Secret Message Machine

See inside
Notes and Credits

*Download to use*
Use Turbo mode
Click the buttons to make secret messages.

Person 1 types their message, the program encrypts it, person 1 copies it and gives it to person 2.

Person 2 puts the encrypted message into this application along with the password to decrypt the message and read it.

Repeat back and forth for secret conversations.
Press the green flag twice when you are done to clear out any secret data before you exit the project.

It only changes lowercase letters.
pass: test
message: This is the first test!

...encrypts to: Tyhy nt nyw 1wy nmtn!

Both people and no one else must know the password! Use any password at least 4 letters long, letters only. Case (lowercase or uppercase) doesn't matter in passwords. Use various letters...
"locomule" works great!
"aaaaaaa" doesn't work so well
"abc" works better than "aaaaaaa"

all code and images by Locomule except the pc image (came with Scratch but I modified it and added the speakers :)


"encrypt" means to alter a message so that it cannot be read by unwanted people

"decrypt" means to change an encrypted message back into its readable state

To copy and paste without writing...

Download this app and open it in Scratch but NOT in presentation mode (open it so you can see the scripts, blocks, etc)

Paste your message to be encrypted into Scratch. Copy the encrypted message by selecting it with your mouse (drag, don't click) and pressing ctrl-c

To copy long output messages...

Right click to select the first output list entry, "output follows..." then roll your mousewheel down one time OR press the down arrow once. You should then have the entire long message selected.

Press ctrl-c to copy it.

To paste messages outside of Scratch...

Right after you have copied the message from Scratch, right-click wherever you want to paste it.

Press ctrl-v to paste it.


by right-clicking the grey area just to the left of the orange output list you can save to and paste from a text file.

This application relies partially on simple letter substitution. However, encrypted messages using this method alone become easy to break as they get longer. To overcome this, the password is transformed into a numerical key that is used to offset each letter substitution by a fluctuating amount.

It is possible to use no password by just hitting enter and it will generate messages that appear to be just as encrypted as properly passworded efforts. However, this is not true. Closer inspection will reveal that letters are substituted without any offest. Given enough data, even someone with minor cryptological experience should be able to figure out the messages.

I bet you use and rely on some form of cryptology every day, whether you know it or not. It has a facinating history!


Shared: 8 Apr 2011 Modified: 8 Apr 2011
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