1. ACE: A Software Tool to Ensure the Integrity of Digital Archives Principal Investigator: Joseph JaJa Graduate Student: Sangchul Song Lead Programmers: Michael McGann Michael Smorul University of Maryland, College Park

2. Main Threats to Integrity of Digital Archives Hardware/media degradation Hardware/software malfunction Operational errors Technology evolution Security breaches, malicious alterations Object transformation (format obsolescence) Infrequent access to most data Evolution of cryptographic schemes

3. Existing Methodologies Core Techniques Replication: mirroring Coding techniques: parity checking (RAID), erasure codes Cryptographic one-way hashing: checksum Techniques for Digital Archives Hashing only Replication + voting scheme Hashing + replication Digital Signatures Time Stamping (PKI vs. hash-linking)

4. ACE – Basic Methodology Three-tiered Cryptographic Information. Each tier is periodically audited separately according to policies set by managers. Integrity Token Witness Cryptographic Summary Information 1 IT/object ~1KB 1 CSI/time window 1 CSI / (n) objects ~100MB/year 1 Witness/week ~2-3KB/year k:1l:1

5. 5 Three-Tiered Cryptographic Information

6. ACE – System Architecture

7. ACE Audit  Each digital object is audited locally using the integrity token, according to the policy set by the local manager.  The integrity management system periodically audits the integrity tokens according to its policies.  Cryptographic summaries are audited as necessary using the published witness values.

8. ACE Summary Third-party auditable Cryptographically rigorous yet cost-effective Update-aware Highly interoperable Scalable High Performance Current Effort: Porting to Portico and DSpace