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draft-wood-icnrg-securereplica-00.txt
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icnrg M. Mosko
Internet-Draft C. Wood
Intended status: Standards Track PARC
Expires: October 5, 2016 April 03, 2016
Secure Replica Service in CCN
draft-wood-icnrg-securereplica-00
Abstract
We describe a mechanism for session migration between an
authentication endpoint and content replica in CCN. The technique
described herein depends on the CCNx-KE protocol.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 5, 2016.
Copyright Notice
Copyright (c) 2016 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
carefully, as they describe your rights and restrictions with respect
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.
Mosko & Wood Expires October 5, 2016 [Page 1]
Internet-Draft Secure Replica Service in CCN April 2016
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Assumptions and Overview . . . . . . . . . . . . . . . . . . 3
3. Session Migration . . . . . . . . . . . . . . . . . . . . . . 4
3.1. MoveChallenge and MoveProof . . . . . . . . . . . . . . . 4
3.2. MoveToken . . . . . . . . . . . . . . . . . . . . . . . . 4
3.3. Verification . . . . . . . . . . . . . . . . . . . . . . 4
3.4. Final Notes . . . . . . . . . . . . . . . . . . . . . . . 5
3.5. Replica Workload . . . . . . . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . 5
5. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.1. Normative References . . . . . . . . . . . . . . . . . . 5
5.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
CCNx-KE is a protocol that enables a consumer and producer to create
a session over which they can communicate securely. Session keys
derived from CCNx-KE are used to encrypt interest and content objects
sent between the consumer and producer, as shown below.
+----------+ +----------+
| Consumer <----(encrypted channel)----> Producer |
+----------+ +----------+
In many cases, the producer must authenticate the consumer before
providing any application data. Moreover, this producer might not be
the one storing the data sought after by the consumer. Therefore, a
mechanism to create a secure session between the consumer and replica
is needed to securely obtain data. One way to do this is for the
consumer to create a session with the replica. However, if consumer
authentication is performed, then the replica is burdened with (a)
authenticating the consumer and (b) must possess the private keys
necessary to prove its identity to the consumer. A better solution
would be to migrate a session from a producer (authenticator) to a
replica (data distributor) securely.
CCNx-KE [CCNXKE] supports the ability to migrate sessions with a
MoveToken. However, the specification does not describe how to
create these tokens. In this document, we describe how to migrate a
CCNx-KE session with a particular MoveToken construction.
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2. Assumptions and Overview
If a consumer is to migrate a session from a producer to a replica,
then the producer must necessarily trust the replica service to
provide the appropriate content. This trust is based on economics
since the producer is likely to pay the replica for its services.
Under this assumption, we also assume that the producer and replica
service can create a secure session amongst themselves. The producer
and replica are assumed to be able to create and share keys on
regular basis. We rely on this assumption in the remainder of the
document.
When a client wishes to obtain data from a replica, the following
steps occur:
1. The consumer creates a session with the (authenticating)
producer.
2. The producer redirects the consumer to the best replica (e.g.,
based on its geographic location).
3. The producer provides the consumer with a MoveToken to use when
migrating to the replica.
This is particular exchange in the context of CCNx-KE is outlined
below. We will describe how MoveChallenge, MovePrefix, MoveProof,
and MoveToken are created in the following sections.
Client Producer Replica (MovePrefix)
(Round 2 Interest)
+ MoveChallenge
+------------------------->
(Round 2 Content)
+ MovePrefix, MoveToken
<--------------------------
(Round 3 Interest)
+ MoveToken, MoveProof
+---------------------------------------------------->
(Round 3 Content)
+ NewSessionID
<----------------------------------------------------+
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3. Session Migration
Session keys produced by CCNx-KE are derived from the traffic secret
constructed by the consumer and producer. Therefore, to decrypt
traffic from the consumer and join the session, the MoveToken must
allow the replica to extract or recover this secret. Moreover, since
this extraction step must involve some computation, the replica must
be allowed to check that the MoveToken was generated by a trusted
producer. This is necessary to avoid trivial computational Denial of
Service (DoS) attacks against the replica.
With the requirements in place, we now describe how to generate the
MoveChallenge, MoveProof, and MoveToken.
3.1. MoveChallenge and MoveProof
The MoveChallenge is as defined in [CCNXKE]. It is a random 256-bit
string defined as follows:
MoveChallenge = SHA256(X)
for a randomly generated 256-bit string X. The value X is also the
MoveProof.
3.2. MoveToken
The MoveToken must allow the replica to (a) check that the consumer
obtained the MoveToken from a trusted or known producer and (b)
extract the traffic secret (TS) to derive the encryption and
decryption keys. Therefore, it is defined as follows
MoveTokenCT, MoveTokenTag = AEnc(K, MoveChallenge + TS)
MoveToken = K_id + MoveTokenCT + MoveTokenTag
where K_id is the key identifier for the key K and + is
concatenation. Also, AEnc is shorthand for authenticated encryption
that produces a ciphertext and authentication tag. One such
algorithm is AES-GCM [GCM].
3.3. Verification
As shown in the protocol diagram above, the consumer must provide
both the MoveProof and MoveToken in the Round 3 Interest (for the
desired data). Upon receipt, the replica performs the following
checks:
1. If K_id is not valid, i.e., the replica has no key with that
identifier, then the Interest is dropped.
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2. Otherwise, the replica computes
MoveTokenCT, MoveTokenTag = MoveToken
MoveChallenge + TS = ADec(K, MoveTokenCT, MoveTokenTag)
If the decryption fails, i.e., if the encryption is not valid (the
ciphertext was tampered with), then the Interest is dropped. 3.
Otherwise, the replica computes
Challenge = SHA256(MoveProof)
If Challenge = MoveChallenge, then the replica accepts the Interest.
Otherwise, the Interest is dropped.
3.4. Final Notes
If the traffic secret is recovered correctly, then the replica
creates a new SessionID (NewSessionID) for the session between the
replica and consumer and returns it with the corresponding
application data requested in the Round 3 Interest. At this point,
both the consumer and replica have a common SessionID and traffic
secret and can then derive the appropriate encryption keys to use
when encrypting traffic.
3.5. Replica Workload
To create a new session, the replica must only perform a single
authenticated decryption and hash function (SHA256) computation. No
public-key cryptographic algorithms are required to verify a
MoveToken and complete the migration.
4. Security Considerations
TODO
5. References
5.1. Normative References
[CCNXKE] Mosko, M., Uzun, E., and C. Wood, "CCNx Key Exchange",
n.d., <TODO>.
[CCNxMessages]
Mosko, M. and I. Solis, "CCNx Messages in TLV Format",
January 2016, <https://tools.ietf.org/html/draft-irtf-
icnrg-ccnxmessages-01>.
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Internet-Draft Secure Replica Service in CCN April 2016
[DTLS12] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", January 2012,
<https://tools.ietf.org/html/rfc6347>.
[GCM] Dworkin, M., "Recommendation for Block Cipher Modes of
Operation: Galois/Counter Mode (GCM) and GMAC",
NIST Special Publication 800-38D, November 2007.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[TLS13] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", December 2015, <https://tools.ietf.org/html/
draft-ietf-tls-tls13-11>.
[TLVENCAP]
Mosko, M. and C. Wood, "CCNx Packet Encapsulation", n.d.,
<https://github.com/PARC/ccnx-tlvencap-rfc>.
5.2. Informative References
[HASHCHAIN]
L. Lamport, "Password Authentication with Insecure
Communication", ANSI Communications of the ACM 24.11, pp
770-772, November 1981.
[RFC5077] Salowey, J., Zhou, H., Eronen, P., and H. Tschofenig,
"Transport Layer Security (TLS) Session Resumption without
Server-Side State", RFC 5077, DOI 10.17487/RFC5077,
January 2008, <http://www.rfc-editor.org/info/rfc5077>.
Authors' Addresses
M. Mosko
PARC
EMail: [email protected]
Christopher A. Wood
PARC
EMail: [email protected]
Mosko & Wood Expires October 5, 2016 [Page 6]