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System Design questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master system design interviews.

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This is a hard difficulty System Design question, commonly asked during Technical Screen rounds at Axon.

What role is this question designed for?

This question is commonly asked for Software Engineer candidates at Axon during technical interviews.

Design a tamper-evident video chain-of-custody audit system

Quick Overview

This question evaluates system design, distributed-systems, security, and compliance competencies by focusing on a scalable, tamper-evident audit logging architecture that preserves chain-of-custody, immutable event capture, ordering, integrity mechanisms, encryption, and reliable delivery in a multi-tenant video-evidence environment.

System Design: Tamper-Evident Audit Logging for Video Evidence Chain of Custody

Design a scalable, tamper-evident audit logging system for video evidence that preserves an accurate chain of custody. The system must record all actions (upload, view, redact/delete sensitive data, transcribe), never lose an event, and support legal discovery.

Context and assumptions (add or adjust as needed):

Multi-tenant environment supporting thousands of agencies and millions of assets (videos, photos, transcripts).
Peak audit event rate: 10–50k events/sec; steady state 1–5B events/month.
Chain-of-custody must be legally defensible, with immutable, verifiable proof of event history.
Devices and users may be offline and later reconnect; the system must handle late/out-of-order arrivals without loss.

Specify the following:

Functional and non-functional requirements.
Architecture and storage choices (e.g., append-only log, replication, WORM/immutable storage).
Event schema, ordering, idempotency, and delivery guarantees (exactly-once vs at-least-once).
Integrity mechanisms (hash chaining/Merkle trees, digital signatures), encryption and key management, and access controls.
Scalability, partitioning, and backpressure handling.
APIs and query patterns for auditors and investigators.
Retention policies, legal hold, and compliance considerations.
Monitoring, audit-of-the-auditor, and disaster recovery.
Cost/latency trade-offs and capacity planning.
Testing, verification, and rollout plan.

Quick Overview

System Design: Tamper-Evident Audit Logging for Video Evidence Chain of Custody

Context and assumptions (add or adjust as needed):

Multi-tenant environment supporting thousands of agencies and millions of assets (videos, photos, transcripts).

Peak audit event rate: 10–50k events/sec; steady state 1–5B events/month.

Chain-of-custody must be legally defensible, with immutable, verifiable proof of event history.

Devices and users may be offline and later reconnect; the system must handle late/out-of-order arrivals without loss.

Specify the following:

Functional and non-functional requirements.

Architecture and storage choices (e.g., append-only log, replication, WORM/immutable storage).

Event schema, ordering, idempotency, and delivery guarantees (exactly-once vs at-least-once).

Integrity mechanisms (hash chaining/Merkle trees, digital signatures), encryption and key management, and access controls.

Scalability, partitioning, and backpressure handling.

APIs and query patterns for auditors and investigators.

Retention policies, legal hold, and compliance considerations.

Monitoring, audit-of-the-auditor, and disaster recovery.

Cost/latency trade-offs and capacity planning.

Testing, verification, and rollout plan.

Design a tamper-evident video chain-of-custody audit system

Quick Overview

System Design: Tamper-Evident Audit Logging for Video Evidence Chain of Custody

Solution

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Design a tamper-evident video chain-of-custody audit system

Quick Overview

System Design: Tamper-Evident Audit Logging for Video Evidence Chain of Custody

Solution

Comments (0)