The Sandi museum is one of Yogyakarta’s more hidden gems: a museum showcasing the history of cryptography and the development of Indonesia’s own National Encryption Agency from the late 1940’s onwards.

The Sandi museum (Sandi is code in Bahasa Indonesia), which is free to visit, appears to be a converted 2 story former house with cryptography exhibits displayed over both floors.

The ground floor features a history of encryption methods as well as the background behind the establishment of Indonesia’s National Encryption Agency.

On the upper floor there are collections of coding machines, ciphers (an algorithm - or step by step procedure for accomplishing a specific end - for performing encryption [encoding a message so that only authorised parties can access the message content] or decryption [transforming encrypted data back into a readable and understandable form] ) and historical artefacts relating to the key people and progress of the country’s own National Encryption Agency.

The ground floor starts with a history of encryption from ancient times featuring selected examples from the Sumerians, Persians, Greeks and Renaissance Italians.

For example, a skytale, shown below, performs a transposition cipher (a simple encryption method where plaintext characters are shifted in a repeatable pattern to produce cipher text) was widely used during Greek and Spartan military campaigns to keep messages secure during communication.

The Alberti Cipher disk, developed by Italian Renaissance author, poet, architect, linguist, artist, philosopher and cryptographer Leon Battista Alberti, is also displayed within this first room of the museum.

This uses two concentric disks; the outer disk (called Stabilis - stationary or fixed) contains an uppercase alphabet for plaintext and the inner ring (called Mobilis - movable) contains a lowercase alphabet for cipher text. How this works is explained here.

The next room showcases a diorama detailing the background behind the establishment of Indonesia’s National Encryption Agency during the late 1940’s.

The code book that was used by Indonesian forces fighting the Dutch occupation at the time seems almost ludicrous when viewed from the standpoint of the digital age and the existence of electronic encryption algorithms such as PGP and RSA.

It’s interesting to see how fast encryption technology has advanced in a little over half a century since the advent of digital computers.

On the upper floor of the museum are collections of different cipher machines used by the Indonesian Encryption Agency which seem extremely antiquated in comparison with recent technological developments (another reminder of just how quickly the world is changing within even our own lifetime - and that pace seems to be accelerating at ever greater speed with each passing year).

There’s also an exhibition and kiosks detailing cryptography related history in modern times, particularly with relation to military campaigns (such as the first Gulf War of 1990/1991) and, quite amusingly, an old-school noticeboard with post-it notes from visitors to the museum sharing their thoughts on their visit there.

Who needs digital technology when pen and paper will suffice? :)

Overall impression

I really liked the Sandi museum and was surprised to learn of some of the more historical methods of cryptography that were used (as a web developer I have some limited knowledge of encryption algorithms and their usage in my activities so visiting this museum was definitely of interest to me).

I was also surprised to learn that Indonesia had its own encryption agency (as did hundreds of other countries around the world - that I had also been unaware of, particularly much, much smaller countries that I would not have associated encryption and cyber security with - although I suppose that the threats that modern technology has brought with it means that every country has had to evolve to counter those).

Learning a little about the history behind this agency was very interesting as was seeing historical artefacts such as the different cipher machines that had been used during the latter half of the previous century.

The museum could add further signage in English though as not all of the exhibits were translated from Bahasa Indonesia (which I am still at a very basic and limited level of understanding with - as I imagine many foreign visitors to Yogyakarta will also be [or, in many cases, not have any knowledge of whatsoever]).

Additionally it would have been nice if the museum featured further exhibits dedicated to discussing digital encryption algorithms (such as PGP, RSA and AES) and cyber security threats as well as more interactive media stalls (I.e. looping video presentations).

This is not to knock the museum and what it offers though as I think, for free visitor entry, you really are getting value for money! If you are interested in cryptography then I don’t think you will be disappointed by visiting the museum should you happen to be in Yogyakarta.

Getting there

Located at Jl. Faridan M Noto No.21, Kotabaru, Yogyakarta the Sandi museum is easily reachable from the city centre by foot, car or bike. If you are visiting Yogyakarta I would personally recommend the use of GoCar to travel there as you can determine what the fares are at the time of booking (if you are using the Gojek app for iOS/Android).