Dev.to
6/29/2026
The original title is about a developer who built an audit log system called LedgerLock. Let me rewrite this for a mobile feed.
Original: I built an audit log that catches its own tampering - and proves it at scale, offline
Short summary
Author built LedgerLock, an append-only audit API using DynamoDB and S3 Object Lock to create cryptographically verified, tamper-proof access logs for regulated industries. The system enforces immutability via IAM policies (preventing UPDATE/DELETE), hash chains, and WORM-sealed Merkle roots—making forgery detectable even if an attacker has full database access. Key technical lessons: concurrent writes require sequential sort keys; sealing performance matters at scale; systems should surface degradation transparently.
- •LedgerLock enforces immutable audit logs at the permission level (no UPDATE/DELETE IAM actions), preventing tampering entirely rather than detecting it after the fact
- •Hash chains link events; Merkle roots sealed to S3 Object Lock (COMPLIANCE mode) create independent proof—forgery caught even with full database admin access
- •Concurrent writes need sequential sort keys, not random IDs; sealing lag transparently tracked; since-seal verification optimizes O(n) walks to O(tail) at scale
Generated with AI, which can make mistakes.
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