> CIP — KEP & e-Correspondence Platform

A full-stack enterprise platform for Turkish KEP (Registered Electronic Mail) and e-Yazışma document management. Unifies four different REM providers (TURKKEP, PTTKEP, TNBKEP, EDMKEP) behind a single interface, automates digital signature workflows, and maintains full audit trails for legal compliance.

Backend (.NET 10, Clean Architecture)

• >Clean Architecture REST API built with Minimal APIs, PostgreSQL 16 and EF Core 10
• >Integrated 4 REM providers via factory pattern with OAuth 2.0 / legacy authentication
• >Real-time operation tracking with SignalR hub and Redis-backed state persistence across restarts
• >JWT + LDAP authentication with 2FA (SMS/Email OTP) and granular per-endpoint rate limiting
• >AES-256-CBC encryption service with PBKDF2 (100k iterations) and per-domain key isolation for secure credential storage
• >OTP system with HMAC-SHA256 constant-time verification and progressive lockout
• >Global exception middleware with RFC 7807 Problem Details and automatic audit logging
• >REM polling background service: staggered scheduling, concurrent sync, race-condition-safe proof download
• >Serilog + Seq structured logging and OpenTelemetry + Prometheus + Grafana metrics pipeline
• >e-Yazışma (EYP) XML package generation with multi-version support (V1.3 / V2.0), compliant with the Turkish national correspondence standard

Frontend (Next.js 16, React 19)

• >Client-heavy application with TypeScript, Tailwind CSS 4 and Radix UI
• >State management with TanStack React Query + Zustand (persist); forms with React Hook Form + Zod
• >Real-time updates via SignalR WebSocket with automatic reconnection (exponential backoff)
• >Full i18n support (Turkish / English) with i18next and namespace-based translation files
• >WCAG accessibility with Radix primitives, ARIA attributes, and keyboard navigation
• >Bulk operations engine (~728 LOC) with abort-signal cancellation, 5-minute polling timeout and per-item error reporting
• >Multi-phase batch workflow (MIME preparation → signing session → bulk send) with OAuth retry and detailed result aggregation
• >Next.js middleware with route-based auth guards and open-redirect prevention
• >EYP viewer with hierarchical tree navigation, signature detail inspection and embedded document preview

CipImza — Desktop Signing App (.NET 10)

• >PKCS#11 digital signing Windows application for USB tokens and smartcards with auto-detection of installed libraries (Akis, SafeNet, etc.)
• >Extended HSM support (Thales Luna, Utimaco, SoftHSM) via PKCS#11 for high-volume server-side signing
• >Custom protocol handler (cipimza://) for seamless browser-to-desktop signing bridge
• >CAdES-BES cryptographic signatures (BouncyCastle) supporting SHA-256/384/512 and RSA/ECDSA
• >RFC 3161 timestamping via HTTP timestamp authority for long-term signature validity
• >Headless signing mode, REST API, API-key authentication and async signing job queue