public seed pseudorandom permutations

Public-seed Pseudorandom Permutations Pratik Soni Stefano Tessaro - PowerPoint PPT Presentation

Public-seed Pseudorandom Permutations Pratik Soni Stefano Tessaro UC Santa Barbara UC Santa Barbara EUROCRYPT 2017 Cryptographic schemes often built from generic building blocks Cryptographic schemes often built from generic building


  1. UCE security 𝑑 ← Gen(1 πœ‡ ) 𝑔 ← Funcs(𝑛, π‘œ) β„Ž 𝑑 𝑔 source 𝑇 𝐼 = (π»π‘“π‘œ, β„Ž) Bellare Hoang Keelveedhi

  2. UCE security 𝑑 ← Gen(1 πœ‡ ) 𝑔 ← Funcs(𝑛, π‘œ) β„Ž 𝑑 𝑔 source 𝑇 𝐼 = (π»π‘“π‘œ, β„Ž) Bellare Hoang Keelveedhi

  3. UCE security 𝑑 ← Gen(1 πœ‡ ) 𝑔 ← Funcs(𝑛, π‘œ) β„Ž 𝑑 𝑔 source 𝑇 𝑀 𝐼 = (π»π‘“π‘œ, β„Ž) 𝐸 distinguisher Bellare Hoang Keelveedhi

  4. UCE security 𝑑 ← Gen(1 πœ‡ ) 𝑑 ← Gen(1 πœ‡ ) 𝑔 ← Funcs(𝑛, π‘œ) β„Ž 𝑑 𝑔 source 𝑇 𝑀 𝒕 𝐼 = (π»π‘“π‘œ, β„Ž) 𝐸 distinguisher Bellare Hoang Keelveedhi

  5. UCE security 𝑑 ← Gen(1 πœ‡ ) 𝑔 ← Funcs(𝑛, π‘œ) β„Ž 𝑑 𝑔 source 𝑇 𝑀 𝒕 𝐼 = (π»π‘“π‘œ, β„Ž) 0/1 𝐸 distinguisher Bellare Hoang Keelveedhi

  6. UCE security 𝑑 ← Gen(1 πœ‡ ) 𝑔 ← Funcs(𝑛, π‘œ) β„Ž 𝑑 𝑔 β‰ˆ source 𝑇 𝑀 𝒕 𝐼 = (π»π‘“π‘œ, β„Ž) 0/1 𝐸 distinguisher Bellare Hoang Keelveedhi

  7. psPRP security 𝑑 ← Gen(1 πœ‡ ) 𝝇 ← 𝐐𝐟𝐬𝐧𝐭(𝒐) 𝝇/𝝇 βˆ’πŸ βˆ’πŸ 𝝆 𝒕 /𝝆 𝒕 𝑇 𝑄 = (π»π‘“π‘œ, 𝜌, 𝜌 βˆ’1 ) 𝐸

  8. psPRP security 𝑑 ← Gen(1 πœ‡ ) 𝝇 ← 𝐐𝐟𝐬𝐧𝐭(𝒐) 𝝇/𝝇 βˆ’πŸ βˆ’πŸ 𝝆 𝒕 /𝝆 𝒕 Makes forward and 𝑇 𝑄 = (π»π‘“π‘œ, 𝜌, 𝜌 βˆ’1 ) backward queries! 𝐸

  9. psPRP security 𝑑 ← Gen(1 πœ‡ ) 𝝇 ← 𝐐𝐟𝐬𝐧𝐭(𝒐) 𝝇/𝝇 βˆ’πŸ βˆ’πŸ 𝝆 𝒕 /𝝆 𝒕 Makes forward and 𝑇 𝑄 = (π»π‘“π‘œ, 𝜌, 𝜌 βˆ’1 ) backward queries! 𝑀 𝒕 𝐸

  10. psPRP security 𝑑 ← Gen(1 πœ‡ ) 𝝇 ← 𝐐𝐟𝐬𝐧𝐭(𝒐) 𝝇/𝝇 βˆ’πŸ βˆ’πŸ 𝝆 𝒕 /𝝆 𝒕 Makes forward and 𝑇 𝑄 = (π»π‘“π‘œ, 𝜌, 𝜌 βˆ’1 ) backward queries! 𝑀 𝒕 0/1 𝐸

  11. psPRP security 𝑑 ← Gen(1 πœ‡ ) 𝝇 ← 𝐐𝐟𝐬𝐧𝐭(𝒐) 𝝇/𝝇 βˆ’πŸ βˆ’πŸ 𝝆 𝒕 /𝝆 𝒕 Makes forward and 𝑇 𝑄 = (π»π‘“π‘œ, 𝜌, 𝜌 βˆ’1 ) backward queries! 𝑀 𝒕 0/1 𝐸 𝑄 is π‘žπ‘‘π‘„π‘†π‘„ -secure if βˆ€ PPT 𝑇, 𝐸 , left and right are indistinguishable.

  12. psPRP security 𝑑 ← Gen(1 πœ‡ ) 𝝇 ← 𝐐𝐟𝐬𝐧𝐭(𝒐) 𝝇/𝝇 βˆ’πŸ βˆ’πŸ 𝝆 𝒕 /𝝆 𝒕 Makes forward and 𝑇 𝑄 = (π»π‘“π‘œ, 𝜌, 𝜌 βˆ’1 ) backward queries! 𝑀 𝒕 0/1 𝐸 𝑄 is π‘žπ‘‘π‘„π‘†π‘„ -secure if βˆ€ PPT 𝑇, 𝐸 , left and right are indistinguishable.

  13. 𝑄 is π‘žπ‘‘π‘„π‘†π‘„ -secure if βˆ€ PPT 𝑇, 𝐸 , …

  14. 𝑄 is π‘žπ‘‘π‘„π‘†π‘„ -secure if βˆ€ PPT 𝑇, 𝐸 , … 𝑑 ← Gen(1 πœ‡ ) 𝜍 ← Perms(π‘œ) 𝜍/𝜍 βˆ’1 βˆ’1 𝜌 𝑑 /𝜌 𝑑 𝑇

  15. 𝑄 is π‘žπ‘‘π‘„π‘†π‘„ -secure if βˆ€ PPT 𝑇, 𝐸 , … 𝑑 ← Gen(1 πœ‡ ) 𝜍 ← Perms(π‘œ) 𝜍/𝜍 βˆ’1 βˆ’1 𝜌 𝑑 /𝜌 𝑑 (+, 0 π‘œ ) (+, 0 π‘œ ) 𝑇

  16. 𝑄 is π‘žπ‘‘π‘„π‘†π‘„ -secure if βˆ€ PPT 𝑇, 𝐸 , … 𝑑 ← Gen(1 πœ‡ ) 𝜍 ← Perms(π‘œ) 𝜍/𝜍 βˆ’1 βˆ’1 𝜌 𝑑 /𝜌 𝑑 𝑧 𝑧 (+, 0 π‘œ ) (+, 0 π‘œ ) 𝑇

  17. 𝑄 is π‘žπ‘‘π‘„π‘†π‘„ -secure if βˆ€ PPT 𝑇, 𝐸 , … 𝑑 ← Gen(1 πœ‡ ) 𝜍 ← Perms(π‘œ) 𝜍/𝜍 βˆ’1 βˆ’1 𝜌 𝑑 /𝜌 𝑑 𝑧 𝑧 (+, 0 π‘œ ) (+, 0 π‘œ ) 𝑇 𝑀 = 𝑧 𝒕 𝐸

  18. 𝑄 is π‘žπ‘‘π‘„π‘†π‘„ -secure if βˆ€ PPT 𝑇, 𝐸 , … 𝑑 ← Gen(1 πœ‡ ) 𝜍 ← Perms(π‘œ) 𝜍/𝜍 βˆ’1 βˆ’1 𝜌 𝑑 /𝜌 𝑑 𝑧 𝑧 (+, 0 π‘œ ) (+, 0 π‘œ ) 𝑇 𝑀 = 𝑧 𝒕 Outputs 1 iff 𝐸 𝑧 = 𝜌 𝑑 0 π‘œ

  19. 𝑄 is π‘žπ‘‘π‘„π‘†π‘„ -secure if βˆ€ PPT 𝑇, 𝐸 , … 𝑑 ← Gen(1 πœ‡ ) 𝜍 ← Perms(π‘œ) 𝜍/𝜍 βˆ’1 βˆ’1 𝜌 𝑑 /𝜌 𝑑 𝑧 𝑧 (+, 0 π‘œ ) (+, 0 π‘œ ) 𝑇 𝑀 = 𝑧 𝒕 1 with prob. 1 Outputs 1 iff 𝐸 𝑧 = 𝜌 𝑑 0 π‘œ

  20. 𝑄 is π‘žπ‘‘π‘„π‘†π‘„ -secure if βˆ€ PPT 𝑇, 𝐸 , … 𝑑 ← Gen(1 πœ‡ ) 𝜍 ← Perms(π‘œ) 𝜍/𝜍 βˆ’1 βˆ’1 𝜌 𝑑 /𝜌 𝑑 𝑧 𝑧 (+, 0 π‘œ ) (+, 0 π‘œ ) 𝑇 𝑀 = 𝑧 𝒕 1 with prob. 1 Outputs 1 iff 𝐸 𝑧 = 𝜌 𝑑 0 π‘œ with prob. 1/2 π‘œ 1

  21. 𝑄 is π‘žπ‘‘π‘„π‘†π‘„ -secure if βˆ€ PPT 𝑇, 𝐸 , … 𝑑 ← Gen(1 πœ‡ ) 𝜍 ← Perms(π‘œ) 𝜍/𝜍 βˆ’1 βˆ’1 𝜌 𝑑 /𝜌 𝑑 β‰ˆ 𝑧 𝑧 (+, 0 π‘œ ) (+, 0 π‘œ ) 𝑇 𝑀 = 𝑧 𝒕 1 with prob. 1 Outputs 1 iff 𝐸 𝑧 = 𝜌 𝑑 0 π‘œ with prob. 1/2 π‘œ 1 π‘žπ‘‘π‘„π‘†π‘„ -security is impossible against all sources!

  22. 𝑄 = (Gen, 𝜌, 𝜌 βˆ’1 ) Sources need to be restricted all sources

  23. 𝑄 = (Gen, 𝜌, 𝜌 βˆ’1 ) Sources need to be restricted all sources 𝒯

  24. 𝑄 = (Gen, 𝜌, 𝜌 βˆ’1 ) Sources need to be restricted 𝑑 ← Gen(1 πœ‡ ) all sources 𝜍 ← Perms(π‘œ) βˆ’1 𝜍/𝜍 βˆ’1 𝜌 𝑑 /𝜌 𝑑 𝒯 𝑇 𝑀 𝒕 𝐸 0/1 𝑄 is π‘žπ‘‘π‘„π‘†π‘„[𝒯] -secure if βˆ€ 𝑇 ∈ 𝒯 and βˆ€ PPT 𝐸 , left and right are indistinguishable.

  25. This talk – unpredictable and reset-secure sources all sources

  26. This talk – unpredictable and reset-secure sources all sources 𝒯 π‘‘π‘£π‘ž unpredictable

  27. This talk – unpredictable and reset-secure sources all sources reset-secure 𝒯 𝑑𝑠𝑑 𝒯 π‘‘π‘£π‘ž unpredictable

  28. This talk – unpredictable and reset-secure sources all sources reset-secure 𝒯 𝑑𝑠𝑑 𝒯 π‘‘π‘£π‘ž unpredictable Both restrictions model that 𝐸 cannot predict the queries made by the sources!

  29. This talk – unpredictable and reset-secure sources all sources reset-secure 𝒯 𝑑𝑠𝑑 𝒯 π‘‘π‘£π‘ž unpredictable Both restrictions model that 𝐸 cannot predict the queries made by the sources! 𝒯 π‘‘π‘£π‘ž βŠ† 𝒯 𝑑𝑠𝑑

  30. This talk – unpredictable and reset-secure sources all sources reset-secure 𝒯 𝑑𝑠𝑑 𝒯 π‘‘π‘£π‘ž unpredictable Both restrictions model that 𝐸 cannot predict the queries made by the sources! π‘žπ‘‘π‘„π‘†π‘„ 𝒯 𝑑𝑠𝑑 is a stronger 𝒯 π‘‘π‘£π‘ž βŠ† 𝒯 𝑑𝑠𝑑 ⟹ assumption than π‘žπ‘‘π‘„π‘†π‘„ 𝒯 π‘‘π‘£π‘ž

  31. Source restrictions – unpredictability 𝜍 ← Perms(π‘œ) 𝜍/𝜍 βˆ’1 𝑇 𝐡

  32. Source restrictions – unpredictability 𝜍 ← Perms(π‘œ) (𝜏, 𝑦 𝑗 ) 𝜏 ∈ {+, βˆ’} 𝜍/𝜍 βˆ’1 𝑇 𝐡

  33. Source restrictions – unpredictability 𝜍 ← Perms(π‘œ) (𝜏, 𝑦 𝑗 ) 𝜏 ∈ {+, βˆ’} 𝜍/𝜍 βˆ’1 𝑇 𝑅 ← 𝑅 βˆͺ { 𝜏, 𝑦 𝑗 , (𝜏 , 𝑧 𝑗 )} 𝐡

  34. Source restrictions – unpredictability 𝜍 ← Perms(π‘œ) (𝜏, 𝑦 𝑗 ) 𝜏 ∈ {+, βˆ’} 𝜍/𝜍 βˆ’1 𝑇 𝑧 𝑗 𝑅 ← 𝑅 βˆͺ { 𝜏, 𝑦 𝑗 , (𝜏 , 𝑧 𝑗 )} 𝐡

  35. Source restrictions – unpredictability 𝜍 ← Perms(π‘œ) (𝜏, 𝑦 𝑗 ) 𝜏 ∈ {+, βˆ’} 𝜍/𝜍 βˆ’1 𝑇 𝑧 𝑗 𝑅 ← 𝑅 βˆͺ { 𝜏, 𝑦 𝑗 , (𝜏 , 𝑧 𝑗 )} 𝑀 𝐡

  36. Source restrictions – unpredictability 𝜍 ← Perms(π‘œ) (𝜏, 𝑦 𝑗 ) 𝜏 ∈ {+, βˆ’} 𝜍/𝜍 βˆ’1 𝑇 𝑧 𝑗 𝑅 ← 𝑅 βˆͺ { 𝜏, 𝑦 𝑗 , (𝜏 , 𝑧 𝑗 )} 𝑀 It should be hard for 𝐡 to predict any of 𝑇 ’s queries or its inverse 𝐡 [ 𝑅 β€² ∩ 𝑅 β‰  𝜚] = negl(πœ‡) Pr 𝑅′

  37. Source restrictions – unpredictability 𝜍 ← Perms(π‘œ) (𝜏, 𝑦 𝑗 ) 𝜏 ∈ {+, βˆ’} 𝜍/𝜍 βˆ’1 𝑇 𝑧 𝑗 𝑅 ← 𝑅 βˆͺ { 𝜏, 𝑦 𝑗 , (𝜏 , 𝑧 𝑗 )} 𝑀 It should be hard for 𝐡 to predict any of 𝑇 ’s queries or its inverse 𝐡 [ 𝑅 β€² ∩ 𝑅 β‰  𝜚] = negl(πœ‡) Pr 𝑅′ 𝒯 π‘‘π‘£π‘ž : 𝐡 is computationally unbounded βŠ† 𝒯 π‘‘π‘£π‘ž : 𝐡 is PPT

  38. Source restrictions – unpredictability 𝜍 ← Perms(π‘œ) (𝜏, 𝑦 𝑗 ) 𝜏 ∈ {+, βˆ’} 𝜍/𝜍 βˆ’1 𝑇 𝑧 𝑗 𝑅 ← 𝑅 βˆͺ { 𝜏, 𝑦 𝑗 , (𝜏 , 𝑧 𝑗 )} 𝑀 It should be hard for 𝐡 to predict any of 𝑇 ’s queries or its inverse 𝐡 [ 𝑅 β€² ∩ 𝑅 β‰  𝜚] = negl(πœ‡) Pr 𝑅′ 𝒯 π‘‘π‘£π‘ž : 𝐡 is computationally unbounded βŠ† π‘žπ‘‘π‘„π‘†π‘„[𝒯 π‘‘π‘£π‘ž ] impossible if iO 𝒯 π‘‘π‘£π‘ž : 𝐡 is PPT exists [BFM14]

  39. Source restrictions – reset-security

  40. Source restrictions – reset-security 𝜍/𝜍 βˆ’1 𝑇 𝜍 ← Perms(π‘œ) 𝑆

  41. Source restrictions – reset-security 𝜍/𝜍 βˆ’1 𝑇 𝜍 ← Perms(π‘œ) 𝑆

  42. Source restrictions – reset-security 𝜍/𝜍 βˆ’1 𝑇 𝜍 ← Perms(π‘œ) 𝑀 𝜍/𝜍 βˆ’1 𝑆

  43. Source restrictions – reset-security 𝜍/𝜍 βˆ’1 𝑇 𝜍 ← Perms(π‘œ) 𝑀 𝜍/𝜍 βˆ’1 𝑆 0/1

  44. Source restrictions – reset-security 𝜍/𝜍 βˆ’1 𝜍/𝜍 βˆ’1 𝑇 𝑇 𝜍 ← Perms(π‘œ) 𝜍 ← Perms(π‘œ) 𝑀 𝑀 𝜍/𝜍 βˆ’1 𝑆 𝑆 βˆ’1 𝜍 1 /𝜍 1 𝜍 1 ← Perms(π‘œ) 0/1 0/1

  45. Source restrictions – reset-security 𝜍/𝜍 βˆ’1 𝜍/𝜍 βˆ’1 𝑇 𝑇 𝜍 ← Perms(π‘œ) 𝜍 ← Perms(π‘œ) β‰ˆ 𝑀 𝑀 𝜍/𝜍 βˆ’1 𝑆 𝑆 βˆ’1 𝜍 1 /𝜍 1 𝜍 1 ← Perms(π‘œ) 0/1 0/1

  46. Source restrictions – reset-security 𝜍/𝜍 βˆ’1 𝜍/𝜍 βˆ’1 𝑇 𝑇 𝜍 ← Perms(π‘œ) 𝜍 ← Perms(π‘œ) β‰ˆ 𝑀 𝑀 𝜍/𝜍 βˆ’1 𝑆 𝑆 βˆ’1 𝜍 1 /𝜍 1 𝜍 1 ← Perms(π‘œ) 0/1 0/1 𝒯 𝑑𝑠𝑑 : 𝑆 is computationally unbounded βŠ† 𝒯 𝑑𝑠𝑑 : 𝑆 is PPT

  47. Source restrictions – reset-security 𝜍/𝜍 βˆ’1 𝜍/𝜍 βˆ’1 𝑇 𝑇 𝜍 ← Perms(π‘œ) 𝜍 ← Perms(π‘œ) β‰ˆ 𝑀 𝑀 𝜍/𝜍 βˆ’1 𝑆 𝑆 βˆ’1 𝜍 1 /𝜍 1 𝜍 1 ← Perms(π‘œ) 0/1 0/1 𝒯 𝑑𝑠𝑑 : 𝑆 is computationally unbounded βŠ† 𝒯 π‘‘π‘£π‘ž βŠ† 𝒯 𝑑𝑠𝑑 𝒯 𝑑𝑠𝑑 : 𝑆 is PPT

  48. Recap π‘žπ‘‘π‘„π‘†π‘„[𝒯 𝑑𝑠𝑑 ] π‘žπ‘‘π‘„π‘†π‘„[𝒯 π‘‘π‘£π‘ž ]

  49. Recap π‘žπ‘‘π‘„π‘†π‘„[𝒯 𝑑𝑠𝑑 ] π‘žπ‘‘π‘„π‘†π‘„[𝒯 π‘‘π‘£π‘ž ]

  50. Recap

  51. Recap Central assumption in UCE theory

  52. Recap Central assumption in UCE theory

  53. Roadmap 1.Definitions 2.Constructions & Applications 3.Conclusions

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