There are multiple ways to get a full disk encrypted arch linux system on raspberry. In this tutorial, we will install a 64-bit arch linux armv8 system, using dropbear as ssh server for remote pre-boot unlocking of the root filesystem. However, it will still be possible to unlock and use the pi as usual, with a keyboard and monitor. We will also create an unencrypted partition in the installation process, usable as a rescue system.
For different setup options, see the end of the document.