LegalFab API Security

Version: 1.0 Last Updated: January 2026

Component Overview

The LegalFab API layer provides secure, programmatic access to platform capabilities. All external integrations, client applications, and inter-service communications are secured through a centralized API Gateway with comprehensive security controls.

Core Capabilities:

Capability	Description	Security Relevance
API Gateway	Centralized entry point for all API traffic	Authentication, rate limiting, routing
Authentication	Multiple authentication methods	Identity verification, token management
Authorization	Fine-grained access control	Permission enforcement, scope validation
Rate Limiting	Request throttling and quota management	DoS protection, fair usage
API Versioning	Backward-compatible API evolution	Stability, deprecation management
Request Validation	Input sanitization and schema validation	Injection prevention, data integrity

Architecture Overview

┌─────────────────────────────────────────────────────────────────────────┐
│                         API SECURITY ARCHITECTURE                       │
├─────────────────────────────────────────────────────────────────────────┤
│                                                                         │
│  ┌────────────────────────────────────────────────────────────────────┐ │
│  │                      EXTERNAL CLIENTS                              │ │
│  │  ┌──────────────┐  ┌──────────────┐  ┌──────────────────────────┐  │ │
│  │  │  Web Apps    │  │  Mobile Apps │  │  Third-Party Integrations│  │ │
│  │  └──────────────┘  └──────────────┘  └──────────────────────────┘  │ │
│  └────────────────────────────────────────────────────────────────────┘ │
│                              │                                          │
│                              ▼                                          │
│  ┌────────────────────────────────────────────────────────────────────┐ │
│  │                      EDGE SECURITY                                 │ │
│  │  ┌──────────────┐  ┌──────────────┐  ┌──────────────────────────┐  │ │
│  │  │  WAF         │  │  DDoS        │  │  Geographic Filtering    │  │ │
│  │  │              │  │  Protection  │  │                          │  │ │
│  │  └──────────────┘  └──────────────┘  └──────────────────────────┘  │ │
│  └────────────────────────────────────────────────────────────────────┘ │
│                              │                                          │
│                              ▼                                          │
│  ┌────────────────────────────────────────────────────────────────────┐ │
│  │                      API GATEWAY                                   │ │
│  │  ┌───────────┐  ┌───────────┐  ┌───────────┐  ┌─────────────────┐  │ │
│  │  │  AuthN    │  │  AuthZ    │  │  Rate     │  │  Request        │  │ │
│  │  │  Service  │  │  Service  │  │  Limiter  │  │  Validator      │  │ │
│  │  └───────────┘  └───────────┘  └───────────┘  └─────────────────┘  │ │
│  │  ┌───────────┐  ┌───────────┐  ┌───────────┐  ┌─────────────────┐  │ │
│  │  │  Router   │  │  Version  │  │  Audit    │  │  Response       │  │ │
│  │  │           │  │  Manager  │  │  Logger   │  │  Transformer    │  │ │
│  │  └───────────┘  └───────────┘  └───────────┘  └─────────────────┘  │ │
│  └────────────────────────────────────────────────────────────────────┘ │
│                              │                                          │
│                              ▼                                          │
│  ┌────────────────────────────────────────────────────────────────────┐ │
│  │                      BACKEND SERVICES                              │ │
│  │  ┌───────────┐  ┌───────────┐  ┌───────────┐  ┌─────────────────┐  │ │
│  │  │ Knowledge │  │  Studio   │  │  AML      │  │  Schema         │  │ │
│  │  │  Fabric   │  │  API      │  │  API      │  │  API            │  │ │
│  │  └───────────┘  └───────────┘  └───────────┘  └─────────────────┘  │ │
│  └────────────────────────────────────────────────────────────────────┘ │
└─────────────────────────────────────────────────────────────────────────┘

API Gateway

The API Gateway serves as the centralized entry point for all API traffic, enforcing security policies before requests reach backend services.

Gateway Capabilities

Capability	Description
Request Routing	Route requests to appropriate backend services
Protocol Translation	Support REST, GraphQL, and WebSocket protocols
Load Balancing	Distribute traffic across service instances
Circuit Breaker	Prevent cascade failures
Request/Response Transformation	Normalize data formats
Caching	Cache responses for performance

Gateway Security Controls

Control	Implementation
TLS Termination	TLS 1.3 with strong cipher suites
Certificate Validation	Mutual TLS for service-to-service
Request Size Limits	Maximum payload size enforcement
Timeout Enforcement	Request and connection timeouts
IP Allowlisting	Optional IP-based access control
Header Validation	Security header enforcement

Authentication

LegalFab supports multiple authentication methods to accommodate different integration patterns.

Authentication Methods

Method	Use Case	Token Lifetime
OAuth 2.0 + OIDC	Web and mobile applications	Access: 1 hour, Refresh: 30 days
API Keys	Server-to-server integrations	Configurable, default 1 year
JWT Bearer Tokens	Microservice communication	15 minutes
Mutual TLS (mTLS)	High-security integrations	Certificate validity
SAML 2.0	Enterprise SSO integration	Session-based

OAuth 2.0 Flows

Flow	Use Case	Security Level
Authorization Code + PKCE	Web and mobile apps	High
Client Credentials	Service-to-service	High
Device Authorization	CLI and IoT devices	Medium
Refresh Token	Token renewal	High

Token Security

Control	Implementation
Token Signing	RS256 or ES256 algorithms
Token Encryption	Optional JWE for sensitive claims
Token Binding	Bind tokens to client fingerprint
Token Revocation	Real-time revocation support
Refresh Token Rotation	New refresh token on each use
Token Introspection	Active token validation endpoint

API Key Management

Feature	Description
Key Generation	Cryptographically secure random keys
Key Rotation	Scheduled and on-demand rotation
Key Scoping	Limit keys to specific APIs or actions
Key Expiration	Configurable expiration policies
Key Revocation	Immediate revocation capability
Usage Tracking	Per-key usage metrics and alerts

Authorization

Fine-grained authorization controls ensure users and applications access only permitted resources.

Authorization Model

Model	Description	Use Case
RBAC	Role-based access control	User permissions
ABAC	Attribute-based access control	Context-aware decisions
Scopes	OAuth scope-based access	API-level permissions
Resource Policies	Resource-specific rules	Data-level access

API Scopes

Scope	Description	Access Level
`read:entities`	Read entity data	Read-only
`write:entities`	Create/update entities	Read-write
`delete:entities`	Delete entities	Destructive
`read:agents`	View agent definitions	Read-only
`execute:agents`	Run agents	Execute
`admin:system`	Administrative operations	Full access

Permission Enforcement

Stage	Check	Action on Failure
Gateway	Token validity, basic scopes	401 Unauthorized
Service	Resource-level permissions	403 Forbidden
Data	Row/field-level access	Filtered response

Rate Limiting

Rate limiting protects the platform from abuse and ensures fair resource allocation.

Rate Limit Tiers

Tier	Requests/Minute	Requests/Hour	Requests/Day	Use Case
Free	60	1,000	10,000	Trial accounts
Standard	300	10,000	100,000	Standard subscriptions
Professional	1,000	50,000	500,000	Professional subscriptions
Enterprise	Custom	Custom	Custom	Enterprise agreements

Rate Limit Headers

Header	Description
`X-RateLimit-Limit`	Maximum requests allowed
`X-RateLimit-Remaining`	Requests remaining in window
`X-RateLimit-Reset`	Time when limit resets (Unix timestamp)
`Retry-After`	Seconds to wait before retrying (on 429)

Rate Limit Strategies

Strategy	Description	Application
Fixed Window	Reset at fixed intervals	Simple rate limiting
Sliding Window	Rolling time window	Smoother distribution
Token Bucket	Burst allowance with refill	API with burst patterns
Concurrent Limit	Max simultaneous requests	Resource-intensive endpoints

Rate Limit Responses

Scenario	HTTP Status	Response
Limit Exceeded	429 Too Many Requests	Retry-After header included
Quota Exhausted	429 Too Many Requests	Upgrade instructions
Burst Exceeded	429 Too Many Requests	Temporary backoff

API Versioning

LegalFab uses URL-based versioning with clear deprecation policies.

Versioning Strategy

Aspect	Approach
Version Format	Semantic versioning (v1, v2, v3)
Version Location	URL path prefix (`/api/v1/...`)
Default Version	Latest stable version
Sunset Header	Deprecation date in response headers

Version Lifecycle

Phase	Duration	Support Level
Current	Ongoing	Full support, new features
Supported	12 months after successor	Bug fixes, security patches
Deprecated	6 months notice	Security patches only
Retired	End of life	No support, returns 410 Gone

Breaking Changes Policy

Change Type	Versioning Impact
New endpoint	Minor version, backward compatible
New optional field	Minor version, backward compatible
New required field	Major version, breaking
Remove endpoint	Major version, breaking
Change field type	Major version, breaking
Rename field	Major version, breaking

Deprecation Headers

Header	Description
`Deprecation`	Deprecation date (RFC 7231 format)
`Sunset`	End-of-life date
`Link`	Reference to successor API documentation

Request Validation

All API requests undergo comprehensive validation before processing.

Validation Layers

Layer	Validation	Action
Transport	TLS version, certificate	Connection refused
Protocol	HTTP method, content-type	400 Bad Request
Schema	JSON schema validation	400 Bad Request with details
Business	Domain rules, constraints	422 Unprocessable Entity

Input Sanitization

Input Type	Sanitization
String fields	HTML encoding, length limits
Numeric fields	Range validation, type coercion
Date fields	Format validation, range checks
File uploads	Type validation, size limits, malware scan
JSON payloads	Schema validation, depth limits

Security Headers

Request Headers (Required):

Header	Purpose
`Authorization`	Authentication token
`Content-Type`	Request content type
`X-Request-ID`	Request correlation ID

Response Headers (Always Included):

Header	Value	Purpose
`Strict-Transport-Security`	`max-age=31536000; includeSubDomains`	Force HTTPS
`X-Content-Type-Options`	`nosniff`	Prevent MIME sniffing
`X-Frame-Options`	`DENY`	Prevent clickjacking
`Content-Security-Policy`	Strict policy	Prevent XSS
`X-XSS-Protection`	`1; mode=block`	XSS filter
`Cache-Control`	`no-store`	Prevent caching sensitive data
`X-Request-ID`	Echo request ID	Request tracing

Error Handling

Standardized error responses provide consistent, secure error information.

Error Response Format

All errors follow RFC 7807 (Problem Details for HTTP APIs):

Field	Description
`type`	URI reference identifying error type
`title`	Short, human-readable summary
`status`	HTTP status code
`detail`	Human-readable explanation
`instance`	URI reference to specific occurrence
`traceId`	Request trace identifier

Error Categories

Status Code	Category	Description
400	Bad Request	Malformed request syntax
401	Unauthorized	Authentication required or failed
403	Forbidden	Insufficient permissions
404	Not Found	Resource does not exist
409	Conflict	Resource state conflict
422	Unprocessable Entity	Validation errors
429	Too Many Requests	Rate limit exceeded
500	Internal Server Error	Unexpected server error
503	Service Unavailable	Temporary unavailability

Error Security

Control	Implementation
Information Hiding	No stack traces or internal details in production
Error Logging	Full details logged server-side with trace ID
Rate Limit Errors	No distinction between invalid and rate-limited
Authentication Errors	Generic message, no user enumeration

API Documentation

Comprehensive API documentation is provided through multiple formats.

Documentation Formats

Format	Purpose	Access
OpenAPI 3.0	Machine-readable specification	Public endpoint
Interactive Docs	Swagger UI for testing	Authenticated access
SDK Documentation	Language-specific guides	Developer portal
Changelog	Version history and changes	Public

Documentation Security

Control	Implementation
Access Control	Some endpoints require authentication to view
Example Sanitization	No real data in examples
Endpoint Discovery	Hidden endpoints not documented
Rate Limiting	Documentation endpoints rate-limited

Webhook Security

Outbound webhooks are secured to ensure reliable and authenticated delivery.

Webhook Authentication

Method	Description
HMAC Signature	SHA-256 signature in header
Shared Secret	Customer-provided secret for signing
mTLS	Mutual TLS for high-security endpoints

Webhook Headers

Header	Description
`X-Webhook-ID`	Unique webhook delivery ID
`X-Webhook-Timestamp`	Delivery timestamp
`X-Webhook-Signature`	HMAC-SHA256 signature
`X-Webhook-Event`	Event type identifier

Webhook Security Controls

Control	Implementation
Replay Prevention	Timestamp validation (5 minute window)
Signature Verification	HMAC signature required
HTTPS Only	Webhooks only delivered over HTTPS
Retry Policy	Exponential backoff with max attempts
Timeout	30 second delivery timeout
IP Allowlist	Optional source IP filtering

Service-to-Service Communication

Internal API communication between microservices is secured with additional controls.

Internal Authentication

Method	Description
Mutual TLS	Certificate-based authentication
Service Tokens	Short-lived JWT tokens
Service Mesh	Istio/Linkerd for zero-trust networking

Internal Authorization

Control	Implementation
Service Identity	Each service has unique identity
Service Policies	Define allowed service interactions
Least Privilege	Services only access required APIs
Network Policies	Kubernetes network policies

Audit Logging

All API activity is logged for security monitoring and compliance.

Logged Events

Event Category	Data Captured	Retention
Authentication	Token issuance, validation, revocation	1 year
Authorization	Permission checks, denials	1 year
API Requests	Method, path, status, latency	90 days
Rate Limiting	Limit hits, throttling events	90 days
Errors	Error details, stack traces (internal)	90 days
Configuration	API key changes, scope modifications	2 years

Log Security

Control	Implementation
PII Redaction	Sensitive data masked in logs
Log Integrity	Tamper-evident logging
Access Control	Restricted log access
Encryption	Logs encrypted at rest

Security Monitoring

Real-time monitoring detects and responds to API security threats.

Monitoring Metrics

Metric	Alert Threshold	Response
Authentication Failures	> 100/minute	Block IP, alert SOC
4xx Error Rate	> 10% of requests	Investigate, alert
5xx Error Rate	> 1% of requests	Page on-call, investigate
Latency P99	> 5 seconds	Scale up, investigate
Rate Limit Hits	> 1000/hour per client	Review client, contact

Threat Detection

Threat	Detection Method	Response
Credential Stuffing	Failed auth patterns	Progressive blocking
API Abuse	Unusual request patterns	Rate limiting, block
Data Exfiltration	Large response volumes	Alert, investigate
Injection Attempts	WAF signatures	Block, alert
Token Theft	Unusual token usage	Revoke, alert