secure-slock - a paranoid fork of suckless' slock

Changes from slock

This fork of slock is based on the latest commit from 25 MAR 2017
- 35633d45672d14bd798c478c45d1a17064701aa9
- I will keep it updated with the latest patches, when possible.
Automatic shutdown - The screenlocked machine will automatically shutdown if:
1. The wrong password is entered more than UNLOCK_ATTEMPTS_MAX times (by default 3), or
2. ALT/CTRL/F1-F13 is pressed to switch VTs or to try to kill the X server. Also, if ALT+SYSRQ is attempted to be used.
- To use this, add the following to your /etc/sudoers file:
  - [username] [hostname] =NOPASSWD: /usr/bin/shutdown -h now
    - Replace [username] and [hostname] with the username and hostname of your machine.
Process killing countermeasures - prevents an attacker from using Alt+sysrq and Ctrl+Alt+Backspace by disabling it before shutdown.
- To use this, add the following to your /etc/sudoers file:
  - [username] [hostname] =NOPASSWD: /usr/bin/tee /proc/sys/kernel/sysrq
    - Replace [username] and [hostname] with the username and hostname of your machine.
Relicensed under the GPLv3
- Any new changes to the source are licensed under GPL, the original slock code is licensed under the MIT license. It is also included in MIT_LICENSE.

Edit config.mk to match your local machine, if needed. Slock will be installed into the /usr/local namespace by default.
Edit config.def.h with your desired changes.
- Then rename it to config.h.
Build slock (as root, if neccessary):
```
$ make clean install
```