Quantum Key Distribution Summer School at the Institute for Quantum Computing

What is Quantum Key Distribution?

The purpose of the Quantum Key Distribution summer school is twofold:

1. To provide a well-structured series of lectures explaining the level of modern know-how in quantum cryptography.
2. To provides better understanding of the topic by using the lecture material in interactive tutorials.

IQC has an excellent atmosphere for research, and just being here would innovate quantum leaps to the future. This summer school really built a solid foundation for understanding concepts of quantum information and cryptography.

Day 1

Basic cryptography

The first day at Quantum Key Distribution class is a considered a crash course on cryptography. Our first speaker is David Jao, he covers some basics of cryptography, such as the use of a single key for encrypting & decrypting. Basically this SKES symmetric key encryption scheme. He defining a protocol as semantically secure and infeasible to crack as 2⁸⁰ operations. Next major topic was hashing functions, and its application and weakness. It’s possible to create two files that have the same hash, and this is called a collision. This is not desirable as collision leads to a malicious hacker to change the content of the document and still pass it off as legitimate (he explained the birthday paradox). Hashing can also be used in conjunction with SKES and/or the use of public key cryptography to increase the speed of data delivery.

Lunch was provided, outside as a picnic style; which consists of a pop, meaty pasta, and bacon salad.

Important concepts

The afternoon lectures were by Douglas Stinson, who also is the author of Cryptography Theory and Practice, which is widely used as a popular and classic textbook on the topic. He began telling us stories of a 1973 article in Scientific American that introduced a new type of cryptography that would take millions of years to crack. And included was a challange for people to decode. Indeed, 9 years later after publication, the challange was decoded. It is referred to “the magic words are squeamish ossifrage“. Remainder of the time was spent discussing the following:

• Shannon’s theorem
• Model for security
• Authenticity codes
• Computational as unconditional security
• Simmons’ model
• Almost strongly universal hashing
• Stinson theorem
• Blom’s key distribution

Night 1: Sleeping in the car

The IQC offered conference rooms for guests starting at $35 per night for a shared room and $50 for a single room. This rate is pretty decent, and all the students were there. Their respective universities will subsidize the cost. I, on the other hand, do not think it is too likely for me to go up to Laurier with a bill and expect them to subsidize. Laurier isn’t known for their sciences. Anyhow, I figure there were some choices as to where I could get a free place to live. Friends that go to UW recommend the sofa lounge in the MC building; others recommend that I go home. Going home isn’t an option because spending 2 hours on the road just so that I can get a good sleep isn’t an efficient way to use resources and a mediocre trade off at best. I could’ve parked in Laurier’s parking lot and slept in the PHI club room. Even during when I lived here at WCH, I wanted to try living off the resources. I decided to sleep in the car.

I drove to IQC around 23:30 looking for a parking spot where it isn’t so bright. After getting setup in the backseat, I was suddenly flooded with light. It turns out that somebody had called UW Police regarding a suspicious vehicle. I explained what I was doing, and they still asked for my drivers license, insurance, ownership. I guess I was a bit surprised because they aren’t official police, and I was thinking whether I’d need to identify myself to them. Still, better get in trouble with UW police than the city. I was allowed to sleep in my car after they asked me a dozen questions about what the heck I was doing in UW. And note to self, know where the ownership document is at all times, and keep insurance paper updated.

Day 2

Quantum Key Distribution

Presented by Douglas Stinson

The case for quantum key distribution Proceedings of quantum comm 2009 workshop on quantum and classsical information security, lecutre notest of the institute for computer sciences, social informatics and etelecommunicaitons engineering vol 36 p 283 296 in Springer, 2010.

RSA is definitely broken.

QKD detectors were not good choices at the moment because they are vulerable to attacks.
Trapdoor vs oneway functions.
Cant just wait until we have one.
Cost benefit analysis fo quantum cryptography by D bernstein dagstuhl.de

QKD provides secret key that is as secure for all future as it is at its creation!

Commercialization of QKD networks

Creation of commercialization with satellite scenarios
The largest market share is the service provider network where satelite with beam a to b and smaller is intra institutional netowkr where they ahve to use the trusted network. Or can youse a quantum repeater.

Getting a communication system out would overcome roadblocks in adopting QKD.

Quantum Secret Sharing

Three channels available; take the emssage and split into 3 parts. Only by having 3 parts can you decode the message. If Eve attacks one node, you’re fine because the information is secure.
Thus given k paths, there should be k-1 keys. If there was k1 k2 k3, then the decoding would need the sum of all keys.

Note to self: I would like to see commercialization of QKD.

Gap or no gap problem:

Under 14.6% symmetric error rate then the QKD can have a one-way bound (data not explainable), but over 25% is no reconstruction possible. What is this gap between 20 and 25%?

Night 5: Pool and chat

As the last day concluded, Erik and I played pingpong and pool. Then dinner time rolled around, he and I along with Charles and Tomasso went to East Side Marios. I had this plate of lasagna and the dish was flamming hot, I accidentally rested my arm on it, and got a 2nd degree burn! We chatted and had Keith’s Red, which was good. Walked back to residence, they planned their trip to Montreal and stuff, while Erik and I played some pool. Stuart and Christina came around doing laundry, and we chatted. I find Masters and PhD students really interesting to talk to, very knowledgable if you’re in the same interesting field. And I crashed on the couch again, didn’t want to bother Erik.

Saturday Niagara Falls & Toronto

Unfortunately shortly after this photo, Tommaso found out that he didn’t bring charger for his batteries…

I met up with Charles, Tomasso, Erik, and Rotem at Shoppers, and we drove to Niagara Falls. The view was great, we walked around and went on a Maiden of the Mist boat tour. It was okay. Went to Tim Horton’s after and I bought everyone Ice Caps and Timbits, but they just really wanted to pay me back I guess. I didn’t want them to, but they make it that I cannot refuse. We went to Toronto and dropped Erik off and walked around downtown (there was a large festival). It was pretty fun, ate at a Mamma’s Pizza. I just ordered whatever Tommasso had. We planned to find a Japanese place, but I didn’t know if there existed a Japantown, so I took them to Chinatown. We parted our ways here, and I bused home. It was too bad we didn’t meet up the other group at Niagara.

As a conclusion, I especially want to thank everyone who has made this possible, people at IQC, people flying around the world, professors, students I’ve met.