System Architecture Specification

Target Platform: NVIDIA Jetson Humanoid Robot Control Architecture (L4T 6.x & QEMU aarch64 virt)
Status: Approved / Baseline

1. Architecture Overview & Trust Boundaries

Hardware Trust Boundary: Enforces hardware isolation between Secure World and Normal World using ARMv8/ARMv9 TrustZone technology.
Physical-Independent Verification: Accurately emulates Secure World (EL3, S-EL1, S-EL0) and Normal World (NS-EL1, NS-EL0) interfaces on QEMU aarch64 virt machines.

💡 Click to view the Archify Interactive Diagram with theme switching and trust boundary zooming.

2. Secure Boot Chain

Cryptographic Chain of Trust: Starts at immutable BootROM (EL3 RoT), sequentially verifying cryptographic signatures before transferring execution control.
TrustZone Cold Boot Sequence:
- TF-A BL1 (EL3): Starts execution from PFLASH0 (flash0.bin) offset 0x0, initializes platform hardware, and loads BL2.
- TF-A BL2 (Secure-EL1): Parses FIP (Firmware Image Package, offset 0x40000), loading BL31 (EL3 Runtime) and BL32 (OP-TEE OS).
- TF-A BL31 (EL3): Initializes SMC dispatchers and transfers execution to S-EL1 Secure World.
- OP-TEE OS (S-EL1): Core initialization, opens UART1 (0x09040000) debug console, starts Early fTPM TA (bc50d971-d4c9-42c4-82cb-343fb7f37896), binds RPMB secure storage, and prepares PSCI handoff.
- Linux Kernel 6.8 Noble (Normal World NS-EL1): Boots via PSCI v1.1 handoff, probes OP-TEE SMC driver (/dev/tee0, /dev/teepriv0), initializes fTPM platform driver (/dev/tpmrm0), enables IMA subsystem, and executes userspace /init.
State Persistence: Emulated eMMC RPMB partition guarantees replay protection and persistence for fTPM NVRAM and OP-TEE secure storage.

💡 Click to view the Archify Interactive Diagram with boot timeline trace animations.

3. NVIDIA Jetson Tegra PKC Secure Boot Simulation Architecture

Emulates physical NVIDIA Jetson on-chip fuses (eFuses) and authenticated Tegra container validation under QEMU:

SoC eFuse Public Key Hash (configs/secureboot/tegra_fuses.json):
- Computes 256-bit SHA-256 hash from DER public key of SoftHSMv2 PKCS#11 RSA-3072 key (SecureBootKey, ID: 06), fused into hardware register model (PKC_HASH).
- Sets SecurityMode: 1 to enforce production Secure Boot mode.
NVIDIA Authenticated Container Specification (NVD1 Container):
- Fixed 512-byte container header layout:
  - Magic Identifier: NVD1 (4 bytes)
  - Container Version: 0x00010000 (4 bytes)
  - Payload Length: Original kernel binary byte length (8 bytes)
  - Payload SHA-256 Digest: (32 bytes)
  - PKC Public Key SHA-256 Digest: (32 bytes)
  - RSA-3072 Digital Signature: PKCS#11 C_Sign payload digest signature (384 bytes)
  - Reserved: Padding (48 bytes)
Boot Verification & Tamper-Rejection Pipeline:
- scripts/sign_jetson_secureboot.sh: Provides 4-stage pipeline (burn-fuses, sign, verify, tamper-test).
- Validates container PKC hash against burned SoC eFuses and verifies cryptographic signature before execution handoff.
- Immediate boot termination upon 1-byte alteration or mismatched eFuse (SECURE_BOOT_VIOLATION, Exit code 2).

4. Dual-Target Kernel Build & Hardening Strategy

Design Principle: Employs a 3-tier kernel configuration structure to eliminate security discrepancies between physical Jetson hardware and QEMU test environments.

                                [ NVIDIA L4T Base defconfig ]
                               (Official tegra_defconfig baseline)
                                             │
                                             ▼
                      [ configs/kernel/security_hardening.config ]
               (KSPP baseline, Forced Module Signing, EROFS, dm-verity, IMA)
                                             │
                       ┌─────────────────────┴─────────────────────┐
                       │                                           │
                       ▼                                           ▼
             [ Real Jetson Target ]                      [ QEMU virt Target ]
         (Production Jetson Flash)                  + [ configs/kernel/qemu_compat.config ]
                                                  (VirtIO drivers, PL011 console, QEMU PCI)

4.1. Key Security Hardening Parameters (`security_hardening.config`)

Memory Defense & Exploit Mitigation:
- CONFIG_KASLR=y: Kernel address space layout randomization.
- CONFIG_STRICT_KERNEL_RWX=y & CONFIG_STRICT_MODULE_RWX=y: Enforces W^X executable memory protection.
- CONFIG_STACKPROTECTOR_STRONG=y: Stack canary buffer overflow defense.
- CONFIG_FORTIFY_SOURCE=y: Runtime buffer bounds checking.
- CONFIG_SLAB_FREELIST_RANDOM=y & CONFIG_SLAB_FREELIST_HARDENED=y: Heap metadata protection.
Integrity Enforcement:
- CONFIG_MODULE_SIG=y & CONFIG_MODULE_SIG_FORCE=y: Strict rejection of unsigned kernel modules.
- CONFIG_MODULE_SIG_ALL=y & CONFIG_MODULE_SIG_SHA256=y: Automated module signing during build.
- CONFIG_DM_VERITY=y & CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG=y: Cryptographic root hash validation.
- CONFIG_EROFS_FS=y: High-performance compressed read-only filesystem.
Trusted Execution & Attestation:
- CONFIG_TEE=y & CONFIG_OPTEE=y: OP-TEE SMC client driver.
- CONFIG_TCG_TPM=y & CONFIG_TCG_FTPM_TEE=y: OP-TEE fTPM communication interface.
- CONFIG_IMA=y & CONFIG_IMA_MEASURE_PCR_IDX=10: Extends binary execution digests into fTPM PCR 10.

5. Storage Integrity Pipeline (EROFS + dm-verity)

Immutable Filesystem: Deploys an unmodifiable read-only EROFS rootfs to eliminate ransomware and persistence malware injection.
Block-Level Verification: Linux dm-verity validates 4KB block-level Merkle tree hashes dynamically upon read access.

💡 Click to view the Archify Interactive Diagram covering offline build signing and runtime measurement flows.

6. Runtime Integrity Measurement (IMA) & fTPM PCR Extension

Dynamic Binary Measurement: Kernel IMA intercepts execve calls, hashing binaries and shared libraries into fTPM PCR 10.
Immutable Audit Trail: Maintains measurement events in /sys/kernel/security/ima/runtime_measurements for remote attestation quotes.

 1. User Process  ──[sys_execve("/usr/bin/robot_node")]──> Linux Kernel VFS
 2. Linux Kernel  ──[Trigger Measurement Hook]───────────> Kernel IMA Engine
 3. Kernel IMA    ──[Compute SHA-256 Digest]─────────────> In-Memory Buffer
 4. Kernel IMA    ──[TPM2_PCR_Extend(PCR 10, Digest)]────> OP-TEE fTPM TA
 5. OP-TEE fTPM   ──[PCR[10] = SHA256(PCR[10] || Digest)]─> Secure NVRAM (RPMB)
 6. Kernel IMA    ──[Append Entry]───────────────────────> /sys/kernel/security/ima/measurements
 7. Linux Kernel  ──[Execute Process]────────────────────> Robot Node Running

7. QEMU aarch64 Virtual Emulation Topology

Parameter	Specification	Description
Machine Model	`virt,secure=on,gic-version=2`	Enables ARMv8 TrustZone secure state
CPU Architecture	`cortex-a57` (4 Cores)	Standard aarch64 core emulation
Memory Allocation	`2048MB` (Normal World + Secure World DRAM)	Physical address space partitioning
PFLASH0	`build/firmware/flash0.bin` (64MB)	Monolithic firmware image with BL1(0x0) and FIP(0x40000)
DTB Injection	`.cache/run/virt_boot.dtb`	Injects `microsoft,ftpm` device node and initrd/bootargs
Persistent Storage	Virtual RPMB Socket (OP-TEE `tee-supplicant`)	Emulates eMMC RPMB hardware partition
Networking	User-net (`hostfwd=tcp::2222-:22,tcp::8443-:8443`)	Forwards SSH debug and mTLS verification ports
Serial Console	PL011 UART0 (Normal), UART1 (OP-TEE Console)	Dedicated channels for automated test log capture

System Architecture Specification

1. Architecture Overview & Trust Boundaries

2. Secure Boot Chain

3. NVIDIA Jetson Tegra PKC Secure Boot Simulation Architecture

4. Dual-Target Kernel Build & Hardening Strategy

4.1. Key Security Hardening Parameters (security_hardening.config)

5. Storage Integrity Pipeline (EROFS + dm-verity)

6. Runtime Integrity Measurement (IMA) & fTPM PCR Extension

7. QEMU aarch64 Virtual Emulation Topology

4.1. Key Security Hardening Parameters (`security_hardening.config`)