Hybrid Public Key Encryption
draft-irtf-cfrg-hpke-02

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Network Working Group                                          R. Barnes
Internet-Draft                                                     Cisco
Intended status: Informational                              K. Bhargavan
Expires: May 7, 2020                                               Inria
                                                       November 04, 2019

                      Hybrid Public Key Encryption
                        draft-irtf-cfrg-hpke-02

Abstract

   This document describes a scheme for hybrid public-key encryption
   (HPKE).  This scheme provides authenticated public key encryption of
   arbitrary-sized plaintexts for a recipient public key.  HPKE works
   for any combination of an asymmetric key encapsulation mechanism
   (KEM), key derivation function (KDF), and authenticated encryption
   with additional data (AEAD) encryption function.  We provide
   instantiations of the scheme using widely-used and efficient
   primitives.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on May 7, 2020.

Copyright Notice

   Copyright (c) 2019 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
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect

Barnes & Bhargavan         Expires May 7, 2020                  [Page 1]
Internet-Draft                    HPKE                     November 2019

   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Requirements Notation . . . . . . . . . . . . . . . . . . . .   4
   3.  Security Properties . . . . . . . . . . . . . . . . . . . . .   4
   4.  Notation  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Cryptographic Dependencies  . . . . . . . . . . . . . . . . .   5
     5.1.  DH-Based KEM  . . . . . . . . . . . . . . . . . . . . . .   6
   6.  Hybrid Public Key Encryption  . . . . . . . . . . . . . . . .   7
     6.1.  Creating the Encryption Context . . . . . . . . . . . . .   8
     6.2.  Encryption to a Public Key  . . . . . . . . . . . . . . .  11
     6.3.  Authentication using a Pre-Shared Key . . . . . . . . . .  11
     6.4.  Authentication using an Asymmetric Key  . . . . . . . . .  12
     6.5.  Authentication using both a PSK and an Asymmetric Key . .  13
     6.6.  Encryption and Decryption . . . . . . . . . . . . . . . .  13
   7.  Single-Shot APIs  . . . . . . . . . . . . . . . . . . . . . .  14
   8.  Algorithm Identifiers . . . . . . . . . . . . . . . . . . . .  15
     8.1.  Key Encapsulation Mechanisms (KEMs) . . . . . . . . . . .  15
     8.2.  Key Derivation Functions (KDFs) . . . . . . . . . . . . .  16
     8.3.  Authenticated Encryption with Associated Data (AEAD)
           Functions . . . . . . . . . . . . . . . . . . . . . . . .  16
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  16
     9.1.  Metadata Protection . . . . . . . . . . . . . . . . . . .  16
     9.2.  Designated-Verifier Signature . . . . . . . . . . . . . .  17
   10. Message Encoding  . . . . . . . . . . . . . . . . . . . . . .  17
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  18
     11.1.  KEM Identifiers  . . . . . . . . . . . . . . . . . . . .  18
     11.2.  KDF Identifiers  . . . . . . . . . . . . . . . . . . . .  18
     11.3.  AEAD Identifiers . . . . . . . . . . . . . . . . . . . .  19
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  19
     12.1.  Normative References . . . . . . . . . . . . . . . . . .  19
     12.2.  Informative References . . . . . . . . . . . . . . . . .  20
   Appendix A.  Test Vectors . . . . . . . . . . . . . . . . . . . .  21
     A.1.  DHKEM(Curve25519), HKDF-SHA256, AES-GCM-128 . . . . . . .  22
       A.1.1.  AuthPSK Setup Information . . . . . . . . . . . . . .  22
     A.2.  DHKEM(Curve25519), HKDF-SHA256, AES-GCM-128 . . . . . . .  23