1. Secure File Storage System

System Design - Part 15 | Design Dropbox | Cloud Storage, Google Drive, OneDrive

Goals: Secure file upload/download, encryption, access control, scalability

Components:

• Frontend upload/download clients
• API Gateway
• Authentication service (Cognito/OIDC)
• File metadata service (DynamoDB)
• Encrypted file storage (S3 + SSE-KMS)
• Virus scanning service
• CDN for delivery (CloudFront)
• Logging and monitoring (CloudTrail, CloudWatch)

Security:

• Use signed URLs for S3
• SSE-KMS encryption for files
• IAM + Cognito roles for access
• Virus scanning on upload

Scalability:

• Auto-scaling Lambda/API backend
• S3 handles horizontal file storage