Chain of Custody

The documentation must establish an unbroken, sequential timeline of events. Every transfer, access, or transformation of the data asset must be recorded with a trusted timestamp that is cryptographically bound to the action. This prevents backdating and proves that a specific entity possessed the data at a specific moment. The sequence of custody is often represented as a Merkle Tree to allow efficient verification of any single event without recomputing the entire history.

To prove that data has not been altered, the chain relies on cryptographic hashing (e.g., SHA-256). A unique digital fingerprint of the asset is generated at the point of creation and recalculated at every subsequent transfer. Any modification, even a single bit flip, produces a completely different hash, immediately signaling a break in integrity. This seal is often anchored to a distributed ledger via blockchain anchoring for an immutable, publicly verifiable proof of existence.

Every custodian in the chain must be uniquely identified and must cryptographically sign for the receipt and transfer of the asset using a digital signature. This is achieved through a Public Key Infrastructure (PKI) , where a private key creates the signature and a public key verifies it. This process provides non-repudiation, meaning a signatory cannot plausibly deny their involvement in the custody sequence.

A defensible chain records not just possession, but every interaction. This requires strict Role-Based Access Control (RBAC) integrated with an immutable audit trail. The system must log:

• Who accessed the data (user or service account)
• What action was performed (viewed, copied, modified, deleted)
• When the action occurred (high-precision timestamp)
• Where the request originated (IP address, geolocation) This granularity is critical for forensic analysis and proving that no unauthorized tampering occurred.

The storage mechanism itself must be resistant to alteration. This is achieved through write-once-read-many (WORM) compliant storage systems. Once a custody record is written, it cannot be overwritten or deleted. This is often combined with a Merkle Tree structure, where each new event is cryptographically linked to the hash of all preceding events, creating a chain where any attempt to retroactively alter a past record would invalidate the entire subsequent sequence.

The documented chronology of data origin, transformations, and custody that establishes a verifiable chain of ownership and integrity. Unlike chain of custody, which focuses on the sequential transfer log, provenance encompasses the full lifecycle including derivation, attribution, and processing history. It answers not just 'who held this data' but 'how was it created and modified'.

A chronologically ordered, write-once-read-many (WORM) log of all events and transactions related to a data asset. Each entry is cryptographically chained to its predecessor using hash-based integrity checks, preventing retroactive alteration. This is the technical mechanism that transforms a simple custody log into a forensically sound, court-admissible record.

The practice of recording a cryptographic hash of a custody record or provenance manifest on a distributed ledger. This creates an immutable, publicly verifiable timestamp proving data existence at a specific point in time without exposing the underlying data. Key benefits:

• Decentralized trust: No single authority can alter the record
• Non-repudiation: Custody events are permanently witnessed
• Cost efficiency: Only hashes are stored on-chain, not the data itself

A cryptographic mechanism using asymmetric key pairs to validate authenticity and integrity. In chain of custody, each custodian digitally signs a receipt when receiving or transferring a data asset. This provides:

• Authentication: Verifies the signer's identity
• Integrity: Detects any post-signing modification
• Non-repudiation: The signer cannot deny their action Common algorithms include ECDSA and Ed25519.