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Security

Secret messages are used in war, to convey forbidden love messages, et cetera.

 

The required complexity of the coding techniques is relative to the opponent. Where illiteracy is rampant, a normal text will already look like code. During the heyday of the Islamic world, we see that with the increase in literacy, the techniques for coding and codebreaking developed considerably.

This Roman lock has a key, but no keyhole, until you solve a secret puzzle...

 

With its four centimetres, this small padlock is an impressive testimony of ancient Roman craftsmanship. There are about 160 known examples of this type of lock and the mask lids are very diverse.

 

Will you succeed in opening all the Roman lock replicas?

Enjoy exploring this library full of secret writing techniques from the ancient world.

 

We investigate how to break ancient codes, and we follow the search for better coding techniques. You can try out secret codes yourself or attempt to break a coded message.

The modern categories of coding techniques in this scheme were also used in antiquity.

 

Xerxes' planned invasion of Greece was betrayed by a spy, who hid his message under the wax of a wax tablet. Julius Caesar and Augustus replaced the letters of the message with other letters by shifting the letters over a fixed distance in the alphabet.

Aeneas Tacticus describes the following technique for encrypting a message: each hole in these disks represents a letter of the alphabet. The disk on the top right shows which letters correspond to which hole. Only the sender and receiver have such a disk and therefore know which letter belongs to which hole.

 

On another disk there are no markings, only the holes are present (the disk on the bottom). A wire is passed through the holes in the order of the letters of the message to be encrypted. Once the entire message has been encrypted, the disk without markings can be sent to the receiver.

 

However ... the ancients made an important cryptographic error. Can you find it?

This is a tetradrachm, a Greek silver coin from the 5th century BC. It shows the head of the goddess Athena on one side and an owl on the other.

 

Do you know the function of the small ball markings around the circumference of this coin?