Data Encryption

So, I was contemplating some security ideas.

I thought this might be safe:

1. User 1 has his file and adjusts the binary on a side determined by his private key and reversible by his public key

2. This side is modified/locked

3. User 2 modifies/locks his side. It is important to know that 1 at each end of the halves must not be modified.

4. User 1 unlocks his side

5. User 2 unlocks his side

However, after contemplation I realized it is still not safe.

If user 2 used some form of redundancy to recover what he locked he must be protected from Mallory otherwise his lock can be found.

Also, Mallory only needs to accept the proper amount of data packets. If she knew both halves after User 1 initially sent it she could then notice what changes were made by User 2. This meant that Mallory could deduce what User 2 encrypted. Now, all she has to do is note what was decrypted by user 1 and now she has both halves.

I don't think data can be TRULY 100% always secured. What do you think?

Then, one could say that the users should be able to modify anything, even modify what was modified by the other user. So, let's say that happens. Well, in order for user 1 to decrypt their side they might would have to put it back in order. For example, let's say I sent YOU 10101. I encrypt it to 11101. Then you, not aware of what I corrected, encrypt it to 10001. I couldn't simply undo my actions because that means I change it to 11101 and send it to you. You would then undo your corrections and get 10001, which is obviously not 10101. This is lossy and lousy. Anyway, so then, I would use a redundant/error-checking system. Now, if Mallory could crack my computer they would have that. Thus, the message is not secure.

In sum, you can only have a secure setting if compression, and encryption are used to the fullest extent AND Mallory can not get into your computer.