Copyright 2000, Odyssey Research Associates, Inc. SL00-0003 1 Semantic Data Integrity DARPA Program Review Cornell Business & Technology Park 33 Thornwood

1Copyright 2000, Odyssey Research Associates, Inc.SL00-0003

Semantic Data IntegrityDARPA Program Review

Cornell Business & Technology Park33 Thornwood Drive, Suite 500

Ithaca, NY 14850-1250(607) 257-1975

David Rosenthal

February 22, 2000


Team Members

• ORA

• WetStone

• Jiri Fridrich (consultant to WetStone)


Technical Objectives

• Support intrusion tolerance by developing improved data integrity methods to recover attacked data

– Many factor influence effectiveness:

• Many different types of threats

• Different types and characteristics of data

• Variety of integrity mechanisms

• Different size and performance constraints

– Want policy-based selection of mechanisms to effectively protect, recover, and reconstruct data that may be accidentally or maliciously damaged


Existing practice

• Current Methods

– Protection of entire object

• One-way hash, Message authentication codes (MAC), Digital signatures

– Replication

– Access control and process control

– Watermarking and self-embedding techniques

• Need better methods to facilitate partial recovery and to focus limited resources where they are needed most


Technical Approach

• Our research is directed in the following areas

– Techniques for identifying and protecting data subsets

– Developing new watermarking/self-embedding techniques

– Exploring how to recover data subsets using secondary data (DSI Marks) and how to partially reconstruct the whole data object

– How to select data protection and recovery mechanisms to meet integrity policy objectives

• Developing software to test the effectiveness of approach


Technical ApproachSoftware

ExtractSemanticSegments

DSIMark

Generation

DSIMarkVerification

DataReconstruction

IntegrityPolicy

DSI MarkDB

SuspectData


Added Cars DetectedForgery

Forged Image Detected Forgery

SDI Workshop Examples



Original Image Segmented Image




AddedHelicopters

DetectedForgery



RemovedHelicopter

DetectedForgery



Technical ApproachSubsets

• Develop methods for forming subsets of an object, taking into account data characteristics and intended usage

– Simple example

• Save signatures of a subset of a picture consisting of just the higher order bits of pixels

• If some lower order bits are changed, the signature on the subset will still check, and the picture can be partially reconstructed

– Apply extra protection for key parts of an object


Technical ApproachSubsets (cont.)

• We believe that a good selection of data subset formation methods can lead to improved

– performance characteristics

– likelihood that partially reconstructed objects will contain correct information about “interesting parts”


Technical ApproachHierarchical Subsets

• We have been experimenting with algorithms for automatically subsetting images based on uniformity criteria (combination of color, intensity, texture similarity)

• Split image into quadrants, test quadrants for uniformity; if a quadrant is uniform, do not subdivide it further. Otherwise, continue subdividing

• Then, merge all “adjacent” segments that share the same uniformity characteristics (or possibly some other desirable characteristics such as a common edge)


Technical ApproachHierarchical Subsets (cont.)

• Impose different integrity mechanisms at different layers of the decomposition, to achieve policy goals more efficiently


Technical Approach Secure Fragile Authentication Watermark

• Investigated some attacks that affect several proposed fragile watermark schemes

• Developed a secure fragile watermark that is resistant to these attacks

– Uses secret key and the watermark is difficult to forge

– Resistant to collage attack


Technical Approach Hybrid Watermark

• Have implemented a hybrid watermark

– Distinguishes between image processing operations (filtering, lossy compression) and feature alteration/removal/replacement

– Embed a semi-local (64 x 64) robust watermark that degrades gradually with alteration

– Embed a local (8x8) fragile watermark on top that breaks with any alterations


Technical ApproachPolicy

• Policy will define the methods to apply to specific objects based on factors, such as:

– Importance of the data or sub-data

– Threats that need to be countered

– Recovery time constraints

– Resource limitations

– Detectability of integrity measure

– Integrity functionality that is available

– Current situation (INFOCON, THREATCON)


Technical ApproachDemonstration Environment

• We are developing an environment for demonstrating and testing our technology

• Current features include:

– Split-and-merge with parameters

– Policy-based integrity mechanism selection

– Malicious alteration

– Damage detection

– Partial reconstruction with self-embedded data


Major Risks and Planned Mitigation

• Risk

– Partial recovery of subsets may not be very practical (too resource-intensive or error-prone)

• Mitigation

– Focus research on more efficient or economical damage detection and less on partial recovery

– Devise policies that control the allowable expenditure of resources


Accomplishments to Date

• Prototype Tool

– Demonstrates hierarchical subset methods

• Watermarking methods

• Some initial results on policy tradeoff analysis


Quantitative Metrics

• Metrics that may be used are

– Size of DSI mark

– Time to apply integrity protection

– Time for partial reconstruction techniques

– Robustness of method


Expected Major Achievements

• If successful, these methods will provide

– A more effective method for data integrity detection and data reconstruction

– A better foundation about how to relate integrity policy objectives with integrity mechanisms


Task schedule

• First version of prototype tool: Feb 2000

• Next version: July 2000

• Final version: December 2000


Key outstanding issues and recommended resolution

• None


Transition of Technology

• Military transition

– Integrity enhancement for expensive transmissions, e.g., air-to-ground targeting data

– Use of integrity technologies such as self-embedding for steganography (information hiding)

– Using embedded info to trace unauthorized disclosure

• Possible commercial transitions

– Injection of key technologies into WetStone’s SMARTWatch integrity checker


What do you need from the DARPA PM?

• No pending requirements

Documents

Copyright 2000, Odyssey Research Associates, Inc. SL00-0003 1 Semantic Data Integrity DARPA Program Review Cornell Business & Technology Park 33 Thornwood