Zhenfei Zhang


Cryptograhy Engineer zhenfei.zhang@hotmail.com Algorand https://zhenfeizhang.github.io/ Boston, MA https://www.linkedin.com/in/zhenfeizhang/ ——————- —————————-

Experience

Cryptography Engineer, Algorand, 2018-now

Identify, develop and standardize cryptographic tools to be used by Algorand blockchain protocol.

Director of Cryptography Research, Security Innovation -> OnBoard Security, 2014-2018

  • Homomorphic encryptions (IARPA project);
  • Post-quantum cryptography;
  • blockchain cryptography.

Highlights

Standards
Contribute to 4 out of 26 2nd round candidates of NIST’s post-quantum standatdization process: Falcon, LAC, NTRU and Round5;
LAC won the first prize of Chinese post-quantum cryptography competition.
Internet draft: BLS-signature, Quantum safe hybrid for TLS 1.2 and TLS 1.3;
Former member of ETSI Quantum-safe Cryptography (QSC) working group;
Former member of ISO/SC27 working group.
Publication and patents
3 U.S. patents; 25+ peer reviewed paper at Asiacrypt 2019, Crypto 2019, Asiacrypt 2018, PKC 2018, IEEE Transaction on Computers, etc.;
See next pages for full list.
Programming Languages
Rust: Cryptographic library at product level.

C: Cryptographic library, nearly product level code, submitted to NIST PQC competition.

Python/Sage:  Proof of concept codes.

\pagebreak

Software

Pixel
A pairing based, forward-secure and aggregatable signature, written in python (PoC) and rust (product level). Improves existing (non-aggregatable) solution by 100x, open sourced and external audited. Source code.
Vector commitment
A pairing based, aggregatable vector commitment, written in rust (product level). To be open sourced soon.
Raptor
A lattice based (linkable) ring signature, written in C as a PoC, aiming to protect user’s anonymity against quantum adversaries. Source code.
NTRUEncrypt
A C implementation of NTRUEncrypt, submitted to NIST PQC standardization process. Source code.
Ring multiplication
A C library for fast ring multiplication using AVX-2; improving prior codes by a factor of 2.23. Source code
libgcrypt-ntru
Enabling NTRUEncrypt for libgcrypt. Source code.

Education

2010-2014
PhD, Computer Science, University of Wollongong, Australia;

Thesis title: Revisiting Fully Homomorphic Encryption Schemes and Their Cryptographic Primitives

2008-2009
Master of Engineering - Research, University of Wollongong, Australia;
2007
Master of Internet Technology, University of Wollongong, Australia;
2001-2005
Bachelor of Computer Science, BeiHang _University, China.

Research Interest

  • Practical aspects of lattice based cryptography;
  • Cryptographic primitives for blockchains privacy, such as ring signatures, zero knowledge proofs;

\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \

See next pages for the full list of patents, standards and publications.
\pagebreak

Patents

  • Chameleon Hash technique and linkable ring signature technique
    • Zhenfei Zhang
    • Provisional patent, 2018.
  • Digital signature technique
    • Jeffrey Hoffstein, Jill Pipher, William J Whyte, Zhenfei Zhang
    • United States Patent Application, 2018.
  • Digital signature method and apparatus
    • Jeffrey Hoffstein, Jill Pipher, Joseph H Silverman, William J Whyte, Zhenfei Zhang
    • United States Patent 15530762, 2017.

Standards

  • BLS Signature Scheme
    • D. Boneh, S.Gorbunov, R. Wahby, H.Wee, Z.Zhang
    • Internet-Draft.
  • Quantum-Safe Hybrid (QSH) Ciphersuite for Transport Layer Security (TLS) version 1.2
    • J. M. Schanck, W. Whyte and Z. Zhang
    • Internet-Draft.
  • Criteria for selection of public-key cryptographic algorithms for quantum-safe hybrid cryptography
    • J. M. Schanck, W. Whyte and Z. Zhang
    • Internet-Draft.
  • Quantum-Safe Hybrid (QSH) Ciphersuite for Transport Layer Security (TLS) version 1.3
    • W. Whyte, Z. Zhang, S. Fluhrer and O. Garcia-Morchon
    • Internet-Draft.
  • Efficient Embedded Security Standards (EESS) #1: Implementation Aspects of NTRUEncrypt
    • W. Whyte and Z. Zhang
    • Consortium for Efficient Embedded Security
  • Quantum Safe Cryptography and Security; An introduction, benefits, enablers and challenges
    • One of 22 contributors
    • European Telecommunications Standards Institute(ETSI) white paper
\pagebreak

Publications

2020

  • MPSign: A Signature from Small-Secret Middle-Product Learning with Errors
    • Shi Bai, Dipayan Das, Ryo Hiromasa, Miruna Rosca, Amin Sakzad, Damien Stehle, Ron Steinfeld, Zhenfei Zhang
    • PKC 2020. IACR eprint. Source code

2019

  • Modular Lattice Signatures, revisited
    • Dipayan Das, Jeffrey Hoffstein, Jill Pipher, William Whyte, Zhenfei Zhang
    • Design, Codes and Cryptography. IACR eprint
  • Middle-Product Learning with Rounding Problem and its Applications
    • Shi Bai, Katharina Boudgoust, Dipayan Das, Adeline Roux-Langlois, Weiqiang Wen, Zhenfei Zhang
    • Asiacrypt 2019. IACR eprint
  • Efficient Lattice-Based Zero-Knowledge Arguments with Standard Soundness: Construction and Applications
    • Rupeng Yang, Man Ho Au, Zhenfei Zhang, Qiuliang Xu, Zuoxia Yu, William Whyte
    • Crypto 2019. IACR eprint.
  • (Linkable) Ring Signature from Hash-Then-One-Way Signature
    • Xingye Lu, Man Ho Au, Zhenfei Zhang
    • TrustCom 2019. IACR eprint.
  • Ring Signatures based on Middle-Product Learning with Errors Problems
    • Dipayan Das, Man Ho Au and Zhenfei Zhang
    • Africacrypt 2019.
  • Raptor: A Practical Lattice-Based (Linkable) Ring Signature
  • Round5: Compact and Fast Post-Quantum Public-Key Encryption
    • Hayo Baan, Sauvik Bhattacharya, Scott Fluhrer, Oscar Garcia-Morchon, Thijs Laarhoven, Ronald Rietman, Markku-Juhani O. Saarinen, Ludo Tolhuizen, Zhenfei Zhang
    • PQCrypto 2019. IACR eprint. Website.
  • Cryptanalysis of an NTRU-based Proxy Encryption Scheme from ASIACCS’15
    • Zhen Liu, Yanbin Pan, Zhenfei Zhang
    • PQCrypto 2019. IACR eprint.

2018

  • LAC: Practical Ring-LWE Based Public-Key Encryption with Byte-Level Modulus
    • Xianhui Lu, Yamin Liu, Zhenfei Zhang, Dingding Jia, Haiyang Xue, Jingnan He, Bao Li
    • Pre-print. IACR eprint. Source code
  • Shorter Messages and Faster Post-Quantum Encryption with Round5 on Cortex M
    • Markku-Juhani O. Saarinen, Sauvik Bhattacharya, Oscar Garcia-Morchon, Ronald Rietman, Ludo Tolhuizen, Zhenfei Zhang
    • Cardis 2018. IACR eprint.
  • On the Hardness of the Computational Ring-LWR Problem and its Applications
    • Long Chen, Zhenfeng Zhang, Zhenfei Zhang
    • Asiacrypt 2018. IACR eprint.
  • A signature scheme from the finite field isomorphism problem.
    • Jeffrey Hoffstein, Joseph H. Silverman, William Whyte, Zhenfei Zhang
    • MathCrypt 2018. IACR eprint, Slides.
  • Practical Signatures from the Partial Fourier Recovery Problem Revisited: A Provably-Secure and Gaussian-Distributed Construction.
    • Xingye Lu, Zhenfei Zhang, Man Ho Au
    • ACISP 2018. Manuscript.
  • Optimizing polynomial convolution for NTRUEncrypt.
  • Fully Homomorphic Encryption from the Finite Field Isomorphism Problem.
    • Yarkin Doröz, Jeffrey Hoffstein, Jill Pipher, Joseph H. Silverman, Berk Sunar, William Whyte, Zhenfei Zhang:
    • PKC 2018. IACR eprint.

2017

  • Choosing parameters for NTRUEncrypt
    • Jeffrey Hoffstein, Jill Pipher, John M. Schanck, Joseph H. Silverman, William Whyte, Zhenfei Zhang
    • CT-RSA 2017. IACR eprint.
  • Round2: KEM and PKE based on GLWR.
    • Hayo Baan, Sauvik Bhattacharya, Óscar García-Morchón, Ronald Rietman, Ludo Tolhuizen, Jose Luis Torre-Arce, Zhenfei Zhang
    • NIST PQC submission. IACR eprint.
  • A signature scheme from Learning with Truncation.
    • Jeffrey Hoffstein, Jill Pipher, William Whyte, Zhenfei Zhang
    • Pre-print. IACR eprint.
  • Anonymous Announcement System (AAS) for Electric Vehicle in VANETs.
    • Man Ho Au, Joseph K. Liu, Zhenfei Zhang, Willy Susilo, Jin Li
    • The Computer Journal. Manuscript.

2016

  • Circuit-extension handshakes for Tor achieving forward secrecy in a quantum world.
  • NTRU modular lattice signature scheme on CUDA GPUs.
    • Wei Dai, Berk Sunar, John M. Schanck, William Whyte, Zhenfei Zhang
    • HPCS 2016. IACR eprint.

2015

  • LLL for ideal lattices: re-evaluation of the security of Gentry-Halevi’s FHE scheme.
    • Thomas Plantard, Willy Susilo, Zhenfei Zhang
    • Design, Codes and Cryptography. Manuscript.
  • DA-Encrypt: Homomorphic Encryption via Non-Archimedean Diophantine Approximation.
    • Jeffrey Hoffstein, Jill Pipher, John M. Schanck, Joseph H. Silverman, William Whyte, Zhenfei Zhang
    • Pre-print. IACR eprint.

2014 and earlier

  • Fully Homomorphic Encryption Using Hidden Ideal Lattice.
    • Thomas Plantard, Willy Susilo, Zhenfei Zhang
    • IEEE Transation on Information Forensics and Security. Manuscript.
  • Adaptive Precision Floating Point LLL.
    • Thomas Plantard, Willy Susilo, Zhenfei Zhang
    • ACISP 2013. Manuscript.
  • On the CCA-1 Security of Somewhat Homomorphic Encryption over the Integers.
    • Zhenfei Zhang, Thomas Plantard, Willy Susilo
    • ISPEC 2012. Manuscript.
  • Lattice Reduction for Modular Knapsack.
    • Thomas Plantard, Willy Susilo, Zhenfei Zhang
    • SAC 2012. Manuscript.
  • Reaction Attack on Outsourced Computing with Fully Homomorphic Encryption Schemes.
    • Zhenfei Zhang, Thomas Plantard, Willy Susilo
    • ISPEC 2012. Manuscript.