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Secure Multiparty RAM Computation in Constant Rounds

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Presentation on theme: "Secure Multiparty RAM Computation in Constant Rounds"β€” Presentation transcript:

1 Secure Multiparty RAM Computation in Constant Rounds
Sanjam Garg Divya Gupta Peihan Miao Omkant Pandey

2 𝐷 1 𝐷 2 𝐷 3 𝐷 𝑃 𝑃 𝐷 (π‘₯) 𝑃 𝐷 (π‘₯) 𝑃 𝐷 (π‘₯) π‘₯ 1 π‘₯ 3 π‘₯ 2

3 Our goal: MPC for RAM How about MPC + RAM ?

4 MPC + RAM Garbled RAM [LO’13, GHLORW’14, GLOS’15, GLO’15]
𝐷 ←GData 𝐷 𝑃 ←GProg 𝑃 π‘₯ ←GInput π‘₯ 𝑦← 𝑃 𝐷 ( π‘₯ ) MPC for circuits [GMW’87, BGW’88, CCD’88, BMR’90, …]

5 𝐷 𝐷 𝐷 𝛱 GData 𝐷 1 𝐷 3 𝐷 2 𝐷 ←GData 𝐷 𝑃 ←GProg 𝑃 π‘₯ ←GInput π‘₯
𝑦← 𝑃 𝐷 ( π‘₯ )

6 𝑃 𝑃 𝑃 𝑃 𝑃 𝛱 GProg 𝑃 𝐷 ←GData 𝐷 𝑃 ←GProg 𝑃 π‘₯ ←GInput π‘₯ 𝑦← 𝑃 𝐷 ( π‘₯ )

7 π‘₯ π‘₯ π‘₯ 𝛱 GInput π‘₯ 1 π‘₯ 3 π‘₯ 2 𝐷 ←GData 𝐷 𝑃 ←GProg 𝑃 π‘₯ ←GInput π‘₯
𝑦← 𝑃 𝐷 ( π‘₯ )

8 𝑦← 𝑃 𝐷 π‘₯ 𝐷 ←GData 𝐷 𝑃 ←GProg 𝑃 π‘₯ ←GInput π‘₯ 𝑦← 𝑃 𝐷 ( π‘₯ )

9 Round Complexity & Efficiency of Multi-Party Computation

10 Round complexity?

11 Our goal: MPC for RAM in π’ͺ 1 rounds

12 π’ͺ 1 -round MPC + π’ͺ 1 -round RAM
Garbled RAM [LO’13, GHLORW’14, GLOS’15, GLO’15] 𝐷 ←GData 𝐷 𝑃 ←GProg 𝑃 π‘₯ ←GInput π‘₯ 𝑦← 𝑃 𝐷 ( π‘₯ ) MPC for circuits [GMW’87, BGW’88, CCD’88, BMR’90, …] Constant Rounds! Constant Rounds!

13 Our goal: MPC for RAM in π’ͺ 1 rounds
π’ͺ 1 -round MPC + π’ͺ 1 -round RAM !

14 Round Complexity & Efficiency of Multi-Party Computation

15 Efficiency?

16 Our goal: MPC for RAM in π’ͺ 1 rounds
+ black-box use of cryptographic primitives

17 Black-box 𝛱 What? Why? Theoretical Practical 𝑓 π‘Ž 𝑓(π‘Ž) 𝑏←𝑓 π‘Ž 𝑓

18 Our goal: MPC for RAM in π’ͺ 1 rounds
+ black-box use of OWFs

19 Black-box MPC + Black-box RAM
Garbled RAM [LO’13, GHLORW’14, GLOS’15, GLO’15] 𝐷 ←GData 𝐷 𝑃 ←GProg 𝑃 π‘₯ ←GInput π‘₯ 𝑦← 𝑃 𝐷 ( π‘₯ ) MPC for circuits [GMW’87, BGW’88, CCD’88, BMR’90, …] Black box? Black box?

20 Black-box MPC + Black-box RAM
Black-box garbled RAM [Garg, Lu, Ostrovsky’15] π’ͺ 1 -round black-box MPC [Beaver, Micali, Rogaway’90]

21 Black-box garbled RAM 𝐷 𝐷 GData 𝐷 ←GData 𝐷 𝑃 ←GProg 𝑃 π‘₯ ←GInput π‘₯
𝑦← 𝑃 𝐷 ( π‘₯ )

22 Black-box MPC 𝐢 𝛱 𝐢 𝛱 𝐢 𝛱 𝐢

23 Black-box RAM + Black-box MPC
GData 𝛱 𝐢 𝛱 𝐢 𝛱 𝐢

24 Black-box RAM + Black-box MPC
GData 𝛱 𝐢 𝛱 𝐢 𝛱 𝐢

25 Black-box garbled RAM [GLO’15]
GData 𝐷 𝐷

26 Black-box RAM + Black-box MPC
GData 𝛱 𝐢 𝛱 𝐢 𝛱 𝐢

27 Against malicious adversaries
GData 𝛱 𝐢 𝛱 𝐢 𝛱 𝐢

28 Our result: MPC for RAM in π’ͺ 1 rounds
+ black-box use of OWFs Semi-honest / Malicious adversaries

29 Thank you!


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