Files encrypted with key don't decrypt properly between GUI and CLI

[kennbr34]

After fixing #7 I noticed that if encrypting with a key and CLI, the GUI will not properly decrypt the file, and vise versa

[kennbr34]

It seems to have something to do with the message buffer size and/or using 128 bit integers instead of 64 bit integers.

If I use a buffer size under 8 bytes, there is no problem decrypting between GUI and CLI. However, if I compile using 64 bit integers instead of the 128 bit integers, it doesn't seem to matter.