Right, please don't take the above as critique of writing up a project like this - it's a fun thing to do. But even if your grandmother could use this, she wou

Right, please don't take the above as critique of writing up a project like this - it's a fun thing to do. But even if your grandmother could use this, she wouldn't be able to use in any meaningful way in order to increase security around secret messages. The only case in which such a project (or an equivalent one that generated a self-decrypting executable that asked for a password, or something like[1]) - is that if the file received isn't a trojan, the data in the file remains secure until decrypted for the first time. But as there's no way to know the file isn't a trojan, unless it's been transmitted via secure channel, it doesn't really add any security. [1] I could see this working for a shell-script and a here-document using gpg: #!/usr/bin/env bash # this is makemsg.sh cat > msg.sh <<eof #!/usr/bin/evn bash # this is msg.sh gpg --decrypt <<eof eof echo "You will now be prompted for a passphrase." echo "After entering the passphrase, typer your" echo "message. End with end-of-file (ctrl-d)" gpg --symmetric --armor >> msg.sh echo eof >> msg.sh echo "Encrypted message msg.sh created" echo " - run msg.sh to read message" Note that msg.sh is rather easy to audit: #!/usr/bin/evn bash # this is msg.sh gpg --decrypt <<eof -----BEGIN PGP MESSAGE----- Version: GnuPG v1 jA0EAwMCtkFEXeN2ydJgyT94WmGBkuSM9wFomkopr6BAfnucTv3kyU/w+Ni54PZi rOdvVl7WUdvt7wZ/Pq64ycM6uqWFp5kXRvw4zCRSKeU= =Jq6V -----END PGP MESSAGE----- eof (Note that I've avoided indenting lines of cipher text to avoid breaking the layout).