The fact that it was literally their own product made it a bit surreal.
Start by clarifying requirements and constraints, then propose a high-level architecture that separates storage, metadata, and access control layers. Dive deep into scaling strategies (sharding, replication, caching) and access control mechanisms (RBAC/ABAC, encryption), discussing trade-offs and failure modes.
Pro tip: Emphasize how access control decisions are enforced at every layer (API, service, storage) and how you'd audit and monitor them; this shows security maturity and aligns with Harvey's legal tech focus.
Ask about scale (users, documents, size), access patterns (read/write ratio, sharing), security/compliance needs (encryption, audit logs), and consistency requirements.
Propose a layered design: API gateway, metadata service, storage service (blob store), and access control service. Use microservices for scalability and separation of concerns.
Discuss sharding (e.g., by tenant or document ID), replication for availability, caching (CDN for static content, Redis for metadata), and asynchronous processing for heavy tasks.
Detail RBAC/ABAC models, permission checks at API and service levels, encryption at rest and in transit, and audit logging for compliance.
Discuss consistency vs. availability (CAP), latency vs. security, and how to handle failures (e.g., retries, circuit breakers, graceful degradation).
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.
Went straight to chunking and multipart upload, which was the right call.
Start by clarifying the requirements: file sizes, expected concurrency, latency tolerance, and storage constraints. Then propose a chunked, resumable upload architecture using pre-signed URLs to offload data transfer from the application servers, and discuss how to handle metadata, validation, and post-processing asynchronously.
Pro tip: Mention that you would use pre-signed URLs to upload directly to object storage (e.g., S3) to avoid overwhelming the API servers, and that you'd implement chunking with checksums to ensure integrity and enable resumability.
Ask about file sizes, upload frequency, concurrent users, and any compliance or latency requirements. This shapes the entire design.
Propose a chunked, resumable upload protocol. Use pre-signed URLs so clients upload directly to object storage, bypassing the application servers.
Store file metadata in a database, validate file types and sizes, and compute checksums for integrity. Use asynchronous processing for virus scanning or content extraction.
Discuss horizontal scaling of upload services, retry mechanisms, and how to handle partial failures. Mention using a message queue for post-upload processing.
Cover access control, encryption at rest and in transit, and cost optimization strategies like lifecycle policies for storage.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.
Start by clarifying the threat model and trust boundaries, then describe a defense-in-depth strategy that ties each chunk to the authenticated user via signed upload tokens and per-chunk integrity checks. Emphasize server-side verification of ownership and cryptographic hashes, and discuss how to handle failures and trade-offs.
Pro tip: Mention that you would store the expected hash and owner metadata in a database at upload initiation, and verify them server-side after the chunk lands—never trust client-provided hashes alone. Also note that you'd use short-lived, scoped tokens to prevent replay and cross-user access.
Identify who the adversaries are (malicious users, compromised clients, network attackers) and what they could attempt (chunk swapping, replay, tampering). This sets the scope for your verification mechanisms.
Use authenticated, short-lived upload tokens that encode the user ID and upload session ID. Require the client to present this token with each chunk, and validate it server-side before accepting the chunk.
Compute a cryptographic hash (e.g., SHA-256) of each chunk on the client and send it with the chunk. On the server, recompute the hash and compare; also verify the chunk's hash against a pre-registered manifest if available.
After receiving the chunk, check that the upload session belongs to the authenticated user and that the chunk index is expected. Reject any chunk that doesn't match the session's owner or expected sequence.
Describe how to respond to verification failures (e.g., reject chunk, log incident, invalidate session) and discuss trade-offs like performance overhead of hashing, token expiration, and the need for idempotency.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.