def decode_aes256_cbc_base64(data, encryption_key):
    """Decrypts base64 encoded AES-256 CBC bytes."""
    if not data:
        return b''
    else:
        # LastPass AES-256/CBC/base64 encryted string starts with an "!".
        # Next 24 bytes are the base64 encoded IV for the cipher.
        # Then comes the "|".
        # And the rest is the base64 encoded encrypted payload.
        return decode_aes256(
            'cbc',
            decode_base64(data[1:25]),
            decode_base64(data[26:]),
            encryption_key)
Decrypts base64 encoded AES-256 CBC bytes.