    
    for cipher_L, cipher_R in self._u4_2_iter_unpack(data[8:last_block_stop_i]):
      yield plain_block
      plain_block = u4_2_pack(
        *decrypt(cipher_L, cipher_R, P, S1, S2, S3, S4, u4_1_pack, u1_4_unpack)
      )
    
    cipher_L, cipher_R = u4_2_unpack(
      data[last_block_stop_i:] + plain_block[extra_bytes:]
    )
    
    yield u4_2_pack(
      *decrypt(cipher_L, cipher_R, P, S1, S2, S3, S4, u4_1_pack, u1_4_unpack)
    )
    yield plain_block[:extra_bytes]