Encrypt and password-protect execution of any bash script, Version 2

read -p 'Script: ' S && C=$S.crypt H='eval "$((dd if=$0 bs=1 skip=//|gpg -d)2>/dev/null)"; exit;' && gpg -c<$S|cat >$C <(echo $H|sed s://:$(echo "$H"|wc -c):) - <(chmod +x $C)
(Please see sample output for usage) Use any script name (the read command gets it) and it will be encrypted with the extension .crypt, i.e.: myscript --> myscript.crypt You can execute myscript.crypt only if you know the password. If you die, your script dies with you. If you modify the startup line, be careful with the offset calculation of the crypted block (the XX string). Not difficult to make script editable (an offset-dd piped to a gpg -d piped to a vim - piped to a gpg -c directed to script.new ), but not enough space to do it on a one liner. Sorry for the chmod on parentheses, I dont like "-" at the end. Thanks flatcap for the subshell abbreviation to /dev/null
Sample Output
$ cat script.bash

#!/bin/bash
echo "hello, world"

$ read -p 'Script: ' S && C=$S.crypt H='eval "$(dd if=$0 bs=1 skip=// 2>/dev/null|gpg -d 2>/dev/null)"; exit;' && gpg -c<$S|cat >$C <(echo $H|sed s://:$(echo "$H"|wc -c):) - <(chmod +x $C)

Script: script.bash
Enter passphrase:
Repeat passphrase:

$ cat script.bash.crypt 

eval "$(dd if=$0 bs=1 skip=70 2>/dev/null|gpg -d 2>/dev/null)"; exit;
%3@5%7%f$2&s*ty7%8@j$j!8)(&@@@

$ ./script.bash.crypt 
Enter passphrase:

hello, world

1 Alternatives + Submit Alt

  • (Please see sample output for usage) script.bash is your script, which will be crypted to script.secure script.bash --> script.secure You can execute script.secure only if you know the password. If you die, your script dies with you. If you modify the startup line, be careful with the offset calculation of the crypted block (the XX string). Not difficult to make script editable (an offset-dd piped to a gpg -d piped to a vim - piped to a gpg -c directed to script.new ), but not enough space to do it on a one liner. Show Sample Output


    5
    echo "eval \"\$(dd if=\$0 bs=1 skip=XX 2>/dev/null|gpg -d 2>/dev/null)\"; exit" > script.secure; sed -i s:XX:$(stat -c%s script.secure): script.secure; gpg -c < script.bash >> script.secure; chmod +x script.secure
    rodolfoap · 2013-03-09 11:16:48 5

What Others Think

How fun! But you can make it shorter by using a subshell. Change: X 2>/dev/null; Y 2>/dev/null into (X;Y)2>/dev/null This saves 12 bytes! read -p 'Script: ' S && C=$S.crypt H='eval "$((dd if=$0 bs=1 skip=//|gpg -d)2>/dev/null)";exit;' && gpg -c<$S|cat >$C <(echo $H|sed s://:$(echo "$H"|wc -c):) - <(chmod +x $C)
flatcap · 288 weeks and 5 days ago
Hey that abbreviation is nice! Thanks flatcap!
rodolfoap · 288 weeks and 4 days ago
When you run [code] bash -x test.crypt [/code] you still able to see lot stuff...
dynaguy · 288 weeks and 4 days ago
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yewriusdf · 288 weeks and 4 days ago
Dynaguy: of course, if you have the password, you see everything. It's the idea. Without password, you can't see nothing. It's the idea.
rodolfoap · 288 weeks and 3 days ago
how can we protect the script from debug? If the set + x is included, it has no effect after the decoding. Good to have a script to give to a customer that the customer can run but never be able to read
frad · 249 weeks and 5 days ago
Should be "set +x", not "set + x". Tested it, works, I can't find no reason to continue showing the code. But if your client has the password, he has access to the code, this is not your solution (I used it to run code in a shared environment, where everybody has access to all files). You should try another approach.
rodolfoap · 249 weeks and 4 days ago
Should be "set +x", not "set + x". Tested it, works, I can't find no reason to continue showing the code. But if your client has the password, he has access to the code, this is not your solution (I used it to run code in a shared environment, where everybody has access to all files). You should try another approach.
rodolfoap · 249 weeks and 4 days ago
Did you run bash -x secure.script? I put set +x in the first line of an unlocked script (script.bash) and it works correctly, when I use bash -x. When I put the password and I run bash -x the "set +x" is ignored and all commands are printed. We can not cut or vim the "script.secure" which is nice. If we could stop the "bash -x" command it will be a perfect solution. I wish to safely distribute long scripts to customers. The other solution I know about is shc
frad · 249 weeks and 4 days ago

What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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