Marc S. Weidner
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Signed-off-by: Marc S. Weidner <msw@coresecret.dev>
270 lines
11 KiB
Markdown
270 lines
11 KiB
Markdown
---
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gitea: none
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include_toc: true
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---
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# 1. CISS.debian.live.builder
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**Centurion Intelligence Consulting Agency Information Security Standard**<br>
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*Debian Live Build Generator for hardened live environment and CISS Debian Installer*<br>
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**Master Version**: 8.13<br>
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**Build**: V8.13.536.2025.12.04<br>
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# 2. CISS.debian.live.builder – Boot & Trust Chain (Technical Documentation)
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**Status:** 2025-11-12<br>
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**Audience:** CICA CISO, CISS staff, technically proficient administrators<br>
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**Summary:** The CISS.debian.live.builder Live-ISO establishes a two-stage verification chain without Microsoft-db: an early ISO-edge check (signature and FPR pin) *before* LUKS unlock, and a late root-FS attestation *after* unlock, reinforced by `dm-crypt (AES-XTS)` and `dm-integrity (HMAC-SHA-512)`.<br>
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# 3. Overview
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* **Trust anchor:** Pinned fingerprint (FPR) of the signing key embedded at build time in initramfs hooks.
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* **Integrity & authenticity verification:**
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1. **Early:** Verify `sha512sum.txt` at the ISO edge using `gpgv` and FPR pin.
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2. **Late:** Verify an attestation hash list inside the decrypted root FS using `gpgv` and FPR pin.
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* **Storage-level AEAD (functional):** `dm-crypt` (AES-XTS-512) and `dm-integrity` (HMAC-SHA-512, 4 KiB).
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* **Remotely unlock:** Hardened Dropbear (modern primitives only), no passwords, no agent/forwarding.
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# 4. Primitives & Parameters
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| Component | Primitive / Parameter | Purpose |
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|--------------|-----------------------------------------------------------|--------------------------------------------------------|
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| LUKS2 | `aes-xts-plain64`, `--key-size 512`, `--sector-size 4096` | Confidentiality (2×256-bit XTS) |
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| dm-integrity | `hmac-sha512` (keyed), journal | Adversary-resistant per-sector integrity, authenticity |
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| PBKDF | `argon2id`, `--iter-time 1000` ms | Key derivation, hardware-agnostic |
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| Signatures | Ed25519, RSA-4096 (FPR pinned) | Public verifiability, non-repudiation |
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| Verification | `gpgv --no-default-keyring` | No agent dependency in initramfs |
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| Hash lists | `sha512sum` format | Deterministic content verification |
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| Dropbear | Modern KEX/AEAD (per `localoptions.h`) | Minimal attack surface, remote unlock |
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# 5. Diagram: CISS Live ISO Boot Flow, complete
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```mermaid
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flowchart TD
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subgraph Trusted HW Manufacturer
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0000["System Power On"] e00@--> 0010["CPU reset 0xFFFFFFF0, POST"];
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0010 e01@--> 0020["UEFI DXE Phase enumerates devices"];
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0020 e02@--> 0030["Secure Boot (if enabled): db, dbx, KEK, PK loaded from NVRAM"];
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e00@{ animation: fast }
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e01@{ animation: fast }
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e02@{ animation: fast }
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end
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subgraph Trusted Secure Boot
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0030 e03@--> |SUCCESSFUL| 0040["Secure Boot: load & verify \\EFI\\BOOT\\BOOTX64.EFI (shim)"];
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0040 e04@--> |SUCCESSFUL| 0050["shim: load & verify \\EFI\\BOOT\\GRUBX64.EFI"];
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0050 e05@--> 0060["GRUB: load vmlinuz + initrd.img, set cmdline"];
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e03@{ animation: fast }
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e04@{ animation: fast }
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e05@{ animation: fast }
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end
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subgraph Trusted Live ISO
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0060 e06@--> 0070["Transfer Control to Kernel Entry Point"];
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0070 e07@--> 0080["Decompress Kernel"];
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0080 e08@--> 0090["/init Phase"];
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0090 e09@--> 0100["Starting CISS.hardened dropbear"];
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0100 e10@--> 0110["Executing live-boot, mounting ISO FS"];
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0110 e11@--> 0122["Executing 0022-ciss: Hardening tmpfs for OverlayFS upper/work"];
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0122 e12@--> 0124["Executing 0024-ciss: LUKS open (dm-crypt & integrity)"];
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0124 e13@--> |SUCCESSFUL| LUKS["Unlocking LUKS2 Argon2id PBKDF → XTS + HMAC-SHA512"];
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LUKS e14@--> ROOT["Assemble RootFS OverlayFS"];
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ROOT e15@--> 0126["Executing 0026-ciss: Hardening early sysctls"];
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0126 e16@--> 0130["Executing 0030-ciss: Verification of authenticity and integrity via embedded and pinned GPG of ISO edge"];
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0130 e17@--> |SUCCESSFUL| 0142["Executing 0042-ciss: Attestation of RootFS"];
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0142 e18@--> 0145["init-bottom: stop CISS.hardened dropbear, tear down initramfs net"];
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0145 e19@--> 9050["Switching root (run-init / pivot_root)"];
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9050 e20@--> 9010["Starting /sbin/init -> systemd"];
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9010 e21@--> 9020["Starting Target Units"];
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0100 -.-> 0145;
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e06@{ animation: fast }
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e07@{ animation: fast }
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e08@{ animation: fast }
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e09@{ animation: fast }
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e10@{ animation: fast }
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e11@{ animation: fast }
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e12@{ animation: fast }
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e13@{ animation: fast }
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e14@{ animation: fast }
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e15@{ animation: fast }
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e16@{ animation: fast }
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e17@{ animation: fast }
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e18@{ animation: fast }
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e19@{ animation: fast }
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e20@{ animation: fast }
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e21@{ animation: fast }
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end
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subgraph Finale State
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9020 e24@--> 9030{{"CISS.debian.live.builder Waiting for Login"}};
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X{{"CISS.debian.live.builder Boot process halted"}};
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e24@{ animation: fast }
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end
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0030 -- FAIL --> X;
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0040 -- FAIL --> X;
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0124 -- FAIL --> X;
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0130 -- FAIL --> X;
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0142 -- FAIL --> X;
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```
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# 6. Diagram: CISS Live ISO LUKS and dm-integrity layering, complete
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```mermaid
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---
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config:
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theme: forest
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---
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flowchart TD
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0{{"Plain device: CD-ROM / USB"}} --> 1["ISO image (ISO9660 + ESP)"];
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1 --> 2["Mount ISO9660 FS → /run/live/medium"];
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2 --> 3["Container file /run/live/medium/live/ciss_rootfs.crypt"];
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3 --> 4["dm-integrity layer (HMAC-SHA-512, 4 KiB)"];
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4 --> 5["dm-crypt LUKS2 (AES-XTS-512) → /dev/mapper/crypt_liveiso"];
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5 --> 6["Mount SquashFS from /dev/mapper/crypt_liveiso → /run/live/rootfs"];
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```
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**Note:** Encrypt-then-MAC at the block layer (functionally AEAD-equivalent). Any manipulation ⇒ hard I/O error.
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# 7. CISS Live ISO LUKS Build-Time Core Steps, complete
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```sh
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cryptsetup luksFormat \
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--batch-mode \
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--cipher aes-xts-plain64 \
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--integrity hmac-sha512 \
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--iter-time 1000 \
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--key-file "/proc/$$/fd/${KEYFD}" \
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--key-size 512 \
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--label crypt_liveiso \
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--luks2-keyslots-size 16777216 \
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--luks2-metadata-size 4194304 \
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--pbkdf argon2id \
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--sector-size 4096 \
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--type luks2 \
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--use-random \
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--verbose \
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"${LUKSFS}"
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```
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**Signing keys:** Ed25519 and RSA-4096; **FPR pinned at build time** in hooks. Signing keys are **additionally** signed by an offline GPG Root-CA (out-of-band trust chain).
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# 8. Early ISO-Edge Verification (CISS modified hook 0030, live-bottom)
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**Goal:** Before consuming any medium content, verify:
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1. **Detached signature of `sha512sum.txt`** using `gpgv` against the embedded public key.
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2. **FPR pinning:** Parse `VALIDSIG` and require exact match with the build-time pinned FPR.
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3. **Optional:** *Script self-IA* – hash the executed hook and compare against the signed list (drift/bitrot detector).
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**Core call (initramfs):**
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```sh
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/usr/bin/gpgv --no-default-keyring --keyring "$KEYFILE" --status-fd 1 --verify sha512sum.txt.sig sha512sum.txt
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# parse [GNUPG:] VALIDSIG ... <FPR> ...
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```
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# 9. Late Root-FS Attestation and dmsetup Health (CISS hook 0045, live-bottom)
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**Goal:** After LUKS unlock, validate the **decrypted** contents and the **actual** mapping topology.
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* **Attestation files:** `/root/.ciss/attest/rootfs.sha512sum.txt[.sig]`
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* **Key source:** `/etc/ciss/keys/*.gpg` (accepted only if FPR == build-pin)
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* **Health check:** `dmsetup table --showkeys` → top `crypt` (AES-XTS), child `integrity` (HMAC-SHA-512, 4096 B)
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**Core calls (initramfs):**
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```sh
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# 1) Signature and FPR pin (no agent)
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/usr/bin/gpgv --no-default-keyring --keyring "$KEYFILE" --status-fd 1 --verify "$SIG" "$DATA"
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# 2) Optional: Content hash verification
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( cd "$ROOTMP" && /usr/bin/sha512sum -c --strict --quiet "$DATA" )
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# 3) dmsetup health
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dmsetup table --showkeys /dev/mapper/crypt_liveiso
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dmsetup table --showkeys CHILD # expect integrity hmac sha512 4096
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```
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# 10. Failure Policy (fail-closed, deterministic)
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* **Abort** on: missing `VALIDSIG`, FPR mismatch, missing key/signature, or a deviating `dmsetup` topology.
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# 11. CISS Dropbear (Hardened Remotely Unlock)
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```text
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• Public-key auth only, no passwords
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• Modern KEX/AEAD (e.g., curve25519, sntrup761x25519-sha512, mlkem768x25519-sha256; AES-GCM)
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• No agent/X11/TCP forwarding, no SFTP
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• Strict timeouts/keep-alives, restricted cipher/KEX set
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• Port 42137 (per CISS convention)
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```
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*Concrete selection compiled via your `localoptions.h` at ISO build time.*
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# 12. Integration Points & Paths
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* **Hooks (build view):**
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* `/usr/lib/live/boot/0022-ciss-overlay-tmpfs`,
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* `/usr/lib/live/boot/0024-ciss-crypt-squash`,
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* `/usr/lib/live/boot/0026-ciss-early-sysctl`,
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* `/usr/lib/live/boot/0030-ciss-verify-checksums`,
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* `/usr/lib/live/boot/0042-ciss-post-decrypt-attest`,
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* **Hooks (boot view):**
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* `/scripts/live-premount/0022-ciss-overlay-tmpfs`,
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* `/scripts/live-premount/0024-ciss-crypt-squash`,
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* `/scripts/live-premount/0026-ciss-early-sysctl`,
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* `/scripts/live-bottom/0030-ciss-verify-checksums`,
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* `/scripts/live-bottom/0042-ciss-post-decrypt-attest`
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* **Key files:**
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* ISO edge (for 0030): embedded public key blob (project-specific fpr)
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* Root FS (for 0042): `/etc/ciss/keys/<FPR>.gpg`
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* **Mounts (typical):** `/run/live/rootfs`, `/run/live/overlay`
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# 13. Diagram: CISS Live ISO Build, Boot and Run Time Trust Chain & Verification Paths
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```mermaid
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flowchart TD
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subgraph ISO Build Time
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A["Embed and pin GPG FPR (into ISO & RootFS as needed)"] e00@--> B["Generate ISO-edge sha512sum.txt and .sig"];
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B e01@--> C["Build filesystem.squashfs and wrap it into ciss_rootfs.crypt"];
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e00@{ animation: fast }
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e01@{ animation: fast }
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end
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subgraph ISO Boot Time
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C e02@--> D["0024 LUKS2, dm-integrity HMAC-SHA512"];
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D e03@-->|SUCCESSFUL| E["ciss_rootfs.crypt opened"];
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E e04@--> F["Mounting RootFS"];
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F e05@--> G["0030 verification of authenticity and integrity via embedded and pinned GPG of ISO edge"];
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G e06@-->|SUCCESSFUL| H["ISO edge verified"];
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H e07@--> I["0042 post-decrypt-attestation of RootFS"];
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I e08@-->|SUCCESSFUL| J["RootFS attestation successful"];
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e02@{ animation: fast }
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e03@{ animation: fast }
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e04@{ animation: fast }
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e05@{ animation: fast }
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e06@{ animation: fast }
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e07@{ animation: fast }
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e08@{ animation: fast }
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end
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subgraph ISO Run Time
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J e09@--> K{{"CISS.debian.live.builder ISO running"}};
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X{{"CISS.debian.live.builder Boot process halted"}};
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e09@{ animation: fast }
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end
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D -- FAIL --> X;
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G -- FAIL --> X;
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I -- FAIL --> X;
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```
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# 14. Closing Remarks
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This achieves a portable, self-contained trust chain without a Microsoft-db, providing strong protection against medium tampering, bitrot and active attacks **both before and after decryption**. The dual verification phases plus `dmsetup` health make the state transparent and deterministic.
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---
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**[no tracking | no logging | no advertising | no profiling | no bullshit](https://coresecret.eu/)**
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<!-- vim: set number et ts=2 sw=2 sts=2 ai tw=128 ft=markdown -->
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