ACP-WGM16/WP-14
International Civil Aviation Organization
17 May 2010
WORKING PAPER
AERONAUTICAL COMMUNICATIONS PANEL (ACP)
16th MEETING OF WORKING GROUP M (Maintenance)
Paris, France 17-19 May 2010
Agenda Item 3a: ATN/OSI Document 9880 Update Status – Security Updates
Amendment Proposal
to
Remove Compressed Elliptic Curve Points
Prepared by: FAA
Presented by: Vic Patel
SUMMARY
This working paper includes draft updates to ICAO Doc 9880 to remove
compressed elliptic curve points.
ACTION
The working group is invited to review Amendment Proposal and consider
approving the change to Doc 9880.
ACP-WGM16/WP-14
1.
-2-
INTRODUCTION
1.1
One of recommendations of the Honeywell Validation Report is to remove compressed
elliptic curve points from Doc 9880.
2.
2.1
DISCUSSION
This AP proposes removing compressed elliptic curve points from Doc 9880.
2.2
With elliptic curve (EC) cryptography keys are a point, i.e., a set of coordinates, on the
selected curve. It is possible to represent the point in compressed form using the complete x-coordinate
and a single additional bit from which the y-coordinate may be derived.
2.3
In full representation the EC point requires 2m bits, where m is the extension degree of
the underlying finite field. For the ATN the curve sect233r1 has been selected where m is 233. Therefore
in full representation an ATN public key would be 466 bits and 234 bits in compressed form.
2.4
All of the standards for elliptic curve systems specify an option to represent elliptic curve
points in compressed form.
2.5
There is uncertainty around ECC patents for point compression. Certicom Corporation
holds U.S. Patent 6,141,420 on techniques for compressing elliptic curve point representations. It is not
clear, however, whether the patent covers the representation or techniques for performing point
compression. According to RSA Laboratories in Crypto FAQ 6.3.4, “Are elliptic curve cryptosystems
patented? It is the implementation technique that is patented, not the prime or representation, and there
are alternative, compatible implementation techniques that are not covered by the patents.”
2.6
form.
Section 5.3.3.1 specifies that all ATN elliptic curve points be represented in compact
2.7
Section 5.3.4.1.4 specifies that the base point G of the ATN selected curve be represented
in compressed form.
AMENDMENT PROPOSAL #XXX
Title:
AP working paper number and date
Document(s) Affected:
Document Version:
Sections of Documents Affected:
Coordinator:
Coordinator's Address:
Refer to SEC 2 standard for ECC Domain
Parameters
M16/WPxx 17 May 2010
ICAO Dc 9880 Part IV-B
Draft June 2009
5.3.3.1 5.3.4.3
Vic Patel
ATO-P, AJP-1740
-3-
Coordinator's Phone:
Coordinator's Fax:
Coordinator's E-mail Address:
Category:
Problem description:
Background:
Backwards compatibility:
Amendment Proposal:
WG-M Status:
ACP-WGM16/WP-14
William J. Hughes Technical Center
Atlantic City Airport, NJ, 08405
USA
+1 609 485 5046
+1 609 485 5630
vidyut.patel@faa.gov
There is uncertainty around certain ECC
patents on techniques for compressing elliptic
curve point representations.
One of recommendations of the Honeywell
Validation Report is to remove compressed
elliptic curve points from Doc 9880.
See below.
SUBMITTED 5/17/2010
Replace all of section 5.3.3.1 with the following:
5.3.3.1 ATN elliptic curve points shall use the full (uncompressed) representation.
Delete 5.3.3.2
Assuming the AP to Refer to SEC 2 standards for elliptic curve domain parameters is accepted, add the
following:
5.3.4.3 Base point representation
The domain parameters TATN as defined in SEC 2 for the 233-bit binary curve sect233r1 shall use the base
point G in its uncompressed form.
3.
3.1
ACTION BY THE MEETING
The ACP WG-M is invited to:
1. Review the revisions to Doc 9880 identified by the AP in this Working Paper and
provide comments and feedback regarding the proposed changes as described.
3.2
Due to the uncertainty associated with patents related to elliptic curve point compression,
the FAA recommends acceptance of these changes and requests endorsement by the Working Group to
update Doc 9880 as described in the AP.