A new build is out for Red_Squirrel's RSPsar Dumper. Only one update in this release: version 3.1 fixes a critical bug from the previous version that can return a corrupted prx. Here's the changelog for RSPsar Dumper v3.1:

- Fixed a critical bug in the previous version of pspdecrypt.prx.
In previous version if you signcheck a encrypted file you obtained a corrupted prx.

Be sure to read the documentation included in the archive for more information on the program.