Mediocre (at best)
The National Cipher Challenge 2016

This site is where all of my cipher crackers and solutions will be hosted.

Let's Go Solutions Let's Go Crackers

Challenge 1

Part A - "A personal tragedy?"


I have scanned the encrypted note the police found on Jamelia’s desk and attached it for you to look at. The police decrypted it for themselves (it is very straightforward once you realise that it has been written backwards - it just uses a Caesar shift cipher). The officer in charge of the investigation made it clear to me that he thinks this proves Jamelia’s death is "just" a personal tragedy. Careless use of the word "just" even if he is right, but I don't think he is. I have spoken to her colleagues, and Jamelia doesn't strike me as a jumper. She was pretty driven and her work was going extremely well. Apparently, she was unhappy about her boyfriend leaving, but a quick scan of her search history suggests she was pretty active in trying to track him down. The police think that shows how desperate she was. I think it shows that she wasn't the sort to give up easily.

On one thing, I do agree with the police, it doesn't seem very likely that a physicist working on gravity waves is caught up in anything too suspicious. Her area is well funded and since the discovery of gravity waves a few months ago, it is in the spotlight. Her head of department says Jamelia was destined for a good career, and I can't see anything in her work that would be of interest to darknet or government actors.

To be honest I am unsure if I am chasing shadows here, but then shadow chasing is one of your specialities so I would be really grateful if you could take a look and let me know if you think I am wasting your time.



Part B - "Jamelia's last testament"

I can't believe he left like that. After everything we said, after everything we agreed. But he has gone, and I can't find him, and this is too big to deal with alone. I can't blame him more than me, we were both blind to what was happening and we are both guilty, but together we might have started to fix it. I can't see how I can do that alone, here, now. So I don't have an option. It has to end. I have to end it.

Challenge 2

Part A - "A spinout called Dynamix"


The note you sent over was trickier than I expected. Jamelia didn’t just reverse the whole message before encrypting it, she put all the punctuation and spacing back in the original places to throw the casual reader off the scent. It wasn’t very sophisticated, but it was devious, and tells us something about the way she thinks. One thing I am certain about, this doesn’t read like a suicide note. Who writes one of those in code?

Our field agent asked around at the university and was told that Jamelia’s boyfriend worked in the same lab as her for a while. His name is martin Traynor and they both did an internship in their second year at a spinout company called Dynamix. That is a small start-up which works on the fringes of the arms industry, but no-one seems to know much about it.

I am not sure why Dynamix would have hired Jamelia; you said that she was working on gravity waves, which are a seismological phenomenon. I read an interesting paper called “gravity waves in earthquakes” which suggested that they might be responsible for the destruction of high rise blocks during some tremors. But unless Dynamix are planning to try to weaponize earthquakes I am not sure why this would be of interest to them. We need to know more about her work and what they hired her to do.

There are a lot of questions even in the first note:

Why did martin leave?
Where is he?
Why couldn’t she get hold of him?
What was too big for Jamelia to handle alone?
What made Jamelia feel guilty?
How was she planning to fix it?

I am hoping that the attached document will answer some of these questions but it will probably just raise others. I found it pasted under the cover of the notebook that the previous message was taken from. I can see why the police missed it, though it wasn’t a very professional job.


Part B - "More questions than answers?"

Questions for martin,

Why are Citadelle interested in Dynamix?
How did Dynamix get my code-base?
What are Dynamix planning to do with it?
Why is he still involved with them?
Who are the PDS syndicate?

I think I know the answers, and I am pretty sure he must do too. The three months we spent working at Dynamix were some of the most exciting I have ever experienced, but surely, knowing what we know now, even martin must have some reservations about working with these people.

I am not sure who to talk to about this. I am certain that some members of the board at Dynamix are completely in the dark about it, no conspiracy with that many members could have survived more than a week, but I have no idea which of them I can trust. I thought I could trust martin, but that was before the PDS hack.

I can’t talk to the police; special branch are certain to flag it given the names of some of the people on the board. With their connections who knows what might happen. The PDS syndicate are too big for me to handle alone. They know almost everything about me, and I know next to nothing about them. If I stay here to fight, then it is only a matter of time until they realise I am on to them. If I haven’t disappeared before then, then I have a feeling they will make me disappear.

Challenge 3

Part A - "Burn Notice"


If Jamelia was working on a scheme to weaponize earthquakes, then we need to know how far she had got. I have sent trinity in to work undercover in Jamelia’s lab and tasked her to try to infiltrate Dynamix from there. Trinity isn’t too happy there, Jamelia’s office isn’t much bigger than a broom closet, but we need to try to find the code base referred to in the hidden diary entry.

In the meantime, I have been working on the list of questions you and Jamelia were asking. First: why did martin leave? According to his flatmate he flew to Geneva for talks with a company called Citadelle. Our local agents are making enquiries, but it seems that they are that rarest of things, an established arms manufacturer with money worries. Second: where is martin now? No-one knows. Citadelle deny any knowledge of him, and there is no record of him leaving the country. He has disappeared.

The most intriguing thing from Jamelia’s last message is the reference to the PDS syndicate. I have heard rumours of this myself in Whitehall. It is all very hush-hush and it is not even clear if it is an official initiative.

The big news for now is a breakthrough on the so-called suicide note. Given how small Jamelia’s office was, trinity wondered why she had kept a broken printer in there next to the working one. Trinity opened it up and found a few modifications which pointed the laser straight at the paper instead of the drum. She got in touch with the lab and got them to take another look at the letter. They found the attached message burned into the paper fibres. It is impossible to see with the naked eye, but the charring shows up under high powered fluoroscopy. Over to you for the decryption.

Part B - "Invisible"

Notes on Dynamix/Citadelle/the PDS syndicate:

Dynamix are a small company that relies on postgraduate interns for most of its good ideas.

The project we worked on for Dynamix was signal recognition in a noisy environment.

Citadelle is a major arms manufacturer that got left behind in the digital age and seems to be looking to buy its way back into the market by taking over smaller, more nimble competitors.

After we left Dynamix we were both approached by someone claiming to work for Citadelle, saying they were impressed by the work we did there and that they would be interested in developing the code we wrote. I told them where to go. I thought martin was going to do the same, but then he told me he wanted to talk with them. He said that our code might be of interest to powerful people and I thought he was trying to get me to join him and work with them. Now I think he was trying to warn me.

After martin disappeared I was approached by someone claiming to work for a government agency known as the PDS syndicate. They wouldn’t tell me what they did, or why they were interested, but they wanted to know where martin had gone.

I have almost finished testing the latest version of the net. It is better than any of the previous versions by several orders of magnitude and I haven’t tuned it yet. I think it has real potential, and I think that Dynamix, Citadelle and the PDS syndicate think that too.

I am afraid. I think I need to hide. I don’t know where to run.

Challenge 4

Part A - "Trinity"

Harry and Charlie,

I am no closer to the PDS syndicate but I think I have begun to unravel why they might be interested in Jamelia and martin.

As she told us in the hidden message I sent last week, Jamelia had been working on signal recognition at Dynamix. At first I was puzzled by this as I couldn’t see how it related to weaponised gravity waves, but then I took a look at her bookshelf and it began to make sense. It was full of books on general relativity, black holes, and neutron stars. Jamelia was not working on gravity waves, but on gravitational waves. I can see how the field agents would have got confused. In the us they sometimes use both names for the same thing – but they really are different. Gravity waves are a seismological phenomenon as you already figured out. Gravitational waves are entirely different. Einstein predicted them a hundred years ago, and they were detected by the LIGO team last year. The signals are given off by things like binary black hole systems and are incredibly faint. They easily get swamped by local noise. It was an amazing feat detecting them and Jamelia was part of that. To add to our confusion, she was in the team responsible for designing the search algorithms and the noise filters used to spot the signal of a galactic event against the noise of seismological activity, so she did know something about gravity waves too.

I still don’t know exactly how Dynamix were using her expertise, or what the PDS syndicate are or do, if you can get any intel on that it might help guide my enquiries. The noises I am hearing suggest that PDS are serious. Lots of cash, lots of influence, so I suggest we increase the security for future messages. When you reply try using a double encryption, reversing things before applying a keyword cipher to the message.

I will be out of contact for the rest of the week. I am taking a crash course in neutron star dynamics in the hope that I can fit in better with the locals. I have a test at Dynamix on Thursday for an internship in their programming section. If I can get access to their network, then maybe we can start to unravel this.

In the meantime, I found the attached memo slip folded up under one leg of Jamelia’s desk. At first I thought it was just a fix for a wobbly desk but it turned out to be a fantastic place to hide a secret! It reminded me of the purloined letter, which, given the keyword is probably no coincidence. It looks like Jamelia and martin shared a love of old detective stories.


Part B - "The Temp Bank"

The temp bank is pretty full and I think we have a real chance of building a system that could actually prevent some of the attacks. The key is to harvest the right intelligence at the right time and flag it for action before it is too late. I think we can really help. The agencies could be swamped with false alerts so our filtering algorithm has to be really smart but then that is what we are good at, right?

The test data PDS provided is amazingly detailed and makes it much easier to see the patterns. I don’t know how they could have got so much information about people. Are they storing everything people do online?

I never thought when I set out on a PhD in mathematical physics that it could lead to something with such immediate impact. I still love cosmology, but there is a real buzz applying what we learned out here at Dynamix, and I can’t believe how lucky I am to have this opportunity. Meeting with someone from Citadelle this afternoon. I will tell you more later!

Looking forward to seeing you again soon,


Challenge 5

Part A - "The PDS Syndicate"


It is hard to make sense of the latest message from martin. What is the temp bank? Is it a network of part time spies? Jamelia implied that it was her coding skills that Dynamix were interested in so I began to wonder if Jamelia was working on a recruitment tool using social media, but that sounds a bit old school. Could she and martin have been developing a screening algorithm for agents, trying to pick out the most reliable ones by data mining? How would that have fitted with her real expertise in signal noise analysis? Surely the data isn't that noisy?

I did have some luck with background on the PDS syndicate. They were initially set up to deal with a future in which quantum transmission makes it impossible to crack ciphers using digital methods. PDS stands for post digital surveillance and they were an arm’s length cabinet office initiative kept completely separate from the other intelligence agencies. I think the plan was total deniability on all sides and it was structured to prevent inter-agency rivalry. The syndicate had prime-ministerial sign off, but after that there is no paper trail and there has been no news of any progress. Insiders think the syndicate was closed down in January after rumours of unauthorised surveillance, but given that bulk collection in the UK is authorised, it is hard to imagine what they were up to.

I know that several of the people who launched PDS left the civil service in February and two now have board positions at Citadelle. To the best of my knowledge none of the seniors had direct contact with Jamelia or martin, but I suppose it is possible that Citadelle was just the vehicle for PDS to keep an eye on the two of them. I still don’t know why they were regarded as special though. Maybe trinity has something for us.

She sent the following message hidden in an image file in Instagram – a sort of “wish you were here” thing so I am guessing that she feels the need to be fairly discrete. She has also increased the security level of her comms, but unfortunately due to a mix up with housekeeping we weren’t able to set up a secure channel for key exchange before trinity left to join the Dynamix team. Fortunately, she is good at improvising and she has taken a lead from martin and used a column transposition cipher. That also explains the steganography: trinity knows that the opposition will find it reasonably straightforward to crack if they spot it. A word of warning; trinity’s cipher is tougher to crack than martin’s, and I had to hunt a little bit for the crib, but maybe you will find it more easily knowing all this. At least she didn’t resort to martin’s reversing trick, so maybe we should consider ourselves lucky. I don’t want to push our luck too far, and I don’t want to expose trinity to more risk than necessary. When you reply, I suggest we follow trinity’s advice and use a vigenere cipher. A keyword of length three should be adequate.



Part B - "A postcard from Dynamix"

Harry and Charlie,

Not much time, and I need to spend the time I have carefully. I have access to the Dynamix network and used it to hack into Citadelle. They have a large database that a number of people here are working on. Mostly maintenance and data entry, but Jamelia’s team seem to have been working on mining the data. Nothing too surprising really and at first I couldn’t see what the fuss was about, but again I got lucky. Jamelia’s account on the machine they gave me had been wiped but they missed a config file that showed me that she had used an online storage service for some of her files, and one of them was huge. The client software kept metadata about the file and it looks like a clone of the database I have seen here, but the file size is way off and the storage scheme seems to have been formatted with pointers to hidden parts of the file that dwarf the database I have seen in the Citadelle servers. I don’t know about the database itself but I also found what looks like an encrypted DB scheme file. If you can send me Jamelia’s old laptop or phone I think there is a chance we could recover some of the documents that she had deleted by syncing it to the server. If her keychain has been copied over that might also give me access to the Citadelle database, which I have codenamed titan.

I think we might be getting close to the truth, but I am also sure that I am not trusted here and that will make it hard to get much more intelligence without raising alarm. Others seem to have fairly free access to the building but my pass only gets me to one floor and three rooms. Everyone is friendly, but no-one is talking and I don’t want to push too hard and make them more suspicious. I would suggest we switch back to substitution ciphers in the future. This is getting serious. Maybe a vigenere or hill cipher next time?


Challenge 6

Part A - "A Ghost?"


I have found martin. He was camped out at a hacker collective in Oslo which he must have thought was safe, but turned out to be a major error. To avoid suspicion from the other hackers he had to spend a lot of time online and the NSA were watching. One of the laptops he was using had been compromised and an automated scan flagged the stream for analysis. We have agents on the way to interview him and I am hoping this will give us enough to unravel this mystery.

In the meantime, I called in a few favours with the E-tjenesten who followed martin to a local bank. He is carrying out all-cash transactions in an effort to stay off grid, which is a little ironic given the way we found him. He is travelling under the name James, and I wondered if that was a hint that he still has feelings for Jamelia, he is using a fake passport which was good enough to fool the bank, and I am looking forward to examining it as I am not sure how he would have obtained one of this quality outside the trade.

We have tied his Norwegian transactions to an account in Switzerland, which I guess is no surprise. We had the usual difficulties getting access from the swiss authorities, but things are a lot easier there than they used to be and with cooperation from the FIS I gained access to a strong box held in martin’s new name.

The enclosed letter from that box promises to shed light on his role in all this, but unfortunately it is, again, encrypted, and this time the cipher is a bit stronger than the ones we have been dealing with. I could wait for the interview with martin, but I have a feeling that the interview will go better if I know more in advance, so I will spend a little time analysing it in the hope of getting a break.

One thing that puzzles me. The manager at the swiss bank mentioned that the last time he saw martin in person he was travelling with a young woman, and the description sounded a lot like Jamelia. I didn’t pick up on this at first because I assumed that this was prior to her death, but when I checked the dates it didn’t tie up. They seem to have been at the bank together three days after Jamelia’s death.

More later, Harry

Part B - "A Proposal"

Jamelia, what do you think about this? Do you think Dynamix would fund it?

Proposal: long base line signal noise analysis in large scale heterogeneous networks
M. Traynor and j. Dalmar


In our work on signal noise analysis for LIGO we have developed new tools for digital analysis of extremely low amplitude signals in an excessively noisy environment. The classical features of this analysis are the exploitation of very long baseline signal collection, and the synthesis of signals from a large sensor network to filter the noise. The principle novel feature is the development of a large database of templates of target signals that allow them to be filtered from the noise and interpreted in real time. We believe this approach can be adapted to a wide variety of signal harvesting problems both within and outside the physical sciences. As an example of a commercial application of the technology we have carried out analysis of a toy model which suggests that this approach may be sensitive enough to track individual footfall across a shopping centre or airport concourse and to carry out gait analysis using seismometers embedded in the building fabric. This would provide a new and less obtrusive alternative to the camera systems currently in use.

It has not escaped our attention that the template bank approach should scale to allow tracking of multiple targets and to search for patterns that may signal antisocial, or potentially even terrorist behaviour patterns. More speculatively, the long base line techniques, which are key to triangulating the source of gravitational waves, could be modified to provide a template based network analysis tool for finding long range correlations in network traffic. This analysis could signal activity spikes among trans-national criminal or terrorist groups triggering surveillance and targeting early intervention to prevent crime.

Challenge 7

Part A - "The interview"

Pending Formatting

notes from interview with martin traynor in attendance minsa and reps from nis the suspect was carrying high quality identity documents in the name of james martin and claimed to be a drop out from a graduate programme in computer science in neuchatel his story checked out with the university authorities analysis showed a high degree of correlation between the biometrics of the suspect and of martin traynor but we did not reveal that we suspected james to be martin he refused requests to provide a dna sample for analysis stating that dna databases were a tool of oppression a search of the suspects belongings found no links with the uk at all despite the fact that voice characteristics suggest he spent a considerable amount of time there as a child the suspect stated that he had left all that behind and was not prepared to talk about it taking care not to reveal what was already known about traynors relationship with the swiss bank we turned to the suspects financial arrangements at first he claimed to work entirely on a cash basis and not to have a bank account but when pressed on this he could not or would not explain where he kept his cash reserve even when we pointed out that he appeared to be too well off for someone living hand to mouth pushing harder we revealed that we had footage of him in the lobby of a bank and he claimed that he had visited on behalf of the collective as part of a phishing expedition on a freelance penetration test of the banks security when challenged about the legality of this he claimed it was a white hat exercise and that no weaknesses had been found so no further action had been taken by the collective under further questioning however it became apparent that the suspect was talking about an entirely different bank from the swiss bank we had been monitoring he seemed to believe that we had footage of him in an oslo branch agents were sent to retrieve lobby footage of this bank and further analysis showed that his visits there tallied with the activities he described at interview however we also noticed that a woman matching dalmars description was often videoed at the same branch during the period under investigation when asked about this the suspect became highly agitated and repeatedly demanded to call his lawyer we pointed out that it was unusual for a member of a hacking collective to have a lawyer onretainer but the suspect refused to answer any more questions until he had been allowed to make the call a call trace showed the mobile that he rang belonged to a law firm which works for the arms manufacturer citadelle the suspect was released on bail pending charges of conspiracy to engage in unauthorised access to computer technology at the bank and is being closely watched all calls to and from the law firm are being monitored and the oslo bank is under twenty four seven surveillance conclusions we believe with near certainty that the suspect is martin traynor and that the woman in the footage is jamelia dalmar we believe they are in communication with one another and are both being protected by citadelle or one of its subsidiaries we believe that they are both living in or near oslo and that they are both now highly likely to be aware that the net is closing in we do not understand how dalmar contrived to fake her death and we still do not have a clear picture of the interaction between the pds syndicate dynamix and citadelle nor do we fully understand why they have a strong interest in traynor and dalmar we believe that some or all of that information maybe contained in the encrypted files on traynors laptop which has been passed to forensics for analysis and to secure the data

Part B - "A Proposal"

Pending Formatting

martin we have made a dreadful mistake and i have been too slow to admit that to myself i have had a visit from the woman from the syndicate and i confronted her about the source of the templates she confirmed my worst fears and now i want to crawl away and die what have we done our software has led to so much suffering when it was designed to do the opposite i asked her how the cabinet office could possibly have authorised this and she laughed and explained that the syndicate no longer worked for the british government call it private enterprise she said we have always been good at that my horror must have been written all over my face she didn’t seem surprised at my reaction but equally she didn’t take it well and civility was abandoned i asked her how it could be legal let alone moral to do what they proposed and her answer was that it was necessary i said we wouldn’t help them and she said it was necessary that we did i said i wouldn’t be able to face my family and friends if we cooperated and she said i wouldn’t have to worry about that for long one way or another the pds syndicate were going to make sure we both disappeared looking back i can see that from the start this whole thing has acted to draw us into its centre and now i am at the event horizon almost unable to escape its pull but i think we have one last chance i am sure she will be visiting you as well she thinks we have no choice but i think a choice is all we have whatever you do hold out for better terms she has to believe that you are on side and motivated by greed so that she wont worry about any qualms you might have convince her that you will convince me to cooperate tell her that you think you should work from the collective in oslo and that you want payment via the bank in switzerland i got the impression that money is not a problem with money in a swiss bank and the expertise and connectivity afforded by the collective i think we have a chance to escape and to try to stop them perhaps we will survive this perhaps we can bring them down.

Challenge 8

Pending Release

Caesar Cracker




Vigenère Cracker