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I'm going to go ahead without you necessarily seeing my smiling face, but it is indeed, well, except for technical difficulties, it's otherwise smiling.

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So, hello and welcome to Saturday at Hack to C.

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So let me get around to my PowerPoint presentation here.

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And let me just basically go through this and I've got some other things to show you.

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So, I'm going to talk today about some work that I'm doing on something called Protected AIS.

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And I'll just quickly give you a little bit of an overview of what I'm working on and what the problem is and what quasi-solution I worked on.

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So, automatic identification system is the system used by vessels at sea for situational awareness.

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We'll see some examples of this coming up in a minute.

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But obviously, this is the way ships let each other know where they are and what kind of ship they are and those kind of things.

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And as we've discussed, and certainly part of the talk yesterday, and you may know from other sources, AIS suffers from a number of security vulnerabilities.

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And so, because of those vulnerabilities, it makes it prone to some spoofing type attacks, replay type attacks, and things like that.

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And so, basically, a bad guy can send bogus messages.

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So, I came up with a proof of concept that uses some public key cryptography methods and provides something that I call Protected AIS.

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And it addresses some of the vulnerabilities, but one of the keys that I also wanted to be able to employ was that whatever solution I designed needed to be backward compatible with the existing protocols, or else it really wouldn't be very much of a demonstration capability.

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So, here are acronyms and abbreviations.

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So, again, for those of you who didn't sit in yesterday, a quick two-minute overview.

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AIS, as I said, it's a situational awareness system used between vessels and ground stations so that vessel traffic management systems know where vessels are that are in their area of responsibility.

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Maritime administrations know about vessels in their AOR.

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Ports can keep track, things like that.

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But also, equally, and possibly even more importantly, vessels can keep track of other vessels with whom they are in proximity.

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And they can get some idea from those other vessels what type of vessel they're looking at, possibly information about their cargo, the size of the vessel, speed, course, bearing, rate of turn, current position, destination, all that kind of stuff.

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And there are a class of vessels, mostly big ones, that are required to transmit AIS information.

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And for the work that I'm doing, this is important because there's two different types of AIS position information broadcasts, Class A and Class B.

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The vessels listed here, the big vessels, are the ones that are required to transmit Class A.

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And Class A really gives more information than Class B.

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Actually, for some of the work I was doing, I needed to know stuff like rate of turn, and Class B didn't say that.

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But Class A and Class B gives me sufficient information about vessels.

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Warships are exempted from being required to use AIS, so warships can transmit AIS, but they are not required to.

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So here's an example of an ECTIS display.

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I'm going to try, actually, another display.

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Let's hope I have the right screen up.

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I don't.

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This is a display coming from the feed that I have at Emory Riddle Aeronautical University in Daytona Beach.

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And so you can see right now, here's the university, we can see right now about 10 vessels.

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A second ago, we could see 11.

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Anyway, and the furthest vessel we can see is only actually about 14 kilometers away.

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But if I mouse over, it tells me, well, it tells me that there's that vessel there.

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But if I click on it, I can actually get a lot more information.

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So this is a Pleasurecraft.

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You can see it's only about a 33 footer.

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Right now, it's offshore, a little bit in Daytona.

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But you can get an idea of where it's located, when we last saw it, course, heading, speed, latitude and longitude.

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Tells us that last saw us a minute ago.

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And we're getting everything here from terrestrial AIS as opposed to satellite.

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And the name of this boat is Fishizzle.

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So anyway, here's the other vessel I was seeing that for some reason just disappeared for a moment.

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Give it a second.

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You know, it'll come up, hopefully.

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OK, this is something called the Janus.

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This is a sailing vessel, sailboat.

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And again, you know, we can get additional information.

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Note in this case, we can find out it's from Fort Lauderdale.

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They may not have programmed in what their destination is, but sometimes, you know, we will get that information as well.

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And then I spent a lot of time the last day talking to you about OpenCPN.

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And OpenCPN, again, here's the Fishizzle.

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That other boat may be right around in here.

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I've been losing boats underneath that marker.

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Let me just go back here.

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OK.

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Anyway, so like I said, this is an example of what you see in an ECDIS display.

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There are a variety of other applications you can use.

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This is FindShip.

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It's a mobile app that I have on my phone.

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I'm getting AIS information from here as well.

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I can use a web browser application.

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This is again from FindShip.

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And, you know, again, you look up a boat by name or MMSI or IMO number and you can, you know, find out where they are.

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Now, the AIS communication protocol largely, it's defined in a couple of international telecommunication union recommendations.

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And generally for radio, it employs this self-organized time division multiple access scheme.

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And so basically each vessel is finding its slot and is transmitting during its slot times, pretty short.

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And during its slot transmissions, it can also reserve other slots that it wants to use that are presumably haven't already been reserved by other boats.

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Now, I told you that, again, just to give a real brief high level overview of what matters for AIS as far as my little project here is concerned.

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The other thing that my project obviously needed was encryption.

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And so here, you know, real quick, we have three different types of crypto functions.

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And I'm classifying them in a pretty standard way based upon the number of keys that they use.

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So a hash function doesn't really have a key.

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It's one way encryption and it's used for message integrity.

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And secret key cryptography uses a single key for both encryption and decryption.

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And we largely use secret key crypto for privacy and confidentiality.

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The stuff that I'm working on, I have no desire to keep private or confidential, so I don't even really use any secret key crypto.

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And then public key crypto, which is really the most interesting out of this.

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We've got two keys.

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One key is used for encryption.

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The other key is used for decryption.

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And the keys are mathematically related.

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But, of course, knowledge of one key doesn't yield knowledge of another key.

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So, therefore, what we can do is we can keep one key a secret, but, you know, my own personal secret, my private key.

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And then the other key I can put out there for the rest of the world to use.

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Public key crypto generally used for authentication as well as non-repudiation and secret key exchange.

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For purposes of my work, all I really care about is message integrity and sender authentication.

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So we'll see a little bit more with hashes or something like that and a little bit more with public key crypto.

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So, again, hash functions and checksums, for that matter, cyclic redundancy checks, you know, do the same thing.

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Basically, these are just mathematical formulas that provide you with the digital fingerprint, if you will, of any sort of binary string.

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It can be a message, a file, a frame, frame in the terms of, you know, like a data link layer transmission, a message packet segment, whatever you whatever you want to call it.

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The cool part about hash functions and, again, checksums as well, is that a particularly sized checksum, like a CRC16 or an MD5, is going to give you the same size hash value or checksum value, regardless of the size of the input.

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So if you're using MD5, you're going to get a 128-bit output.

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Use a CRC16, you're going to get a 16-bit output.

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The value of your checksum or your hash makes it impossible to determine what was the length of the original message and certainly makes it impossible to figure out the contents of the original message.

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So that's, of course, why they always call these things one-way encryption.

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Now, public key crypto, of course, is a tad more complicated.

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But as I suggested before, I can keep one of the keys, my own closely held secret.

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So, again, that's my private key.

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The other key I can post anywhere I want.

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So, for example, on my website, I have posted my public GPG key.

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I also have it posted at multiple key servers.

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And so the idea is this.

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If I've got two parties to a communication, Alice and Bob, we always have Alice and Bob.

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If Alice uses Bob's public key to encrypt a message and send it to Bob, Bob presumably is the only one that can decrypt the message by using his own private key.

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So that's one way of having secure communication from Alice to Bob.

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Now, if Alice encrypts a message with her own private key, anybody who can get to her public key could decrypt it.

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But what that does is it proves that Alice is the only one who could have sent it.

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So , despite the little typo that I have here, that method can be used to authenticate Alice as the sender.

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And if you like pictures, I know these look like Lois and Clark, but that's supposed to be Alice and Bob.

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So, presumably, everybody has their own private keychain.

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And in their private keychain, they have their private keys.

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Now, they can also have a public keychain, and there may be a shared database of public keychains.

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And that's really the direction I want to go in.

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But again, this page sort of replicates what I said on the previous page.

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If Alice sends a message encrypted with her own private key, Bob can decrypt it using her public key, and he can get the public key from the database.

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And again, that authenticates Alice as the sender.

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If she wants to send a message to Bob, she can use that same database to get Bob's public key, send it to Bob, Bob's the only one who can decrypt it.

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And again, that's where I get my private... that's one way of getting privacy.

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Although, typically, we don't use public key cryptography for, you know, that kind of communication.

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Now, I told you all of that so I can tell you this.

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Here's my problem statement.

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AIS, as we've described before, has a number of security weaknesses.

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One of them is there's no geographic validity check for the sender.

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There is no timing check on when the message was sent.

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There's no authentication of who the sender actually was.

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And there's no message integrity check.

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So, in fact, there's no way to prove that the message that you received is the message that I sent.

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Now, there are a number of issues that this brings up.

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Obviously, I can spoof messages, make bogus vessels if I want.

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I showed an example yesterday of making virtual ATONs that were bogus.

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I can also send out false SOS messages via AIS.

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I can send out closest point of approach messages that are fake, fake weather reports, all that kind of stuff.

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So, this page is also another way of looking at this.

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This is all the message pathways from vessel to vessel or to AIS gateways, vessel traffic management, that kind of stuff.

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And the two hooded fellows there on the chart are supposed to represent bad guys.

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And this is merely showing different attack vectors.

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So, if you're attacking a vessel or, in some cases, some of the land shore facilities as well, you can do this via radio.

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In some cases, you can also attack the system using software-based threats just via the Internet.

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And actually, for my purposes, it doesn't really matter what your vector is.

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The National Marine Electronics Association, NMEA, is one of the organizations that standardizes what these messages look like and is certainly the go-to place internationally for connecting devices to each other on board vessels.

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A lot of the NMEA work has gone forward as an international organization for standardization ISO work.

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But in any case, the NMEA 0183 specification, which has been around now for about 35 years, is probably the most commonly used over the air because that's what the ITU is using.

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There is, of course, a significant embedded base of 183 equipment, particularly on large ships.

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And there are newer standards, NMEA 2000 and OneNet, which is coming out sometime this year.

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Right now, they're not used so much over the air.

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They're used within a vessel.

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And NMEA 2000 actually is used quite a lot on recreational vessels or personally owned vessels, much more than it is in the commercial world.

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Now, I told you all of that so I could show you... I want to show you what an AIS message actually looks like, because that's important to the protocol work that I did.

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And again, if I go back here to OpenCPN...

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So, oh, this is an interesting... there's Fishizzle again.

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I'm going to go right here because, unfortunately, it's a Class B, so it's not telling me my rate of turn.

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But you can see here, this is its course, 172.

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Its head... actually, I'm sorry, its course is 172.

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Its heading is 217 degrees.

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I mean, I would be very interested in knowing its rate of turn right now, particularly since it's been a couple minutes since we heard from them.

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But in any case, if I go up here and I show my NMEA debug window...

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I can see the messages that are coming out over the air.

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And actually, I normally can.

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I'm not sure why I am not now.

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Well, again, the hazards of doing a live demonstration.

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Okay, we'll come back.

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We'll have some data in here later, I hope.

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But in any case, this is what the messages look like.

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So let me try to interpret a little bit what you're looking at here.

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So a 0183 AIS sentence has, for purposes of my discussions, it has a header.

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And in the header, there is a prefix.

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There is an identifier of what type of device you are looking at.

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And then there's some sequencing information, if it's AIS, and a channel number, so you know what channel the transmission is on.

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Then you have the content.

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The content in AIS, it's called an encapsulated payload.

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And we'll talk a little bit about that.

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And then there's a trailer.

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And the trailer mainly has information telling me how many padding bits am I going to have to make sure that I have six bit alignment.

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And what is the checksum for this particular transmission?

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Not the message as a whole, but the individual transmission.

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And the padding bits and the checksum just covers the content area.

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So put another way, here is a standard AIS message.

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So, for example, the exclamation point at the beginning says this is an NMEA formatted message and it has special encapsulation.

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So, for example, if you look at a GPS message, GPS messages start, I think, with a dollar sign.

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That just indicates, yeah, this is an NMEA formatted message, but there's nothing special about the format.

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You can basically just read everything.

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You don't have to translate it to a different format.

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The next field, the AIVDM, identifies the talker ID.

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That's the device.

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In this case, AI means AIS.

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And then the encapsulation format is identified in the next three characters.

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That's the VDM.

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In this case, VDM stands for VHF data link message.

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That means it's a message coming from another source.

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Now, the transmission that I'm showing you here is referred to as a sentence.

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A message may be composed or will be composed of one or more sentences, usually never more than five sentences.

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But in any case, the first number here tells me how many sentences are required to fully compose this message.

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In this case, there's only one sentence.

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The next number is the sentence or the fragment number of the message.

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Now, in this case, there's only one sentence, so this is going to be sentence number one.

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But as you can imagine, if the number of sentences, say, were three, well, then I'm going to have a sentence number one, two, and three.

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But how do I reassemble that?

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Well, that's the next field, which is usually null when you only have a one-sentence message, but it's a serial number.

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So you could use pretty much any number you want here.

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This provides for the reassembly of the fragments.

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So if I had that message I just mentioned, you know, a three-sentence message, let's say it's got serial number seven, I would have something here that would be a 317-327-337.

206
00:20:17,330 --> 00:20:21,210
The next identifier is going to be an A or a B.

207
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It tells me which channel number, which frequency I'm using for AIS.

208
00:20:25,550 --> 00:20:27,570
Then I actually have the content.

209
00:20:27,770 --> 00:20:35,310
I'm not going to get into what the encapsulated payload looks like, but it's in something called Armored ASCII and everything's put into six-bit bytes.

210
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Then I have a number telling me what is the number of padding bits that I need to add to get six-bit alignment for my content.

211
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And then lastly, I have a checksum.

212
00:20:49,690 --> 00:20:52,170
The checksum is actually a pretty naive checksum.

213
00:20:52,170 --> 00:20:57,570
It basically is nothing more than an exclusive OR of everything in the content field.

214
00:20:59,710 --> 00:21:02,090
Now, I told you that so I can tell you this.

215
00:21:03,170 --> 00:21:13,770
Some of the tools that I've mentioned, one of the tools I have allows me to create any, pretty much, AIS message I want.

216
00:21:13,770 --> 00:21:15,290
I can create most messages.

217
00:21:15,290 --> 00:21:24,630
There are some message types I actually just have not built in yet, largely because they're not commonly used and largely because I just haven't added them yet.

218
00:21:24,630 --> 00:21:31,330
But if I go around here, so here's this menu program that I have.

219
00:21:31,750 --> 00:21:36,170
So, for example, let's say I want to create a type one message.

220
00:21:36,170 --> 00:21:40,930
A type one message, as you can see there, is a position report, class A position report.

221
00:21:40,930 --> 00:21:42,270
So there we go.

222
00:21:42,370 --> 00:21:44,270
It wants to know the talker ID.

223
00:21:44,310 --> 00:21:48,530
I can choose all sorts of different talker IDs.

224
00:21:49,230 --> 00:21:54,570
And in this case, I'm just going to accept the defaults because I want an AIVDM message.

225
00:21:55,230 --> 00:21:58,130
And then I need to have an MMSI.

226
00:21:58,130 --> 00:22:00,930
That's the Maritime Mobile Service Identifier.

227
00:22:01,310 --> 00:22:09,070
And actually, for purposes of what I'm doing, you can choose any nine digit number you want.

228
00:22:09,150 --> 00:22:13,570
For the protected part, you have to choose ones for which there are key pairs.

229
00:22:14,210 --> 00:22:25,590
And I'm just going to take all the defaults here, with the exception of when I get to my latitude and longitude.

230
00:22:25,950 --> 00:22:31,270
My latitude, I'm going to put it 29.1 because I wanted to match the example in the book.

231
00:22:31,590 --> 00:22:36,410
The longitude is minus eight zero, zero eight zero.

232
00:22:36,410 --> 00:22:38,630
This is actually off the coast of Daytona Beach.

233
00:22:38,630 --> 00:22:41,250
I'm not going to use protected mode for this.

234
00:22:41,770 --> 00:22:44,010
And I'm just going to let this go out channel A.

235
00:22:44,010 --> 00:22:46,090
And I get a message that looks like this.

236
00:22:46,250 --> 00:22:54,830
Now, what this allows me to do is I could then copy this and paste it as a command, and it will now create for me the message that I want.

237
00:22:54,850 --> 00:23:03,570
Now, you can actually batch all this together so that you don't have to, you know, do this all stepwise.

238
00:23:03,570 --> 00:23:12,350
But when I just ran that command, the PAIS underscore ping command, it then created, you know, the binary of the encapsulated payload.

239
00:23:12,350 --> 00:23:15,190
Anyway, that's what I'm showing here.

240
00:23:15,310 --> 00:23:17,610
So I ran that ping command.

241
00:23:17,610 --> 00:23:23,390
Then I ran the other command that gives me the encapsulated payload.

242
00:23:23,390 --> 00:23:30,770
And now I can run another program called AIS NMEA, and it now creates for me an AIS message.

243
00:23:30,770 --> 00:23:37,670
And so from here, I can either transmit this, I can put it into a file with some timestamps, and I can make things happen.

244
00:23:38,310 --> 00:23:54,750
Some of you, if you heard me talk yesterday and you saw that I created some virtual ATONs, well, basically what I did is I determined what's the latitude and longitude of where I wanted the ATON to be, what type of ATON did I want it to be, and I just created a bunch of these messages,

245
00:23:54,750 --> 00:23:59,230
put them in a file, and just sent it up to OpenCPN so that they would appear.

246
00:24:01,750 --> 00:24:05,610
Now, once I've created the message, I need to be able to parse it.

247
00:24:05,830 --> 00:24:12,070
So here, again, is the AIS message right there.

248
00:24:12,830 --> 00:24:23,730
And so this parser shows, basically, obviously parsing it, telling me what the talker ID is, verifying the checksum, and then, you know, showing me what all the contents were.

249
00:24:23,730 --> 00:24:28,430
And you'll notice the only contents of real interest, well, it's a message type one.

250
00:24:28,430 --> 00:24:30,710
That's the one we put in.

251
00:24:30,710 --> 00:24:32,770
There's the latitude and the longitude.

252
00:24:33,290 --> 00:24:38,470
And again, if you wanted, you could take that URL and, you know, look it up in Google Maps or something like that.

253
00:24:38,470 --> 00:24:42,310
But in any case, that's the tool that I have.

254
00:24:42,470 --> 00:24:45,210
Now, where I'm going with this is this.

255
00:24:45,210 --> 00:24:58,450
I could take that same message, I could go to a public AIS message parser, like I've done here at AGGsoft, put in the message, decode it, and it tells me all the stuff that's there.

256
00:24:58,650 --> 00:25:06,690
One thing I would like you to notice is it is telling me that it is showing all 26 of 26 entries.

257
00:25:07,870 --> 00:25:12,310
And this will be important later on when I talk about the backward compatibility stuff.

258
00:25:14,570 --> 00:25:19,790
Here, by the way, are the 27 different AIS message types.

259
00:25:20,750 --> 00:25:26,090
Like I said, my tools deal right now, I think, with 17 or 18 of these.

260
00:25:26,450 --> 00:25:31,550
But in any case, what I'm also showing you here is the length of the message.

261
00:25:32,470 --> 00:25:36,490
A lot of the messages are exactly 168 bits.

262
00:25:36,730 --> 00:25:40,410
Some of the messages are different sizes.

263
00:25:40,410 --> 00:25:42,430
Some are variable length.

264
00:25:42,990 --> 00:25:50,010
And anyway, I mention this because, again, this will be something that will come up a little bit later on.

265
00:25:52,270 --> 00:25:57,210
So here is what my demonstration and capability tool did.

266
00:25:57,210 --> 00:26:05,890
First thing, I decided that I can use crypto methods to deal with the problem of message bit integrity.

267
00:26:05,890 --> 00:26:09,050
Again, not just individual sentence integrity.

268
00:26:09,090 --> 00:26:17,130
If I've got a message that's 1,000 bits, well, a standard message can only be about 168 bits.

269
00:26:17,150 --> 00:26:22,490
So a 1,000-bit message is going to need multiple fragments, multiple sentences.

270
00:26:22,490 --> 00:26:31,250
The way the checksum works in NMEA right now is there's a checksum on each sentence, but there's no checksum on the message as a whole.

271
00:26:32,250 --> 00:26:35,790
There's no timing integrity, so I needed a timestamp.

272
00:26:35,790 --> 00:26:44,210
There's no validity and authentication of the sender, so this sounds like public-key cryptography is just screaming for that.

273
00:26:44,210 --> 00:26:46,850
But I also needed to have backward compatibility.

274
00:26:46,850 --> 00:26:53,090
I needed to have a method that I could apply, and it wouldn't screw up the system just by being used.

275
00:26:53,450 --> 00:26:56,070
So here is my proposed solution.

276
00:26:56,310 --> 00:26:59,250
I call this working in protected mode.

277
00:26:59,250 --> 00:27:02,290
So I'm a sender, and I have a message to send.

278
00:27:02,290 --> 00:27:15,250
What my equipment will do is it creates a 16-character what I call protect string, and the protect string comprises a timestamp and a checksum for the entire payload.

279
00:27:15,250 --> 00:27:30,850
That protect string is now encrypted with the sender's private key, and that protection string is now just appended to the normal content of an NMEA sentence.

280
00:27:31,030 --> 00:27:49,090
If you're a receiver and you're operating in protected mode, when you get a message and you detect that there is a protect string, what you do is the first thing is you know the MIMSY of the sender, so you can decrypt it with the sender's public key.

281
00:27:49,090 --> 00:27:52,750
That allows you then to recover the timestamp and the checksum.

282
00:27:52,750 --> 00:28:08,270
You now compute a checksum, make sure it matches the received checksum, and then you compare the timestamp to the current time to see, well, is this message arriving anywhere near in a reasonable time?

283
00:28:09,830 --> 00:28:23,490
Now, as far as public key cryptography is concerned, I decided to use the MIMSY as the key, and the reason being was MIMSYs are different from the IMO number of a vessel.

284
00:28:24,490 --> 00:28:28,010
IMO numbers are attached to a vessel.

285
00:28:28,170 --> 00:28:31,370
MIMSYs are pretty much attached to AIS equipment.

286
00:28:31,750 --> 00:28:48,730
And so my idea was, well, if each MIMSY has an assigned private-public key pair, then the AIS device keeps as a closely held secret its private key, and the public key we now have to make somehow available.

287
00:28:48,890 --> 00:28:50,810
And we'll talk about that later.

288
00:28:51,830 --> 00:28:56,050
So anyway, graphically, here again is the example.

289
00:28:56,050 --> 00:29:00,270
I've got my AIS device there on the left.

290
00:29:00,270 --> 00:29:04,510
It has some sort of certificate where it has its own private key.

291
00:29:04,510 --> 00:29:16,550
It has access to a public key database when it prepares its outgoing messages, just like it always has, if it's going to be using this so-called protect mode.

292
00:29:16,550 --> 00:29:21,790
It creates the protect string, encrypted again with the device's private key.

293
00:29:21,790 --> 00:29:25,050
It gets appended to the AIS message.

294
00:29:25,150 --> 00:29:30,570
And now it needs to get all of the time slots that it needs to send out the entire message.

295
00:29:30,710 --> 00:29:45,210
When it receives an incoming message and it detects the presence of a protect string, it can then, you know, again, it knows the MIMSY, go get the public key of the sender, and it can then decrypt everything.

296
00:29:46,070 --> 00:29:49,710
So my new sentence structure then looks like this.

297
00:29:49,770 --> 00:29:51,470
I still have a header.

298
00:29:51,750 --> 00:29:53,550
I have content.

299
00:29:54,210 --> 00:30:01,950
And if the message were small enough, actually, there would be a protect string, and then there would be trailer.

300
00:30:02,050 --> 00:30:09,030
I actually think I've misdrawn this picture, and I will actually redraw it before it gets out into the wild.

301
00:30:09,030 --> 00:30:11,210
The sentence structure doesn't change.

302
00:30:11,210 --> 00:30:13,870
The protect string gets added to the content.

303
00:30:13,870 --> 00:30:19,310
And if it requires more than one sentence, every sentence looks the same, header, content, trailer.

304
00:30:19,310 --> 00:30:22,450
But now the protect string is part of the content.

305
00:30:24,670 --> 00:30:26,790
So what does my protect string look like?

306
00:30:26,790 --> 00:30:28,470
Well, I mentioned it's a timestamp.

307
00:30:28,730 --> 00:30:30,530
I've got a four-digit year.

308
00:30:30,670 --> 00:30:34,910
I've been writing Y2K-compliant code since 1973.

309
00:30:35,250 --> 00:30:41,170
Anyway, I've got a four-digit year, month, day, hour, minute, second, all that kind of stuff.

310
00:30:41,170 --> 00:30:44,330
It should be clear that you need to have the year.

311
00:30:44,330 --> 00:30:51,310
If you don't have the year, if you only had month and day, somebody could do a replay attack one year later.

312
00:30:51,690 --> 00:30:55,790
And so, like I said, you need to have a complete timestamp.

313
00:30:56,870 --> 00:30:58,390
Then I have a checksum.

314
00:30:58,650 --> 00:31:05,870
Right now, I've only used an 8-bit exclusive or checksum because it's the same as that's used for the rest of the NME message.

315
00:31:05,870 --> 00:31:07,850
And I figured, well, you know, code reuse.

316
00:31:08,230 --> 00:31:10,530
It'd be trivial to put in a CRC8.

317
00:31:10,530 --> 00:31:12,090
I'll talk about that in a minute.

318
00:31:12,150 --> 00:31:21,290
Anyway, and then I use a 256-bit RSA key to encrypt the timestamp and checksum.

319
00:31:21,370 --> 00:31:27,410
Now, I need to slow down here for a second because there really is a reason that I chose this.

320
00:31:27,410 --> 00:31:40,510
I chose RSA because when I was looking at the various crypto libraries, the RSA library had a feature that I wasn't finding in any of the other libraries.

321
00:31:40,510 --> 00:31:44,030
And when we talk about the library in a minute, I'll tell you what that feature was.

322
00:31:44,030 --> 00:31:55,990
The second thing is when I use a 256-bit key, I generate a 258-bit encrypted string.

323
00:31:55,990 --> 00:32:06,850
And as you can see here from the slide, that generates a 26 to 154% protocol overhead, which is awful.

324
00:32:06,970 --> 00:32:20,070
But the first time I ran this, when I was doing my experiments and I had a standard RSA key, you know, two kilobits, four kilobits, I was generating a several thousand-bit encrypted string.

325
00:32:20,070 --> 00:32:29,590
Well, if 258 bits is 154% overhead, you can imagine what a, you know, 3000-bit encrypted string was.

326
00:32:29,610 --> 00:32:38,590
So I found the 256-bit key was the shortest length key that would encrypt the 16-byte protection string.

327
00:32:38,610 --> 00:32:43,710
If I used a 128-bit key, I could only encrypt a 5-byte string.

328
00:32:43,710 --> 00:32:49,410
And if I used a 512-bit key, I got a 540-bit protect string.

329
00:32:49,410 --> 00:33:02,010
So, again, you can see what I was trying to do here was trade off getting the protection of encryption, but at the same time not overwhelming the protocol with a ton of overhead.

330
00:33:03,550 --> 00:33:13,270
So the OpenSSL RSA Crypto library has the functions that are listed there that generate key functions, encrypt, decrypt, and all that kind of stuff.

331
00:33:13,270 --> 00:33:23,090
But when you use the encrypt function, it not defaulted, it meant you encrypted using the public key.

332
00:33:23,370 --> 00:33:26,830
And when you decrypted, you decrypted with the private key.

333
00:33:26,930 --> 00:33:31,890
If you wanted message authentication, you had to use the sign function.

334
00:33:32,190 --> 00:33:40,010
But a digital signature is huge because they add all sorts of other things that I didn't want to add.

335
00:33:40,010 --> 00:33:53,390
What I wanted was merely the feature of a signature that provided me authentication for the sender, but I didn't need everything and all the baggage that came with the signature.

336
00:33:53,390 --> 00:34:01,990
So the OpenSSL RSA library also has functions called private encrypt and public decrypt.

337
00:34:01,990 --> 00:34:12,850
So that allowed me to encrypt with my private key so that you could decrypt with my public key and now you would know that I was the real sender.

338
00:34:12,850 --> 00:34:22,070
So the only functions out of this Crypto library that I use are the generate key, so I can generate a public-private key pair, and private encrypt and public decrypt.

339
00:34:22,190 --> 00:34:27,570
Those were, no pun intended, those were the keys to making this all work.

340
00:34:28,430 --> 00:34:31,570
Anyway, so here's another example.

341
00:34:31,610 --> 00:34:38,930
This is the same message that we had before, but when I do the ping command, everything differents in red.

342
00:34:38,930 --> 00:34:44,510
So what I did is I added a switch called the protect switch.

343
00:34:44,510 --> 00:34:46,650
So this tells me we're in protected mode.

344
00:34:46,650 --> 00:34:57,570
So now what happens when I ran this program, or ran this particular message, it tells me that the payload is going to be appended with a timestamp and a checksum.

345
00:34:57,570 --> 00:35:04,450
So there's the timestamp and the checksum, and it's going to be encrypted with the private key associated with that particular MNSI.

346
00:35:04,730 --> 00:35:09,930
Now, if I go back here for a second, I always forget where I put these things.

347
00:35:09,950 --> 00:35:12,830
You'd think that after all this time I would know.

348
00:35:12,830 --> 00:35:15,550
I have my public and private key ring.

349
00:35:15,550 --> 00:35:20,950
So if I do an ls-la of my public key ring...

350
00:35:20,950 --> 00:35:28,650
So here are all the public keys that I have stored in my experimentation.

351
00:35:28,650 --> 00:35:30,050
I just needed numbers.

352
00:35:30,050 --> 00:35:38,130
And you can probably imagine that I have their private keys in a different key ring, and so there's the private keys.

353
00:35:38,130 --> 00:35:49,010
So in any case, when I run the program, that's why it's important that I use a key that I have my public and my private keys for.

354
00:35:49,010 --> 00:35:54,810
In any case, so now I run my next program that's going to create my binary string.

355
00:35:55,090 --> 00:36:02,910
If you were to go back to the other slide and do a comparison, everything here in black matches what was in example number one.

356
00:36:02,910 --> 00:36:05,150
Everything here in red has been appended.

357
00:36:05,710 --> 00:36:12,670
So now, when I create this message, it's now 426 bits.

358
00:36:12,670 --> 00:36:14,290
It's going to be using two fragments.

359
00:36:14,290 --> 00:36:16,310
I've decided to use serial number seven.

360
00:36:16,310 --> 00:36:17,870
I don't know why seven's so hot.

361
00:36:17,870 --> 00:36:22,770
But in any case, you can see down here, here are the two sentences that get generated.

362
00:36:24,250 --> 00:36:30,190
And when I parse it, again, I have now two sentences that need to be parsed.

363
00:36:30,190 --> 00:36:40,370
The first sentence now is sentence number one of two, and again has jazz that we didn't see before.

364
00:36:40,650 --> 00:36:42,570
The checksum, you know, works.

365
00:36:42,570 --> 00:36:43,510
That's good.

366
00:36:43,510 --> 00:36:52,090
And if I go down here, you'll notice that when I parse the message, everything in black is the exact same as it was before.

367
00:36:52,090 --> 00:36:54,270
But now we have some additional information.

368
00:36:54,270 --> 00:36:56,730
We've got the protected AIS information.

369
00:36:56,730 --> 00:36:58,670
So I know my sender is Mimsy.

370
00:36:58,670 --> 00:37:03,430
I know that it's authenticated because I compared it to the certificate that I have.

371
00:37:04,150 --> 00:37:05,630
There's the timestamp.

372
00:37:05,630 --> 00:37:07,890
I compare it to the received timestamp.

373
00:37:07,890 --> 00:37:13,950
Well, you can see it got there about six months later, but or at least six months later.

374
00:37:14,710 --> 00:37:15,890
Now, I guess I'm sorry.

375
00:37:15,890 --> 00:37:17,270
That's only about 10 days later.

376
00:37:17,270 --> 00:37:19,850
I have some examples that are even worse.

377
00:37:19,850 --> 00:37:27,290
I just set a threshold saying here's a I'll tell you how many seconds since the message was sent to when you received it.

378
00:37:27,530 --> 00:37:30,130
If it's over 30, I just say it's over 30.

379
00:37:30,130 --> 00:37:32,790
You could actually tune that, presumably.

380
00:37:33,450 --> 00:37:36,850
But in any case, and then I've got the checksum and it's verified.

381
00:37:36,930 --> 00:37:39,250
And again, that's the checksum over the entire message.

382
00:37:39,250 --> 00:37:42,230
So then I know the message hasn't been screwed with.

383
00:37:43,070 --> 00:37:54,270
When I take these two sentences and I poke them in to the AGGsoft decoder, you will notice I get the same AIS information I got before.

384
00:37:54,270 --> 00:38:03,990
And if you recall, the last time we saw this, I wanted you to pay attention to the fact that it was giving me one to 26 of 26 entries.

385
00:38:04,030 --> 00:38:06,650
That's what the software is telling me now as well.

386
00:38:06,650 --> 00:38:11,230
So basically, a Type 1 message is 168 bits.

387
00:38:11,250 --> 00:38:18,190
The AGGsoft software and OpenCPN as well will just say, oh, Type 1.

388
00:38:18,190 --> 00:38:20,150
Type 1 is 168 bits.

389
00:38:20,150 --> 00:38:21,410
That's all I'm looking at.

390
00:38:21,410 --> 00:38:24,310
And it ignored all the other bits.

391
00:38:24,330 --> 00:38:29,150
So this was a way of saying, OK, I can demonstrate I've got some backward compatibility.

392
00:38:31,110 --> 00:38:34,890
So what my little project was able to show was this.

393
00:38:34,890 --> 00:38:38,750
I can solve the message integrity problem using a checksum.

394
00:38:38,890 --> 00:38:41,770
I can solve timing integrity by using a timestamp.

395
00:38:41,770 --> 00:38:49,910
I can deal with validity and authentication because I have public key cryptography and I can use the sender's private key.

396
00:38:49,910 --> 00:39:00,210
I can get backward compatibility because it appears that what my experimentation so far is that software and devices will ignore any of the excess bits.

397
00:39:00,230 --> 00:39:03,410
Geographic integrity, I didn't even try to work on that.

398
00:39:03,410 --> 00:39:15,290
Because geographic integrity needs to say, you know, I'm a device telling you that I'm at latitude 29 north, 80 degrees longitude west or longitude 80 west.

399
00:39:15,290 --> 00:39:17,050
How do I prove that?

400
00:39:17,050 --> 00:39:20,230
And I need to have some other methods to do that.

401
00:39:21,350 --> 00:39:24,470
So obviously, the big problem is key distribution.

402
00:39:24,770 --> 00:39:29,210
This only works if you can figure out how to distribute your public and private key pairs.

403
00:39:29,670 --> 00:39:36,270
However, the method that I've described isn't dependent upon your key distribution method.

404
00:39:36,270 --> 00:39:38,970
It just observes, yeah, you probably need to have one.

405
00:39:40,090 --> 00:39:42,950
So the other nice thing is this.

406
00:39:42,950 --> 00:39:54,630
Let's say your device, and it's going to take you 10 seconds to figure out somebody else's or get access to their public key.

407
00:39:54,910 --> 00:40:03,710
The fact is, I can accept the message for what it's worth and display it, even though it's taking me 10 seconds to go figure out whether the message is valid or not.

408
00:40:03,710 --> 00:40:10,610
So, you know, in my ideal world, I see that you could have messages that you have authenticated, and they're in one color.

409
00:40:10,610 --> 00:40:20,930
You've got other messages that are being authenticated, they're in another color, and messages that cannot be authenticated, they're in third color.

410
00:40:21,610 --> 00:40:25,610
But in any case, there are a variety of ways of doing key distribution.

411
00:40:25,610 --> 00:40:34,710
We could use existing public key infrastructure methods, such as, you know, X.509 certificates that we use today with things like SSL.

412
00:40:34,750 --> 00:40:39,610
We could use a model, a distributed hierarchical database, such as the DNS.

413
00:40:39,650 --> 00:40:50,630
There are currently a billion hosts in the DNS, and yet we can get an IP address from a host name in, you know, milliseconds.

414
00:40:50,630 --> 00:40:54,670
Well, there's way less than a billion assigned MIMSIs.

415
00:40:54,790 --> 00:40:58,150
So maybe we could do some sort of database like that.

416
00:40:58,150 --> 00:41:03,390
And that probably is the way a lot of the literature suggests we could go.

417
00:41:03,930 --> 00:41:06,550
You could do something like PGP's Web of Trust.

418
00:41:06,550 --> 00:41:10,270
I will observe that a Web of Trust just isn't scalable.

419
00:41:10,270 --> 00:41:20,850
I mean, PGP Web of Trust is barely scalable between me and the other, you know, couple hundred people I know that use PGP.

420
00:41:21,230 --> 00:41:27,770
But it's certainly not going to be scalable to a very mobile industry, such as maritime.

421
00:41:28,650 --> 00:41:33,110
And I mentioned here, there's some other papers that have talked about a number of other things.

422
00:41:33,830 --> 00:41:42,470
And in terms of using public key crypto or using some sort of identity based crypto, there are all sorts of ways of doing this.

423
00:41:42,530 --> 00:41:47,190
Most are observing if they don't want to change the entire AIS protocol.

424
00:41:47,290 --> 00:41:53,210
We don't want to have a centralized certificate authority that doles it out to everybody.

425
00:41:53,210 --> 00:41:55,630
And you have to go back to that central CA.

426
00:41:55,650 --> 00:41:58,590
Most are talking about having some sort of hierarchy.

427
00:41:58,910 --> 00:42:01,390
So, for example, and I'm making this up.

428
00:42:01,390 --> 00:42:04,670
I haven't talked to anybody about this, certainly in a formal way.

429
00:42:04,670 --> 00:42:07,750
But let's say you use the MIMSI.

430
00:42:07,830 --> 00:42:11,190
Well, every country has its own maritime authority.

431
00:42:11,190 --> 00:42:15,350
And within the MIMSI, there is an identifier that identifies the country.

432
00:42:15,350 --> 00:42:17,970
So maybe every country has its own database.

433
00:42:18,210 --> 00:42:20,710
So I'm able to look at the MIMSI.

434
00:42:20,710 --> 00:42:22,610
I can figure out the country ID.

435
00:42:22,610 --> 00:42:24,030
I go to that country ID.

436
00:42:24,030 --> 00:42:26,610
It's been pre-programmed in where their database is.

437
00:42:26,610 --> 00:42:28,470
You know, all ships are connected to the Internet.

438
00:42:28,470 --> 00:42:29,890
So they could be able to do that.

439
00:42:29,890 --> 00:42:33,530
So anyway, like I said, I'm just sort of making that up as a possible example.

440
00:42:34,010 --> 00:42:36,870
There are still open issues with this.

441
00:42:37,410 --> 00:42:47,290
What I've described here certainly does not protect me against a bad actor who legitimately has an AIS device that can operate in protected mode.

442
00:42:48,450 --> 00:42:54,630
And it also doesn't stop anybody who's got a device from sending purposely false information.

443
00:42:54,690 --> 00:42:59,050
Now, presumably, they're only going to be able to do it once.

444
00:43:00,050 --> 00:43:05,310
Because, you know, once they've started to send bad information, everybody's on them.

445
00:43:05,590 --> 00:43:13,250
The other thing is backward compatibility means I'm willing to accept messages that can't be authenticated.

446
00:43:13,250 --> 00:43:18,350
Well, that means nothing stops a bad actor from just never being authenticated.

447
00:43:18,350 --> 00:43:32,970
But if you're differentiating between authenticated messages being authenticated and unauthenticated, so, you know, it puts the bad actor in the unauthenticated space.

448
00:43:33,390 --> 00:43:36,990
Anyway, any number of places to go for future research with this.

449
00:43:37,170 --> 00:43:40,530
Right now, like I said, I use a checksum that's a bitwise exclusive.

450
00:43:40,530 --> 00:43:42,590
Or I could use a CRC8.

451
00:43:42,590 --> 00:43:44,690
Hell, I could use a CRC16.

452
00:43:45,090 --> 00:43:46,590
Both would be better.

453
00:43:46,590 --> 00:43:53,150
Both would keep the protect string well within what a 128-bit key could manage.

454
00:43:53,270 --> 00:43:56,770
My current timestamp is 112 bits.

455
00:43:56,810 --> 00:44:04,010
I could use a Unix epic time and not human readable time if I wanted to make it smaller.

456
00:44:04,010 --> 00:44:13,970
It turns out if I make it smaller, it still doesn't make the protect string any smaller because I still have to use a 128-bit key.

457
00:44:13,970 --> 00:44:16,310
A 256-bit key, rather, sorry.

458
00:44:16,610 --> 00:44:20,590
I still end up with a 258-bit protected string.

459
00:44:22,010 --> 00:44:25,690
So, like I said, I could manipulate that, make it a little bit less human readable.

460
00:44:26,490 --> 00:44:28,310
Public sharing I'm doing.

461
00:44:28,310 --> 00:44:31,070
My public key sharing is done via a web of trust.

462
00:44:31,070 --> 00:44:36,670
I think at some really official level, you need something way more dynamic and distributed.

463
00:44:36,670 --> 00:44:39,470
But this is sort of where I ended doing my research.

464
00:44:39,570 --> 00:44:46,030
And I was able to get this to work with almost all message types that I support.

465
00:44:46,030 --> 00:44:52,270
I couldn't get it to work with message types that were hugely of variable length.

466
00:44:52,270 --> 00:45:02,870
Because the problem is one way in which you detect that you've got a protect string, like on a type one message, is you see I'm expecting 168 bits.

467
00:45:02,870 --> 00:45:11,290
Anything beyond that, I'm just going to assume is a protect string, particularly if it is whatever 168 plus 258 is.

468
00:45:11,290 --> 00:45:14,610
You know, if that's how long the message is, I've got a protect string.

469
00:45:14,610 --> 00:45:23,270
If I've got a variable length message, though, I don't know, well, was the message, you know, a thousand bits?

470
00:45:23,270 --> 00:45:28,750
Or was the message 650 bits and I've got another 350 bits of protect string out there?

471
00:45:28,750 --> 00:45:30,330
You know, you got the idea.

472
00:45:30,330 --> 00:45:35,490
Variable length was a little bit difficult, unless I could flag that I had a protected string attached.

473
00:45:35,490 --> 00:45:38,830
But there's no way within the current protocol to do that.

474
00:45:39,970 --> 00:45:45,770
So anyway, I've got some references for further reading, if people would like to furtherly read.

475
00:45:46,530 --> 00:45:49,390
And obviously, here's my contact information.

476
00:45:49,390 --> 00:45:54,890
I've not yet put this software up online, although I'm being incented.

477
00:45:54,890 --> 00:45:55,710
Well, not incented.

478
00:45:55,710 --> 00:45:58,550
I'm being encouraged to do so, and I probably will.

479
00:45:58,550 --> 00:46:09,550
One thing I do have to say, though, is that the tools that I currently have up on my website, I believe, are usable by people.

480
00:46:09,550 --> 00:46:14,330
If they can read my readme.txt file, they'll be usable.

481
00:46:14,590 --> 00:46:18,530
The protected AIS is not quite as ready for primetime.

482
00:46:18,530 --> 00:46:26,170
But if people want to play with it, like I said, I will put it up at one of the sites I've been talking to to read out about that.

483
00:46:26,170 --> 00:46:31,590
But if you want to ping me earlier, I'm at the point of not minding sharing them.

484
00:46:32,970 --> 00:46:39,990
In any case, that's pretty much what I had to say about that.

485
00:46:40,310 --> 00:46:44,070
And so let me come back around to here.

486
00:46:45,570 --> 00:46:49,790
And I've got, well, let's see, I've got a number of comments.

487
00:46:50,770 --> 00:46:53,930
Okay, they can see my desktop now.

488
00:46:54,270 --> 00:46:57,610
Let me see what readout's got here for me.

489
00:47:01,360 --> 00:47:05,480
Yeah, readout makes the point that I could have used elliptic curve.

490
00:47:07,480 --> 00:47:09,480
I'd have to look at elliptic curve.

491
00:47:09,480 --> 00:47:12,480
Again, the real...

492
00:47:12,480 --> 00:47:15,700
Again, I hesitate to use the word key here.

493
00:47:15,700 --> 00:47:27,140
The issue that I have is I need a library that will allow me to encrypt with a private key and decrypt with a public key.

494
00:47:27,380 --> 00:47:29,260
But other than that, absolutely.

495
00:47:29,260 --> 00:47:37,660
And I, you know, I will freely admit, though, I never got around to looking at the ECC libraries, because as soon as I found RSA, I got real excited.

496
00:47:37,660 --> 00:47:43,740
But clearly, ECC will give me the same level of protection with a far smaller key.

497
00:47:48,840 --> 00:47:51,960
And let me go back to here.

498
00:47:52,740 --> 00:47:56,940
And let's see.

499
00:47:57,100 --> 00:47:58,660
There's a message here somewhere.

500
00:47:58,660 --> 00:47:59,900
I just don't know where it is.

501
00:48:02,680 --> 00:48:07,480
Anyway, if there are other questions, absolutely let me know.

502
00:48:07,480 --> 00:48:09,200
I will have these slides.

503
00:48:09,400 --> 00:48:10,560
There are a couple of corrections.

504
00:48:10,560 --> 00:48:11,960
I'm embarrassed about this.

505
00:48:11,960 --> 00:48:17,600
Believe it or not, you probably will believe it, I was editing this slide deck up until about 15 minutes before the talk.

506
00:48:18,340 --> 00:48:21,640
So there are a couple errors that I found as I was going through.

507
00:48:21,640 --> 00:48:28,140
I will fix them and I will get these slides out and so that they get posted as soon as they can get posted.

508
00:48:50,450 --> 00:48:52,370
I'm hearing lots of beeps.

509
00:49:03,820 --> 00:49:07,600
Well, I've got another talk coming up in about five minutes.

510
00:49:10,300 --> 00:49:16,900
And so what I will do is, well, I'll hang out here for a couple minutes.

511
00:49:16,900 --> 00:49:18,840
They'll reset me in a few minutes.

512
00:49:18,900 --> 00:49:24,280
And I have a little like challenge problem that I want to share with people.

513
00:49:24,520 --> 00:49:27,240
It'll only take about 15 or 20 minutes to go through that.

514
00:49:27,240 --> 00:49:29,900
But otherwise, you know, thank you all very, very much.

515
00:49:29,900 --> 00:49:40,180
And like I said, ping me one way or another if you've got questions or comments and, you know, my pleasure to be here and thanks for listening to this.

516
00:57:32,820 --> 00:57:36,520
Okay, folks, I think we are back.

517
00:57:36,960 --> 00:57:40,560
Let me try once again sharing my screen.

518
00:57:46,100 --> 00:57:51,620
And once again, I'm going to live dangerously and show the whole thing.

519
00:57:53,160 --> 00:58:10,500
So when we were talking about ideas for talks and projects and things like that, one of the things that I just happened to mention and somebody said, well, this seems like it'd be an interesting, you know, little challenge type of project to do.

520
00:58:10,500 --> 00:58:15,700
And I'm going to talk to you about something called AIS point prediction.

521
00:58:16,160 --> 00:58:18,220
So so here's the general idea.

522
00:58:18,220 --> 00:58:22,660
And if I was better at drawing graphics, I could have drawn you some graphics.

523
00:58:22,760 --> 00:58:29,180
So I'm going to try going out here to OpenCPN to see what kind of things we got going out here.

524
00:58:29,700 --> 00:58:32,020
What I really need and I probably don't have.

525
00:58:32,020 --> 00:58:33,820
Well, actually, I probably do have.

526
00:58:33,820 --> 00:58:38,820
But you see these vessels out here.

527
00:58:39,660 --> 00:58:42,460
This vessel right here, the Janus, we know is a sailboat.

528
00:58:42,460 --> 00:58:44,560
It looks like it's about to come in Ponce Inlet.

529
00:58:44,840 --> 00:58:47,600
The Sea King, I don't know anything about the Sea King.

530
00:58:47,740 --> 00:58:48,900
It's also a Type B.

531
00:58:48,900 --> 00:58:50,540
That's too bad, but that's OK.

532
00:58:51,400 --> 00:59:03,060
On AIS messages, vessels that are by Code of Federal Regulations required to transmit, Class A type of vessels.

533
00:59:03,060 --> 00:59:09,960
So the really big ones have a lot of passengers, have a certain tonnage or horsepower.

534
00:59:09,980 --> 00:59:11,700
They're Class A.

535
00:59:11,720 --> 00:59:16,840
And a Class A is going to be telling me all the information that's down here.

536
00:59:16,840 --> 00:59:20,940
They'll be telling me a speed, course, heading and turn rate.

537
00:59:21,260 --> 00:59:27,080
They'll also be communicating relatively frequently.

538
00:59:27,440 --> 00:59:33,940
Class B vessels, the smaller ones, aren't required to transmit.

539
00:59:34,160 --> 00:59:40,660
And in fact, in a Class B position report, there's no way to even tell me about a turn rate.

540
00:59:40,660 --> 00:59:43,980
So the reason I'm telling you that is so that I can tell you this.

541
00:59:43,980 --> 00:59:53,040
My question is, and here's an example of Louisiana, which was just offshore pretty recently, a tanker, offshore Daytona.

542
00:59:53,040 --> 01:00:08,700
So if I know a ship's latitude, longitude, speed over ground, course over ground and turn rate, can I predict where they will be the next time they give me a position report?

543
01:00:09,440 --> 01:00:13,880
And in some ways, this sounds like a trivial exercise.

544
01:00:14,440 --> 01:00:16,460
I fooled around a little bit with it.

545
01:00:16,460 --> 01:00:17,320
Not a lot.

546
01:00:17,320 --> 01:00:19,920
It's a really interesting exercise.

547
01:00:21,660 --> 01:00:30,100
And the idea came to me some time ago, the idea being, you know, I'm at a particular place.

548
01:00:30,100 --> 01:00:36,320
And suppose a bad guy spooks their AIS latitude, longitude of a vessel.

549
01:00:36,320 --> 01:00:39,300
And they try to, let's say, knock Louisiana off the air.

550
01:00:39,300 --> 01:00:41,760
And now they spook, bing, Louisiana.

551
01:00:42,220 --> 01:00:51,080
Well, suppose their next position report puts me five miles away.

552
01:00:51,320 --> 01:00:56,420
Well, there's no way that I can move five miles in a minute.

553
01:00:56,420 --> 01:01:07,720
So my AIS receiver could maybe flash red to say, we just got something that just doesn't seem right.

554
01:01:08,640 --> 01:01:22,680
Now, the other thing, by the way, that this AIS message will tell us, this position message, this and other things, is you'll notice that this is also giving me the destination and ETA of when I plan on getting there.

555
01:01:22,680 --> 01:01:33,280
So this vessel, which I saw the other day, probably about four or five days ago, is expected tomorrow morning at seven in the morning UTC to be in Texas.

556
01:01:33,280 --> 01:01:37,580
So it must have, well, it must have been several days ago.

557
01:01:37,860 --> 01:01:41,120
Anyway, so where I'm going with this is this.

558
01:01:41,120 --> 01:01:46,680
Again, an AIS type one, two or three message is a class A position report.

559
01:01:46,760 --> 01:01:50,900
And the information that matters to me is it's going to give me a latitude.

560
01:01:51,580 --> 01:02:00,240
For those of you that are not familiar with the relationship between latitude, longitude and distance, it is vaguely as follows.

561
01:02:00,240 --> 01:02:03,860
One degree of latitude is 60 nautical miles.

562
01:02:03,860 --> 01:02:07,180
One minute of latitude is one nautical mile.

563
01:02:08,900 --> 01:02:17,720
Longitude is about, one degree of longitude is about 60 nautical miles at the equator, which is zero degrees latitude, of course.

564
01:02:17,720 --> 01:02:28,800
But for every other, any other latitude, a degree of longitude, the linear distance is going to be some function of the latitude.

565
01:02:29,220 --> 01:02:32,560
And think about a globe.

566
01:02:32,560 --> 01:02:40,080
And of course, as you get closer and closer to the North Pole, one degree of longitude gets to be almost nothing.

567
01:02:40,140 --> 01:02:44,940
Whereas one degree of longitude at the equator is 60 nautical miles.

568
01:02:44,940 --> 01:02:47,420
Anyway, I mentioned that later on.

569
01:02:47,880 --> 01:02:52,160
Then we're going to have the course in degrees, zero degrees being true north.

570
01:02:52,160 --> 01:02:56,780
And so an actual course will be somewhere between zero and 359.

571
01:02:56,920 --> 01:03:05,160
The speed in knots, a knot, of course, is a nautical mile per hour, which translates to about 1.15 miles per hour.

572
01:03:05,580 --> 01:03:10,840
I'm going to have a rate of turn, which is generally expressed in the number of degrees per minute, left or right.

573
01:03:10,840 --> 01:03:19,200
And the time between transmission is going to be a function of what is your speed and what is your rate of turn.

574
01:03:20,060 --> 01:03:22,400
And it turns out there's a standard for this.

575
01:03:22,400 --> 01:03:25,860
And if only the standard matched the reality, life would be a good thing.

576
01:03:26,280 --> 01:03:33,040
But here is actually an example and talks about some of the additional issues related to the problem.

577
01:03:33,340 --> 01:03:38,980
So I only care about the class A transponder types, although I'm showing you class Bs as well.

578
01:03:38,980 --> 01:03:45,760
So technically speaking, if you're a class A vessel and you're an anchor, you just need to transmit every three minutes.

579
01:03:45,920 --> 01:03:48,760
Now, you may be saying, but I'm an anchor.

580
01:03:48,760 --> 01:03:50,180
I'm not moving.

581
01:03:50,180 --> 01:03:58,320
Well, again, AIS class A devices, you might be talking about a vessel that is several hundred meters in length.

582
01:03:58,320 --> 01:04:18,540
If it's anchored or moored, the position of the bridge might be actually composing a circle that if that ship were to swing around its anchor in a 360 degree circle, you might be talking about a radius of many hundreds of meters.

583
01:04:18,540 --> 01:04:25,240
Well, a nautical mile is about 2,000 yards.

584
01:04:25,740 --> 01:04:31,860
So I might, like I said, I might have a pretty big swing radius.

585
01:04:31,860 --> 01:04:41,680
In any case, if I'm sailing, not sailing, obviously, but underway, between zero and 14 knots, I'm supposed to be transmitting every 10 seconds.

586
01:04:41,700 --> 01:04:50,700
If I am sailing at a speed of zero to 14 knots and changing course, I need to be transmitting every 3.33 seconds.

587
01:04:50,700 --> 01:04:54,360
So that's how you read the chart in terms of transmission rate.

588
01:04:54,440 --> 01:05:01,220
What I did is I then translated this and said, well, what's the maximum distance I can travel in that amount of time?

589
01:05:01,220 --> 01:05:09,920
Well, if I'm going 14 knots and I'm transmitting every 10 seconds, I'm only going to be traveling 77 yards.

590
01:05:09,920 --> 01:05:11,480
That's not very far.

591
01:05:11,780 --> 01:05:24,920
And you can sort of see as my, as I progressed here, what I was trying to give was an idea of exactly how far might I be going between transmissions.

592
01:05:25,580 --> 01:05:31,900
Now, I mentioned, I wish the reality were, you know, match the standard.

593
01:05:31,960 --> 01:05:36,920
Sometimes we will see vessels going by that are class A vessels and they're pretty big class A vessels.

594
01:05:36,920 --> 01:05:43,640
And like the Louisiana, the Louisiana was going at 15 knots.

595
01:05:43,640 --> 01:05:48,700
Well, at 15 knots, even in a straight line, they should be transmitting every six seconds.

596
01:05:48,720 --> 01:05:53,220
But we had like a minute, that slide that I showed.

597
01:05:53,220 --> 01:06:01,960
So in any case, you know, so the distance or rather the rate between transmissions is something else we need to take into account.

598
01:06:02,280 --> 01:06:06,780
So then I said, well, okay, I've got, I've got a ship here.

599
01:06:07,380 --> 01:06:08,960
That's supposed to be a ship.

600
01:06:08,960 --> 01:06:13,460
And it's at some latitude and longitude, which I'm calling lat zero and long zero.

601
01:06:13,500 --> 01:06:15,460
I know my course over ground.

602
01:06:15,480 --> 01:06:17,380
I know my rate of turn.

603
01:06:17,680 --> 01:06:21,840
And so the question is, all right, well, I've got a triangle in here.

604
01:06:21,840 --> 01:06:24,280
I've got some angle theta.

605
01:06:24,280 --> 01:06:28,980
Now, this may or may not be the right approach to go, by the way, but I've got some angle theta.

606
01:06:29,260 --> 01:06:37,900
And so at some T time later on, I've got my new latitude and longitude, lat one and long one.

607
01:06:38,260 --> 01:06:49,340
And so I will observe that I can figure out the radius of this circle because it's going to be related to the speed over ground and the rate of turn.

608
01:06:49,340 --> 01:06:57,920
I can figure out the distance that I've traveled, that circular distance, that arc, if you will.

609
01:06:57,920 --> 01:07:03,600
That's going to be somehow related to the velocity times the time between the transmissions, the actual time.

610
01:07:03,600 --> 01:07:06,940
And then I've got this delta x and delta y.

611
01:07:06,940 --> 01:07:15,920
Well, delta x is going to be a function of the angle of the circle, the speed over ground and the time, which as will my delta y.

612
01:07:15,920 --> 01:07:31,820
But then my actual change in latitude and longitude has got to be a function of the course plus theta, meaning that if I was just going due north or due anything, it'd be easy.

613
01:07:31,820 --> 01:07:46,880
But as we start to change off of zero degrees, we start to see, you know, some complications because, again, a degree of latitude is the same everywhere in terms of linear length.

614
01:07:46,880 --> 01:07:51,260
But the linear length of a degree of longitude is not going to be the same.

615
01:07:51,420 --> 01:07:56,540
So, like I said, we have, you know, that issue to deal with.

616
01:07:58,940 --> 01:08:12,600
So, again, my targets that I'm going for is if there's no rotation of the ship and the ship is moving in a straight line, well, that's almost easy to do.

617
01:08:13,220 --> 01:08:17,040
If the rate of turn is not zero, my ship is turning.

618
01:08:18,300 --> 01:08:31,300
And so then the other thing I was thinking of is not only can I, how well can I predict my next point, but, you know, we just had a tropical storm down here last week, went up the East Coast.

619
01:08:31,300 --> 01:08:38,320
And so we always look at the National Hurricane Center and they give us this cone of certainty for

620
01:09:11,940 --> 01:09:16,380
, so that if my next point is in the box, do I claim victory?

621
01:09:16,560 --> 01:09:23,600
And am I looking for, well, a really small box or how big will I let my box be?

622
01:09:23,600 --> 01:09:26,740
If I'm going in a straight line, they really are sort of boxes.

623
01:09:26,740 --> 01:09:33,120
If my rate of turn isn't zero, then the boxes actually become a cone.

624
01:09:33,120 --> 01:09:35,900
Am I anywhere in the right range at all?

625
01:09:37,200 --> 01:09:46,200
So, like I said, in terms of a problem, I was just thinking that this sounds like an interesting problem to tinker with.

626
01:09:46,460 --> 01:09:51,740
And, and there's all sorts of places to look at historical information.

627
01:09:51,740 --> 01:10:03,860
What you need to work on, though, if you get historical information, and I could even provide you some, is you need type one, type two, or type three position reports from the same vessel.

628
01:10:04,500 --> 01:10:09,440
And, and the type one, again, because you need rate of turn.

629
01:10:09,440 --> 01:10:15,360
Now, I mentioned something about the length of the degree of latitude and longitude.

630
01:10:15,420 --> 01:10:27,320
So, again, the length of the degree of latitude in meters, there's, there's a formula that I know is used at a number of the government sites.

631
01:10:27,320 --> 01:10:37,400
It was actually easy to find the formula because they have these pages where they have like a JavaScript and you can, you know, put in, you know, what your latitude is.

632
01:10:37,400 --> 01:10:40,340
It will tell you the length of a degree of latitude in meters.

633
01:10:40,340 --> 01:10:44,400
Well, of course, if you right click and look at the page source, you can see their formula.

634
01:10:44,400 --> 01:10:48,100
But it's been used a lot and I've seen it documented in a few places.

635
01:10:48,260 --> 01:10:56,380
In any case, the length of the degree of longitude, again, you will also notice is a function of the latitude.

636
01:10:57,100 --> 01:11:04,420
The length of the degree of latitude and longitude, here, here's, here's a table that I produced largely from those formulas.

637
01:11:04,420 --> 01:11:11,720
And you will notice that a degree of latitude, in terms of nautical miles, it almost doesn't matter where you are.

638
01:11:11,720 --> 01:11:16,860
It's about 60 miles, 60 nautical miles to a degree.

639
01:11:16,860 --> 01:11:23,280
If you look at a degree of longitude, the number of nautical miles, again, at the equator, it's about 60.

640
01:11:23,280 --> 01:11:36,320
And then as you go towards the poles, it increasingly gets smaller and smaller, and then rapidly gets smaller once you get above about, you know, 45 degrees, either north or south.

641
01:11:36,320 --> 01:11:38,800
And that actually, you know, makes sense.

642
01:11:38,800 --> 01:11:43,020
Until, of course, you get to the pole and then the degree of longitude is zero nautical miles.

643
01:11:45,000 --> 01:11:49,220
And again, I've given you some websites where they have more information about this.

644
01:11:49,400 --> 01:11:54,460
And that, more or less, was the challenge.

645
01:11:54,940 --> 01:11:59,020
And as I said, I think it's sort of an interesting problem.

646
01:12:00,100 --> 01:12:05,240
And for a few people, I don't know where we sort of go from there.

647
01:12:05,780 --> 01:12:11,720
I, like I said, I talked to Reid out about this, and I think he talked to a couple of other people.

648
01:12:11,720 --> 01:12:12,800
Interesting problem.

649
01:12:12,800 --> 01:12:19,860
I think what we're looking for is maybe to have some intermediaries, intermediate solutions at some point in the next year.

650
01:12:19,860 --> 01:12:25,360
Maybe revisit this at, have to see, 3.0 next year.

651
01:12:25,500 --> 01:12:29,300
And anyway, so that's where I am.

652
01:12:30,880 --> 01:12:33,380
So, questions, comments?

653
01:12:33,960 --> 01:12:35,900
Let me go back up here.

654
01:12:37,120 --> 01:12:37,720
I...

655
01:12:39,240 --> 01:12:43,120
I'm no longer at Hack the C village.

656
01:12:49,860 --> 01:12:53,040
So I'll sit here for a couple of minutes while we go into Q&A.

657
01:13:20,390 --> 01:13:23,090
Well, where I'm sitting is a lot of dead air.

658
01:13:23,810 --> 01:13:25,830
I'm going to hang out for another few minutes.

659
01:13:26,330 --> 01:13:29,290
Clearly, if anybody's got anything, let me know.

660
01:13:29,570 --> 01:13:35,110
And again, contact me by email or, you know, whatever seems to work.

661
01:13:37,150 --> 01:13:42,150
And, you know, let me know if you have questions and how we might, you know, go forward with this.

662
01:13:42,310 --> 01:13:47,210
And other than that, I thank everybody for attending whatever talks of mine you attended.

663
01:13:47,210 --> 01:13:48,010
I had a blast.

664
01:13:48,010 --> 01:13:49,090
Hope you had a blast.

665
01:13:49,090 --> 01:13:50,370
And go from there.