In the previous Christmas contests the young Partisans (17 yrs & younger) were asked to decode a One Time Pad (OTP) message and send it to John Jacob Schmidt.

This year, John Jacob Schmidt will give you a coded message on his show and you will need to send him a different coded message by email. The correct return message will be your contest entry.

There are several posts on how to receive OTP messages but we thought that it might be useful to review how to send messages with an OTP.

Below is the conversion table. The table is only used to convert your message into numbers. This is only the first step in making a secret message. We always use the same conversion table.

The word DOG on the conversion table would be 72574. (D=72 O=5 G=74)

Once we have our message “DOG” converted into numbers, the next step is to scramble up those numbers so that only you and the people you want will know what it means. We do that with the One Time Pad.

In this example, we will use the One Time Pad from a previous contest labeled “NATIVITY.” We tell the other person which One Time Pad to use by the key or the first group of five numbers on the pad. Nothing else happens with the first five numbers. It is just to make sure that the sender and receiver are using the correct pad. In the pad below, the key is 23242.

Note: We had to add ten to the 4 to make it 14 so that we could subtract 8 from it. If you have to do this, use only the last digit.

The message DOG has now been encoded using One Time Pad Nativity: 23242 01276

A good way to remember if you should subtract or add is to think about what you are doing. If you want to “take away” the meaning of your message then you subtract. If you want to “give” meaning to somebody else’s message then you add.

It is really important that you keep your work neat to avoid mistakes. You might want to use graph paper to keep your numbers lined up. Keep the numbers in groups of five.

There are some other rules for using the One Time Pad but the actual contest is designed to be challenging but not impossible for our younger Partisans.

Visit for further instructions after Thanksgiving.

Good luck young Partisans!


OTP practice exercises:

2019 Young Partisan OTP Contest Primer Posting- PRINTABLE VERSION