thesis High performance algorithms for lattice-based

High performance algorithms for lattice-based
cryptanalysis
Technische Universität Darmstadt
Artur Mariano, MSc
(geboren in Guarda, Portugal)
Tag der Einreichung: 03.08.2016
Tag der mündlichen Prüfung: 22.09.2016
Dissertation approved by the Fachbereich Informatik in fulfillment of the
requirements for the degree of Dr.-Ing.
Referenten:
Prof. Dr. Christian Bischof
Prof. Dr. Keshav Pingali
Darmstadt, 2016
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Acknowledgements
"I am not the man I once was. I do not want to go back in time, to be the second son, the second man.",
Vasco da Gama, Portuguese explorer.
I was once told by an experienced researcher that “it should come at no surprise that even the most
persistent drop out of their PhD, because a PhD is more of a test of character than one of intellect. Going
abroad increases these odds, because there you lose control of many variables.”. I remember thinking
that most of what I had achieved up until that point was due to my persistence and hard work, rather than
my intellect, and I thought that would be enough to overcome any problem I might have down the road.
Little did I know.
Living abroad for 4 years teaches you more than you can possibly imagine, but you must be prepared
for adversities. If the road gets dark (and Germany lacks sunlight a lot!), you will have to pull it off. The
good news is that you will not want to be the man you once were. Throughout this journey of mine, I
encountered many people who I will remember forever. Without many of them, this thesis would not have
been possible. I am extremely appreciative of all of them, who I humbly acknowledge in the following
lines.
I thank my advisor, professor Christian Bischof, for giving me the opportunity to engage in a topic
that fascinated me from day one, giving me complete independence to carry out my research, improving
the readability of my papers, and reviewing this dissertation.
I want to especially thank the people with whom I worked the most during my PhD, Özgür Dagdelen
and Fábio Correia, but not only for the great work we have done together. Özi for introducing me to the
German and Turkish cultures, for going to bat for me whenever I ran low on motivation and battery, and
for his invaluable friendship. Fábio for his devotion to the work I proposed, for engaging in discovering
the most remote parts of Germany and German with me, and for preventing me from getting homesick
many times.
I want to thank all my co-authors, including Christian Bischof, Özgür Dagdelen and Fábio Correia, for
the possibility of working together. Roberto Ribeiro, Alberto Proença, Cristiano Sousa, Mattias Diener,
Philippe Navaux, Erik Agrell, Bo-Yin Yang, Florian Göptert, Johannes Buchmann, Leonel Sousa and
Paulo Garcia. I particularly thank Shahar Timnat, for his highly valuable contributions to my ideas, Robert
Fitzpatrick, for sharing his genius with me, and Thijs Laarhoven, for embarking with me on such beautiful
work and visiting me in Darmstadt.
I also thank my student Cristiano Sousa for the numerous conversations we had about my work
and helping me out at many stages of my work. To my previous advisor, Alberto Proença, I thank his
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support in starting my PhD and for the many possibilities of collaboration with graduate students from the
University of Minho, some of whom I brought to Germany. He instilled in me a unique ability to critically
question my own results, regardless of they were good or bad, and I am sure that this shaped the type of
researcher I went on to be.
To my colleagues at the Institute of Scientific Computing; Johannes Willkomm for his endless
availability, Alex Hück for the nice chats over coffee and keeping my mental sanity, and Jan Patrick for
his effort and patience in teaching me German. To the people at the HRZ whom I interacted with, such
as Sergey Boldyrev for the intellectual conversations and Geert Geurts for his friendship. Pal, Dank u
wel. Señora Novato, for preventing my Spanish from getting rusty and for being so nice to me, muchas
gracias, and Andreas Wolf for giving me access to hardware that was essential to my work. To Ilona
from House of IT, for her motivational smile and good mood. To the guys from the third floor, especially
Giorgia, Felix Günther, and Paul Bächer, for creating such a nice environment. To Giulia and Sabrina, for
understanding my Latino heart so well. You prevented me from cracking up many times!
To the people who hosted me, including Georg Hager (RRZE, Erlangen, Germany) and Leonel Sousa
(IST, Lisbon, Portugal). To my colleagues at the IST, especially Diego Souza and Aleksandar Ilic, for the
formidable environment at the office, it felt like home to me, folks!
To Wolfgang from ProPhysio, for his ability to heal up my injuries from my workouts, in magical
physiotherapy sessions. To the nice buddies who worked out with me at the gym, like Marcel, Alvaro, and
the rest of the gang.
To people from CASED. To Ana, for helping me out when I first got in Germany, muito obrigado, to
Rodrigo, for his friendship and opportunity to keep up with Spanish, tanbien muchas gracias amigo.
To CROSSING, a DFG project that funded a great part of my PhD, numerous trips to conferences,
visits of guests of mine and other things. To Stefanie Kettler, CROSSING’s secretary.
To the University of Minho, which I graduated from, and LabCG, my former research group, as well
as all its members, namely Luis Paulo Santos, Nuno, Ricardo, Roberto and Waldir.
To all the great (mainly Soul music) singers who eased the write up of this dissertation. James Brown,
Marvin Gay, Nina Simone, Ben King, Otis Redding, Bob Neuwirth, Leela James, Alloe Blacc and Annie
Lennox. To the Corner café in Grafenstrasse, DA, for being my office during a good chunk of the write up.
To my references and sources of inspiration, in science and out of it: Rogério Alves (Portuguese
lawyer - exceptionally talented user of Portuguese), Bryan Stevenson (American lawyer and activist -
inspiring activist against segregation and over-incarceration of black people and minorities), Warren Buffet
(American investor - living proof that we don’t have to cut corners in life in order to succeed), Gordon
Ramsay (Scottish Chef - portrays passion and perfectionism in what we do), Kai Greene (American
bodybuilder - portrays will, hard work and humility at its best), Bruno de Carvalho (Portuguese, President
of Sporting Clube de Portugal - personifies courage and love) and Anderson ’The spider’ Silva (Brazilian
mixed martial artist - personifies humility, raw talent and faith). And to my role model and a person whom
I relate to a lot, Percy Julian, American exceptional scientist, writer and activist, and proof that hard work
and persistence always win, even when everybody want us to fail.
Last but not least, I want to thank my family - especially my beloved mother - and friends, who
supported me from the very first day on. To my grandmother, who is not around any more to see her
grandson graduating, I dedicate this thesis.
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"Keep your eyes on the prize, hold on."
Folk song that became influential during the American civil rights movement of the 1950s and ’60s.
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