Say you have the secret message encrypted with AES-256 in CBC mode
where the first 16 Byte is the initial vector, the second 16 Byte is the ciphertext. The plaintext of the secret message above is (ASCII encoded)
We're blown. Run
Now my question, how can you change the secret message such that you get the plaintext
Meeting tonight! if you decrypt it?
I have tried to find some examples on the internet but I couldn't find any : /
However I could find a model that describes how CBC decryption works:
We're blown. Run is made up of 16 chracters which means we just have one plaintext block. From the model, we also see that the ciphertext is decrypted and XOR'd such that it creates the ciphertext. As it looks like, there are changes required in the initial vector so we get the desired message
Meeting tonight!. But how is this done exactly?