I. System Architecture Design  Master Control Unit  Utilizes high-performance embedded chips (such as ARM Cortex-M7), supports multi-threading processing and encryption algorithm acceleration.  Integrated Real-Time Clock (RTC) for precise operation time recording.  Equipped with encryption chips (such as ATECC608A) for managing keys and sensitive data.  Modular Design  Authentication modules (password, fingerprint, face, mobile APP) operate independently, communicating with the master control via SPI/UART.  Lock drive modules (electromagnetic lock/motor) are controlled by an H-bridge circuit, supporting over-current protection.  Communication modules (Bluetooth/Wi-Fi/4G) enable remote notifications and interaction with the APP.  II. Security Protection Design  Physical Protection  The lock body housing uses anti-drilling steel plate (hardness ≥ HRC60), and the lock tongue structure resists hydraulic shear (≥10 tons).  The circuit board is encapsulated with potting compound, shielding electromagnetic interference (EMI).  Anti-tampering Mechanisms  Brute force protection: Vibration sensors (threshold ≥ 5g) trigger alarms, and the system locks after 3 abnormal vibrations.  Technical lock picking protection: Dynamic password algorithm (TOTP), fingerprint/face liveness detection (infrared + 3D structured light).  Combined verification strategy: High-security mode requires "password + biometric" two-factor authentication.  Data Security  Logs and passwords are encrypted and stored using AES-256, with keys managed by the encryption chip.  Communication links use TLS 1.3 protocol to prevent man-in-the-middle attacks.  III. Core Function Implementation  Modules  Technical Solutions  Authentication     • Fingerprint: FAP20 standard optical sensor (false acceptance rate ≤ 0.002%)  • Face: Infrared camera + liveness detection algorithm  • Password: Virtual keyboard with random scrambling display  Alarm System  • Sound and light alarm: 105dB buzzer + RGB LED  • Remote notification: Pushed to the APP via MQTT protocol  Emergency Unlocking  • Physical keyhole hidden under the bottom cover (requires a special tool to open)  • Backup password set by the administrator through a secure channel  Power Management  • Main power: 12V lithium battery (endurance ≥ 6 months)  • Standby power: Supercapacitor (maintains power for 48 hours after a power outage)  IV. Reliability Enhancement Design  Abnormal Handling  Lock failure 3 times locks for 5 minutes, with subsequent attempts increasing lockout time incrementally.  Automatic switching to standby power during a power outage, triggering low-power mode.  Log Management  Storage capacity ≥ 100,000 records, supports exporting via SD card/USB drive (requires admin authorization).  Log hash chain for tamper-proofing, automatically backs up to the cloud every 30 days (optional feature).  V. User Interaction Design  Operation Interface  4-inch touchscreen (scratch-resistant glass) + LED status light (red/green/yellow tricolor).  Voice prompts (optional multi-language support).  Mobile APP Features  Real-time viewing of unlock records, receiving alarm notifications.  Remote temporary authorization (time-limited password/one-time facial recognition request).  VI. Testing and Verification  Environmental Testing  Temperature (-20℃ to 70℃), humidity (5% to 95%) tolerance testing.  Electromagnetic interference testing (EN 61000-4 standard).  Offensive and Defensive Testing  Simulating brute force destruction (drill/cut), technical lock picking (signal sniffing/replay attacks).  Biometric forgery attacks (silicone fingerprints/photo/3D masks).  VII. Cost and Mass Production  Components  Cost Percentage  Notes  Master Control and Encryption Chip  35%  Domestic substitution can reduce costs by 20%  Biometric Authentication Module  40%  Fingerprint module ($50), Face module ($120)  Communication and Power  15%  Wi-Fi + 4G dual-mode ($60)  Structural Parts  10%  Custom mold costs (one-time investment of $50,000)