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Lec 18: (s)aPAKE Protocols

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SPHF-Based aPAKE

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Recall SPHF-based PAKE

 

 

 

 

 

 

 

 

 

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  •  

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Naïve (insecure) SPHF-based aPAKE

 

 

 

 

 

 

 

 

 

 

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  •  

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Secure SPHF-based aPAKE

 

 

 

 

 

 

 

 

 

 

 

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(Corrected) SPHF-based aPAKE [BP13]

 

 

 

 

 

 

 

 

 

 

 

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From aPAKE to Strong aPAKE

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Strong aPAKE

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Naïve approach does not work…

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aPAKE

 

 

​

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​

​

…

…

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Use oblivious pseudorandom function (OPRF)

 

 

 

 

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OPRF + aPAKE → saPAKE [JKX18]

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OPRF

 

aPAKE

 

 

 

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References

  • [BP13] Fabrice Benhamouda and David Pointcheval. Verifier-Based Password-Authenticated Key Exchange: New Models and Constructions. https://eprint.iacr.org/2013/833
  • [JKX18] Stanislaw Jarecki, Hugo Krawczyk, and Jiayu Xu. OPAQUE: An Asymmetric PAKE Protocol Secure Against Pre-Computation Attacks. In EUROCRYPT 2018.