Verifiable Random Functions (VRFs)
draft-goldbe-vrf-01
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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).
Status of This Memo
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Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
Goldberg, et al. Expires January 1, 2018 [Page 1]
Internet-Draft VRF June 2017
carefully, as they describe your rights and restrictions with respect
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described in the Simplified BSD License.
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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