Chain of custody refers to the chronological documentation of the handling of digital or physical evidence. It ensures the integrity and admissibility of evidence during an investigation or legal proceeding.
⚠️ Improper handling can render evidence inadmissible.
Contents
🔐 Why It Matters
- Maintains trust in the evidence
- Ensures legal defensibility
- Tracks every access, transfer, and analysis event
🧱 Core Elements of Chain of Custody
- Identification
- Clearly label evidence (e.g. system image, logs, USB drive)
- Assign a unique identifier or barcode
- Collection
- Collected by trained personnel
- Use forensically sound methods (write blockers, hashes)
- Preservation
- Protect from tampering or degradation
- Calculate and store cryptographic hash (e.g. SHA-256)
- Documentation
- Log who collected it, when, where, how
- Use standardised Chain of Custody forms
- Storage
- Secure, access-controlled storage
- Digital evidence stored on read-only or write-protected media
- Transfer & Access
- Every person accessing evidence must sign and timestamp
- Record purpose of access or analysis
- Presentation
- Ensure documentation supports authenticity when presented in court or internal review
🗂 Sample Chain of Custody Log Entry
| Field | Example |
|---|---|
| Evidence ID | IMG-001-ServerXYZ |
| Description | Disk image of compromised server |
| Collected By | Jane Doe |
| Date/Time | 2025-06-21 10:45 |
| Location | Data Centre A |
| Transfer To | John Smith (Forensic Lead) |
| Reason for Access | Timeline analysis |
| Hash (SHA-256) | a1b2c3... |
✅ Best Practices
- Always use tamper-evident packaging for physical media
- Automate digital evidence logging with timestamped logs
- Implement access control and logging in forensic toolchains
- Conduct regular audits of evidence handling procedures
🔒 In digital forensics, an unbroken chain of custody is your strongest proof of integrity.