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immudb

immudb provides cryptographic verification for audit-critical event sourcing where tamper-proof guarantees are essential.

Why immudb​

StrengthBenefit
Immutable by designEvents cannot be altered post-write
Cryptographic proofMerkle tree verification
Tamper detectionAny modification breaks proofs
Audit complianceSOC 2, HIPAA, financial regulations

Trade-offs​

ConcernConsideration
PerformanceSlower than non-verified writes
ComplexityProof verification adds overhead
Storage growthMerkle proofs increase storage

Implementation Note​

Angzarr connects to immudb via its PostgreSQL wire protocol compatibility layer. This means:

  • Uses the standard sqlx PostgreSQL driver
  • Connection strings follow PostgreSQL format
  • Query syntax is PostgreSQL-compatible

Configuration​

[storage]
backend = "immudb"

[storage.immudb]
host = "localhost"
port = 3322
database = "angzarr"
username = "immudb"
password = "immudb"

Environment Variables​

export IMMUDB_HOST="localhost"
export IMMUDB_PORT="3322"
export IMMUDB_DATABASE="angzarr"
export IMMUDB_USERNAME="immudb"
export IMMUDB_PASSWORD="immudb"
export STORAGE_BACKEND="immudb"

Cryptographic Verification​

Every event write returns a proof:

// Write event
let tx = store.add_event(&event).await?;

// Verify event wasn't tampered
let verified = store.verify_event(&event, &tx.proof).await?;
assert!(verified);

Merkle Tree Structure​

            Root Hash
           /         \
      Hash(0-1)    Hash(2-3)
      /     \      /     \
   H(e0)  H(e1)  H(e2)  H(e3)
     |      |      |      |
   Event0 Event1 Event2 Event3

Modifying any event changes its hash, which propagates up, changing the root. Old root hashes become invalid.

Audit Trail​

Query historical state with cryptographic proof:

// Get event at specific transaction
let event = store.get_event_at_tx(&cover, sequence, tx_id).await?;

// Verify it matches the state at that time
let proof = store.get_proof_at_tx(tx_id).await?;

Docker Setup​

# Start immudb
docker run -d \
  --name immudb \
  -p 3322:3322 \
  -p 9497:9497 \
  codenotary/immudb:latest

# Web console at http://localhost:9497

When to Use immudb​

  • Financial services — Regulatory compliance
  • Healthcare — HIPAA audit trails
  • Legal — Tamper-proof records
  • Supply chain — Provenance tracking
  • Government — Public records integrity

Testing​

# Run immudb tests (requires testcontainers)
cargo test --test storage_immudb --features immudb

Next Steps​