Encryption/Decryption

[Ghostmela]

Hello good people, I have an encryption method that encrypts multiple files with different extensions, on each encrypted file, i appended a .locked extension. I can only decrypt each file then set the outputfile to file.txt, .zip... Example.. Decrypt(File, outputfile.zip, password). My question is, how do i decrypt the files so it’s return to is normal extension like .doc, .txt, .zip without me adding it myself