Re: [Cfrg] J-PAKE and Schnorr NIZK for informational RFCs
Watson Ladd <watsonbladd@gmail.com> Tue, 15 November 2016 19:15 UTC
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From: Watson Ladd <watsonbladd@gmail.com>
Date: Tue, 15 Nov 2016 11:14:58 -0800
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To: Feng Hao <feng.hao@newcastle.ac.uk>
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Subject: Re: [Cfrg] J-PAKE and Schnorr NIZK for informational RFCs
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Dear Feng, Let me make this very clear, to avoid your misunderstandings: J-PAKE is substantially less efficient than SPAKE2 over the same group. SPAKE2 with M and N generated by hashing is secure, and the proofs found in the SPAKE2 paper do work for this case. If we use a small subgroup of a finite field group, then the necessary validations for group membership double the cost of SPAKE2, but J-PAKE is still slower. J-PAKE requires an additional round, while SPAKE2 fits into the same flow as Diffie-Hellman. There is no relevance of KOY, or Jiang-Gong, or any other paper that may or may not (I didn't bother to look) present its own definitions and security model. SPAKE2 requires exactly 4 exponentations in the subgroup if we do not do anything smart about them. Two of these can be combined and replaced with a dual base exponentiation via Strauss's algorithm. Do you have anything to say to this? Sincerely, Watson
- [Cfrg] J-PAKE and Schnorr NIZK for informational … Feng Hao
- Re: [Cfrg] J-PAKE and Schnorr NIZK for informatio… Watson Ladd
- Re: [Cfrg] J-PAKE and Schnorr NIZK for informatio… Feng Hao
- Re: [Cfrg] J-PAKE and Schnorr NIZK for informatio… Mike Hamburg
- Re: [Cfrg] J-PAKE and Schnorr NIZK for informatio… Feng Hao
- Re: [Cfrg] J-PAKE and Schnorr NIZK for informatio… Feng Hao
- Re: [Cfrg] J-PAKE and Schnorr NIZK for informatio… Watson Ladd
- Re: [Cfrg] J-PAKE and Schnorr NIZK for informatio… Feng Hao
- Re: [Cfrg] J-PAKE and Schnorr NIZK for informatio… Watson Ladd
- Re: [Cfrg] J-PAKE and Schnorr NIZK for informatio… Feng Hao
- Re: [Cfrg] J-PAKE and Schnorr NIZK for informatio… Stanislav V. Smyshlyaev
- Re: [Cfrg] J-PAKE and Schnorr NIZK for informatio… Michel Abdalla
- Re: [Cfrg] J-PAKE and Schnorr NIZK for informatio… Watson Ladd
- Re: [Cfrg] J-PAKE and Schnorr NIZK for informatio… Feng Hao
- Re: [Cfrg] J-PAKE and Schnorr NIZK for informatio… Feng Hao
- Re: [Cfrg] J-PAKE and Schnorr NIZK for informatio… Michel Abdalla
- Re: [Cfrg] J-PAKE and Schnorr NIZK for informatio… Mike Hamburg
- Re: [Cfrg] J-PAKE and Schnorr NIZK for informatio… Feng Hao