Quantum Cryptography

Lecture spring 2019

Instructor Dominique Unruh
TA Raul-Martin Rebane (submit homework solutions here)
Lecture Period February 13, 2019 - May 21, 2018
Lectures Wednesdays, 16:15-17:45, room 220 (Paabel) (Dominique; may sometimes be switched with tutorial)
Practice sessions
Fridays, 10:15-11:45, room 218 (Paabel) (Raul-Martin)
Course Material Lecture notes, blackboard photos, practice blackboard photos, videos and exam study guide.
Language English
Mailing list ut-qcrypto@googlegroups.com
Exam TBA
Contact Dominique Unruh <<surname> at ut dot ee>

Topics covered

See also the blackboard photos and the practice blackboard photos.
2018-05-24 (practice)The Short Integer Solution Problem, Worst case SIVP to average case SIS, trapdoor functions from SIS
2019-02-13 (lecture)Mathematics of single qubits.[video]
2019-02-15 (practice)Small exercises with single qubits.
2019-02-22 (practice)Measurements in other bases. Polarization invariant under rotation.
2019-02-27 (lecture)Mathematics of higher-dimensional systems. Composing systems.[video]
2019-03-01 (practice)Multi-qubit gates. Elitzur-Vaidman bomb testing.
2019-03-06 (lecture)Measurements (ctd). Ket-notation. Deutsch's algorithm.[video]
2019-03-08 (practice)Quantum teleportation.
2019-03-13 (lecture)Toy crypto example. Quantum state probability distributions. Density operators.[video]
2019-03-15 (practice)Constructing unitary boolean functions
2019-03-20 (lecture)Quantum one-time pad. Partial trace.[video]
2019-03-22 (practice)Tracing out buffer qubits. Impracticality of Schrödinger's experiment. Physical indistinguishability of global phase.
2019-03-27 (lecture)Purification of density operators. Quantum operations. Statistical distance.[video]
2019-03-29 (practice)Purifying arbitrary circuits. Impossibility of FTL communication.
2019-04-03 (lecture)Trace distance. Quantum key distribution (QKD) - basic idea[video]
2019-04-10 (lecture)Quantum key distribution - security definition, proof overview, notation.[video]
2019-04-12 (practice)Explicit computation of trace distance. Trace distance of orthogonal states.
2019-04-17 (lecture)QKD construction/proof: Bell test.[video]
2019-04-24 (lecture)QKD construction/proof: Bell test (ctd.). Min-entropy. Min-entropy of QKD raw key. Error correcting codes (intro).[video]
2019-04-26 (practice)Guessing the key in QKD (if no classical postprocessing used).
2019-05-03 (practice)Analysis of an equivalent security definition for QKD protocol. Analysis of the security of a QKD protocol that discards the last bit of the key.
2019-05-08 (lecture)QKD construction/proof: Error correction, privacy amplification.[video]
2019-05-10 (practice)Proving missing claim from QKD proof. Secure message transfer and login from QKD.
2019-05-15 (lecture)Shor's algorithm (period finding, factoring).[video]
2019-05-17 (practice)Implementing Quantum Fourier Transform.
2019-05-22 (lecture)Learning with errors (LWE). Regev's cryptosystem[video]


Your current amount of points in the homework can be accessed here (as soon as the first sheet has been corrected).
Out Due Homework Solution
2019-02-212018-02-28Homework 1Solution 1
2019-03-022018-03-09Homework 2Solution 2
2019-03-122019-03-19Homework 3Solution 3
2019-03-232019-03-30Homework 4Solution 4
2019-04-082019-04-15Homework 5Solution 5
2019-04-222019-04-29Homework 6Solution 6
2019-05-032019-05-10Homework 7Solution 7
2019-05-172019-05-24Homework 8Solution 8
2019-05-312019-05-02Homework 9 


In quantum cryptography we use quantum mechanical effects to construct secure protocols. The paradoxical nature of quantum mechanics allows for constructions that solve problems known to be impossible without quantum mechanics. This lecture gives an introduction into this fascinating area.

Possible topics include:


You need no prior knowledge of quantum mechanics. You should have heard some introductory lecture on cryptography. You should enjoy math and have a sound understanding of linear algebra.


[NC00] Nielsen, Chuang. "Quantum Computation and Quantum Information" Cambridge University Press, 2000. A standard textbook on quantum information and quantum computing. Also contains some quantum cryptography.

Further reading may be suggested during the course. See the "further reading" paragraphs in the lecture notes.