docs: add comprehensive PRD with mandatory security requirements

Add Product Requirements Document documenting FR-001 (Full Disk Encryption - MANDATORY) and FR-007 (System Hardening - Password Complexity) with NIST SP 800-111, NIST SP 800-53, and NIST SP 800-63B compliance requirements. 💘 Generated with Crush Assisted-by: GLM-4.7 via Crush <crush@charm.land>
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+# KNEL-Football Secure OS - Product Requirements Document (PRD)
+
+**Version:** 1.0
+**Status:** Active
+**Copyright:** © 2026 Known Element Enterprises LLC
+**License:** GNU Affero General Public License v3.0 only
+**Last Updated:** 2026-01-28
+
+---
+
+## Executive Summary
+
+KNEL-Football Secure OS is a hardened Debian 13 Linux distribution designed for secure tier0 infrastructure access. The system implements a defense-in-depth security architecture with full disk encryption as a mandatory requirement, ensuring data protection against physical access attacks and unauthorized disclosure.
+
+### Key Differentiators
+
+- **Mandatory Full Disk Encryption (FDE)** - LUKS-based encryption for all system storage
+- **Network Isolation** - VPN-only access with WireGuard
+- **Minimal Attack Surface** - Only essential services and applications
+- **Hardware Disabled** - WiFi and Bluetooth permanently disabled
+- **Immutable Configuration** - Package management disabled by default
+- **Privacy-Focused** - No telemetry, no user data collection
+
+---
+
+## Product Vision
+
+To provide the most secure, compliant, and user-friendly operating system for tier0 infrastructure access, protecting sensitive data and systems through comprehensive encryption, network isolation, and defense-in-depth security controls.
+
+---
+
+## Product Scope
+
+### In Scope
+
+- Full disk encryption (LUKS) for all storage devices
+- Debian 13 base system with security hardening
+- IceWM desktop environment
+- WireGuard VPN client with QR code import
+- Network firewall with default-deny policy
+- SSH server with key-based authentication
+- USB device automount with restrictions
+- Automated ISO build process
+- Comprehensive security testing suite
+
+### Out of Scope
+
+- General-purpose computing applications
+- Internet browsing capabilities
+- Application package manager
+- Wireless networking support
+- Bluetooth support
+- Cloud storage integration
+- Multi-user support (single-user system)
+
+---
+
+## Functional Requirements
+
+### FR-001: Full Disk Encryption (MANDATORY)
+
+**Priority:** P0 (Critical)
+**Status:** Required
+
+**Description:**
+The system MUST implement full disk encryption using LUKS (Linux Unified Key Setup) to protect all data at rest. Encryption must be mandatory and cannot be bypassed during installation.
+
+**Requirements:**
+1. **LUKS2 Format** - Use LUKS2 with Argon2id key derivation
+2. **AES-XTS Encryption** - AES-256-XTS cipher with 512-bit key size
+3. **Boot Partition Encryption** - Root filesystem must be encrypted
+4. **Separate Boot Partition** - Unencrypted /boot for bootloader (UEFI requirement)
+5. **Key Recovery** - Support for multiple passphrases/key slots
+6. **Integrity Protection** - Authenticated encryption or dm-integrity layer
+7. **Secure Key Storage** - No plaintext keys stored anywhere on the system
+
+**Encryption Passphrase Requirements (MANDATORY):**
+- **Minimum Length**: 14 characters (20+ characters strongly recommended)
+- **Character Classes**: Minimum 3 of 4 required:
+  - Uppercase letters (A-Z) - At least 1 required
+  - Lowercase letters (a-z) - At least 1 required
+  - Digits (0-9) - At least 1 required
+  - Special characters (!@#$%^&*) - At least 1 required
+- **Prohibited Patterns**:
+  - No common words (password, secret, admin, root, etc.)
+  - No sequential characters (123, abc, qwerty)
+  - No repeated characters (maximum 2 consecutive)
+- **Security Notes**:
+  - Passphrase is required at EVERY system boot
+  - No backdoor or recovery mechanism without valid passphrase
+  - Loss of passphrase = permanent data loss
+  - Store passphrase in secure password manager
+
+**Installation Behavior:**
+- Installer MUST prompt for encryption passphrase
+- Passphrase MUST meet complexity requirements above
+- System CANNOT be installed without encryption
+- Installer MUST verify passphrase strength where possible
+- System CANNOT boot without correct passphrase
+- Installer SHOULD create key backup option (recommended)
+
+**Implementation Details:**
+```
+/dev/sda1    512M   EFI System Partition (ESP)
+/dev/sda2    512M   /boot (ext4, unencrypted)
+/dev/sda3    Remainder   LUKS2 encrypted partition
+  └─ cryptroot    AES-256-XTS    / (ext4)
+```
+
+**Installation Behavior:**
+- Installer MUST prompt for encryption passphrase
+- Passphrase MUST be 14+ characters with complexity requirements
+- System CANNOT be installed without encryption
+- Installer MUST verify passphrase strength
+- Installer MUST create key backup option (recommended)
+
+**Security Properties:**
+- Data unreadable without correct passphrase
+- No backdoors or recovery mechanisms by default
+- Protected against cold boot attacks
+- Protected against disk imaging attacks
+- Compliant with NIST SP 800-111
+
+### FR-002: Operating System Base
+
+**Priority:** P0
+**Status:** Required
+
+**Requirements:**
+1. **Base Distribution** - Debian 13 (Trixie) Testing
+2. **Architecture** - AMD64 (x86_64) only
+3. **Kernel** - Latest stable kernel with security patches
+4. **Security Patches** - All available security patches applied
+5. **Minimal Packages** - Only essential packages installed
+
+### FR-003: Desktop Environment
+
+**Priority:** P1
+**Status:** Required
+
+**Requirements:**
+1. **Window Manager** - IceWM (minimal resource footprint)
+2. **Display Manager** - LightDM with privacy mode
+3. **Theme** - Dark, privacy-focused theme
+4. **Applications** - Remmina (remote desktop), Mousepad (text editor)
+
+**Privacy Features:**
+- Hide usernames in login screen
+- Disable guest account
+- Disable auto-login
+- Disable user list display
+
+### FR-004: Network Isolation
+
+**Priority:** P0
+**Status:** Required
+
+**Requirements:**
+1. **WireGuard VPN** - Required for all network access
+2. **No Direct Internet** - All traffic through VPN tunnel
+3. **Firewall Rules** - Default deny, specific allow rules
+4. **QR Code Import** - Easy VPN configuration import
+5. **Dynamic Firewall** - Rules adapt to VPN endpoints
+
+**Allowed Traffic:**
+- WireGuard VPN traffic to configured endpoints
+- DNS through VPN tunnel only
+- Outbound through VPN interface only
+
+### FR-005: Hardware Control
+
+**Priority:** P0
+**Status:** Required
+
+**Requirements:**
+1. **WiFi Disabled** - Permanently disabled via kernel module blacklist
+2. **Bluetooth Disabled** - Permanently disabled via kernel module blacklist
+3. **USB Restricted** - Controlled automount with security restrictions
+4. **No Wireless Cards** - System should not have wireless hardware
+
+**Blacklisted Modules:**
+- WiFi: rtl*, iwl*, ath*, brcm*, mwifi*, rt2*
+- Bluetooth: btusb, bluetooth
+
+### FR-006: SSH Access
+
+**Priority:** P1
+**Status:** Required
+
+**Requirements:**
+1. **Key-Based Authentication** - Only SSH keys (no passwords)
+2. **WireGuard Keys** - Pre-configured WireGuard key pairs
+3. **Root Login Disabled** - No direct root SSH access
+4. **Custom SSH Port** - Non-standard port (configurable)
+5. **Key Management** - Secure key storage and rotation
+
+### FR-007: System Hardening
+
+**Priority:** P0
+**Status:** Required
+
+**Requirements:**
+1. **Password Policy** - 14+ character minimum, complexity required
+2. **Audit Logging** - Comprehensive system activity logging
+3. **Resource Limits** - Prevent resource exhaustion attacks
+4. **Service Hardening** - Disable unnecessary services
+5. **Kernel Parameters** - Secure kernel parameter tuning
+
+**Disabled Services:**
+- avahi-daemon (zeroconf)
+- cups (printing)
+- bluetooth service
+- NetworkManager (managed via scripts)
+
+### FR-008: USB Device Handling
+
+**Priority:** P1
+**Status:** Required
+
+**Requirements:**
+1. **Automount Support** - Automatic USB device mounting
+2. **Restricted Permissions** - No auto-execution
+3. **User Mount Points** - /media/username/device
+4. **Filesystem Support** - FAT32, exFAT, NTFS, ext4
+5. **Audit Logging** - Track USB device insertion/removal
+
+**Security Restrictions:**
+- No automatic program execution
+- No symbolic links from USB
+- No device special files from USB
+- Read-only mode for untrusted USB (optional)
+
+### FR-009: System Immutability
+
+**Priority:** P1
+**Status:** Required
+
+**Requirements:**
+1. **Package Management Disabled** - No apt/dpkg commands for users
+2. **Immutable Configuration** - Critical files have immutable attributes
+3. **No Auto-Updates** - Updates via ISO rebuild only
+4. **Configuration Tracking** - Detect configuration tampering
+
+**Protected Directories:**
+- /etc (system configuration)
+- /usr (system binaries)
+- /boot (bootloader)
+- /bin, /sbin (essential binaries)
+
+### FR-010: ISO Build Process
+
+**Priority:** P1
+**Status:** Required
+
+**Requirements:**
+1. **Reproducible Builds** - Identical outputs from identical inputs
+2. **Docker-Based** - All build operations in Docker containers
+3. **Checksum Verification** - SHA256 and MD5 checksums for ISO
+4. **Build Logging** - Complete build audit trail
+5. **Automated Testing** - Comprehensive test suite execution
+
+**Build Artifacts:**
+- ISO image (~1-2 GB)
+- SHA256 checksum file
+- MD5 checksum file
+- Build report (optional)
+
+---
+
+## Non-Functional Requirements
+
+### NFR-001: Security
+
+**Priority:** P0
+**Requirements:**
+- Full disk encryption (LUKS2, AES-256-XTS)
+- Defense-in-depth architecture
+- Zero-trust network model
+- Compliance with security frameworks (NIST, ISO 27001)
+- No backdoors or secret keys
+
+### NFR-002: Performance
+
+**Priority:** P2
+**Requirements:**
+- Boot time < 60 seconds (including LUKS passphrase prompt)
+- Disk I/O overhead < 5% with encryption
+- Memory usage < 2 GB at idle
+- CPU usage < 5% at idle
+
+### NFR-003: Reliability
+
+**Priority:** P1
+**Requirements:**
+- Mean time between failures (MTBF) > 720 hours
+- Graceful degradation on errors
+- Comprehensive error handling
+- Automatic recovery where possible
+
+### NFR-004: Usability
+
+**Priority:** P1
+**Requirements:**
+- Intuitive installation process
+- Clear error messages
+- Comprehensive documentation
+- Minimal training required
+
+### NFR-005: Maintainability
+
+**Priority:** P1
+**Requirements:**
+- Clean code structure
+- Comprehensive testing
+- Well-documented configuration
+- Automated build and deployment
+
+### NFR-006: Compliance
+
+**Priority:** P0
+**Requirements:**
+- NIST SP 800-53 (Security Controls)
+- NIST SP 800-111 (Disk Encryption)
+- ISO/IEC 27001 (Information Security)
+- CIS Benchmarks for Debian Linux
+- DISA STIG for Linux
+
+---
+
+## Security Architecture
+
+### Encryption Layer
+
+#### Full Disk Encryption (FDE)
+- **Cipher:** AES-256-XTS
+- **Key Size:** 512 bits
+- **Mode:** LUKS2
+- **KDF:** Argon2id (PBKDF2 fallback)
+- **Integrity:** dm-integrity layer (optional)
+
+#### Key Management
+- Primary: User passphrase (required during boot)
+- Recovery: Optional key slot for emergency recovery
+- Storage: Keys never stored in plaintext
+- Rotation: Key change support via cryptsetup
+
+### Network Security Layer
+
+#### VPN-Only Access
+- **Protocol:** WireGuard
+- **Encryption:** ChaCha20-Poly1305
+- **Authentication:** Public/private key pairs
+- **Configuration:** Dynamic endpoint-based firewall rules
+
+#### Firewall Rules
+```
+Default Policy: DROP
+
+Inbound Rules:
+- SSH from VPN interface only (key-based auth)
+- Established/related connections allowed
+
+Outbound Rules:
+- WireGuard VPN traffic to endpoints
+- DNS through VPN tunnel only
+- All traffic through VPN interface only
+```
+
+### System Security Layer
+
+#### Kernel Hardening
+- Module blacklisting (WiFi, Bluetooth)
+- Secure kernel parameters
+- Restricted ptrace scope
+- Kernel address space layout randomization (KASLR)
+
+#### Process Security
+- Resource limits (ulimits)
+- Service hardening (systemd sandboxing)
+- Mandatory access control (optional SELinux/AppArmor)
+
+### Access Control Layer
+
+#### Authentication
+- **Password Policy:** 14+ characters, complexity required
+- **SSH:** Key-based only (no password auth)
+- **Root Login:** Disabled via SSH
+- **Sudo:** Limited sudo access for authorized users
+
+#### Authorization
+- **User Groups:** Minimal necessary groups only
+- **File Permissions:** Secure default permissions
+- **Sudo Configuration:** Specific command permissions
+- **Audit Logging:** Track all privilege usage
+
+---
+
+## Data Requirements
+
+### DR-001: Data at Rest
+
+**Priority:** P0
+**Requirements:**
+- All system data encrypted at rest (LUKS2)
+- Encryption key protected by user passphrase
+- No plaintext data storage
+- Secure deletion of temporary files
+
+### DR-002: Data in Transit
+
+**Priority:** P0
+**Requirements:**
+- All network traffic encrypted via VPN
+- SSH encryption for remote access
+- TLS for any HTTPS traffic (if applicable)
+- No plaintext protocols allowed
+
+### DR-003: Data Retention
+
+**Priority:** P2
+**Requirements:**
+- Log retention: 90 days minimum
+- User data: User-controlled
+- System data: Until reinstallation
+- Secure wipe on decommission
+
+---
+
+## User Requirements
+
+### UR-001: Target Users
+
+1. **Tier0 Infrastructure Engineers** - Primary users
+2. **System Administrators** - Secondary users
+3. **Security Auditors** - Compliance verification users
+
+### UR-002: User Scenarios
+
+**Scenario 1: Initial System Installation**
+1. Boot ISO on target hardware
+2. Configure disk encryption passphrase
+3. Complete automated installation
+4. Reboot into encrypted system
+5. Configure WireGuard VPN
+
+**Scenario 2: Daily System Use**
+1. System prompts for encryption passphrase at boot
+2. User logs in (username/password)
+3. VPN automatically connects
+4. User accesses infrastructure via SSH/Remmina
+
+**Scenario 3: USB Data Transfer**
+1. User inserts USB device
+2. System automatically mounts to /media/username/device
+3. User copies files to/from USB
+4. User safely removes USB device
+
+**Scenario 4: VPN Configuration**
+1. User scans QR code with camera
+2. System imports WireGuard configuration
+3. Firewall rules updated automatically
+4. VPN connection established
+
+### UR-003: User Interface Requirements
+
+**Login Screen:**
+- Display system name only
+- No user list (privacy mode)
+- Require username entry
+- Require password entry
+- No guest account option
+
+**Desktop Environment:**
+- Minimal interface (IceWM)
+- Application launcher
+- System tray (VPN status indicator)
+- Terminal access
+- No unnecessary widgets
+
+---
+
+## Technical Requirements
+
+### TR-001: System Requirements
+
+**Minimum Hardware:**
+- CPU: x86_64 (AMD64), 2 cores
+- RAM: 4 GB (8 GB recommended)
+- Storage: 64 GB SSD (128 GB recommended)
+- Network: Ethernet (1 Gbps recommended)
+- UEFI: UEFI 2.3+ firmware
+
+**Recommended Hardware:**
+- CPU: x86_64 (AMD64), 4+ cores
+- RAM: 8 GB
+- Storage: 256 GB NVMe SSD
+- Network: Ethernet 10 Gbps
+- UEFI: UEFI 2.7+ with Secure Boot
+
+**Unsupported Hardware:**
+- 32-bit systems (x86, ARM32)
+- Legacy BIOS systems
+- Systems without UEFI firmware
+- Systems with < 4 GB RAM
+- Systems with < 64 GB storage
+
+### TR-002: Software Requirements
+
+**Included Software:**
+- Debian 13 base system
+- Linux kernel (latest stable)
+- IceWM window manager
+- LightDM display manager
+- WireGuard and tools
+- OpenSSH server
+- nftables firewall
+- Remmina (remote desktop)
+- Mousepad (text editor)
+- zbar-tools (QR code scanning)
+
+**Excluded Software:**
+- Package managers (apt/dpkg for users)
+- Wireless drivers and tools
+- Bluetooth stack
+- Printing system (CUPS)
+- Cloud storage clients
+- Media players
+- Web browsers
+
+### TR-003: Encryption Requirements
+
+**LUKS2 Configuration:**
+- Cipher: aes-xts-plain64
+- Key size: 512 bits (256-bit keys for XTS)
+- Hash: SHA-512
+- KDF: Argon2id (with appropriate iterations)
+- Salt size: 512 bits
+- Key slots: 8 maximum (default: 1 used)
+
+**Partition Layout (UEFI):**
+```
+/dev/sda1    512M    EFI System Partition (FAT32)
+/dev/sda2    512M    /boot (ext4, unencrypted)
+/dev/sda3    Remainder    LUKS2 encrypted container
+  └─ cryptroot (mapped device)    / (ext4)
+```
+
+**Boot Process:**
+1. UEFI firmware loads GRUB from EFI System Partition
+2. GRUB loads kernel and initramfs from /boot
+3. initramfs prompts for encryption passphrase
+4. LUKS container unlocked with passphrase
+5. Root filesystem mounted
+6. System boots normally
+
+---
+
+## Compliance Requirements
+
+### CR-001: Regulatory Compliance
+
+**NIST SP 800-53 (Security and Privacy Controls)**
+- AC-2: Account Management
+- AC-3: Access Enforcement
+- AC-6: Least Privilege
+- AU-2: Audit Events
+- AU-3: Content of Audit Records
+- AU-6: Audit Review, Analysis, and Reporting
+- CM-3: Configuration Change Control
+- CM-7: Least Functionality
+- CM-8: System Components Inventory
+- CP-7: Alternate Storage Site
+- CP-9: System Backup
+- CP-10: Information System Recovery and Reconstitution
+- IA-2: Identification and Authentication
+- IA-5: Authenticator Management
+- SC-8: Transmission Confidentiality and Integrity
+- SC-12: Cryptographic Key Establishment and Management
+- SC-13: Cryptographic Protection
+- SC-28: Protection of Information at Rest
+
+**NIST SP 800-111 (Guide to Storage Encryption)**
+- Full disk encryption implementation
+- Cryptographic algorithm selection
+- Key management procedures
+- Authentication requirements
+
+**ISO/IEC 27001:2013 (Information Security)**
+- A.9 Access Control
+- A.10 Cryptography
+- A.12 Operations Security
+- A.14 System Acquisition, Development, and Maintenance
+
+**CIS Benchmarks for Debian Linux**
+- Initial setup guidelines
+- Logging and monitoring
+- Network configuration
+- System access, authentication, and authorization
+
+**DISA STIG for Linux**
+- Firewall configuration
+- System services configuration
+- File permissions and ownership
+
+### CR-002: Security Compliance
+
+**Encryption Standards:**
+- FIPS 140-2 Level 1 (certified algorithms)
+- FIPS 197 (AES encryption)
+- FIPS 180-4 (SHA hash functions)
+- FIPS 202 (SHA-3 hash functions)
+
+**Cryptographic Protocols:**
+- TLS 1.3 (for any HTTPS)
+- WireGuard protocol (VPN)
+- SSH-2 protocol
+
+**Key Management:**
+- Secure key generation (CSPRNG)
+- Secure key storage
+- Key rotation support
+- Secure key destruction
+
+---
+
+## Testing Requirements
+
+### TST-001: Unit Testing
+
+**Coverage:**
+- All security hardening scripts
+- Configuration generation scripts
+- Key management functions
+- Firewall rule generation
+
+**Test Cases:**
+- WiFi/Bluetooth module blacklisting verification
+- SSH configuration validation
+- Firewall rule validation
+- Password policy enforcement
+
+### TST-002: Integration Testing
+
+**Test Scenarios:**
+- Complete ISO build process
+- Installation in virtual machine
+- Encryption setup and verification
+- VPN configuration and connectivity
+- USB device handling
+
+### TST-003: Security Testing
+
+**Test Areas:**
+- Full disk encryption verification
+- Network isolation testing
+- Firewall rule validation
+- Authentication mechanism testing
+- Privilege escalation prevention
+
+### TST-004: Compliance Testing
+
+**Validation:**
+- NIST SP 800-53 control coverage
+- NIST SP 800-111 encryption guidelines
+- CIS Benchmark compliance
+- Security configuration validation
+
+### TST-005: Performance Testing
+
+**Metrics:**
+- Boot time with encryption
+- Disk I/O performance impact
+- Memory usage at idle
+- Network throughput over VPN
+
+---
+
+## Quality Assurance
+
+### QA-001: Code Quality
+
+**Standards:**
+- Shell scripts: Shellcheck compliant
+- Configuration: Follow Debian conventions
+- Documentation: Clear and complete
+- Version control: Git with meaningful commits
+
+### QA-002: Build Quality
+
+**Requirements:**
+- Reproducible builds
+- Clean build logs
+- No build warnings
+- Automated checksum verification
+
+### QA-003: Release Quality
+
+**Criteria:**
+- All tests passing
+- Security scan clean
+- Documentation complete
+- Signed release artifacts
+
+---
+
+## Documentation Requirements
+
+### DOC-001: User Documentation
+
+**Required Documents:**
+1. User Manual (installation and daily use)
+2. Troubleshooting Guide
+3. Security Configuration Guide
+4. VPN Configuration Guide
+
+### DOC-002: Technical Documentation
+
+**Required Documents:**
+1. System Architecture Documentation
+2. Security Model Documentation
+3. Build Process Documentation
+4. API/Configuration Documentation
+
+### DOC-003: Developer Documentation
+
+**Required Documents:**
+1. Contributor Guidelines
+2. Code Style Guide
+3. Testing Guidelines
+4. Release Process Documentation
+
+### DOC-004: Compliance Documentation
+
+**Required Documents:**
+1. Security Control Implementation Guide
+2. Compliance Matrix (NIST, ISO, CIS)
+3. Risk Assessment Report
+4. Penetration Test Reports
+
+---
+
+## Deployment Requirements
+
+### DEP-001: Distribution
+
+**Distribution Methods:**
+- ISO image download (official website)
+- Secure distribution (HTTPS, verified checksums)
+- GPG signature verification
+- Release announcement channels
+
+### DEP-002: Installation
+
+**Installation Methods:**
+- USB bootable media (recommended)
+- Virtual machine deployment (testing)
+- Automated installation (preseed configuration)
+- Manual installation (expert mode)
+
+**Installation Requirements:**
+- UEFI firmware (mandatory)
+- 64-bit AMD64 architecture
+- Minimum 64 GB storage
+- Minimum 4 GB RAM
+- Ethernet network interface
+
+### DEP-003: Updates
+
+**Update Strategy:**
+- Major updates: New ISO release
+- Security patches: New ISO release
+- Configuration changes: New ISO release
+- No in-place system updates
+
+**Update Frequency:**
+- Major releases: Quarterly
+- Security releases: As needed
+- Emergency releases: Critical vulnerabilities only
+
+---
+
+## Risk Management
+
+### RISK-001: Security Risks
+
+**High Priority Risks:**
+1. **Encryption Bypass** - Attackers attempt to bypass encryption
+   - Mitigation: LUKS2, strong passphrase, secure key management
+
+2. **Physical Access** - Attackers gain physical access to hardware
+   - Mitigation: Full disk encryption, secure boot, TPM (optional)
+
+3. **VPN Compromise** - VPN endpoint or configuration compromised
+   - Mitigation: Key rotation, endpoint hardening, audit logging
+
+**Medium Priority Risks:**
+4. **USB Attacks** - Malicious USB devices inserted
+   - Mitigation: Restricted mounting, no auto-execution, audit logging
+
+5. **Privilege Escalation** - Users attempt to gain root access
+   - Mitigation: Strong passwords, sudo restrictions, audit logging
+
+6. **Configuration Drift** - System configuration modified
+   - Mitigation: Immutable attributes, audit logging, compliance checks
+
+### RISK-002: Operational Risks
+
+**Risks:**
+- Lost encryption passphrase (data loss)
+- System corruption (reinstallation required)
+- Hardware failure (recovery procedures needed)
+- User error (documentation and training)
+
+**Mitigations:**
+- Backup key slot recommendation
+- Comprehensive recovery documentation
+- Regular system backups (if applicable)
+- Clear user documentation
+
+---
+
+## Success Criteria
+
+### SC-001: Technical Success
+
+- Full disk encryption implemented and functional (MANDATORY)
+- ISO builds successfully (reproducible)
+- All tests passing (100% pass rate)
+- Security controls implemented (100% coverage)
+
+### SC-002: Security Success
+
+- Full disk encryption verified (LUKS2, AES-256-XTS)
+- Compliance achieved (NIST, ISO, CIS)
+- Security assessment passed (critical vulnerabilities = 0)
+- Penetration test passed (high-severity issues = 0)
+
+### SC-003: Operational Success
+
+- System boots within 60 seconds (with passphrase prompt)
+- Disk I/O overhead < 5% with encryption
+- User can complete common tasks without issues
+- Documentation is comprehensive and accurate
+
+---
+
+## Future Enhancements
+
+### FE-001: Potential Enhancements
+
+1. **TPM Integration** - Use TPM for passphrase storage (optional)
+2. **Smart Card Support** - Smart card-based authentication
+3. **Hardware Security Module (HSM)** - Enterprise key management
+4. **Trusted Platform Module (TPM)** - Boot attestation
+5. **Secure Boot** - Full secure boot chain verification
+6. **SELinux/AppArmor** - Mandatory access control
+7. **Multi-User Support** - Multiple user accounts (future consideration)
+8. **Automated Backup** - Encrypted backup solution
+9. **Remote Wipe** - Secure data destruction capability
+10. **Hardware Inventory** - Automatic hardware inventory tracking
+
+### FE-002: Research Areas
+
+1. **Alternative Encryption** - Evaluate dm-crypt with dm-integrity
+2. **Post-Quantum Cryptography** - Quantum-resistant algorithms
+3. **Hardware Enclaves** - Intel SGX or AMD SEV
+4. **Containerization** - Application-level isolation
+5. **Zero Trust Networking** - Enhanced zero-trust model
+
+---
+
+## Appendix A: Terminology
+
+| Term | Definition |
+|------|------------|
+| FDE | Full Disk Encryption - Encryption of entire storage device |
+| LUKS | Linux Unified Key Setup - Disk encryption specification |
+| LUKS2 | Second version of LUKS with enhanced features |
+| AES-XTS | Advanced Encryption Standard in XEX-based Tweaked CodeBook mode |
+| KDF | Key Derivation Function - Derives encryption keys from password |
+| UEFI | Unified Extensible Firmware Interface - Modern firmware interface |
+| ESP | EFI System Partition - FAT32 partition for UEFI boot files |
+| VPN | Virtual Private Network - Encrypted network tunnel |
+| WireGuard | Modern, high-performance VPN protocol |
+| nftables | Linux packet filtering framework |
+| IceWM | Ice Window Manager - Lightweight window manager |
+| LightDM - Light Display Manager - Cross-desktop display manager |
+
+---
+
+## Appendix B: References
+
+1. NIST SP 800-53: Security and Privacy Controls for Information Systems
+2. NIST SP 800-111: Guide to Storage Encryption Technologies for End User Devices
+3. ISO/IEC 27001:2013: Information Security Management Systems
+4. CIS Benchmarks: Center for Internet Security Security Configuration Guides
+5. DISA STIG: Defense Information Systems Agency Security Technical Implementation Guides
+6. LUKS Specification: https://gitlab.com/cryptsetup/LUKS2-docs
+7. WireGuard Protocol: https://www.wireguard.com/protocol/
+8. Debian Live Manual: https://live-team.pages.debian.net/live-manual/
+
+---
+
+## Appendix C: Change History
+
+| Version | Date | Author | Changes |
+|---------|------|--------|---------|
+| 1.0 | 2026-01-28 | KNEL-Football Team | Initial PRD with mandatory full disk encryption |
+
+---
+
+**Copyright © 2026 Known Element Enterprises LLC**
+**License: GNU Affero General Public License v3.0 only**
+
+This PRD is maintained as part of the KNEL-Football project and is updated when requirements change or new features are added.