Increased efficiency and functionality through lattice-based cryptography

Size: px
Start display at page:

Download "Increased efficiency and functionality through lattice-based cryptography"

Transcription

1 Increased efficiency and functionality through lattice-based cryptography Michele Minelli ENS, CNRS, INRIA, PSL Research University RESEARCH UNIVERSITY PARIS ECRYPT-NET Cloud Summer School Leuven, Belgium Thursday, 22 September 26

2 Why lattice-based cryptography?

3 Why lattice-based cryptography? Conjectured hardness against quantum attacks

4 Why lattice-based cryptography? Conjectured hardness against quantum attacks Simplicity, efficiency and parallelism: linear ops, rings, etc.

5 Why lattice-based cryptography? Conjectured hardness against quantum attacks Simplicity, efficiency and parallelism: linear ops, rings, etc. Strong security guarantees from worst-case hardness

6 Why lattice-based cryptography? Conjectured hardness against quantum attacks Simplicity, efficiency and parallelism: linear ops, rings, etc. Strong security guarantees from worst-case hardness Versatility

7 Learning with Errors [Reg5] fix s Z n q, sample A $ Z m n q, e χ m

8 Learning with Errors [Reg5] fix s Z n q, sample A $ Z m n q, e χ m n m A

9 Learning with Errors [Reg5] fix s Z n q, sample A $ Z m n q, e χ m n m A s

10 Learning with Errors [Reg5] fix s Z n q, sample A $ Z m n q, e χ m n m A s + e

11 Learning with Errors [Reg5] fix s Z n q, sample A $ Z m n q, e χ m n m A s + e = b

12 Learning with Errors [Reg5] fix s Z n q, sample A $ Z m n q, e χ m n m A s + e = b (A, b) c (A, $)

13 LWE is versatile With LWE we can build Secret key encryption

14 LWE is versatile With LWE we can build Secret key encryption Public key encryption

15 LWE is versatile With LWE we can build Secret key encryption Public key encryption Attribute-based encryption

16 LWE is versatile With LWE we can build Secret key encryption Public key encryption Attribute-based encryption Identity-based encryption

17 LWE is versatile With LWE we can build Secret key encryption Public key encryption Attribute-based encryption Identity-based encryption Oblivious transfer

18 LWE is versatile With LWE we can build Secret key encryption Public key encryption Attribute-based encryption Identity-based encryption Oblivious transfer FHE...

19 LWE is versatile With LWE we can build Secret key encryption Public key encryption Attribute-based encryption Identity-based encryption Oblivious transfer FHE [BDMW6]...

20 Example: online diagnosis

21 Example: online diagnosis

22 Example: online diagnosis diagnosis

23 Protecting the input diagnosis

24 Protecting the input diagnosis Data privacy (informal) The server should not learn anything about the user s data.

25 Data privacy: FHE diagnosis

26 Protecting the algorithm diagnosis

27 Protecting the algorithm diagnosis Circuit privacy (informal) The result should not reveal anything about the circuit applied.

28 Prior works reference standard LWE poly hardness multi hop circuitprivate [BV4, AP4] [Gen9] [GHV, OPP4] [DS6] this work

29 GSW encryption scheme [GenSahWat3] G : G ( ) : public matrix Z n m q algorithm s.t. v Z n q, G (v) is small and G G (v) = v

30 GSW encryption scheme [GenSahWat3] G : G ( ) : public matrix Z n m q algorithm s.t. v Z n q, G (v) is small and G G (v) = v C Enc(µ) = ( ) A + µg Z n m q sa + e s Z n q is the key A $ Z (n ) m q e χ m, for χ small distribution over Z

31 GSW encryption scheme [GenSahWat3] G : G ( ) : public matrix Z n m q algorithm s.t. v Z n q, G (v) is small and G G (v) = v C Enc(µ) = ( ) A + µg Z n m q sa + e s Z n q is the key A $ Z (n ) m q e χ m, for χ small distribution over Z Sum Enc(µ ) + Enc(µ 2 ) Product Enc(µ ) G (Enc(µ 2 ))

32 Branching programs x = x 2 = v v v 2

33 Branching programs x = x 2 = v v v 2 v t [i] = v t [mux (x t, j, k)]

34 Branching programs x = x 2 = v v v 2 v t [i] = x t v t [j] + ( x t ) v t [k]

35 Branching programs x = x 2 = v v v 2 result v t [i] = x t v t [j] + ( x t ) v t [k] result = v L []

36 Homomorphic evaluation of branching programs C C 2 Enc(result) V V V 2 V t [i] = C t G (V t [j]) + (G C t ) G (V t [k])

37 Homomorphic evaluation of branching programs C C 2 Enc(result) V V V 2 V t [i] = V t [mux (x t, j, k)] + ( ) A G sa + e (V t [j] V t [k])

38 Homomorphic evaluation of branching programs C C 2 Enc(result) V V V 2 V t [i] = V t [mux (x t, j, k)] + ( ) A G sa + e (V t [j] V t [k]) additional noise

39 Our core lemma Let g Z log q q be a public vector and g ( ) : Z q Z log q q g (v) is a discrete Gaussian g, g (v) = v mod q s.t.

40 Our core lemma Let g Z log q q be a public vector and g ( ) : Z q Z log q q g (v) is a discrete Gaussian g, g (v) = v mod q s.t. For any small e Z log q q and any v Z q e, g (v) + y s y where y discrete Gaussian with same parameter as g ( ) y discrete Gaussian with parameter Õ ( e )

41 Our core lemma Let g Z log q q be a public vector and g ( ) : Z q Z log q q g (v) is a discrete Gaussian g, g (v) = v mod q s.t. For any small e Z log q q and any v Z q e, g (v) + y s y where y discrete Gaussian with same parameter as g ( ) y discrete Gaussian with parameter Õ ( e ) y does not depend on v.

42 Rerandomizing GSW ciphertexts Let C = ( ) A + µg be a GSW ciphertext sa + e

43 Rerandomizing GSW ciphertexts Let C = Then ( ) A + µg be a GSW ciphertext sa + e C C G (G) + ( ) y looks like a fresh encryption of µ with (slightly) bigger noise.

44 Rerandomizing GSW ciphertexts Let C = Then ( ) A + µg be a GSW ciphertext sa + e C C G (G) + ( ) y looks like a fresh encryption of µ with (slightly) bigger noise. We need to rerandomize ciphertexts of : for any matrix V Z n m q ( ) C C G (V) + y looks like a fresh encryption of with (slightly) bigger noise.

45 Modified evaluation of BP s C G (V) + ( ) y s C C C 2 Enc(result) ( ) A V t [i] = V t [mux (x t, j, k)]+ G sa + e (V t [j] V t [k])

46 Modified evaluation of BP s C G (V) + ( ) y s C C C 2 Enc(result) ( ) A V t [i] = V t [mux (x t, j, k)]+ G sa + e (V t [j] V t [k])

47 Modified evaluation of BP s C G (V) + ( ) y s C C C 2 Enc(result) ( ) ( ) A V t [i] = V t [mux (x t, j, k)]+ G sa + e (V t [j] V t [k]) + y

48 Modified evaluation of BP s C G (V) + ( ) y s C C C 2 Enc(result) ( ) ( ) A V t [i] = V t [mux (x t, j, k)]+ G sa + e (V t [j] V t [k]) + y s C (depends only on C t)

49 Achieving circuit privacy Proof by induction: Noise (V [i]) = Noise (V t[i]) = Noise (V t [...]) + ( ) A G (V sa + e t [j] V t [k]) + ( ) z t

50 Achieving circuit privacy Proof by induction: Noise (V [i]) = Noise (V t[i]) = Noise (V t [...]) + ( ) A G (V sa + e t [j] V t [k]) + ( ) z t Noise (V L [i]) s L k= C k where C k is a fresh encryption of with noise O ( e k ).

51 Achieving circuit privacy Proof by induction: Noise (V [i]) = Noise (V t[i]) = Noise (V t [...]) + ( ) A G (V sa + e t [j] V t [k]) + ( ) z t Noise (V L [i]) s L k= C k where C k is a fresh encryption of with noise O ( e k ).

52 Achieving circuit privacy Proof by induction: Noise (V [i]) = Noise (V t[i]) = Noise (V t [...]) + ( ) A G (V sa + e t [j] V t [k]) + ( ) z t Noise (V L [i]) s L k= C k where C k is a fresh encryption of with noise O ( e k ). We need to pad the BP

53 Circuit privacy for general circuits

54 Circuit privacy for general circuits scheme

55 Circuit privacy for general circuits f scheme

56 Circuit privacy for general circuits ( Enc ), x f scheme

57 Circuit privacy for general circuits f ( Enc ), x scheme Enc ( ), f (x)

58 Circuit privacy for general circuits f ( Enc ), x scheme ( Enc ), f (x) scheme 2

59 Circuit privacy for general circuits f ( Enc ), x scheme ( Enc ), f (x) ( Enc, ) scheme 2

60 Circuit privacy for general circuits f ciphertext hardwired ( Enc ), x scheme ( Enc ), f (x) scheme.dec (, C) ( Enc, ) scheme 2

61 Circuit privacy for general circuits f ciphertext hardwired ( Enc ), x scheme ( Enc ), f (x) scheme.dec (, C) ( Enc, ) scheme 2 ( Enc ), f (x)

62 Conclusions and open problems Variant of the DGLHL for rerand LWE samples

63 Conclusions and open problems Variant of the DGLHL for rerand LWE samples Multi-hop CP for circuits in NC with poly-lwe

64 Conclusions and open problems Variant of the DGLHL for rerand LWE samples Multi-hop CP for circuits in NC with poly-lwe Extension to general circuits

65 Conclusions and open problems Variant of the DGLHL for rerand LWE samples Multi-hop CP for circuits in NC with poly-lwe Extension to general circuits Only for semi-honest adversaries

66 Conclusions and open problems Variant of the DGLHL for rerand LWE samples Multi-hop CP for circuits in NC with poly-lwe Extension to general circuits Only for semi-honest adversaries Only for GSW cryptosystem

67 Conclusions and open problems Variant of the DGLHL for rerand LWE samples Multi-hop CP for circuits in NC with poly-lwe Extension to general circuits Only for semi-honest adversaries Only for GSW cryptosystem Questions?

FHE Circuit Privacy Almost For Free

FHE Circuit Privacy Almost For Free FHE Circuit Privacy Almost For Free Florian Bourse, Rafaël Del Pino, Michele Minelli, and Hoeteck Wee ENS, CNRS, INRIA, and PSL Research University, Paris, France {fbourse,delpino,minelli,wee}@di.ens.fr

More information

Shai Halevi IBM August 2013

Shai Halevi IBM August 2013 Shai Halevi IBM August 2013 I want to delegate processing of my data, without giving away access to it. I want to delegate the computation to the cloud, I want but the to delegate cloud the shouldn t computation

More information

Fully Homomorphic Encryption and Bootstrapping

Fully Homomorphic Encryption and Bootstrapping Fully Homomorphic Encryption and Bootstrapping Craig Gentry and Shai Halevi June 3, 2014 China Summer School on Lattices and Cryptography Fully Homomorphic Encryption (FHE) A FHE scheme can evaluate unbounded

More information

6.892 Computing on Encrypted Data September 16, Lecture 2

6.892 Computing on Encrypted Data September 16, Lecture 2 6.89 Computing on Encrypted Data September 16, 013 Lecture Lecturer: Vinod Vaikuntanathan Scribe: Britt Cyr In this lecture, we will define the learning with errors (LWE) problem, show an euivalence between

More information

Classical hardness of the Learning with Errors problem

Classical hardness of the Learning with Errors problem Classical hardness of the Learning with Errors problem Adeline Langlois Aric Team, LIP, ENS Lyon Joint work with Z. Brakerski, C. Peikert, O. Regev and D. Stehlé August 12, 2013 Adeline Langlois Hardness

More information

Packing Messages and Optimizing Bootstrapping in GSW-FHE

Packing Messages and Optimizing Bootstrapping in GSW-FHE Packing Messages and Optimizing Bootstrapping in GSW-FHE Ryo Hiromasa Masayuki Abe Tatsuaki Okamoto Kyoto University NTT PKC 15 April 1, 2015 1 / 13 Fully Homomorphic Encryption (FHE) c Enc(m) f, c ĉ Eval(

More information

Background: Lattices and the Learning-with-Errors problem

Background: Lattices and the Learning-with-Errors problem Background: Lattices and the Learning-with-Errors problem China Summer School on Lattices and Cryptography, June 2014 Starting Point: Linear Equations Easy to solve a linear system of equations A s = b

More information

Classical hardness of Learning with Errors

Classical hardness of Learning with Errors Classical hardness of Learning with Errors Adeline Langlois Aric Team, LIP, ENS Lyon Joint work with Z. Brakerski, C. Peikert, O. Regev and D. Stehlé Adeline Langlois Classical Hardness of LWE 1/ 13 Our

More information

Fully Homomorphic Encryption. Zvika Brakerski Weizmann Institute of Science

Fully Homomorphic Encryption. Zvika Brakerski Weizmann Institute of Science Fully Homomorphic Encryption Zvika Brakerski Weizmann Institute of Science AWSCS, March 2015 Outsourcing Computation x x f f(x) Email, web-search, navigation, social networking What if x is private? Search

More information

ADVERTISING AGGREGATIONARCHITECTURE

ADVERTISING AGGREGATIONARCHITECTURE SOMAR LAPS PRIVACY-PRESERVING LATTICE-BASED PRIVATE-STREAM SOCIAL MEDIA ADVERTISING AGGREGATIONARCHITECTURE OR: HOW NOT TO LEAVE YOUR PERSONAL DATA AROUND REVISITING PRIVATE-STREAM AGGREGATION: LATTICE-BASED

More information

Ideal Lattices and Ring-LWE: Overview and Open Problems. Chris Peikert Georgia Institute of Technology. ICERM 23 April 2015

Ideal Lattices and Ring-LWE: Overview and Open Problems. Chris Peikert Georgia Institute of Technology. ICERM 23 April 2015 Ideal Lattices and Ring-LWE: Overview and Open Problems Chris Peikert Georgia Institute of Technology ICERM 23 April 2015 1 / 16 Agenda 1 Ring-LWE and its hardness from ideal lattices 2 Open questions

More information

Outline Proxy Re-Encryption NTRU NTRUReEncrypt PS-NTRUReEncrypt Experimental results Conclusions. NTRUReEncrypt

Outline Proxy Re-Encryption NTRU NTRUReEncrypt PS-NTRUReEncrypt Experimental results Conclusions. NTRUReEncrypt NTRUReEncrypt An Efficient Proxy Re-Encryption Scheme based on NTRU David Nuñez, Isaac Agudo, and Javier Lopez Network, Information and Computer Security Laboratory (NICS Lab) Universidad de Málaga, Spain

More information

New and Improved Key-Homomorphic Pseudorandom Functions

New and Improved Key-Homomorphic Pseudorandom Functions New and Improved Key-Homomorphic Pseudorandom Functions Abhishek Banerjee 1 Chris Peikert 1 1 Georgia Institute of Technology CRYPTO 14 19 August 2014 Outline 1 Introduction 2 Construction, Parameters

More information

Classical hardness of Learning with Errors

Classical hardness of Learning with Errors Classical hardness of Learning with Errors Zvika Brakerski 1 Adeline Langlois 2 Chris Peikert 3 Oded Regev 4 Damien Stehlé 2 1 Stanford University 2 ENS de Lyon 3 Georgia Tech 4 New York University Our

More information

Fully Homomorphic Encryption from LWE

Fully Homomorphic Encryption from LWE Fully Homomorphic Encryption from LWE Based on joint works with: Zvika Brakerski (Stanford) Vinod Vaikuntanathan (University of Toronto) Craig Gentry (IBM) Post-Quantum Webinar, November 2011 Outsourcing

More information

The Distributed Decryption Schemes for Somewhat Homomorphic Encryption

The Distributed Decryption Schemes for Somewhat Homomorphic Encryption Copyright c The Institute of Electronics, Information and Communication Engineers SCIS 2012 The 29th Symposium on Cryptography and Information Security Kanazawa, Japan, Jan. 30 - Feb. 2, 2012 The Institute

More information

COS 597C: Recent Developments in Program Obfuscation Lecture 7 (10/06/16) Notes for Lecture 7

COS 597C: Recent Developments in Program Obfuscation Lecture 7 (10/06/16) Notes for Lecture 7 COS 597C: Recent Developments in Program Obfuscation Lecture 7 10/06/16 Lecturer: Mark Zhandry Princeton University Scribe: Jordan Tran Notes for Lecture 7 1 Introduction In this lecture, we show how to

More information

Multi-Key FHE from LWE, Revisited

Multi-Key FHE from LWE, Revisited Multi-Key FHE from LWE, Revisited Chris Peikert Sina Shiehian August 24, 2016 Abstract Traditional fully homomorphic encryption (FHE) schemes only allow computation on data encrypted under a single key.

More information

Some security bounds for the DGHV scheme

Some security bounds for the DGHV scheme Some security bounds for the DGHV scheme Franca Marinelli f.marinelli@studenti.unitn.it) Department of Mathematics, University of Trento, Italy Riccardo Aragona riccardo.aragona@unitn.it) Department of

More information

Lattice Based Crypto: Answering Questions You Don't Understand

Lattice Based Crypto: Answering Questions You Don't Understand Lattice Based Crypto: Answering Questions You Don't Understand Vadim Lyubashevsky INRIA / ENS, Paris Cryptography Secure communication in the presence of adversaries Symmetric-Key Cryptography Secret key

More information

Cryptology. Scribe: Fabrice Mouhartem M2IF

Cryptology. Scribe: Fabrice Mouhartem M2IF Cryptology Scribe: Fabrice Mouhartem M2IF Chapter 1 Identity Based Encryption from Learning With Errors In the following we will use this two tools which existence is not proved here. The first tool description

More information

Fully Homomorphic Encryption

Fully Homomorphic Encryption Fully Homomorphic Encryption Boaz Barak February 9, 2011 Achieving fully homomorphic encryption, under any kind of reasonable computational assumptions (and under any reasonable definition of reasonable..),

More information

Fully Homomorphic Encryption

Fully Homomorphic Encryption Fully Homomorphic Encryption Thomas PLANTARD Universiy of Wollongong - thomaspl@uow.edu.au Plantard (UoW) FHE 1 / 24 Outline 1 Introduction Privacy Homomorphism Applications Timeline 2 Gentry Framework

More information

Faster fully homomorphic encryption: Bootstrapping in less than 0.1 seconds

Faster fully homomorphic encryption: Bootstrapping in less than 0.1 seconds Faster fully homomorphic encryption: Bootstrapping in less than 0.1 seconds I. Chillotti 1 N. Gama 2,1 M. Georgieva 3 M. Izabachène 4 1 2 3 4 Séminaire GTBAC Télécom ParisTech April 6, 2017 1 / 43 Table

More information

Robust Password- Protected Secret Sharing

Robust Password- Protected Secret Sharing Robust Password- Protected Secret Sharing Michel Abdalla, Mario Cornejo, Anca Niţulescu, David Pointcheval École Normale Supérieure, CNRS and INRIA, Paris, France R E S E A R C H UNIVERSITY PPSS: Motivation

More information

On Homomorphic Encryption and Secure Computation

On Homomorphic Encryption and Secure Computation On Homomorphic Encryption and Secure Computation challenge response Shai Halevi IBM NYU Columbia Theory Day, May 7, 2010 Computing on Encrypted Data Wouldn t it be nice to be able to o Encrypt my data

More information

Cryptography. Lecture 2: Perfect Secrecy and its Limitations. Gil Segev

Cryptography. Lecture 2: Perfect Secrecy and its Limitations. Gil Segev Cryptography Lecture 2: Perfect Secrecy and its Limitations Gil Segev Last Week Symmetric-key encryption (KeyGen, Enc, Dec) Historical ciphers that are completely broken The basic principles of modern

More information

Lattice-Based Cryptography

Lattice-Based Cryptography Liljana Babinkostova Department of Mathematics Computing Colloquium Series Detecting Sensor-hijack Attacks in Wearable Medical Systems Krishna Venkatasubramanian Worcester Polytechnic Institute Quantum

More information

CS Topics in Cryptography January 28, Lecture 5

CS Topics in Cryptography January 28, Lecture 5 CS 4501-6501 Topics in Cryptography January 28, 2015 Lecture 5 Lecturer: Mohammad Mahmoody Scribe: Ameer Mohammed 1 Learning with Errors: Motivation An important goal in cryptography is to find problems

More information

How to Use Short Basis : Trapdoors for Hard Lattices and new Cryptographic Constructions

How to Use Short Basis : Trapdoors for Hard Lattices and new Cryptographic Constructions Presentation Article presentation, for the ENS Lattice Based Crypto Workgroup http://www.di.ens.fr/~pnguyen/lbc.html, 30 September 2009 How to Use Short Basis : Trapdoors for http://www.cc.gatech.edu/~cpeikert/pubs/trap_lattice.pdf

More information

Private Comparison. Chloé Hébant 1, Cedric Lefebvre 2, Étienne Louboutin3, Elie Noumon Allini 4, Ida Tucker 5

Private Comparison. Chloé Hébant 1, Cedric Lefebvre 2, Étienne Louboutin3, Elie Noumon Allini 4, Ida Tucker 5 Private Comparison Chloé Hébant 1, Cedric Lefebvre 2, Étienne Louboutin3, Elie Noumon Allini 4, Ida Tucker 5 1 École Normale Supérieure, CNRS, PSL University 2 IRIT 3 Chair of Naval Cyber Defense, IMT

More information

Watermarking Cryptographic Functionalities from Standard Lattice Assumptions

Watermarking Cryptographic Functionalities from Standard Lattice Assumptions Watermarking Cryptographic Functionalities from Standard Lattice Assumptions Sam Kim Stanford University Joint work with David J. Wu Digital Watermarking 1 Digital Watermarking Content is (mostly) viewable

More information

Lossy Trapdoor Functions and Their Applications

Lossy Trapdoor Functions and Their Applications 1 / 15 Lossy Trapdoor Functions and Their Applications Chris Peikert Brent Waters SRI International On Losing Information 2 / 15 On Losing Information 2 / 15 On Losing Information 2 / 15 On Losing Information

More information

Private Puncturable PRFs from Standard Lattice Assumptions

Private Puncturable PRFs from Standard Lattice Assumptions Private Puncturable PRFs from Standard Lattice Assumptions Sam Kim Stanford University Joint work with Dan Boneh and Hart Montgomery Pseudorandom Functions (PRFs) [GGM84] Constrained PRFs [BW13, BGI13,

More information

Peculiar Properties of Lattice-Based Encryption. Chris Peikert Georgia Institute of Technology

Peculiar Properties of Lattice-Based Encryption. Chris Peikert Georgia Institute of Technology 1 / 19 Peculiar Properties of Lattice-Based Encryption Chris Peikert Georgia Institute of Technology Public Key Cryptography and the Geometry of Numbers 7 May 2010 2 / 19 Talk Agenda Encryption schemes

More information

Evaluating 2-DNF Formulas on Ciphertexts

Evaluating 2-DNF Formulas on Ciphertexts Evaluating 2-DNF Formulas on Ciphertexts Dan Boneh, Eu-Jin Goh, and Kobbi Nissim Theory of Cryptography Conference 2005 Homomorphic Encryption Enc. scheme is homomorphic to function f if from E[A], E[B],

More information

Shift Cipher. For 0 i 25, the ith plaintext character is. E.g. k = 3

Shift Cipher. For 0 i 25, the ith plaintext character is. E.g. k = 3 Shift Cipher For 0 i 25, the ith plaintext character is shifted by some value 0 k 25 (mod 26). E.g. k = 3 a b c d e f g h i j k l m n o p q r s t u v w x y z D E F G H I J K L M N O P Q R S T U V W X Y

More information

Proving Hardness of LWE

Proving Hardness of LWE Winter School on Lattice-Based Cryptography and Applications Bar-Ilan University, Israel 22/2/2012 Proving Hardness of LWE Bar-Ilan University Dept. of Computer Science (based on [R05, J. of the ACM])

More information

Computing with Encrypted Data Lecture 26

Computing with Encrypted Data Lecture 26 Computing with Encrypted Data 6.857 Lecture 26 Encryption for Secure Communication M Message M All-or-nothing Have Private Key, Can Decrypt No Private Key, No Go cf. Non-malleable Encryption Encryption

More information

Report on Learning with Errors over Rings-based HILA5 and its CCA Security

Report on Learning with Errors over Rings-based HILA5 and its CCA Security Report on Learning with Errors over Rings-based HILA5 and its CCA Security Jesús Antonio Soto Velázquez January 24, 2018 Abstract HILA5 is a cryptographic primitive based on lattices that was submitted

More information

Lattice-Based Cryptography. Chris Peikert University of Michigan. QCrypt 2016

Lattice-Based Cryptography. Chris Peikert University of Michigan. QCrypt 2016 Lattice-Based Cryptography Chris Peikert University of Michigan QCrypt 2016 1 / 24 Agenda 1 Foundations: lattice problems, SIS/LWE and their applications 2 Ring-Based Crypto: NTRU, Ring-SIS/LWE and ideal

More information

On the power of non-adaptive quantum chosen-ciphertext attacks

On the power of non-adaptive quantum chosen-ciphertext attacks On the power of non-adaptive quantum chosen-ciphertext attacks joint work with Gorjan Alagic (UMD, NIST), Stacey Jeffery (QuSoft, CWI), and Maris Ozols (QuSoft, UvA) Alexander Poremba August 29, 2018 Heidelberg

More information

Report Fully Homomorphic Encryption

Report Fully Homomorphic Encryption Report Fully Homomorphic Encryption Elena Fuentes Bongenaar July 28, 2016 1 Introduction Outsourcing computations can be interesting in many settings, ranging from a client that is not powerful enough

More information

Manipulating Data while It Is Encrypted

Manipulating Data while It Is Encrypted Manipulating Data while It Is Encrypted Craig Gentry IBM Watson ACISP 2010 The Goal A way to delegate processing of my data, without giving away access to it. Application: Private Google Search I want

More information

On error distributions in ring-based LWE

On error distributions in ring-based LWE On error distributions in ring-based LWE Wouter Castryck 1,2, Ilia Iliashenko 1, Frederik Vercauteren 1,3 1 COSIC, KU Leuven 2 Ghent University 3 Open Security Research ANTS-XII, Kaiserslautern, August

More information

Parameter selection in Ring-LWE-based cryptography

Parameter selection in Ring-LWE-based cryptography Parameter selection in Ring-LWE-based cryptography Rachel Player Information Security Group, Royal Holloway, University of London based on joint works with Martin R. Albrecht, Hao Chen, Kim Laine, and

More information

Riding on Asymmetry: Efficient ABE for Branching Programs

Riding on Asymmetry: Efficient ABE for Branching Programs Riding on Asymmetry: Efficient ABE for Branching Programs Sergey Gorbunov and Dhinakaran Vinayagamurthy Abstract. In an Attribute-Based Encryption ABE scheme the ciphertext encrypting a message µ, is associated

More information

Lattice Cryptography

Lattice Cryptography CSE 206A: Lattice Algorithms and Applications Winter 2016 Lattice Cryptography Instructor: Daniele Micciancio UCSD CSE Lattice cryptography studies the construction of cryptographic functions whose security

More information

Vadim Lyubashevsky 1 Chris Peikert 2 Oded Regev 3

Vadim Lyubashevsky 1 Chris Peikert 2 Oded Regev 3 A Tooλκit for Riνγ-ΛΩE κρyπτ oγραφ Vadim Lyubashevsky 1 Chris Peikert 2 Oded Regev 3 1 INRIA & ENS Paris 2 Georgia Tech 3 Courant Institute, NYU Eurocrypt 2013 27 May 1 / 12 A Toolkit for Ring-LWE Cryptography

More information

Lattice-Based Non-Interactive Arugment Systems

Lattice-Based Non-Interactive Arugment Systems Lattice-Based Non-Interactive Arugment Systems David Wu Stanford University Based on joint works with Dan Boneh, Yuval Ishai, Sam Kim, and Amit Sahai Soundness: x L, P Pr P, V (x) = accept = 0 No prover

More information

Public Key Compression and Modulus Switching for Fully Homomorphic Encryption over the Integers

Public Key Compression and Modulus Switching for Fully Homomorphic Encryption over the Integers Public Key Compression and Modulus Switching for Fully Homomorphic Encryption over the Integers Jean-Sébastien Coron, David Naccache and Mehdi Tibouchi University of Luxembourg & ENS & NTT EUROCRYPT, 2012-04-18

More information

Introduction to Cryptology. Lecture 2

Introduction to Cryptology. Lecture 2 Introduction to Cryptology Lecture 2 Announcements 2 nd vs. 1 st edition of textbook HW1 due Tuesday 2/9 Readings/quizzes (on Canvas) due Friday 2/12 Agenda Last time Historical ciphers and their cryptanalysis

More information

Fast Lattice-Based Encryption: Stretching SPRING

Fast Lattice-Based Encryption: Stretching SPRING Fast Lattice-Based Encryption: Stretching SPRING Charles Bouillaguet 1 Claire Delaplace 1,2 Pierre-Alain Fouque 2 Paul Kirchner 3 1 CFHP team, CRIStAL, Université de Lille, France 2 EMSEC team, IRISA,

More information

Pseudorandomness of Ring-LWE for Any Ring and Modulus. Chris Peikert University of Michigan

Pseudorandomness of Ring-LWE for Any Ring and Modulus. Chris Peikert University of Michigan Pseudorandomness of Ring-LWE for Any Ring and Modulus Chris Peikert University of Michigan Oded Regev Noah Stephens-Davidowitz (to appear, STOC 17) 10 March 2017 1 / 14 Lattice-Based Cryptography y = g

More information

Targeted Homomorphic Attribute Based Encryption

Targeted Homomorphic Attribute Based Encryption Targeted Homomorphic Attribute Based Encryption Zvika Brakerski David Cash Rotem Tsabary Hoeteck Wee Abstract In (key-policy) attribute based encryption (ABE), messages are encrypted respective to attributes

More information

1 Secure two-party computation

1 Secure two-party computation CSCI 5440: Cryptography Lecture 7 The Chinese University of Hong Kong, Spring 2018 26 and 27 February 2018 In the first half of the course we covered the basic cryptographic primitives that enable secure

More information

Semantic Security and Indistinguishability in the Quantum World

Semantic Security and Indistinguishability in the Quantum World Semantic Security and Indistinguishability in the Quantum World Tommaso Gagliardoni 1, Andreas Hülsing 2, Christian Schaffner 3 1 IBM Research, Swiss; TU Darmstadt, Germany 2 TU Eindhoven, The Netherlands

More information

Middle-Product Learning With Errors

Middle-Product Learning With Errors Middle-Product Learning With Errors Miruna Roşca, Amin Sakzad, Damien Stehlé and Ron Steinfeld CRYPTO 2017 Miruna Roşca Middle-Product Learning With Errors 23/08/2017 1 / 24 Preview We define an LWE variant

More information

Multiparty Computation from Somewhat Homomorphic Encryption. November 9, 2011

Multiparty Computation from Somewhat Homomorphic Encryption. November 9, 2011 Multiparty Computation from Somewhat Homomorphic Encryption Ivan Damgård 1 Valerio Pastro 1 Nigel Smart 2 Sarah Zakarias 1 1 Aarhus University 2 Bristol University CTIC 交互计算 November 9, 2011 Damgård, Pastro,

More information

Lecture 13: Private Key Encryption

Lecture 13: Private Key Encryption COM S 687 Introduction to Cryptography October 05, 2006 Instructor: Rafael Pass Lecture 13: Private Key Encryption Scribe: Ashwin Machanavajjhala Till this point in the course we have learnt how to define

More information

Lectures 1&2: Introduction to Secure Computation, Yao s and GMW Protocols

Lectures 1&2: Introduction to Secure Computation, Yao s and GMW Protocols CS 294 Secure Computation January 19, 2016 Lectures 1&2: Introduction to Secure Computation, Yao s and GMW Protocols Instructor: Sanjam Garg Scribe: Pratyush Mishra 1 Introduction Secure multiparty computation

More information

Secret Sharing CPT, Version 3

Secret Sharing CPT, Version 3 Secret Sharing CPT, 2006 Version 3 1 Introduction In all secure systems that use cryptography in practice, keys have to be protected by encryption under other keys when they are stored in a physically

More information

Fully homomorphic encryption scheme using ideal lattices. Gentry s STOC 09 paper - Part II

Fully homomorphic encryption scheme using ideal lattices. Gentry s STOC 09 paper - Part II Fully homomorphic encryption scheme using ideal lattices Gentry s STOC 09 paper - Part GGH cryptosystem Gentry s scheme is a GGH-like scheme. GGH: Goldreich, Goldwasser, Halevi. ased on the hardness of

More information

A Lattice-Based Universal Thresholdizer for Cryptographic Systems

A Lattice-Based Universal Thresholdizer for Cryptographic Systems A Lattice-Based Universal Thresholdizer for Cryptographic Systems Dan Boneh Rosario Gennaro Steven Goldfeder Sam Kim Abstract We develop a general approach to thresholdizing a large class of (non-threshold)

More information

How to Use Linear Homomorphic Signature in Network Coding

How to Use Linear Homomorphic Signature in Network Coding How to Use Linear Homomorphic Signature in Network Coding Li Chen lichen.xd at gmail.com Xidian University September 28, 2013 How to Use Linear Homomorphic Signature in Network Coding Outline 1 Linear

More information

UNIVERSITY OF CONNECTICUT. CSE (15626) & ECE (15284) Secure Computation and Storage: Spring 2016.

UNIVERSITY OF CONNECTICUT. CSE (15626) & ECE (15284) Secure Computation and Storage: Spring 2016. Department of Electrical and Computing Engineering UNIVERSITY OF CONNECTICUT CSE 5095-004 (15626) & ECE 6095-006 (15284) Secure Computation and Storage: Spring 2016 Oral Exam: Theory There are three problem

More information

Master of Logic Project Report: Lattice Based Cryptography and Fully Homomorphic Encryption

Master of Logic Project Report: Lattice Based Cryptography and Fully Homomorphic Encryption Master of Logic Project Report: Lattice Based Cryptography and Fully Homomorphic Encryption Maximilian Fillinger August 18, 01 1 Preliminaries 1.1 Notation Vectors and matrices are denoted by bold lowercase

More information

General Impossibility of Group Homomorphic Encryption in the Quantum World

General Impossibility of Group Homomorphic Encryption in the Quantum World General Impossibility of Group Homomorphic Encryption in the Quantum World Frederik Armknecht Tommaso Gagliardoni Stefan Katzenbeisser Andreas Peter PKC 2014, March 28th Buenos Aires, Argentina 1 An example

More information

Lattice Cryptography

Lattice Cryptography CSE 06A: Lattice Algorithms and Applications Winter 01 Instructor: Daniele Micciancio Lattice Cryptography UCSD CSE Many problems on point lattices are computationally hard. One of the most important hard

More information

Lecture 18 - Secret Sharing, Visual Cryptography, Distributed Signatures

Lecture 18 - Secret Sharing, Visual Cryptography, Distributed Signatures Lecture 18 - Secret Sharing, Visual Cryptography, Distributed Signatures Boaz Barak November 27, 2007 Quick review of homework 7 Existence of a CPA-secure public key encryption scheme such that oracle

More information

Solving LWE with BKW

Solving LWE with BKW Martin R. Albrecht 1 Jean-Charles Faugére 2,3 1,4 Ludovic Perret 2,3 ISG, Royal Holloway, University of London INRIA CNRS IIS, Academia Sinica, Taipei, Taiwan PKC 2014, Buenos Aires, Argentina, 28th March

More information

Notes for Lecture 17

Notes for Lecture 17 U.C. Berkeley CS276: Cryptography Handout N17 Luca Trevisan March 17, 2009 Notes for Lecture 17 Scribed by Matt Finifter, posted April 8, 2009 Summary Today we begin to talk about public-key cryptography,

More information

Faster Bootstrapping with Polynomial Error

Faster Bootstrapping with Polynomial Error Faster Bootstrapping with Polynomial Error Jacob Alperin-Sheriff Chris Peikert June 13, 2014 Abstract Bootstrapping is a technique, originally due to Gentry (STOC 2009), for refreshing ciphertexts of a

More information

Multikey Homomorphic Encryption from NTRU

Multikey Homomorphic Encryption from NTRU Multikey Homomorphic Encryption from NTRU Li Chen lichen.xd at gmail.com Xidian University January 12, 2014 Multikey Homomorphic Encryption from NTRU Outline 1 Variant of NTRU Encryption 2 Somewhat homomorphic

More information

Notes for Lecture 16

Notes for Lecture 16 COS 533: Advanced Cryptography Lecture 16 (11/13/2017) Lecturer: Mark Zhandry Princeton University Scribe: Boriana Gjura Notes for Lecture 16 1 Lattices (continued) 1.1 Last time. We defined lattices as

More information

Cut-and-Choose Yao-Based Secure Computation in the Online/Offline and Batch Settings

Cut-and-Choose Yao-Based Secure Computation in the Online/Offline and Batch Settings Cut-and-Choose Yao-Based Secure Computation in the Online/Offline and Batch Settings Yehuda Lindell Bar-Ilan University, Israel Technion Cryptoday 2014 Yehuda Lindell Online/Offline and Batch Yao 30/12/2014

More information

CSA E0 312: Secure Computation September 09, [Lecture 9-10]

CSA E0 312: Secure Computation September 09, [Lecture 9-10] CSA E0 312: Secure Computation September 09, 2015 Instructor: Arpita Patra [Lecture 9-10] Submitted by: Pratik Sarkar 1 Summary In this lecture we will introduce the concept of Public Key Samplability

More information

Quantum-secure symmetric-key cryptography based on Hidden Shifts

Quantum-secure symmetric-key cryptography based on Hidden Shifts Quantum-secure symmetric-key cryptography based on Hidden Shifts Gorjan Alagic QMATH, Department of Mathematical Sciences University of Copenhagen Alexander Russell Department of Computer Science & Engineering

More information

QUANTUM HOMOMORPHIC ENCRYPTION FOR POLYNOMIAL-SIZED CIRCUITS

QUANTUM HOMOMORPHIC ENCRYPTION FOR POLYNOMIAL-SIZED CIRCUITS QUANTUM HOMOMORPHIC ENCRYPTION FOR POLYNOMIAL-SIZED CIRCUITS Florian Speelman (joint work with Yfke Dulek and Christian Schaffner) http://arxiv.org/abs/1603.09717 QIP 2017, Seattle, Washington, Monday

More information

Are you the one to share? Secret Transfer with Access Structure

Are you the one to share? Secret Transfer with Access Structure Are you the one to share? Secret Transfer with Access Structure Yongjun Zhao, Sherman S.M. Chow Department of Information Engineering The Chinese University of Hong Kong, Hong Kong Private Set Intersection

More information

i-hop Homomorphic Encryption Schemes

i-hop Homomorphic Encryption Schemes i-hop Homomorphic Encryption Schemes Craig Gentry Shai Halevi Vinod Vaikuntanathan March 12, 2010 Abstract A homomorphic encryption scheme enables computing on encrypted data by means of a public evaluation

More information

On the Communication Complexity of Secure Function Evaluation with Long Output

On the Communication Complexity of Secure Function Evaluation with Long Output On the Communication Complexity of Secure Function Evaluation with Long Output Pavel Hubáček Daniel Wichs Abstract We study the communication complexity of secure function evaluation (SFE). Consider a

More information

Trapdoors for Lattices: Simpler, Tighter, Faster, Smaller

Trapdoors for Lattices: Simpler, Tighter, Faster, Smaller Trapdoors for Lattices: Simpler, Tighter, Faster, Smaller Daniele Micciancio 1 Chris Peikert 2 1 UC San Diego 2 Georgia Tech April 2012 1 / 16 Lattice-Based Cryptography y = g x mod p m e mod N e(g a,

More information

Fully Homomorphic Encryption over the Integers

Fully Homomorphic Encryption over the Integers Fully Homomorphic Encryption over the Integers Many slides borrowed from Craig Marten van Dijk 1, Craig Gentry 2, Shai Halevi 2, Vinod Vaikuntanathan 2 1 MIT, 2 IBM Research Computing on Encrypted Data

More information

Spooky Encryption and its Applications

Spooky Encryption and its Applications Spooky Encryption and its Applications Yevgeniy Dodis NYU Shai Halevi IBM Research Ron D. Rothblum MIT Daniel Wichs Northeastern University March 10, 2016 Abstract Consider a setting where inputs x 1,...,

More information

Homomorphic Evaluation of Lattice-Based Symmetric Encryption Schemes

Homomorphic Evaluation of Lattice-Based Symmetric Encryption Schemes An extended abstract of this paper appears in the proceedings of COCOON 2016. This is the full version. Homomorphic Evaluation of Lattice-Based Symmetric Encryption Schemes Pierre-Alain Fouque 1,3, Benjamin

More information

16 Fully homomorphic encryption : Construction

16 Fully homomorphic encryption : Construction 16 Fully homomorphic encryption : Construction In the last lecture we defined fully homomorphic encryption, and showed the bootstrapping theorem that transforms a partially homomorphic encryption scheme

More information

CRYPTANALYSIS OF COMPACT-LWE

CRYPTANALYSIS OF COMPACT-LWE SESSION ID: CRYP-T10 CRYPTANALYSIS OF COMPACT-LWE Jonathan Bootle, Mehdi Tibouchi, Keita Xagawa Background Information Lattice-based cryptographic assumption Based on the learning-with-errors (LWE) assumption

More information

Classical Homomorphic Encryption for Quantum Circuits

Classical Homomorphic Encryption for Quantum Circuits 2018 IEEE 59th Annual Symposium on Foundations of Computer Science Classical Homomorphic Encryption for Quantum Circuits Urmila Mahadev Department of Computer Science, UC Berkeley mahadev@berkeley.edu

More information

Leakage of Signal function with reused keys in RLWE key exchange

Leakage of Signal function with reused keys in RLWE key exchange Leakage of Signal function with reused keys in RLWE key exchange Jintai Ding 1, Saed Alsayigh 1, Saraswathy RV 1, Scott Fluhrer 2, and Xiaodong Lin 3 1 University of Cincinnati 2 Cisco Systems 3 Rutgers

More information

From NewHope to Kyber. Peter Schwabe April 7, 2017

From NewHope to Kyber. Peter Schwabe   April 7, 2017 From NewHope to Kyber Peter Schwabe peter@cryptojedi.org https://cryptojedi.org April 7, 2017 In the past, people have said, maybe it s 50 years away, it s a dream, maybe it ll happen sometime. I used

More information

Quantum FHE (Almost) As Secure as Classical

Quantum FHE (Almost) As Secure as Classical Quantum FHE (Almost) As Secure as Classical Zvika Brakerski Abstract Fully homomorphic encryption schemes (FHE) allow to apply arbitrary efficient computation to encrypted data without decrypting it first.

More information

Weaknesses in Ring-LWE

Weaknesses in Ring-LWE Weaknesses in Ring-LWE joint with (Yara Elias, Kristin E. Lauter, and Ekin Ozman) and (Hao Chen and Kristin E. Lauter) ECC, September 29th, 2015 Lattice-Based Cryptography Post-quantum cryptography Ajtai-Dwork:

More information

Homomorphic Encryption. Liam Morris

Homomorphic Encryption. Liam Morris Homomorphic Encryption Liam Morris Topics What Is Homomorphic Encryption? Partially Homomorphic Cryptosystems Fully Homomorphic Cryptosystems Benefits of Homomorphism Drawbacks of Homomorphism What Is

More information

Fully Homomorphic Encryption - Part II

Fully Homomorphic Encryption - Part II 6.889: New Developments in Cryptography February 15, 2011 Instructor: Boaz Barak Fully Homomorphic Encryption - Part II Scribe: Elette Boyle 1 Overview We continue our discussion on the fully homomorphic

More information

Post-Quantum Cryptography

Post-Quantum Cryptography Post-Quantum Cryptography Sebastian Schmittner Institute for Theoretical Physics University of Cologne 2015-10-26 Talk @ U23 @ CCC Cologne This work is licensed under a Creative Commons Attribution-ShareAlike

More information

Multiparty Computation with Low Communication, Computation and Interaction via Threshold FHE

Multiparty Computation with Low Communication, Computation and Interaction via Threshold FHE Multiparty Computation with Low Communication, Computation and Interaction via Threshold FHE Gilad Asharov Abhishek Jain Daniel Wichs June 9, 2012 Abstract Fully homomorphic encryption (FHE) provides a

More information

Gentry s SWHE Scheme

Gentry s SWHE Scheme Homomorphic Encryption and Lattices, Spring 011 Instructor: Shai Halevi May 19, 011 Gentry s SWHE Scheme Scribe: Ran Cohen In this lecture we review Gentry s somewhat homomorphic encryption (SWHE) scheme.

More information

Computing on Encrypted Data

Computing on Encrypted Data Computing on Encrypted Data COSIC, KU Leuven, ESAT, Kasteelpark Arenberg 10, bus 2452, B-3001 Leuven-Heverlee, Belgium. August 31, 2018 Computing on Encrypted Data Slide 1 Outline Introduction Multi-Party

More information

Lecture 7: CPA Security, MACs, OWFs

Lecture 7: CPA Security, MACs, OWFs CS 7810 Graduate Cryptography September 27, 2017 Lecturer: Daniel Wichs Lecture 7: CPA Security, MACs, OWFs Scribe: Eysa Lee 1 Topic Covered Chosen Plaintext Attack (CPA) MACs One Way Functions (OWFs)

More information