For example (very simplified), encryption / decryption usually works as follows:

```
encrypted_data = encrypt (data, key)
data = decrypt (encrypted_data, key)
```

I wonder if it is possible to change the input **dates** so that the function **encode** would be reversible without that **key** (here the modification is called as **+ x**):

```
encrypted_data = encrypt (data + x, key)
data = modified_decrypt (encrypted_data, x)
```

What I mean by modification is: perhaps it is possible to add a repeated pattern to the input data, or it may be a permutation, or it may find a particular x as a function of data.

If yes how? If not, why?

I know it would be specific to an encryption algorithm. So I need to know if this is possible with a popular encryption algorithm.

P.S. Possible applications include: data recovery for such viruses as Wannacry or identification of information loss in organizations, etc.