They unmix it with the cipher text, returning it to plain text.

Then you take the next 128 bits, encrypt it, and that's the next block of cipher text.

We encrypt that XORed result as our first block of cipher text.

Suppose Alice has sent to Bob the cipher text blocks .

So if you know the cipher text and you know the plaintext, you can get the key stream.

To see how this works, consider that the cipher text we send is just C(K) xor "$1000.00".

For example, you could encrypt your own data through the cipher and get out the cipher text.

And that's going to produce this cipher text.

In the following examples, two cipher texts contain the same message.

If any words in the cipher text are known or can be guessed, then the plain text and also the key, will be revealed.