Digital evidence preservation encompasses the techniques, procedures, and infrastructure required to maintain the integrity, authenticity, and availability of electronic evidence throughout its lifecycle. Preservation extends beyond initial evidence collection to include secure storage, access control, integrity verification, and chain of custody maintenance for the duration of legal, regulatory, or investigative proceedings. Proper preservation ensures that evidence remains admissible and trustworthy regardless of how many years pass between collection and presentation.
Preservation begins at collection with forensically sound acquisition methods that create bit-for-bit copies without modifying original evidence. Cryptographic hash values (SHA-256 minimum) are computed at acquisition and recorded in chain of custody documentation. Evidence is stored in write-once or tamper-evident storage systems with access controls limiting who can view, copy, or transfer evidence items. Environmental controls protect physical storage media from degradation. Regular integrity checks verify hash values against the original recordings. Metadata records capture the provenance of each evidence item: who collected it, when, where, using what tools, and the hash at each custody transfer. Long-term preservation addresses format obsolescence by maintaining the ability to read evidence in its original format or migrating to current formats with documented verification. Cloud evidence preservation adds complexity, requiring point-in-time snapshots of ephemeral resources and coordination with cloud service providers.
Digital evidence can be altered, corrupted, or lost at any point after collection if preservation is inadequate. Courts and regulators require demonstrated integrity throughout the evidence lifecycle, and any gap in the chain of custody may render evidence inadmissible. Cyber investigations and litigation often span years, during which storage media can degrade, file formats can become obsolete, and organizational changes can disrupt access. A robust preservation program ensures that evidence collected during an incident today remains usable and trustworthy whenever it is needed.
CDA's Locker infrastructure is purpose-built for digital evidence preservation, providing encrypted storage with full audit trails and integrity verification. Our RGA and TID domain missions include establishing evidence preservation programs during C-BUILD campaigns. CDA operators follow NIST SP 800-86 preservation guidelines, and our theater includes missions for building organizational evidence management capabilities that scale with the client's legal and regulatory requirements.