dbis_core/docs/adr/0004-authentication-strategy.md

ADR-0004: Zero-Trust Authentication Strategy

Status

Accepted

Context

The DBIS Core Banking System requires secure authentication for all API requests. Traditional authentication methods are insufficient for sovereign-grade financial infrastructure that handles:

• Multi-sovereign operations
• High-value transactions
• Regulatory compliance requirements
• Cross-border operations

Decision

Implement a zero-trust authentication strategy using:

1. Sovereign Identity Tokens (SIT): JWT-based tokens with sovereign bank identity
2. Request Signature Verification: HSM-backed cryptographic signatures for each request
3. Multi-layer Validation: Token validation + signature verification + timestamp/nonce checks
4. HSM Integration: Hardware Security Module for key management and signing

Consequences

Positive

• Strong security with multiple validation layers
• HSM-backed cryptographic operations
• Replay attack prevention (timestamp/nonce)
• Sovereign identity verification
• Scalable across multiple sovereign banks

Negative

• More complex implementation
• Requires HSM infrastructure
• Slightly higher latency per request
• More complex client implementation

Risks

• HSM availability dependency
• Signature verification performance at scale
• Key rotation complexity

Alternatives Considered

1. Simple JWT Only: Basic JWT authentication

   • Pros: Simple, fast
   • Cons: Insufficient security for financial operations

2. API Keys: Static API keys

   • Pros: Very simple
   • Cons: No cryptographic verification, weak security

3. Zero-Trust with HSM: Chosen approach

   • Pros: Strong security, regulatory compliance, sovereign-grade
   • Cons: More complex

Implementation

• JWT tokens with sovereign bank identity
• Request signature headers (X-SOV-SIGNATURE, X-SOV-TIMESTAMP, X-SOV-NONCE)
• HSM service integration for signature verification
• Middleware: zeroTrustAuthMiddleware in src/integration/api-gateway/middleware/auth.middleware.ts

References

• Zero Trust Architecture: https://www.nist.gov/publications/zero-trust-architecture
• HSM Best Practices: https://www.nist.gov/publications/guidelines-selection-and-use-approval-cryptographic-modules