Message text
Code groups
The HollyBed is an app for practicing sending and receiving Morse code groups.
This is a greater communication challenge than sending ordinary text whose content is highly predictable and tolerant of errors.
The app provides five letter code groups with the characters A-Z from user-specified text messages with a larger alphabet. The idea is is to convert a text message to code groups and see if these groups can be sent and received correctly. The code groups can be decoded to see how much of the original text message survived the communication and to see if the checksum was correct.

HollyBed is not a cryptographic system. Every copy of HollyBed.jar can decode any code groups produced by any another copy HollyBed.jar, regardless of version. There is no private (or public) key; no security at all.

Nevertheless, sending code groups over the air is not recommended!

One way to practice receiving code groups with HollyBed is to send the code groups via a Morse code trainer, such as the free and excellent Just Learn Morse Code app by Sigurd Stenersen, LB3KB. Save the code group output from HollyBed to a file and read the file into the app where you can play the groups at any speed. To try again with a different set of code groups, decode the current groups, then encode them again. The message will remain the same, however, the code groups will change.

To practice sending code groups, send the groups to a Morse code decoding app, such as MRP40 by Norbert Pieper. Copy the received groups from the app and paste them into HollyBed. Then see if they can be decoded. If there's an error, locate the position of the error in the message text by putting the cursor in front of it. Then press the Tools:Locate error menu item to see the code group with the error. The About:Instructions menu item has more detailed instructions.

You'll probably find sending and receiving code groups accurately more difficult than you thought.

Installation

The HollyBed app is a free Java application contained in a Java archive file, HollyBed.jar. To run the app your computer must have the free Java JRE available from https://java.com/en/. The jar file, HollyBed.jar, is version: HollyBed 1.2 / Build date: 2018.09.01 - 18.38. It is signed and the size and SHA-1 hash of the file are:
Size: 148061 bytes

SHA1: 4d728d2e4a612d88fc4e70cfe8fd5d2a99bc7596.

Users are encouraged to verify the file.

On most systems, the HollyBed application can be started by clicking on the HollyBed.jar file or by opening that file from the command line, i.e.

> java -jar HollyBed.jar .
Once started, additional information is available under the About menu "Instructions" item.

On Linux systems the HollyBed.jar must be given execution privilege via

> chmod +x HollyBed.jar .

18 April 2018