Safely Turn Authentication Credentials Into Entropy (STACIE)
draft-ladar-stacie-03

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Last updated 2018-05-16
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Network Working Group                                         L. Levison
Internet-Draft                                               Lavabit LLC
Intended status: Experimental                               May 17, 2018
Expires: November 18, 2018

      Safely Turn Authentication Credentials Into Entropy (STACIE)
                         draft-ladar-stacie-03

Abstract

   This document specifies a method for Safely Turning Authentication
   Credentials Into Entropy (STACIE) using an efficient Zero Knowledge
   Password Proof (ZKPP), and is provided as a standalone component
   suitable for use as a building block in other protocol development
   efforts.  The scheme was created to fill the emerging need for a
   standard which allows a single low entropy password to be used for
   user authentication and the derivation of strong encryption keys.
   The design is modular, and is conservative in its use of an arbitrary
   one-way cryptographic hash function.  The security of the scheme
   depends on the difficulty associated with reversing the hash function
   output back into the plain text input.  STACIE attempts to make
   discovering the plain text input through the use of brute force more
   difficult by correlating the amount of processing to the length of a
   user's plain text password.  The shorter the plain text password, the
   more processing is required, with the amount of additional,
   artificially required, work scaling exponentially for each character.

Status of This Memo

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   This Internet-Draft will expire on November 18, 2018.

Levison                 Expires November 18, 2018               [Page 1]
Internet-Draft                   stacie                         May 2018

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Encodings . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Derivation Process  . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  Hash Rounds . . . . . . . . . . . . . . . . . . . . . . .   7
     4.2.  Entropy Extraction  . . . . . . . . . . . . . . . . . . .   9
     4.3.  Key Derivation  . . . . . . . . . . . . . . . . . . . . .  12
     4.4.  Token Derivation  . . . . . . . . . . . . . . . . . . . .  13
     4.5.  Realm Key Derivation  . . . . . . . . . . . . . . . . . .  14
   5.  Encryption  . . . . . . . . . . . . . . . . . . . . . . . . .  17
     5.1.  Envelope  . . . . . . . . . . . . . . . . . . . . . . . .  17
     5.2.  Payload . . . . . . . . . . . . . . . . . . . . . . . . .  18
   6.  Password Changes  . . . . . . . . . . . . . . . . . . . . . .  21
     6.1.  Shallow Password Change . . . . . . . . . . . . . . . . .  21
     6.2.  Deep Password Change  . . . . . . . . . . . . . . . . . .  22
     6.3.  Hybrid Password Change  . . . . . . . . . . . . . . . . .  22
   7.  Protocol  . . . . . . . . . . . . . . . . . . . . . . . . . .  22
     7.1.  Create User . . . . . . . . . . . . . . . . . . . . . . .  22
     7.2.  Login . . . . . . . . . . . . . . . . . . . . . . . . . .  23
       7.2.1.  Login Request . . . . . . . . . . . . . . . . . . . .  23
       7.2.2.  Login Response  . . . . . . . . . . . . . . . . . . .  24
     7.3.  Password Authentication . . . . . . . . . . . . . . . . .  26
       7.3.1.  Authenticate Request  . . . . . . . . . . . . . . . .  26
       7.3.2.  Authenticate Response . . . . . . . . . . . . . . . .  27
     7.4.  Password Change . . . . . . . . . . . . . . . . . . . . .  28
     7.5.  Fetch Realm Shards  . . . . . . . . . . . . . . . . . . .  28
     7.6.  Add a Realm Shard . . . . . . . . . . . . . . . . . . . .  28
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