Badge Talk: Solar-Powered Crypto Puzzles

all right I like to walk around but I'm going to try to avoid that and just uh stay here and not grab the mic um I have material for this but I'm flexible to kind of drift whichever way questions lead so if you have questions please don't uh wait until the end interrupt me I'll ask again for questions at the end but if if you want to talk about anything I'm talking about just raise your hand and I'll try to spot you and um and address that but uh I'm going to talk about the badge and I will end by talking about some of the challenges on the badge unless everybody tells me they want more time to work on

it but okay so this year's badge was um completely different than a lot of badges that we've done I say that every year but this this one I'm is based on crypto all the all the challenges are crypto based and I really wanted to do something um on solar power and so this badge if you've noticed it has a large solar I say large but as a small solar cell at the bottom there's no battery in the badge what's that solar cell Powers up a capacitor on the back enough to refresh the screen then the screen will change to a random image one of the mini puzzles that are on the badge the uh what are these called the puzzle what

is this called the word crossword thank you thank you crossword puzzle um the solutions are on the badge or at least the hints to the crosswords or on the badge on you can see on the back a one through five is in the um hieroglyphics hieroglyphics there um and then the other up to 15 so the other 10 are images that will scroll through and those images hint to the the word that would be the solution I made a huge mistake though powering this on solar in Utah in April and that mistake as I assumed it would be spring by April um but as you can see we're still in Winter or third winter but uh just I was just it was just

snowing what two hours ago today and that really puts a damper on getting solar panel uh solar energy so here's kind of some of this designs uh we did this last besides was in December right so I actually had started on this badge before that one was over this image down in the bottom right is my prototype that I brought here and stuck in a window to make sure it'll at least work that prototype you can see it has a larger solar panel on it and then I've just got the e-paper display showing what the current voltage is of the capacitor how many just how many um seconds or not seconds yeah how many intervals so that 2 represents

20 seconds between updates so it's basically telling me that it was able to in 20 seconds get enough power to refresh the screen again and that's when it's sitting in the sun not in the sun that's very different and I will talk about that and then the image is just the chi-cad 3D renders of what the badge should look like before I shipped it off to um the assembler you'll notice that has a larger cap my prototypes had a larger cap on it and a lot of my time was spent both trying to minimize how much power I needed to refresh the screen and how much power I utilized when I was sleeping or to refresh the screen and

every every Improvement allowed me to get a smaller solar panel and a smaller capacitor and I was hoping to get even smaller on the capacitor but I didn't quite make it so here I spent a lot of my time analyzing power consumption of the badge and this is the power consumption as it does a refresh it's really really small it uses less than 20 millijoules of power and that's really hard to convey how much a millijoule is so let's say um in and out in an hour the badge uses 1.7 milliwatts and we'll equate that to one penny right um for reference an LED would use 30 milliwatts just just turning on an LED is 30 milliwatts so

you can see like this is the amount of power I'm playing with like 1 30th of what you use just for an LED a Raspberry Pi for example which is uses 4.5 Watts so that's like 25 to 50 world I think that's 50 50 rolls of pennies to one penny of what the badge is using it's really not much um and the downside to that is the batch doesn't interact really well right because it most of the time it is in a deep deep sleep waiting for enough power to even just turn on the screen that's kind of the downside to this design is there's not a lot of back and forth because it just doesn't have the Cycles

or the power to to spend waiting for user input um so along the way these are the different solar panels I I went through trying to get the badge I started with that large one and I give two numbers here the top number is what the the solar panel is supposed to be able to do and that's under nominal conditions under perfect sun it could provide 600 Milli 600 millijoules however in typical sunlight in here in Utah or a rare environment I got about 10 out of it so it's a whole lot smaller than what um you know they're touted as and then you just keep going down the chain the middle one this kind of squarish looking

one is a different type of solar panel and so it um for its size it doesn't produce a lot of electricity it's a m i I'm not even gonna try to say the word but it was specifically designed that solar panel Works to work off of indoor lights like fluorescent lights rather than um wavelengths from the Sun so I was thinking maybe that would work better when we could actually have it work indoors but that one was horrible and so I got down to the second to last one I wanted to get down to that very tiny one on the side on the end and technically the batch will work with that littler one if it's in the Sun for

longer and a lot and a perfect sun and I'm really glad I didn't try to go with that one because like you said today's cloudy it wouldn't have worked if I if I tried to force that um the other thing I wanted to talk about that's weird my laptop didn't update but those did so um the thing I want to talk about what I didn't really realize I kind of knew but I didn't really know is how well your eyes automatically accumulate to the current level of light and so it's hard for me to gauge like oh it's a sunny day this is good sun and it's oh it's bright in my office that's about the same they're

not about the same so all of the solar panels were rated for bright sun which will put out um about a thousand watts per meter squared um but in an overcast sky that down by a power of 10. so an overcast Sky there's one tenth the amount of power being able to be generated by a solar panel we talked about like department stores it just keeps going down from there office space is 100th of what there would be outside this I wouldn't consider office space lighting this is even worse than office space riding this room here right like it's actually pretty dark so although the solar panel can produce more it has to be in those nominal

conditions which presents a problem for me because like I could use the bigger solar panel so that I can get the light I need in this office but then as soon as you step outside that's way too much power for the badge to handle right so if I did a bigger solar panels to accommodate that then I had to have additional circuitry to handle the case where it's way more than the capacitor is meant for and so it's this balancing game I'll be trying to trying to encourage trying to find the right um range and I just try to encourage everyone to go outside that was my solution um but again it's snowing so that was

probably not the right solution um but uh yeah that's about the badge design about the puzzles I got a lot of my Inspirations from these two books I don't know if any of you have looked them or you guys are uh crypto or puzzle freaks these books are a lot of fun um they have a lot of hard challenges and the answers are in the book but for most of the puzzles the answers are in the book but they're very there's a really good set of brain teasers I'd highly encourage you if you guys kind of like this kind of thing to pick up those books they're just fun to have on your shelf right the plum the thrum

thumb through when you have spare time man uh but with that I wanted to say first off thank you to all those that helped build the badge and helped um test the badge I had two testers pause I saw Paul and then there was another individual that was testing but I don't see them here raise your hand if you were one of my beta testers with the puzzles yeah so Paul thank you very much for for testing these puzzles I throw things at him and make him do all the leg work to see if it was actually solvable and then all these guys um most of the assembly was done in China except for the screens and what

was the other thing we needed to do I think it was and then just packaging it all so all these guys made assembly line where they would attach the the screens on the back tape them down or put some double tape to put them down on the front and then package them all up with the the crossword puzzle and everything for you guys so really thankful for all of them for that so with that um do you guys want to talk first before we go to the puzzles do you have any questions about the badge itself or do you want to talk about the puzzles if you don't want to talk about the puzzles uh now's probably a good time to leave

if you wanted to spend some time working on them at home yes I see one over here what does the button do yes so the button was actually for me more than for you but it does do the button is a reset um for the chip there's our power so it needs at least 2.5 volts to be able to refresh the screen the capacitor needs to get up to that level but the chip can turn on at 1.8 volts so if you hit that refresh button or reset button it'll immediately the the Eye of raw will blink really quick just to say it's on that tells you that tells me that you've got one at least 1.8 volts and two of

the chips working um and so that's that was really my way of um Quality Assurance when they went through the line to make sure it would at least blink the light and know that the chip was working but all it it will reset the device and the devices are set to show the b-sides logo the first time it has power so if you keep hitting refresh you're always just going to see it or you're going to keep hitting reset you're always going to see the b-sides logo first before it goes to any other screen but that was really the only point of that button yeah there isn't a lot of interactive features there's one thing that you can do to change how it

behaves other than the reset button but um other than that there's not a lot interaction with it it's kind of passive um you could there's there's two chips on there there's a flash chip and the chip itself you could actually replace the images and and once I paste the code up there you can see how so if you want to put your own images you're on this and then you don't have it hang in your office that's something you can do with it too but that's kind of an advanced level thing uh any other questions before we get to puzzles thank you for that that was a good one yes no no there was no capacity touch

buttons again that was one of those features that I like I can't have the chips into such a deep sleep it can't be waiting for cents um but it would have been nice to do I was just so limited with what I could do with no batteries okay I'm gonna talk puzzles so these are all the screens that the badge can go through I don't think many of you had seen the bottom half of those screens actually the top one two three four five six seven eight nine ten eleven twelve and then skipping number 14 you would you would see the the top 12 except for the one that looks like static and it will cycle through those screens each

most of them have a number in the top corner and that course that says which puzzle it corresponds to there are a few that don't one the B side screen and then two this one right next to the B side screen I'm going to talk about it first it um anybody recognize that logo yes that's Stargate so they used a cipher in Stargate they called the Ancients Cipher and that's what that Cipher is down below there so right below it it has these little symbols and that says free the serif uh Sarah's another term for you know peasant worker or indentured servant and on the back you notice there are a bunch of uh guys harvesting wheat and with

resistors tied to their legs if you remove those resistors then the badge will open up and give you the other 10 screens the other 10 screens are all hints to help solve the original puzzles and so they are all using the same substitution Cipher that the first five puzzles on the back of the screen are using so I'm going to start just going through these the first five are pretty straightforward that they're a substitution Cipher that once you solve it yes I see a question

yeah you should sorry you should you you should 15 should stroke show you 14 shouldn't or 14 will show up you see there's two 14s up there you should get the one with the I and the QR code and 15 but you shouldn't be the man I'm making this more confusing than it is everything up to that bird you should be able to get without taking off those resistors Asterix the fuzzy one won't show up ever um and the fuzzy one will get I'll tell you why it's um it was an issue that just didn't work so well but you should be able to get everything up to through 15. so all the puzzles are available all the hints are

not available until you take the resistors off okay let's walk through some of these this puzzle um this one is known as the Cheryl's birthday puzzle it was actually based off of a high school mathematics competition uh question where Cheryl gave her friends hints to when her birthday is and you had to use data back and forth about what each of the people used so for example this one in this case you're given what eight words at the top and Cleopatra and King Tut both know part of those words like Cleopatra knows the first letter and King Tut knows the second letter and based on the statements they say back and forth to each other you can narrow down what the

answer is so for example Cleopatra says I don't know what the clue is but I know the King Tut doesn't know it either that's enough to say that whatever letter she knows is ambiguous enough that none of the tail letters are alone so for example um the first two rows have the letters end with the letter e or letter L which don't and no other words end in those so for Cleopatra to know that Tut couldn't know the answer she had to not she had to know that the first letter wasn't b or J is that confusing so that's how you roll up the first two based on her statement there and now King Tut responds with I didn't

know but now I do so that allows us to rule out things that if he he knows those two rows and that would allow us I'm going to try to say this without confusing people um if he knew G he still wouldn't know the answer right because it's got to be one of the two bottom rows and G is ambiguous because it shows up there so what he knew had to be some other letter than G so that leaves us with leap rack and rain and then Cleopatra says then I also know the clue so she it couldn't be Rack or rain because those two both start with ale so it had to be leap so the answer

to that part would be leap some blink leap is the the hint to solve the uh the crossword puzzle for that one that was a interesting a kind of a fun brain teaser um seven seven is just an image to have that anybody if you have if you solve this you can tell me okay I'd love to hear yours how you came to this more than I did so um if you have an answer you're good if not I can talk about what I tried to tell you here this one is not crypto Bay related but rather they're all hinting at something that occurred they're talking about an event um the big eagle in the middle is very

reminiscent of a three-letter agency's symbol um the guys down at the middle which appear to be I would say using a telephone and somebody's listening in um the their symbols on the side they represent using the same Cipher MK something seven and that's the top we see the effs um symbol or I'm gonna I'm going let's see left to right that's supposed to print 30 years a broken lock a swordfish enough swordfish uh shooting what yes and then the ship is a clipper ship these are all hinting at the Clipper chip which was a NSA chip used back in the 90s to intercept encrypted Communications on the telephones so that's what the hints they were all

clip mentioning there oh skipjack it's it's right on my slide okay this one is hinting at the Four Square algorithm so there's some crypto at the top um you got four squares with some words um four squares a encryption algorithm where you put two words in or you can put up to four but usually you only use two words to start the box and then you start in the top left and grab the letter that's over in the top right and then for the second letter you start in the top bottom or the bottom right and grab the letter in the bottom left so that a in the top I mean this is I guess

I can't say so but look look up the Wikipedia Foursquare to see how to do that there's a lot of pages that can tell you how to do that and then for your two words you would just use snake and sphinx um this one was a hard one it was very obtuse in my mind but Orion's Belt if you looked at the stars that were lit up and and Drew the Dos between them that would make a elliptic curve and that was your clue for that one is the answer was an elliptic curve that one was pretty obtuse this one is rather difficult one taking great directly from the gchq gchq handbook puzzle book there was a

puzzle basically similar way the resistors around the outside represent a fractional resistance so um you can see here like two resistors in parallel that's half of one resistance if you put resistors in parallel and so if you looked at the first row second column one half then you get the letter T and you would just go through each resistor around the chain to put together the solution there this is a rubius puzzle this is probably one of the easier ones um you've seen like if you remember some of you might remember the old Concentration game show where you get uh images and you had to spell it out so this would be a not without the T Bone

without the B so you'd say not own known rain with rain plus a p i would be praying but plain text text it would be if known plain text is the the key to that one it's a rubius um more of a tongue t teaser type we'll keep going this one was very difficult I don't think I'll spell this one out um but this is assembly code our pseudo assembly code which will iterate over a set of numbers and push a certain set of those numbers to the stack the numbers that pushes to the stack are a set of primes and a particularly interesting set of primes if you're a crypto fan that it's The Miser frames

immersion or prime sorry excuse me this one I didn't even write a description for this one is just binary code but you're just missing some bits um the the things are broken but um ASCII code in assemble in binary there's a lot of bits that you can not use like the first bit of any ASCII character are always zero one if it's a capital or zero zero if it's lowercase and so you can get away with not having the first two bits in general and distill the cold ASCII and then some of these others are missing bits in the end but that just means hey it's either an o or a p right like as you start to bit

the rest of this together you should be able to deduce what that says and then the the actual puzzle that you're trying to solve with that has to do with that as well so 14 this is when I talked about I kind of got confusing with the original image I wanted to show was the static but the static to solve this oh I gotta show this to you this is kind of fun this is how you solve this one this is called visual cryptography and as soon as you line them up exactly right a message shows up and that's what that's how that's supposed to be solved however if you try to take an image of it and do that

manually it's not going to work because the the your skewed right you're not directly aligned so I had this other image with a QR code on it and the QR code takes you to the digital version of that image so that you could do this without having to take a picture of it but um yeah play around with digital or visual cryptography because it it's pretty cool just to it's so weird how all of a sudden all that static turns into something sensible and then 15 15 was using flax mf4 so each of those little Egyptians on the lake are holding a certain flag pattern and uh if you can be used just the simple flag semi-4 encoding to decode

what they're trying to say okay that is it I really want to appreciate thank you guys for sticking around um I had prizes for just about anybody who solved it but I have plenty of them left and those prizes are a little uh eye of raw pin and a like a solar panel so if you want just this tiny one if you wanted to try with your own circuits at home come grab one and then I have some deep flash programmers they that I wanted to give out to those guys in case you want to try to hack on your own badge if any of you are interested please just come on up and we'll hand

those out and I mean I think there's probably enough for everybody in here if you want one so but uh thank you guys very much I hope you guys enjoyed it or at least we're okay with wearing it around your neck while you were here but uh thanks guys I appreciate it