An encrypted file cannot, given P!=NP (and a host of other assumptions, but P!=NP is the foundation), be decrypted. So require proof that the file is not decry

An encrypted file cannot, given P!=NP (and a host of other assumptions, but P!=NP is the foundation), be decrypted. So require proof that the file is not decryptable by other means before you can compel entering a password ;)