Quantum Computing and Cryptography

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Quantum computing is a new way of computing — one that could allow humankind to perform computations that are simply impossible using today’s computing technologies. It allows for very fast searching, something that would break some of the encryption algorithms we use today. And it allows us to easily factor large numbers, something that would…

A moderately-simple explanation of why symmetric cryptography is probably (or can probably be made, where it’s not) safe from our future quantum computer overlords, but asymmetric (split-key) cryptography probably isn’t. On the journey of developing the theory of computation, are we passing through within our lifetimes the short-but-inevitable bubble during which split-key cryptography is computationally viable? If so, what will our post-split-key cryptographic future look like? Interesting to think about.

Five-Eyes Intelligence Services Choose Surveillance Over Security

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The Five Eyes — the intelligence consortium of the rich English-speaking countries (the US, Canada, the UK, Australia, and New Zealand) — have issued a “Statement of Principles on Access to Evidence and Encryption” where they claim their needs for surveillance outweigh everyone’s needs for security and privacy. …the increasing use and sophistication of certain…

How many times must security professionals point out that there’s no such thing as a secure backdoor before governments actually listen? If you make a weakness in cryptography to make it easier for the “good guys” – your spies and law enforcement – then either (a) a foreign or enemy power will find the backdoor too, making everybody less-secure than before, or (b) people will use different cryptographic systems: ones which seem less-likely to have been backdoored.

Solving the information black hole is a challenging and important problem of our time. But backdoors surely aren’t the best solution, right?

Intercepting HTTPS Traffic from Android Emulator

Mostly for my own benefit, as most other guides online are outdated, here’s my set-up for intercepting TLS-encrypted communications from an emulated Android device (in Android Emulator) using Fiddler. This is useful if you want to debug, audit, reverse-engineer, or evaluate the security of an Android app. I’m using Fiddler 5.0 and Android Studio 2.3.3 (but it should work with newer versions too) to intercept connections from an Android 8 (Oreo) device using Windows. You can easily adapt this set-up to work with physical devices too, and it’s not hard to adapt these instructions for other configurations too.

Intercepting a HTTPS connection to DanQ.me on a virtual Android device.

1. Configure Fiddler

Install Fiddler and run it.

Configuring Fiddler

Under Tools > Options > HTTPS, enable “Decrypt HTTPS traffic” and allow a root CA certificate to be created.

Click Actions > Export Root Certificate to Desktop to get a copy of the root CA public key.

Fiddler's Connections settings

On the Connections tab, ensure that “Allow remote computers to connect” is ticked. You’ll need to restart Fiddler after changing this and may be prompted to grant it additional permissions.

If Fiddler changed your system proxy, you can safely change this back (and it’ll simplify your output if you do because you won’t be logging your system’s connections, just the Android device’s ones). Fiddler will complain with a banner that reads “The system proxy was changed. Click to reenable capturing.” but you can ignore it.

2. Configure your Android device

Android Device Manager - New Device

Install Android Studio. Click Tools > Android > AVD Manager to get a list of virtual devices. If you haven’t created one already, create one: it’s now possible to create Android devices with Play Store support (look for the icon, as shown above), which means you can easily intercept traffic from third-party applications without doing APK-downloading hacks: this is great if you plan on working out how a closed-source application works (or what it sends when it “phones home”).

Android emulator showing network settingsIn Android’s Settings > Network & Internet, disable WiFi. Then, under Mobile Network > Access Point Names > {Default access point, probably T-Mobile} set Proxy to the local IP address of your computer and Port to 8888. Now all traffic will go over the virtual cellular data connection which uses the proxy server you’ve configured in Fiddler.

Android network proxy settings

Drag the root CA file you exported to your desktop to your virtual Android device. This will automatically copy the file into the virtual device’s “Downloads” folder (if you’re using a physical device, copy via cable or network). In Settings > Security & Location > Encryption & Credentials > Install from SD Card, use the hamburger menu to get to the Downloads folder and select the file: you may need to set up a PIN lock on the device to do this. Check under Trusted credentials > User to check that it’s there, if you like.

Installing a Root CA in Android.

Test your configuration by visiting a HTTPS website: as you browse on the Android device, you’ll see the (decrypted) traffic appear in Fiddler. This also works with apps other than the web browser, of course, so if you’re reverse-engineering a API-backed application encryption then encryption doesn’t have to impede you.

3. Not working? (certificate pinning)

A small but increasing number of Android apps implement some variation of built-in key pinning, like HPKP but usually implemented in the application’s code (which is fine, because most people auto-update their apps). What this does is ensures that the certificate presented by the server is signed by a certification authority from a trusted list (a trusted list that doesn’t include Fiddler’s CA!). But remember: the app is running on your device, so you’re ultimately in control – FRIDA’s bypass script “fixed” all of the apps I tried, but if it doesn’t then I’ve heard good things about Inspeckage‘s “SSL uncheck” action.

Summary of steps

If you’re using a distinctly different configuration (different OS, physical device, etc.) or this guide has become dated, here’s the fundamentals of what you’re aiming to achieve:

  1. Set up a decrypting proxy server (e.g. Fiddler, Charles, Burp, SSLSplit – note that Wireshark isn’t suitable) and export its root certificate.
  2. Import the root certificate into the certificate store of the device to intercept.
  3. Configure the device to connect via the proxy server.
  4. If using an app that implements certificate pinning, “fix” the app with FRIDA or another tool.

Quantum Key Distribution Whitepaper

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a post (ncsc.gov.uk)
This white paper describes our current position on quantum key distribution (QKD). QKD is an approach to key distribution that relies on the properties of quantum mechanics to provide security.

For all the practical, business and security reasons given above, at this point in time we:

  • do not endorse QKD for any government or military applications
  • advise against replacing any existing public key solutions with QKD for commercial applications

The UK should continue its research and development of QKD systems. But this should be balanced by a growing body of practical QKD vulnerability research, and accompanied by the development of methods for quantifying and validating the security claims of real-world QKD systems. Responsible innovation should be accompanied by independent validation.

Wise words from the NCSC here:while QKD continues to depend upon conventional components that often lack battle-testing they may have vulnerabilities. Furthermore, current implementations of quantum cryptography fail to address the bigger and harder problems of authentication and identity – key distribution, while not perfectly solved, is still something that we understand very well… and many real-world attacks target other parts of the process (which QKD does not seek to solve).

The Alice and Bob After Dinner Speech

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John Gordon: The Alice and Bob After Dinner Speech (urbigenous.net)

Good evening Ladies and Gentlemen.

There comes a time when people at a technical conference like this need something more relaxing. A change of pace. A shift of style. To put aside all that work stuff and think of something refreshingly different.

So let’s talk about coding theory. There are perhaps some of you here tonight who are not experts in coding theory, but rather have been dragged here kicking and screaming. So I thought it would be a good idea if I gave you a sort of instant, five minute graduate course in coding theory.

Coding theorists are concerned with two things. Firstly and most importantly they are concerned with the private lives of two people called Alice and Bob. In theory papers, whenever a coding theorist wants to describe a transaction between two parties he doesn’t call then A and B. No. For some longstanding traditional reason he calls them Alice and Bob.

Now there are hundreds of papers written about Alice and Bob. Over the years Alice and Bob have tried to defraud insurance companies, they’ve played poker for high stakes by mail, and they’ve exchanged secret messages over tapped telephones.

If we put together all the little details from here and there, snippets from lots of papers, we get a fascinating picture of their lives. This may be the first time a definitive biography of Alice and Bob has been given.

In papers written by American authors Bob is frequently selling stock to speculators. From the number of stock market deals Bob is involved in we infer that he is probably a stockbroker. However from his concern about eavesdropping he is probably active in some subversive enterprise as well. And from the number of times Alice tries to buy stock from him we infer she is probably a speculator. Alice is also concerned that her financial dealings with Bob are not brought to the attention of her husband. So Bob is a subversive stockbroker and Alice is a two-timing speculator.

But Alice has a number of serious problems. She and Bob only get to talk by telephone or by electronic mail. In the country where they live the telephone service is very expensive. And Alice and Bob are cheapskates. So the first thing Alice must do is MINIMIZE THE COST OF THE PHONE CALL.

The telephone is also very noisy. Often the interference is so bad that Alice and Bob can hardly hear each other. On top of that Alice and Bob have very powerful enemies. One of their enemies is the Tax Authority. Another is the Secret Police. This is a pity, since their favorite topics of discussion are tax frauds and overthrowing the government.

These enemies have almost unlimited resources. They always listen in to telephone conversations between Alice and Bob. And these enemies are very sneaky. One of their favorite tricks is to telephone Alice and pretend to be Bob.

Well, you think, so all Alice has to do is listen very carefully to be sure she recognizes Bob’s voice. But no. You see Alice has never met Bob. She has no idea what his voice sounds like.

So you see Alice has a whole bunch of problems to face. Oh yes, and there is one more thing I forgot so say – Alice doesn’t trust Bob. We don’t know why she doesn’t trust him, but at some time in the past there has been an incident.

Now most people in Alice’s position would give up. Not Alice. She has courage which can only be described as awesome. Against all odds, over a noisy telephone line, tapped by the tax authorities and the secret police, Alice will happily attempt, with someone she doesn’t trust, whom she cannot hear clearly, and who is probably someone else, to fiddle her tax returns and to organize a coup d’etat, while at the same time minimizing the cost of the phone call.

A coding theorist is someone who doesn’t think Alice is crazy.

I’ve always been a fan of the “expanded universe” of cyptography placeholders Alice & Bob, and this humorous speech – partially-reproduced here – is a great example of Alice & Bob headcanon at its best.

GIF MD5 hashquine

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GIF MD5 hashquine - Rogdham (rogdham.net)

TL;DR: Quick access to GIF MD5 hasquine ressources:

Introduction

A few days ago, Ange Albertini retweteed an tweet from 2013 asking for a document that shows its own MD5 or SHA1 hash.

Later, he named such a document an hashquine, which seems to be appropriate: in computing, a quine is a program that prints its own source code when run.

Now, creating a program that prints its own hash is not that difficult, as several ways can be used to retrieve its source code before computing the hash (the second method does not work for compiled programs):

  • Reading its source or compiled code (e.g. from disk);
  • Using the same technique as in a quine to get the source code.

However, conventional documents such as images are likely not to be Turing-complete, so computing their hash is not possible directly. Instead, it is possible to leverage hash collisions to perform the trick.

This is the method that I used to create the following GIF MD5 hashquine:

hashquine and md5sum

Once I managed to do create it, I figured out that it was not the first GIF MD5 hashquine ever made, since spq beat me to it.

I will take that opportunity to look at how that one was done, and highlight the differences.

Finally, my code is on Github, so if you want to create your own gif md5 hashquine, you could easily start from there!

Creating a GIF MD5 hashquine

To create the hasquine, the two following ressources were used exhaustively:

A note about MD5 collisions

We say that MD5 is obsolete because one of the properties of a cryptographic hash function is that it should not be possible to find two messages with the same hash.

Today, two practical attacks can be performed on MD5:

  1. Given a prefix P, find two messages M1 and M2 such as md5(P || M1) and md5(P || M2) are equal (|| denotes concatenation);
  2. Given two prefixes P1 and P2, find two messages M1 and M2 such as md5(M1 || P1) and md5(M2 || P2) are equal.

To the best of my knowledge, attack 1 needs a few seconds on a regular computer, whereas attack 2 needs a greater deal of ressources (especially, time). We will use attack 1 in the following.

Please also note that we are not able (yet), given a MD5 hash H, to find a message M such as md5(M) is H. So creating a GIF displaying a fixed MD5 hash and then bruteforcing some bytes to append at the end until the MD5 is the one displayed is not possible.

Overview

The GIF file format does not allow to perform arbitrary computations. So we can not ask the software used to display the image to compute the MD5. Instead, we will rely on MD5 collisions.

First, we will create an animated GIF. The first frame is not interesting, since it’s only displaying the background. The second frame will display a 0 at the position of the first character of the hash. The third frame will display a 1 at that same position. And so on and so forth.

In other words, we will have a GIF file that displays all 16 possibles characters for each single character of the MD5 “output”.

If we allow the GIF to loop, it would look like this:

GIF showing all possible MD5 characters

Now, the idea is, for each character, to comment out each frame but the one corresponding to the target hash. Then, if we don’t allow the GIF to loop, it will end displaying the target MD5 hash, which is what we want.

To do so, we will, for each possible character of the MD5 hash, generate a MD5 collision at some place in the GIF. That’s 16×32=512 collisions to be generated, but we average 3.5 seconds per collision on our computer so it should run under 30 minutes.

Once this is done, we will have a valid GIF file. We can compute its hash: it will not change from that point.

Now that we have the hash, for each possible character of the MD5 hash, we will chose one or the other collision “block” previously computed. In one case, the character will be displayed, on the other it will be commented out. Because we replace some part of the GIF file with the specific collision “block” previously computed at that very same place, the MD5 hash of the GIF file will not change.

All what is left to do is to figure out how to insert the collision “blocks” in the GIF file (they look mostly random), so that:

  • It is a valid GIF file;
  • Using one “block” displays the corresponding character at the right position, but using the other “block” will not display it.

I will detail the process for one character.

Example for one character

Let’s look at the part of the generated GIF file responsible for displaying (or not) the character 7 at the first position of the MD5 hash.

The figure below shows the relevant hexdump displaying side by side the two possible choices for the collision block (click to display in full size):

hexdump of two version of a character

The collision “block” is displayed in bold (from 0x1b00 to 0x1b80), with the changing bytes written in red.

In the GIF file formats, comments are defined as followed:

  • They start with the two bytes 21fe (written in white over dark green background);
  • Then, an arbitrary number of sub-blocks are present;
  • The first byte (in black over a dark green background) describes the length of the sub-block data;
  • Then the sub-block data (in black over a light green background);
  • When a sub-block of size 0 is reached, it is the end of the comment.

The other colours in the image above represent other GIF blocks:

  • In purple, the graphics control extension, starting a frame and specifying the duration of the frame;
  • In light blue, the image descriptor, specifying the size and position of the frame;
  • In various shades of red, the image data (just as for comments, it can be composed of sub-blocks).

To create this part of the GIF, I considered the following:

  • The collision “block” should start at a multiple of 64 bytes from the beginning of the file, so I use comments to pad accordingly.
  • The fastcoll software generating a MD5 collision seems to always create two outputs where the bytes in position 123 are different. As a result, I end the comment sub-block just before that position, so that this byte gives the size of the next comment sub-block.
  • For one chosen collision “block” (on the left), the byte in position 123 starts a new comment sub-block that skips over the GIF frame of the character, up to the start of a new comment sub-block which is used as padding to align the next collision “block”.
  • For the other chosen collision “block” (on the right), the byte in position 123 creates a new comment sub-block which is shorter in that case. Following it, I end the comment, add the frame displaying the character of the MD5 hash at the right position, and finally start a new comment up to the comment sub-block used as padding for the next collision “block”.

All things considered, it is not that difficult, but many things must be considered at the same time so it is not easy to explain. I hope that the image above with the various colours helps to understand.

Final thoughts

Once all this has been done, we have a proper GIF displaying its own MD5 hash! It is composed of one frame for the background, plus 32 frames for each character of the MD5 hash.

To speed-up the displaying of the hash, we can add to the process a little bit of bruteforcing so that some characters of the hash will be the one we want.

I fixed 6 characters, which does not add much computations to create the GIF. Feel free to add more if needed.

Of course, the initial image (the background) should have those fixed characters in it. I chose the characters d5 and dead as shown in the image below, so that this speed-up is not obvious!

Background and hash compared

That makes a total of 28 frames. At 20ms per frame, displaying the hash takes a little over half a second.

Analysis of a GIF MD5 hashquine

Since I found out that an other GIF MD5 hashquine has been created before mine once I finished creating one, I thought it may be interesting to compare the two independent creations.

Here is spq’s hashquine:

spq's hashquine

The first noticeable thing is that 7-digits displays have been used. This is an interesting trade-off:

  • On the plus side, this means that only 7×32=224 MD5 collisions are needed (instead of 16×32=512), which should make the generation of the GIF more than twice as fast, and the image size smaller (84Ko versus 152Ko, but I also chose to feature my avatar and some text).
  • However, there is a total of 68 GIF frames instead of 28, so the GIF takes more time to load: 1.34 seconds versus 0.54 seconds.

Now, as you can see when loading the GIF file, a hash of 32 8 characters is first displayed, then each segment needed to be turned off is hidden. This is done by displaying a black square on top. Indeed, if we paint the background white, the final image looks like this:

Using a white background reveals black squares

My guess is that it was easier to do so, because there was no need to handle all 16 possible characters. Instead, only a black square was needed.

Also, the size (in bytes) of the black square (42 bytes) is smaller than my characters (58 to 84 bytes), meaning that it is more likely to fit. Indeed, I needed to consider the case in my code where I don’t have enough space and need to generate an other collision.

Other than that, the method is almost identical: the only difference I noticed is that spq used two sub-block comments or collision alignment and skipping over the collision bytes, whereas I used only one.

For reference, here is an example of a black square skipped over:

hexdump of a commented square

And here is another black square that is displayed in the GIF:

hexdump of a used square

Conclusion

Hashquines are fun! Many thanks to Ange Albertini for the challenge, you made me dive into the GIF file format, which I probably wouldn’t have done otherwise.

And of course, well done to spq for creating the first known GIF MD5 hashquine!

Asymmetric Cryptography: Works Like Magic

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Asymmetric Cryptography: Works Like Magic (cyberhoboing with dominic tarr)
It’s a common complaint that cryptography is too hard for regular people to understand - and that all our current cryptographically secure applications are designed for cyborgs and not humans. While...

It’s a common complaint that cryptography is too hard for regular people to understand – and that all our current cryptographically secure applications are designed for cyborgs and not humans. While the latter charge may well be correct, I argue that the former most certainly isn’t, because we have been teaching children the basic security principles behind asymmetric cryptography for probably thousands of years.

What am I talking about? A fairly tail called Rumplestiltskin, which is actually about bitcoin!

You probably heard this fairly tale as a child – but let me refresh your memory.

There is a miller, who drunkenly brags that is daughter can spin straw into gold.

probably, he was posting about his half baked cryptocurrency ideas on bitcointalk, and creating money “gold” from pointless work “spinning straw” sounds A LOT like bitcoin mining.

Anyway, the king is very impressed with his story.

the king is a venture capitalist?

And wants to see a demonstration, oh and if it doesn’t work he will cut off both their heads.

I have not heard about venture capitalists being quite this evil, but it seems some of them are into this medieval stuff

Of course, the miller and his daughter don’t actually have the ability to create gold by magic, so they are in big trouble! but just then a magic imp appears.

a hacker, who understands cryptography

The imp says he can spin straw into gold, but for a price: the daughter’s first born child.

in the modern version he wants her naked selfies

It’s a terrible deal, but the alternative is death, so they reluctantly accept. The imp spins straw into gold in 3 increasingly dramatic episodes.

The kind is satisified, and marries the daughter, making her queen.

their startup is aquired

One year later, the first child is born. The imp returns demanding his prize. Because they love their baby, the King and Queen pleads with the imp to get out of the deal. They offer him all their riches, but the imp is not interested! Desperately, they ask is there any other way? any at all? The imp replies, “Of course not! not unless you can guess my True Name”

the true name is actually his private key. If they can guess that, the hacker looses his magical power over them

“Okay I will try and guess your name” says the Queen. The imp just laughs! “you’ll never guess it!” “but I’ll give you three days to try!”

The imp skips off into the forrest, and the queen trys to think of his name for 3 days… but can’t figure it out.

The queen trys to brute force his private key. but there is not enough compute in the entire kingdom!

But then, the a messenger is travelling through the forrest, and he happens past a strange little man, dancing around a camp fire, singing:

ha ha ha!
te he he!
they’ll never guess my private key!
just three days! not enough to begin,
to guess my name is rumplestiltskin!

Being a messenger, he had a good memory for things he heard. When he arrived back at the castle, he mentioned the curious story to the queen.

the hacker had been careless with his private key

When the imp arrived in the morning, the queen greeted him by name. He was furious! He stamped his foot so hard the ground split open and then he fell into the gaping hole, never to be seen again. The king, queen, baby lived happily ever after, etc, etc.

they stole all his bitcoin


The simularities between this fairly tale and cryptography is uncanny. It has proof of work, it has private keys, it has an attempted brute force attack, and a successful (if accidental) end point attack. The essential point about your private key is captured successfully: the source of your magic is just a hard to guess secret, and that it’s easy to have a hard to guess name, but what gets you in the end is some work around when they steal your key some other way. This is the most important thing.

It’s not a talisman that can be physically protected, or an inate power you are born with – it’s just a name, but it must be an ungessable name, so the weirder the better.

“rumplestiltskin” is the german name for this story, which became wildly known in english after the brothers grim published their collection of folktales in the early 19th century, but according to wikipedia there are versions of this story throughout the europe, and the concept that knowing the true name of a magical creature give one power over it is common in mythology around the world.

How did the ancients come up with a children’s story that quite accurately (and amusingly) explains some of the important things about asymettric cryptography, and yet we moderns did not figure out the math that makes this possible this until the 1970’s?

Since the villian of the story is magical, really they have chosen any mechanism for the imps magic, why his name? Is this just a coincidence, or was there inspiration?

The astute reader has probably already guessed, but I think the simplest (and most fun) explaination is the best: extraterrestials with advanced cryptosystems visited earth during prehistory, and early humans didn’t really understand how their “magic” worked, but got the basic idea

To be continued in PART 2…

A hacker stole $31M of Ether – how it happened and what it means for Ethereum

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Yesterday, a hacker pulled off the second biggest heist in the history of digital currencies.

Around 12:00 PST, an unknown attacker exploited a critical flaw in the Parity multi-signature wallet on the Ethereum network, draining three massive wallets of over $31,000,000 worth of Ether in a matter of minutes. Given a couple more hours, the hacker could’ve made off with over $180,000,000 from vulnerable wallets.

But someone stopped them…

Hacker figure among code

Defeating Quantum Algorithms with Hash Functions

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In this post I’ll explain why quantum computers are useless to find hash function collisions, and how we can leverage this powerlessness to build post-quantum signature schemes. I’ll then describe a quantum computing model that you can try at home, and  one where hash function collisions are easy to find…

TLS 1.3 FTW

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In common slang, FTW is an acronym “for the win” and while that’s appropriate here, I think a better expansion is “for the world.”

We’re pleased to announce that we have sponsored the development of TLS 1.3 in OpenSSL. As it is one of the most widely-used TLS libraries, it is a good investment for the overall health and security of the Internet, so that everyone is able to deploy TLS 1.3 as soon as possible…

Against DNSSEC

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All secure crypto on the Internet assumes that the DNS lookup from names to IP addresses are insecure. Securing those DNS lookups therefore enables no meaningful security. DNSSEC does make some attacks against insecure sites harder. But it doesn’t make those attacks infeasible, so sites still need to adopt secure transports like TLS. With TLS properly configured, DNSSEC adds nothing…

Geocaching Like Batman

As the days get longer and the weather gets better, woodland trails and city alleyways alike begin to more-frequently see a particular brand of explorer. Clutching GPS devices (or, increasingly, mid- to high-end mobile phones), these satellite-guided adventurers shy away from normal people, whom they call “muggles”. Outwardly, this is out of concern for the continuity of their tiny treasure, but as often as not, it’s because geocachers – and especially urban geocachers, who often don’t even have the excuse of “getting some fresh air” to justify their hobby – are likely to be seen as a little odd., “You do what for a hobby? Find lost lunchboxes?”

Geocache GC13WZQ, from a distance..
There’s a “hidden in plain sight” urban geocache in this picture. Can you spot it? (probably not, at this resolution)

I’ve written plenty about geocaching already, but the only important thing to know for this particular anecdote is how geocaches are rated to indicate how hard they are. There are two scales, each scored from one to five “stars”. The first scale is difficulty, which is about how challenging the geocache is to find – a 1-star rating means that it’s in plain sight, not camouflaged, etc., while higher ratings might mean that it’s well-concealed, tiny, disguised as something else, or requires that you solve a puzzle in order to determine where it is. The second scale is terrain, which is about how challenging the geocache is to get to. A 1-star rating is typically accessible by wheelchair – you certainly don’t need to leave paved roads and footpaths to get it; higher ratings might mean steep gradients, tree climbing, long hikes, and so on. The highest terrain ratings often mean that specialised skills or equipment are required (for example, rock climbing gear or a scuba tank).

Geocache GC13WZQ, zoomed-in
There it is: that capsule, magnetically-attached to the girder that supports the bridge, is the geocache.

As you can imagine, caches with a 5-star “terrain” rating are rarer, and are especially uncommon in built-up areas. Half-way up cliffs… deep inside caves… miles out to sea: these are the places you’d expect to see geocaches with the highest level of “terrain” score. So imagine my surprise when I discover GC13WZQ (“Swing Lower”), a geocache with a 1-star “difficulty” rating but a 5-star “terrain” rating, just a few minutes walk from Oxford City Centre. In the seven years this cache has been in place, it had seen fewer than 110 successful visitors: contrast to its neighbour, GCK57Z (“Swing Low”) – a virtual cache less than 10 metres away – which has seen about six times as many visits in only 3 years longer. This, I thought, was a cache I had to see.

The sides of the bridge, boarded up and with barbed wire. Photo by OxfordLad on Geocaching.com.
OxfordLad (who took this photo), and other geocachers claimed that, since early 2014, the cache was made entirely inaccessible by the boarding-up of the sides of the bridge.

Folks recently attempting to find the geocache had reported (OxfordLad, izybuzyfingers, twitcher50) that it had been made inaccessible by the recent addition of boards and barbed wire to the edges of the bridge. Counter-arguments were raised (sandvika, Mad H@ter) to show that this didn’t make the cache inaccessible; it merely made it accessible only by boat, which had already been suggested in the “attributes” for the cache.

Geocache with "boat" attribute
Only an idiot would attempt a ‘requires boat’ geocache without a boat. Right?

I’m not a believer in the idea that any particular geocache can only be found one particular way. Also: I don’t have a boat. So I decided to make an expedition to “Swing Lower” my own damn way. Approaching the bridge under which the cache is located, I immediately saw the boards and barbed wire that had been reported by those that had attempted it earlier in the year. But as I would soon discover, anybody who was put off by a little bit of plywood and the risk of damp feet really wasn’t built of the right stuff to be able to do what was required next. Put simply: boards and barbed wire are the least of your problems when you’re hunting for GC13WZQ.

Dan, braced between two I-beams about 5 feet apart, underneath a bridge.
It’s not the most conventional way to cross a bridge, I’ll admit.

The bigger challenge was getting to the cache once underneath the bridge. I discovered (perhaps with a little inspiration from “Jackhuber”) that it was possible to brace myself against a pair of the beams that run the length of the bridge and – facing down – shuffle sideways to get to the centre of the bridge. I felt acutely aware of the fact that until I got over the central channel, the depth of the water might not be enough to break my fall (especially if I slipped and fell head-first), but was reassured by the fact that I’d brought fellow ‘cacher and coworker kateevery and she was ready, perhaps not to swim out and get me but at least to call 999, should the need arise.

Dan holding the geocache he's found above his head, triumphantly.
This is how Freddie Mercury holds a geocache.

So there you go. To all of you wusses for whom “there are boards and barbed wire in the way” was an excuse: you hadn’t even begun to face the challenge of “Swing Lower”. I’ve written up a Batman-themed description of the expedition as part of my log report.

A screenshot of the clue for GC54F78, one of the caches in my new series.
Can you make out the coordinates in this image? No? Maybe it’d help if you looked at geo.danq.me.

This conveniently coincides with the week that I launched my new collection of puzzle geocaches, the Oxford Steganography Series – four geocaches (GC54F78, GC54F7B, GC54F7J, GC54F7N) whose coordinates are concealed within images or text, each of which contains a transparency film that can be used (I made a video showing how) to determine the coordinates of a fifth, bonus cache. I’m reasonably pleased with the series, and I’ve been enjoying reading the reports of the ‘cachers who’ve been out hunting for them, so far.

Something like HTTPS Everywhere for new Opera?

This self-post was originally posted to /r/operabrowser. See more things from Dan's Reddit account.

by an author

I’m looking for an extension that will automatically redirect-to-HTTPS for particular domains, e.g. to ensure that I’m using the secure version of Wikipedia, etc., whenever I go there. The HTTPS Everywhere plugin from the EFF does this for Firefox and Chrome; what can I do to make this work in Opera?