Matej Peranić | Security of Communication: It’s Not Quantum Physics… Or Is It?

[Music] um welcome and thank you for staying to this last lecture that will be something completely different from everything youve heard today there won't be a single line of code uh uh my name is mate peranich and unlike most of you here today I'm not a cyber security expert um I'm an experimental physicist so I will talk a bit about uh Quant quum physics and uh how can we use quantum physics in the terms of security and Communications um to start with I don't want to bother you too much with with physics and uh Quantum but uh I feel like I have to introduce some some Basics so that uh I will refer to later

later on so um when we say quantum physics what are we actually talking about so we are talking about uh effects that we see the nature uh behaves on the scales on 10 to the minus 10 uh which is basically when we get to the level of atoms and smaller uh in this lecture I will mostly focus and talk about photons um basically particles of light um and when we get to this scales we see that the nature behaves a bit bit differently than on our everyday scale one uh interesting uh thing is that uh we see that the matter exhibits properties of both particles and waves which you learned in high school probably uh that

uh light has these properties and um as a consequence uh we cannot uh describe the nature um like we can describe it in uh in microscopic scales but we have to use uh probability probability and statistics this leads us to the principle of superposition which basically says that uh well if you have uh a classical system that can have for example if you measure it and it it can have two outcomes for example I have this coin and U it can have uh head or tail in Quantum systems they have this uh superposition principle that says while you're not making a measurement uh they're Sim simultaneously in both of these states which we can um we can

imagine that that it's going on when I flip this coin and while the coin is in the air uh it's we we cannot say that is it is in uh one or the other state we can say that there is 50% of chance that we'll measure it uh the state of head and 50% uh that it will be tail the important thing here is that uh I make measurement to get the information of the state of the system so what what we say is that the measurement actually disturbs the state of the quantum system which is an important property that I will refer to later and this superposition principle basical basically um Ena us uh to introduce uh

Quantum bits or cubits so unlike the classical Computing where we have zero or one in qu in Quantum Computing and uh cubits uh can be represented uh with uh probabilities uh and um statistics the other property is entanglement uh quantum entanglement says that if you produce two particles let's say two photons uh in certain way in certain conditions they will behave as one system no matter how far they are so if you make measurement on one particle it will be this the second one that is entangled with this one will be immediately affected so uh if anything of this sounds strange that's okay because it is strange for us on our microscopic level and it was strange even for Einstein who

said entanglement he called spooky action at distance and for the superposition there is this famous quot quote that uh he said uh the God does not play dice uh so he was very skeptical about this interpretation of quantum physics but uh it's basically the best we have and all the experiments are confirming it uh the last thing I will say about this uh uh quantum andys physics theory is uh the so-called no cloning theorem uh which basically says that it is impossible to clone Quantum State um and based upon uh this uh based upon these uh properties we can um look into Quantum technologies that have been developed recently there are three main areas uh I will mention first first we

have Quantum Computing uh which I will separate into Quantum development of quantum computers and Quantum algorithms so when I say quantum computers development of quantum computers is mostly building a hardware and uh Quantum algorithms are basically uh then the code that uh you can run on those uh quantum computers to use uh to make it useful uh then we have Quantum uh Communications which I will mostly talk about today and some ideal goal of communic quantum Communications would be development of Quantum Internet what should what what is envisioned as the Quantum Internet well basically uh interconnected Quantum networks so what are quantum networks Quantum networks are basically uh full mesh uh networks so networks in which

each user is connected to any other user in the network uh but their security uh and their communication is based uh it's um Quantum safe no matter is it uh post Quantum cryptography or Quant or uh Quantum key distribution uh I will mention that later also and the third Big Field is quantum sensing and Metrology um so using this properties you can uh uh make use of quantum systems to develop uh to develop more accurate and more sensitive uh devices so first of all quantum computers um threat or treat so we are building them because we have the idea that we can make something useful out of it so uh due to superposition principle that I said uh they have the ability to

explore multiple Solutions simultaneously and decide which is the best solution for a certain problem um there are different realizations uh for example superconductors those superconductors are gener in general materials that um when uh they don't show electrical resistance but the problem with superconductors is that uh these materials uh show this property only on low temperatures when I say low temperatures I mean really really low temperatures below 1 Kelvin so uh then the other um brand of development is the So-Cal topological cubits you have maybe recently heard of Microsoft's mayano one chip that is based on uh these topological cubits uh then photonic cubits where you can basically encode your information like I already mentioned in photons in some state of

photon for example you can uh use polarization of photon to encode information so how can you do that well basically you I guess you may you remember from the high school what is polarization so the waves can travel like this so then you can say you can call that vertical polarization or like this and then that's horizontal polarization and then you can say okay if I measure that the fot incoming Photon has vertical polarization I can call that one and if it's horizontal that's zero and basically then by measuring uh number of incoming photons you can um you can uh get a string of these bits or cubits um when talking about cubits um I

will just warn you uh when you read some news about quantum computers they often says oh we've developed new chip with I don't know how many cubits be careful what they are saying and what they are talking about because there is difference between physical and logical cubits uh physical cubits are uh actually the true uh um um Quantum systems that are on the chip itself that can be I don't know Quantum dots whatever atoms whatever uh and logical cubits is basically um those cubits that are useful so like I I already mentioned for examp for example on for the superconductors um even the slightest um um for example if they absorb some energy uh they will uh Disturbed and

those cubits won't be functional anymore because they won't be uh in the state that you can control so there is a difference between physical and logical cubits and there are several uh ways of dealing with that one of which is okay you can say uh let's uh build chip with as many as physical cubits possible and we will encode the same information in a lot of them so if some of them are not working okay we have a backup but that's problematic because then you have to control everything and then you have a big hardware and um uh the other approach is to try to reduce the difference between physical and logical cubits that's uh Direction called um uh

Direction called uh error correction so uh basically you try to uh reduce the noise in the system so that uh the Lo number of logical cubits is as closer as possible to the physical cubits so we are building them because we believe they can help us uh to solve some problems that classical computers are not able or it would take a lot of computational power or a lot of time for these problems to solve some of which are optimization problems simulations of some Quantum system search problems and so on what I'm trying to say here is basically you can imagine uh uh building a new material or building a a new drug uh instead of uh creating new material uh

with slight changes and then doing some experimental testing on them you can basically we believe that it's POS will be possible with quantum computers to make simulations of that and and then you will reduce the cost of uh creating uh new uh large number of new materials and testing them um however there is this uh problem possible problem is that quantum computers are good in uh are good at uh solving we believe they will be good at solving the problems on which uh classical security relies upon so the most famous one is factorization of large numbers and shes algorithm you probably heard about that so uh we can think in the direction of will they replace classical

computers uh they probably won't replace classical computers like I said they're good at different things um how far are we from functional quantum computer um well we already have some functional Quant computers but it also the question is what do you mean by functional in the context of um security we can ask ourselves when when will quantum computers be good enough to uh be a real threat for our classical security protocols um and the estimation says about 10 to 15 years uh like maybe 5 years ago the estimation was 10 to 15 years years uh so we basically don't know that's the problem um so are there actually a real threat well I would say they are because the

real threat I don't so what we know about uh development of quantum computers is basically what uh we we are giving we we so the companies that are producing quantum computers are giving us some informations about the development and mostly we have I don't know IBM we have Google we have Microsoft uh we have some private companies uh in US in Australia working on that and they all have this Western World actually has nice divided so we have government then we have military we have uh scientific Community uh we have some companies and there is some money going from the government to Scientific Community to the uh military scientific Community usually gets its funding through some grants and when you get

some Grant you have to uh justify the money that you got so you have to publish some papers you have to say oh I did this this and this so basically we know what's going on on the west but what we don't know is what's going on on on the East so when I say East I mean basically uh first of all China for example because all this um uh like I said government military scientific Community everything is blurred out and we don't have the trace of money and we don't know basically what's going on because if we if they don't have to justify the money uh their uh get they get for the development we

don't know uh what they are working on and I will just here give parallel to to this AI hype that we are currently at uh so you've seen what happened with the Deep seek nobody knew basically what they were developing and and what they did is they took hardware and knowledge from the West they developed something much more efficient and for much less money than the west and uh the problem is that we don't know what's going on in this uh area uh I will mention some things that we know but uh the threat I would say it's real and uh we can maybe monitor what's going on on the west but not so on from from the

East so um basically we can wake up one morning and uh They will announce that they have functional quantum computer possible to break Classical cryptography uh and then we are in a problem so what are the possible solutions well there are two big um streams uh one is post Quantum cryptog cryptography and the other one is uh Quantum key distribution uh here are some properties of these two approaches uh post Quantum cryptography um the easiest way to explain it is basically it's an extension of classical uh cryptography methods that we have so they're based on some mathematical problems that are believed to be hard to solve even for quantum computers uh the good thing is it does not require

additional Hardware it's scalable and compatible with uh existing protocols the question is is it good enough so if we are developing something that should protect us from uh a threat that has not yet been fully developed how do we know if is it safe is it good enough on the other hand we have Quantum key distribution so post Quantum the main difference is that postquantum cryptography can be implemented on this more software level Quantum key distribution is based on the fundamental laws of nature and uh it's more focused on the protection of the infrastructure however it does require additional Hardware there is an authentication problem so the Authentication is not solved inside of the uh qqd protocols uh

and there is a distance limit because due to attenuation you have to uh In classical um Communications you can use repeaters like I said here you cannot use repeaters since repeaters uh would make measurement if you make measurement you will disturb the state of the system it can work on the existing Telecom infrastructure so basically I mean uh fibers and uh it is absolutely secure when I say theoretically uh on to the level of implementation so uh ignoring the problems possible problems with the uh equipment or noise or something like that so the protocol itself it's safe so these are some pros and cons of each of them but as you can see where the pqc

is bad qkd is good and vice versa so the question pkc or qkd I don't think that's the the right question because I believe that in the future we'll use it simultaneously both post Quantum and qkd so uh I believe that many of you are already familiar more or less with postquantum and the classical protocols for sure you know them better than I do so I won't go into details of pqc I worked mainly with qkd so I will just explain uh what is the main parts of qkd and this absolute security where does it come from so I will straight uh I will jump straight to the one of the protocols with uh in entanglement based

protocol and this we'll read this from the top to the bottom so imagine that you have two parties that wants to communicate Alis and Bob and uh they want to uh build secret key so how can they do that using qkd so here we have source of the entangled photons and those entangled photons are being then sent towards Alice and Bob in some way fibers free space whatever Alice and Bob they have um some experimental some devices that can measure uh incoming uh photons uh depending on their polarization so they have some polarization analysis modules and they can uh meas make measurement in two bases we call this horizontal vertical base and this is diagonal anti-diagonal

base um what are po those are basically polarizers and polarizers are basically our sunglasses so polarizers are basically transmitting the light of certain polarization if you have horizontal Al polarizer and you have incoming horizontal Photon it will transmit if it gets vertical it won't get transmitted what they do they basically make measurements so they count photons um they receive and they keep the results of the measurements secret so Bob has his string of results of his measurements Alice has a string of uh results of her measurements but what they do then they uh publicly announce which basis did they choose to make these measurements uh if someone is listening this public Channel they don't get the

information about the results and they're one step behind Alice and Bob they cannot do anything with the information of Basics choices because Alis and Bob are actually comparing them and where they use the same basis they decide to keep this uh this bit as you can see here in that way they uh create secret key uh shared here means in a sense that's shared among them not publicly shared um so why is this absolutely secure well so like I said if someone tries to break uh listen public Channel they're one step behind but what if someone tries to EAS drop uh here in uh the infrastructure so someone wants to tap the fiber or something like that

so if they try to make measurement like I said by making a measurement they will disturb the state and Alis and Bob in their security analysis they will notice that what else can they do an E dropper can try to make measurement and make a copy of that but like I said there is no cloning theorem that says oh you cannot copy a state of a photon so basically an e dropper cannot uh interrupt um they can interrupt this uh distribution of photons but they will be noticed how well uh Alis and Bob uh they're measuring these photons and they're in parallel measuring something called Quantum B Terror rate um so it's basically they they measure how many uh

photons they receive uh is in um wrong polarization let's put it in that way the easiest way to explain and uh for the entangled based QD protocols this Quantum bet rate should be below 11% if it's higher then they can discard the key and start the process all over again so there there is possibility that somewhere there is some noise there is always some noise there is some disturbances they will influence and uh on the quantum bet Terror rate all of that just to be sure is pointed to an E dropper so now when we've shown how to connect two users we can ask okay how can we create a full mesh Network a network where each user is connected to

every other user so one uh idea is to entangle more photons so if you have 10 people you can entangle 10 photons and distribute them to towards each of them but that's hard to produce and hard to maintain so the approach that is usually uh taken is to um create photons so this Source sorry so this source of polarization so this source of entangled polarization photons um it's producing photons of not only one way wavelength but the distribution of the wavelengths looks something like this and then we can choose uh pairs of photons of different wavelengths and distribute them among uh all users in the network uh there centered around 1550 nanometers which is standard wavelength for uh the

in fiber Telecom Communications because there is minimum attenuation on that wavelength and this distribution uh of photons basically corresponds to standard itu channels uh so The Logical table looks something like this and this is the example uh of an quantum network that we built at University of Bristol with four users each user is basically receiving uh three uh photons of three different wavelengths uh that are connecting each user to every other user uh this is the example from the network with six users uh we've just show you the the secret key rate that we measured this is basically um uh yeah the result that we got here we had some T1 T3 two T2 and T3 stand for the time

when the detectors had their cooling cycles and so on and so on we had even during night we had some um breakage of electricity unexpected but you see that everything is more or less stable um depending on the noise in the in fibers uh they had more uh Better or Worse results but it it we were happy with this um so what are the existing implementations I already mentioned China they have uh the longest qidd uh Backbone in the world uh from Beijing to Shanghai with with different apologies in different cities um and also upon uh not only that uh they have a dedicated satellite called misuse to qkd uh so uh with this satellite uh they have

demonstrated the first uh video conference call um protected by qkd with Austria um why with Austria so the person who is leading uh the development of quantum Technologies in China his name is punan and uh he is a student of anon singer who was the main person in Austria for the development of quantum Technologies and singer won Nobel Prize in physics for the development in this field a couple of years ago so basically they have person who is um directly worked under the uh Nobel Prize winner and uh they have unlimited basically resources for uh in in in this field uh this is the example from UK uh I was in Bristol working on their uh

implementation of uh qkd network uh in Reading there is a big telecommunication Hub so it's uh almost halfway between Bristol and London in Cambridge uh C Cambridge is a good position because uh R&D facilities of toiba are in Cambridge and they're working mostly with them and I think that in IPS which they have a ground station where they do experiments uh in free space with satellites where is Europe well Europe realized couple of years ago that it's uh that we are miles behind especially behind China and um United States so they have decided to invest some money in the development of Quant communication infrastructure and there is ongoing Pro uh ongoing project called Euro qci uh they have decided to give some

money to every country in Europe um and to develop um some infrastructure as you have already seen on the example of the UK some countries already have some infrastructure for example uh we didn't have so this this is a good project for Croatia to develop uh something so there is an ongoing project also in ctia I think that um it lasts till mid 2026 or something like that um the last um the last big uh thing they published uh they said that they did in within this project is uh they have deployed dark fibers between institutions that are uh working on this project dedicated to qkd so they will use it for further tests uh and uh here this project is um

the institutions in these projects are some scientific institutions like rer bosich Institute Institute of physics uh then there are other shil uh caret uh and some uh some institutions like uh fair and uh facult some other faculties uh the funny fact is that funny fact interesting to say is that basically the first um qkd implementation between uh different countries was done between Croatia Italy and Slovenia and I've I've put this picture here so that you can see that basically uh some of this equipment is already uh plug and play um you can find more details in this paper about how they used it and how it was conducted uh so uh the outlook for this field well USA

is mostly focused on the post Quantum protocols uh their National Institute for standards and Technology they uh had call for uh papers for standardization of pqc protocols and there was four rounds of submissions and they have selected some of the protocols for different um things in the uh for the pkc while other countries are also investing in qkd which is also potential for uh companies if you are working uh in the development of uh for example in Telecom company or if you're working on a new hardware or so but also um what can you do in your companies to get Quantum safe well you can identify critical assets uh make an inventory of sensitive data and

systems and uh develop a timeline and strategy for transition toward pqc qkd whatever is uh more relevant for your company company uh there will be probably some transition period when you'll have Pro uh some hybrid approach with classical um classical algorithms and pqc uh upon qkd uh and to regularly update risk assessments and strategies something that you probably all know about but I think that you should also consider it uh in the terms of quantum threats so should we Implement Quantum safe Solutions well I think you know what is the answer so I don't think that's really uh the good question to ask maybe better question would be when should we Implement Quantum safe Solutions uh and

although this topic is maybe look into the future I would say yesterday because like I said if I if I were you and if I were a cyber security expert I would always think in the worst case scenario the worst case scenario is that okay someone already has fully functional quantum computer that can break Classical algorithms what would be the consequence of that there will be some data leakage and uh someone would already have uh some uh comparative advantage in some field of economy or uh I don't know mil or whatever and we would notice that what is the second worst case scenario okay no one has today fully functional quantum computer but maybe they will

develop it tomorrow in week month or so what will they do with it they will gather again some informations and so on and for some period of time we basically won't know that they have it so we we are in the same situation as the worst case scenario so we won't know at first that they'll have it that's why it's important to uh be proactive and to secure uh yourself from the possible threat like I already mentioned I think that this development will go in the potential of uh hybrid pqc and qkd implementation where pqc can be layered on top of qkd pqc can protect this software lever and be developed on the software level while qkd will

um protect critical infrastructure at first I'm sure it will be in um governmental institutions for governmental institutions for military purposes and so on uh and then combining them basically you can get a single key for further encryption and communication and that would be it thank you for your attention and if you have some question questions feel free to [Applause] ask I got a question thank for a nice lecture really interesting uh I got um a bone to pick with um this whole Quantum area to be honest and I like what you said that in the end you need a hybrid solution so what what puzzles me is a lot of people are you know so companies

uh not companies Nations European Union is investing a lot of f money uh to actually Finance the the networks to do um Quantum key exchange uh distribution and okay you you demonstrated China does this over long distances but that's only to negotiate for a key basically and but when you do get that key in the end to send large volumes of crypted data you going still be using the normal high volume backbone of the internet for the massive in uh transfer data just the encryption key exchange will be done through qqd and the way the these algorithms and now correct me if I'm wrong for key exchange uh work is that you get basically a binary key which is doesn't

have any properties except being basically very random and secure which means it's good for symmetric cryptography yes but not for asymmetric and we still knew asymmetric encryption for a lot of things so for our world to exist as we know it we still need dig signatures uh you know uh asymmetric public key encryption which still has a problem of key exchange which we don't solve basically with qqd yeah you're right so uh uh qkd is only for symmetrical uh key exchange and it cannot be used for asymmetrical uh so there is no uh as much as I know uh adoption of qkd for that yes correct we are missing that uh yeah we are missing that but you

know uh I think that you there is uh you have to start from somewhere no that's true yeah so you you can build upon this if you uh if you get um that that's the whole thing so you have classical now encryption and algorithms you will get something a bit better with pqc but you're not you don't know how often maybe you'll have to uh refine it due to fast development of the threats possible threats and then you have uh uh a part of your communication that you can protect also with qkd yeah so it's not uh full solution yeah yeah good correct thanks thanks for question anyone else

okay uh just uh if I understood correctly from the presentation uh in order for the quantum uh cryptography to be implemented properly and in a secure way you need specialized equipment uh for the qkd uh yes so you like I show on the protocol you need to have for example if you want to implement this entanglement based uh protocol you need a source of uh intangle photons which is something that you normally don't have and you need to have the vectors those are critical you know critical points um when I was uh looking into um n recommendations they they they recommend to go towards pqc and they said they have five reasons why qkd is not good

enough three of those are basically uh considering uh how to say it techn logical development of qkd so they say oh you need dedicated infrastructure for that when I started working the uh for the analysis of uh incoming photons each user uh needed four detectors then during when we worked in Bristol we managed to do this protocol this analysis with only two detectors I've read now that uh they've developed a protocol that uses only one detector so I think that this this is more a question of technology and it will go on and it it will be better and better and I don't think that technology the development of Technology should be stopping us from getting into

somewhere the reason why I'm asking is because uh I've seen uh postquantum implementations uh that exist and I am aware that um some software for instance signal already implements or at least states that they Implement uh Quantum uh algorith algorithms to be post Quantum safe but then my question is if uh if this is just words or is this actually properly implemented and you can count on it that it's post Quantum safe okay so post Quantum as I mentioned uh so what I said about the the additional Hardware is it's considering qkd and post Quantum cryptography is something that you can apply on the existing infrastructure so I don't know in details I cannot tell you is it proper

implementation or or not for this certain scenario but the advantage of postquantum cryptography is that is basically just um you take classical protocols and you extend them to be be safe from what you believe that will be threat from quantum computers and you don't need dedicated additional hardware for it thank you for the question I saw one hand here okay hi hi thanks for the presentation I have a question regarding the implementation of uh a network that will support quantum key distribution yeah uh what is more feasible or it what will be uh less expensive to do like to use fabrics and connect the whole world with Fabrics or maybe go with the uh satellites okay um

I mentioned in one slide that the bad thing about uh qkd is uh the problem of uh High losses uh and uh the the distance limit so that you cannot use repeaters so uh for the the approach uh will be probably combined so if you want to use it on the Metropolitan scale you will use INF fiber and then if you want to connect the whole world for example you will have to use sat lights and therefore you will need also some uh hybrid points where this uh key exchange will go between um metropolitan area towards satellite to connect it with other uh base uh ground station okay thanks anyone else

no it's the last lecture he's keeping you here I feel something going my way uh one thing that's also probably maybe a a a big stepping stone uh for I would say worldwide adoption is the cost of this technology so you know uh everybody today uses basically some kind of cryptography every single second so my phone just updated five times why I spoke to you and it's everything is encrypted and there is some key exchange going on but it's unlikely that this phone or my pc at home or even my you know large desktop will have in the next 10 years the hardware to do proper uh you know key exchange so it's more likely that it will be like a service

and if I'm depending on let's say a service and there's like a cardnet or something that has the facilities to do QD and then sends me that key through a normal Network again then it's probably no longer safe for me so as you said it's probably going to be just for military high grade government something like that but they can have facilities and for me if I want to to do proper key exchange I'm going to probably have to write something on a piece of paper and give it to someone that's going to be more safe yeah than anything else similar thing with quantum computers you won't use quantum computers to do PowerPoint presentation uh or you won't

have quantum computers that sits uh next to your desk you will probably uh you will uh connect to it to through cloud or something like that also with qkd since uh yeah we'll probably wait for some time to get uh the hardware on the level that uh it won't be as expensive as it is today but the first uh government military and then Banks uh hospitals uh Big Data Centers they they they are probably the first users uh of qkd for example in Switzerland they're they already implemented qkd uh in some banks and you know they have uh a lot of referendums and votes so they this infrastructure is already um Implement they have implemented for

that infrastructure qkd yeah maybe just a comment probably you know this whole audience knows maybe know that's new for you maybe it's not there's a really a big craze now in the security Community about post Quantum cryptography everybody's like that's like the it's almost like AI it's almost as Ai and everybody's talking that you have to have it as as you said yesterday uh everybody's saying all the algorithms are dead even though basically all RSI is semi Dead with short algorithm not even elliptic curves are dead dead all the symmetric stuff is perfectly fine and everything is is which is actually encrypted is encrypted with session symmetric you know keys and only the initial exchange of the those keys is

encrypted with something like SSA for instance and nowadays all pen testers everybody tests that are TLS handshakes we have you know perfect forward secrecy so you cannot like save it and decrypt it later so I haven't seen a single analysis of how much actually the key exchanges nowadays over the Internet is actually really vulnerable to you know future quantum computers because you know how many of them don't have forward secrecy and really do use only SSA uh algorithm I haven't seen an analysis but ER like screaming that everything is dead so it's I think it's a hype yeah it's it's a bit of hype but and it's not that because everything is still working but the problem is that um the situation

here it's there is no Gray Zone basically it's it's it's white or or or or uh it's white or black it's zero or one once you'll have it you'll be in problems so and you don't know when it will it happen and when will it happen so that yeah that I think that's a problem that that that's why this whole hype is and you know when you look into this analysis they all say okay there is also this uh you know Harvest now decrypt later uh type of uh attacks so let's let's get everything uh ready for that thanks no problem hello uh could you perhaps explain what's the actual fan out of this system because to

me it looks like a point too connection pretty much because the internet doesn't work that way the first time you hit a a router or something you have to re-encode data from what I'm seeing here and compared to like open bsds entren uh that that version of the lce uh encryption seems to be uh more like likely to be implemented compared to something like this as I'm seeing it right now uh yeah th this is uh all so what I showed this is point to point uh and um I I would have to check for example the the real life implementations what they did what what what they did after uh this point too uh exchange and uh

what did they do with with a key um the results and the schemes that I've shown you were uh basically results from the scientific research so we worked um on on on the problem of uh how to deal with disturbances in in the communication channels so we weren't so uh focused on the on the the the life cycle of the key and what happens with the key afterwards uh but more into Sol some more technical issues here are we done yeah uh thank you mate for this