Supabase Postgres Audit Trail: Tamper-Evident Hash Chain

Stop audit tampering in its tracks with a Supabase Postgres tamper-evident audit trail

This n8n workflow creates an append-only Supabase Postgres audit trail using a hash-chained, tamper-evident record design—then verifies the chain integrity on demand or on a schedule. It can also run a functional test to confirm your database rejects UPDATE and DELETE attempts.

What this workflow does

• Run as a demo, verification job, or event receiver: execute manually to generate demo events, run on a schedule to verify integrity, or be called from another workflow via Execute Workflow to receive an audit event payload.
• Generate (demo) audit events: for demo runs, it creates five fictional events and uses SHA-256 to hash each original payload, preparing audit fields including workflow/execution context, actor, reason, and details.
• Validate and normalize incoming events: enforces required fields and allowed values, normalizes optional fields, and derives a correlation ID when one isn’t provided.
• Write to Supabase with database sequencing + hash chaining: inserts the validated event into the audit_log table and returns the assigned sequence number, timestamp, and record hash.
• Verify the hash chain integrity: recomputes the chain in Supabase for demo runs and reports whether the chain is intact or identifies the first broken sequence.
• Optional tamper-resistance test: accepts a confirmation form submission and attempts UPDATE and DELETE; reports PASS when Supabase rejects both operations.

Use cases

• Enterprise SaaS operators needing auditability for critical actions stored in Supabase.
• Automation engineers implementing immutable audit trails for workflow-driven systems.
• Scheduled integrity checks to detect unexpected changes in your audit history.

Technical details

• Supabase (Postgres): writes to audit_log, relies on SQL objects (table, triggers, verification functions) created via the provided SQL.
• Nodes used in n8n: if, set, code, no op, crypto, postgres.
• Hashing: SHA-256 for payload hashing and chain verification.