Verifiable Random Functions (VRFs)
draft-goldbe-vrf-01

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Last updated 2017-07-21 (latest revision 2017-06-30)
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Network Working Group                                        S. Goldberg
Internet-Draft                                         Boston University
Intended status: Standards Track                         D. Papadopoulos
Expires: January 1, 2018                          University of Maryland
                                                               J. Vcelak
                                                                     NS1
                                                           June 30, 2017

                   Verifiable Random Functions (VRFs)
                          draft-goldbe-vrf-01

Abstract

   A Verifiable Random Function (VRF) is the public-key version of a
   keyed cryptographic hash.  Only the holder of the private key can
   compute the hash, but anyone with public key can verify the
   correctness of the hash.  VRFs are useful for preventing enumeration
   of hash-based data structures.  This document specifies several VRF
   constructions that are secure in the cryptographic random oracle
   model.  One VRF uses RSA and the other VRF uses Eliptic Curves (EC).

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Goldberg, et al.         Expires January 1, 2018                [Page 1]
Internet-Draft                     VRF                         June 2017

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Rationale . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Requirements  . . . . . . . . . . . . . . . . . . . . . .   3
     1.3.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  VRF Algorithms  . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  VRF Security Properties . . . . . . . . . . . . . . . . . . .   4
     3.1.  Full Uniqueness or Trusted Uniqueness . . . . . . . . . .   4
     3.2.  Full Collison Resistance or Trusted Collision Resistance    5
     3.3.  Full Pseudorandomness or Selective Pseudorandomness . . .   5
     3.4.  An additional pseudorandomness property . . . . . . . . .   6
   4.  RSA Full Domain Hash VRF (RSA-FDH-VRF)  . . . . . . . . . . .   7
     4.1.  RSA-FDH-VRF Proving . . . . . . . . . . . . . . . . . . .   8
     4.2.  RSA-FDH-VRF Proof To Hash . . . . . . . . . . . . . . . .   8
     4.3.  RSA-FDH-VRF Verifying . . . . . . . . . . . . . . . . . .   9
   5.  Elliptic Curve VRF (EC-VRF) . . . . . . . . . . . . . . . . .   9
     5.1.  EC-VRF Proving  . . . . . . . . . . . . . . . . . . . . .  11
     5.2.  EC-VRF Proof To Hash  . . . . . . . . . . . . . . . . . .  11
     5.3.  EC-VRF Verifying  . . . . . . . . . . . . . . . . . . . .  12
     5.4.  EC-VRF Auxiliary Functions  . . . . . . . . . . . . . . .  13
       5.4.1.  EC-VRF Hash To Curve  . . . . . . . . . . . . . . . .  13
       5.4.2.  EC-VRF Hash Points  . . . . . . . . . . . . . . . . .  14
       5.4.3.  EC-VRF Decode Proof . . . . . . . . . . . . . . . . .  15
     5.5.  EC-VRF Ciphersuites . . . . . . . . . . . . . . . . . . .  15
     5.6.  When the EC-VRF Keys are Untrusted  . . . . . . . . . . .  16
       5.6.1.  EC-VRF Validate Key . . . . . . . . . . . . . . . . .  17
   6.  Implementation Status . . . . . . . . . . . . . . . . . . . .  17
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  18
     7.1.  Key Generation  . . . . . . . . . . . . . . . . . . . . .  18
       7.1.1.  Uniqueness and collision resistance with untrusted
               keys  . . . . . . . . . . . . . . . . . . . . . . . .  18
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