Amit Sahai

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Amit Sahai
Amit Sahai.JPG
Born
Amit Sahai

1974 (age 51–52)
Thousand Oaks, California, U.S.
Alma mater
Known for
Awards
Scientific career
Fields Computer science, cryptography
Institutions Princeton University (2000–2004)
UCLA (2004–present)
Thesis Frontiers in Zero Knowledge  (2000)
Doctoral advisor Shafi Goldwasser [1]
Doctoral students
Website www.cs.ucla.edu/~sahai/

Amit Sahai (born 1974) is an Indian-American computer scientist and cryptographer. He is a professor of computer science and (by courtesy) mathematics at the University of California, Los Angeles, where he holds the Symantec Endowed Chair in Computer Science and directs the Center for Encrypted Functionalities, a National Science Foundation Frontiers Center. [2] He is a Fellow of the ACM, [3] a Fellow of the International Association for Cryptologic Research, [4] and a Simons Investigator. [5]

Contents

Sahai is known for foundational contributions to cryptography, including the co-invention of indistinguishability obfuscation, attribute-based encryption, and functional encryption. In 2020, Sahai and collaborators resolved a central open problem in cryptography by constructing indistinguishability obfuscation from well-founded assumptions, a result described as achieving the "crown jewel" of the field. [6] He received the 2022 Michael and Sheila Held Prize for this work [7] and delivered an invited special sectional lecture at the International Congress of Mathematicians in 2022. [8]

Early life and education

Sahai was born in 1974 in Thousand Oaks, California, to parents who had immigrated from India. [9] His brother is Anant Sahai, a professor of electrical engineering and computer sciences at the University of California, Berkeley. [10]

He received a B.A. in mathematics with a minor in computer science from the University of California, Berkeley, summa cum laude , in 1996. [9] At Berkeley, Sahai was named Computing Research Association Outstanding Undergraduate of the Year in North America and was a member of the three-person team that won first place at the 1996 ACM International Collegiate Programming Contest. [11]

Sahai received his Ph.D. in computer science from MIT in 2000 under the supervision of Shafi Goldwasser. [1] His dissertation, Frontiers in Zero Knowledge, addressed fundamental questions in the theory of zero-knowledge proofs.

Career

From 2000 to 2004, Sahai was an assistant professor of computer science at Princeton University. [9] In 2004, he joined the faculty at UCLA, where he holds the Symantec Endowed Chair in Computer Science and a courtesy appointment in the Department of Mathematics. [2] [12] He directs the Center for Encrypted Functionalities, an NSF Frontiers Center focused on the theory and applications of program obfuscation and secure computation. [13]

Sahai serves as an editor of the Journal of Cryptology and has served on the program committees of major conferences including FOCS (program co-chair, 2023) and TCC (program chair, 2013). [2] Since 2023, he has served as an advisor to the Prison Mathematics Project. [14]

Research

Indistinguishability obfuscation

A central thread in Sahai's research concerns indistinguishability obfuscation (iO), a cryptographic primitive that aims to make computer programs unintelligible while preserving their functionality. In 2001, Sahai co-authored a seminal paper with Boaz Barak, Oded Goldreich, Russell Impagliazzo, Steven Rudich, Salil Vadhan, and Ke Yang that formalized the notion of cryptographic obfuscation and demonstrated the impossibility of achieving the strongest form, known as virtual black-box obfuscation. [15] That paper also proposed the weaker but still powerful notion of indistinguishability obfuscation.

In 2013, Sahai and collaborators constructed the first candidate general-purpose iO scheme, a development described as "a watershed moment for cryptography." [16] [17] However, the security of this scheme and its successors relied on newly introduced assumptions that were subsequently broken, leaving the status of iO uncertain.

In 2020, Sahai, together with Aayush Jain and Huijia Lin, resolved this long-standing open problem by constructing iO from the subexponential hardness of four well-studied cryptographic assumptions, including LWE and LPN. [18] The result was widely covered in the scientific press, with Quanta Magazine describing iO as the "crown jewel" of cryptography. [6] The paper received a Best Paper Award at STOC 2021. [19]

Functional encryption and attribute-based encryption

Sahai co-authored the paper that introduced attribute-based encryption, originally termed "fuzzy identity-based encryption," with his doctoral student Brent Waters. [20] This work, presented at Eurocrypt 2005, received the 2020 IACR Test of Time Award. [21] Sahai and collaborators also helped formalize functional encryption, a generalization of public-key encryption in which secret keys can be associated with functions that determine what information a decryptor can learn from a ciphertext. [22] The concept was described by the BBC World Service as promising "safer data" through more fine-grained access control. [23]

Zero-knowledge proofs and secure computation

Sahai has made several contributions to the theory of zero-knowledge proofs. With Cynthia Dwork and Moni Naor, he introduced the concept of concurrent zero-knowledge proofs, addressing the security of zero-knowledge protocols when many instances run simultaneously. [24] With Yuval Ishai, Eyal Kushilevitz, and Rafail Ostrovsky, he co-authored the paper that introduced the MPC-in-the-head technique, which uses secure multi-party computation protocols to construct efficient zero-knowledge proofs. [25]

In secure multi-party computation, Sahai co-authored the first universally composable secure MPC protocol [26] and the first such protocol that avoided the need for trusted setups, using a technique called "angel-aided simulation." [27] He also co-developed the IPS compiler for building efficient MPC protocols from oblivious transfer. [28]

Non-interactive proof systems

Sahai's 2008 paper with Jens Groth, "Efficient Non-interactive Proof Systems for Bilinear Groups," introduced a new type of non-interactive proof system offering improved efficiency for cryptographic applications over bilinear groups. [29] The paper received the 2023 IACR Test of Time Award for Eurocrypt. [30]

Recognition

Sahai was named an Alfred P. Sloan Foundation Research Fellow in 2002. [19] He received an Okawa Research Grant Award in 2007, a Xerox Foundation Faculty Award in 2010, and a Google Faculty Research Award in 2010. [19] He received the Pazy Memorial Award in 2012. [2]

He was elected an ACM Fellow in 2018 "for contributions to cryptography and to the development of indistinguishability obfuscation." [3] In 2019, he was named a Fellow of the International Association for Cryptologic Research "for fundamental contributions, including to secure computation, zero knowledge, and functional encryption, and for service to the IACR." [4] He was named a Simons Investigator by the Simons Foundation in 2021 [5] and a Fellow of the Royal Society of Arts the same year. [2]

In 2022, Sahai received the Michael and Sheila Held Prize from the National Academy of Sciences for "outstanding, innovative, creative, and influential research" in his development of indistinguishability obfuscation. [7] That year, he was also invited to deliver a special sectional lecture at the International Congress of Mathematicians. [8]

He was elected a Fellow of the American Mathematical Society in the 2024 class of fellows. [31]

Sahai's papers have received multiple Test of Time Awards from the IACR (for Eurocrypt 2020, Eurocrypt 2023, and ACM CCS 2016), as well as a Best Paper Award at STOC 2021. [19] [30] For his teaching, he received the 2016 Lockheed Martin Excellence in Teaching Award from UCLA Samueli. [2]

Selected publications

References

  1. 1 2 Amit Sahai at the Mathematics Genealogy Project OOjs UI icon edit-ltr-progressive.svg
  2. 1 2 3 4 5 6 "Amit Sahai". UCLA Samueli School of Engineering. Retrieved 2026-02-06.
  3. 1 2 2018 ACM Fellows Honored for Pivotal Achievements that Underpin the Digital Age, Association for Computing Machinery, December 5, 2018
  4. 1 2 "Amit Sahai, IACR Fellow, 2019". IACR.
  5. 1 2 "Simons Investigators, Mathematics and Physical Sciences, 2021". Simons Foundation.
  6. 1 2 Klarreich, Erica (2020-11-10). "Computer Scientists Achieve 'Crown Jewel' of Cryptography". Quanta Magazine .
  7. 1 2 "2022 NAS Awards Recipients Announced". National Academy of Sciences. 2022.
  8. 1 2 "Professor Amit Sahai Invited to Deliver Special Sectional Lecture at ICM". UCLA Computer Science.
  9. 1 2 3 "EQuad News, Princeton University, Fall 2000, Volume 13, No. 1". Archived from the original on 2015-12-12. Retrieved 2016-03-31.
  10. ↑ Colvin, Richard Lee (1990-03-20). "2 From Thousand Oaks Are Star Academic Performers". Los Angeles Times . Archived from the original on 2026-02-06. Retrieved 2026-02-06.
  11. ↑ "History – ICPC 1996".
  12. ↑ "UCLA Computer Science Professor Amit Sahai to Join the Department". UCLA Mathematics. 2022-08-18.
  13. ↑ "Center for Encrypted Functionalities".
  14. ↑ Tillinghast-Raby, Amory (2023-06-02). "Pioneering Advanced Math from Behind Bars". Scientific American . Retrieved 2025-11-15.
  15. ↑ Barak, Boaz; Goldreich, Oded; Impagliazzo, Russell; Rudich, Steven; Sahai, Amit; Vadhan, Salil; Yang, Ke (April 2012). "On the (im)possibility of obfuscating programs". Journal of the ACM. 59 (2): 1–48. CiteSeerX   10.1.1.21.6694 . doi:10.1145/2160158.2160159. S2CID   220754739.
  16. ↑ Klarreich, Erica (2014-02-03). "Cryptography Breakthrough Could Make Software Unhackable". Quanta Magazine .
  17. ↑ Sanjam Garg; Craig Gentry; Shai Halevi; Mariana Raykova; Amit Sahai; Brent Waters (2013). "Candidate Indistinguishability Obfuscation and Functional Encryption for all Circuits". 2013 IEEE 54th Annual Symposium on Foundations of Computer Science. IEEE. pp. 40–49. CiteSeerX   10.1.1.672.1968 . doi:10.1109/FOCS.2013.13. ISBN   978-0-7695-5135-7. S2CID   15703414.
  18. ↑ Jain, Aayush; Lin, Huijia; Sahai, Amit (2021). Indistinguishability obfuscation from well-founded assumptions. Proceedings of the 53rd Annual ACM SIGACT Symposium on Theory of Computing (STOC 2021). pp. 60–73. doi:10.1145/3406325.3451093.
  19. 1 2 3 4 "Amit Sahai". Simons Institute for the Theory of Computing. 9 December 2013.
  20. ↑ "A Q&A with UCLA Professor of Computer Science Amit Sahai". NTT Research.
  21. ↑ "Announcing the 2023 IACR Test-of-Time Award for Eurocrypt". IACR. April 14, 2023.
  22. ↑ Dan Boneh; Amit Sahai; Brent Waters (2011). "Functional Encryption: Definitions and Challenges". Theory of Cryptography. Lecture Notes in Computer Science. Vol. 6597. Springer Berlin Heidelberg. pp. 253–273. doi:10.1007/978-3-642-19571-6_16. ISBN   978-3-642-19570-9. S2CID   9847531.
  23. ↑ "Number keys promise safer data". BBC News.
  24. ↑ Dwork, Cynthia; Naor, Moni; Sahai, Amit (2004). "Concurrent Zero Knowledge". Journal of the ACM. 51 (6): 851–898. CiteSeerX   10.1.1.43.716 . doi:10.1145/1039488.1039489. S2CID   52827731.
  25. ↑ Yuval Ishai; Eyal Kushilevitz; Rafail Ostrovsky; Amit Sahai (2009). "Zero-Knowledge Proofs from Secure Multiparty Computation". SIAM J. Comput. 39 (3): 1121–1152. doi:10.1137/080725398.
  26. ↑ Ran Canetti; Yehuda Lindell; Rafail Ostrovsky; Amit Sahai (2002). "Universally composable two-party and multi-party secure computation". Proceedings of the thirty-fourth annual ACM symposium on Theory of computing. pp. 494–503. CiteSeerX   10.1.1.121.4746 . doi:10.1145/509907.509980. ISBN   978-1581134957. S2CID   564559.
  27. ↑ Manoj Prabhakaran; Amit Sahai (2004). "New notions of security". Proceedings of the thirty-sixth annual ACM symposium on Theory of computing. pp. 242–251. doi:10.1145/1007352.1007394. ISBN   978-1581138528. S2CID   10001022.
  28. ↑ Yuval Ishai; Manoj Prabhakaran; Amit Sahai (2008). "Founding Cryptography on Oblivious Transfer – Efficiently". Advances in Cryptology – CRYPTO 2008. Lecture Notes in Computer Science. Vol. 5157. pp. 572–591. doi:10.1007/978-3-540-85174-5_32. ISBN   978-3-540-85173-8.
  29. ↑ Groth, Jens; Sahai, Amit (2008). "Efficient Non-interactive Proof Systems for Bilinear Groups". Advances in Cryptology – EUROCRYPT 2008. Lecture Notes in Computer Science. Vol. 4965. Springer Berlin Heidelberg. pp. 415–432. doi:10.1007/978-3-540-78967-3_24. ISBN   978-3-540-78966-6.
  30. 1 2 "Announcing the 2023 IACR Test-of-Time Award for Eurocrypt". IACR. April 14, 2023.
  31. ↑ "2024 Class of Fellows of the AMS". American Mathematical Society. Retrieved 2023-11-09.
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