Lets suppose that there is someone motivated enough to distroy you. This people has months to mess with your system and substitute your usual decrypt command with a slightly modified version that 1) decrypts a file as usual when entered the right password and 2) runs a last extra line of code that inserts a child porn image or short video in the file. The timestamp of the decrypted file was changed to now. So you will not suspect that the file has been significatively modified also in the same operation. If the decrypt executable is closed and not easily available to examine... what could you do to prove your innocence?

Is possible for the jury (or the lawyer) to re-encrypt the file again exactly as in the first time to detect if the file was changed?