Revert to our code, rather than Schneier's
Revert "Accidentally introduced a few syntax errors in the last commit. They're fixed now."

This reverts commit 5c41aa3fb05ffe8ac4039afe31c446dacc0437a5.
Revert "More use of Schneier's original code to ensure correctness of encrypt and decrypt"

This reverts commit a67982ac4f44d810f95f040f14892809a254c67c.
Revert "Fixing indentations"

This reverts commit 14a741c24ab7a010f1875e6b4cf3823046b67dc1.
Revert "Renamed"

This reverts commit 1d4b1598539b9ab5d3a88cc05165ce45f3f38ef7.
Finished reverting to our code, rather than Schneier's.

Revert "Use Schneier's F function, just so we know we're right"

This reverts commit f98d94fdb50e70680939af5677e060f55ffd224f.