V9.14.022.2026.06.10: Document rootfs attestation boundary

config/hooks/live/zzzz_ciss_crypt_squash.hook.binary

@@ -9,17 +9,90 @@
 # SPDX-LicenseComment: This file is part of the CISS.debian.installer.secure framework.
 # SPDX-PackageName: CISS.debian.live.builder
 # SPDX-Security-Contact: security@coresecret.eu
+# shellcheck disable=SC2154
 set -Ceuo pipefail
 
-# Final live-build binary hook for encrypted root filesystem packaging. Preallocate a LUKS2 container, formats it with the
+# Final live-build binary hook for encrypted root filesystem packaging. Preallocate a LUKS2 container, format it with the
-# generated build secret, copies the generated filesystem.squashfs into the opened encrypted mapping, then closes the container,
+# generated build secret, copy the generated filesystem.squashfs into the opened encrypted mapping, generate and sign a
-# shreds the temporary LUKS secret, and removes the plaintext SquashFS from the ISO payload.
+# SHA-512 attestation manifest for the complete decrypted mapper, then close the container, shred the temporary LUKS secret,
+# and remove the plaintext SquashFS from the ISO payload.
 
 printf "\e[95m🧪 '%s' starting ... \e[0m\n" "${0}"
 
 __umask=$(umask)
 umask 0077
 
+#######################################
+# Prints a fatal error message and terminates the hook.
+# Globals:
+#   None
+# Arguments:
+#   1: Error message
+# Returns:
+#   42: always exits with failure
+#######################################
+die() {
+  declare message="${1}"
+  printf "\e[91m❌ %s \e[0m\n" "${message}" >&2
+  exit 42
+}
+
+#######################################
+# Checks whether a required command exists.
+# Globals:
+#   None
+# Arguments:
+#   1: Command name
+# Returns:
+#   0: on success
+#   42: if the command is missing
+#######################################
+require_command() {
+  declare command_name="${1}"
+
+  command -v "${command_name}" >/dev/null 2>&1 || die "Required command not found: '${command_name}'."
+
+  return 0
+}
+
+#######################################
+# Checks whether a required file exists and is readable.
+# Globals:
+#   None
+# Arguments:
+#   1: File path
+#   2: Human-readable file description
+# Returns:
+#   0: on success
+#   42: if the file is missing or unreadable
+#######################################
+require_file() {
+  declare file_path="${1}"
+  declare description="${2}"
+
+  [[ -f "${file_path}" && -r "${file_path}" ]] || die "Missing or unreadable ${description}: '${file_path}'."
+
+  return 0
+}
+
+#######################################
+# Checks whether a required environment variable is non-empty.
+# Globals:
+#   None
+# Arguments:
+#   1: Variable name
+# Returns:
+#   0: on success
+#   42: if the variable is empty or unset
+#######################################
+require_variable() {
+  declare variable_name="${1}"
+
+  [[ -n "${!variable_name:-}" ]] || die "Required environment variable is empty or unset: '${variable_name}'."
+
+  return 0
+}
+
 #######################################
 # Pre allocates space for LUKS container.
 # Globals:
@@ -65,8 +138,25 @@ readonly -f preallocate
 
 declare ROOTFS="${VAR_HANDLER_BUILD_DIR}/binary/live/filesystem.squashfs"
 declare LUKSFS="${VAR_HANDLER_BUILD_DIR}/binary/live/ciss_rootfs.crypt"
+declare MAPPER_DEV="/dev/mapper/crypt_liveiso"
+declare ROOTFS_ATTESTATION="${LUKSFS}.decrypted.sha512sum.txt"
+declare ROOTFS_ATTESTATION_SIG="${ROOTFS_ATTESTATION}.sig"
 declare KEYFD=""
 
+require_command gpg
+require_command gpgv
+require_command sha512sum
+require_file "${ROOTFS}" "final SquashFS payload"
+require_variable VAR_SIGNING_KEY_FPR
+require_variable VAR_SIGNING_KEY_PASSFILE
+require_variable VAR_VERIFY_KEYRING
+require_file "${VAR_SIGNING_KEY_PASSFILE}" "GPG signing passphrase file"
+require_file "${VAR_VERIFY_KEYRING}" "GPG verification keyring"
+
+[[ "${VAR_SIGNER:-false}" == "true" ]] || die "Rootfs attestation requires an enabled artifact signer."
+
+rm -f -- "${ROOTFS_ATTESTATION}" "${ROOTFS_ATTESTATION_SIG}"
+
 # shellcheck disable=SC2155
 declare -i VAR_ROOTFS_SIZE=$(stat -c%s -- "${ROOTFS}")
 
@@ -126,7 +216,7 @@ fi
 cryptsetup open --key-file "/proc/$$/fd/${KEYFD}" "${LUKSFS}" crypt_liveiso
 
 # shellcheck disable=SC2155
-declare -i LUKS_FREE=$(blockdev --getsize64 /dev/mapper/crypt_liveiso)
+declare -i LUKS_FREE=$(blockdev --getsize64 "${MAPPER_DEV}")
 declare -i SQUASH_FS="${VAR_ROOTFS_SIZE}"
 
 if (( LUKS_FREE >= SQUASH_FS )); then
@@ -140,8 +230,22 @@ else
 
 fi
 
-dd if="${ROOTFS}" of=/dev/mapper/crypt_liveiso bs=8M status=progress conv=fsync
+dd if="${ROOTFS}" of="${MAPPER_DEV}" bs=8M status=progress conv=fsync
 sync
+
+# The selected boot root is the complete decrypted mapper. Hashing this exact block payload binds the signed manifest to the
+# bytes later mounted as SquashFS, including the mapper padding after the SquashFS image.
+LC_ALL=C sha512sum "${MAPPER_DEV}" >| "${ROOTFS_ATTESTATION}"
+
+gpg --batch --yes --pinentry-mode loopback --passphrase-file "${VAR_SIGNING_KEY_PASSFILE}" --local-user "${VAR_SIGNING_KEY_FPR}" \
+  --detach-sign --output "${ROOTFS_ATTESTATION_SIG}" "${ROOTFS_ATTESTATION}"
+
+gpgv --keyring "${VAR_VERIFY_KEYRING}" "${ROOTFS_ATTESTATION_SIG}" "${ROOTFS_ATTESTATION}"
+
+(cd / && LC_ALL=C sha512sum -c --strict --quiet "${ROOTFS_ATTESTATION}")
+
+chmod 0444 "${ROOTFS_ATTESTATION}" "${ROOTFS_ATTESTATION_SIG}"
+
 cryptsetup close crypt_liveiso
 
 exec {KEYFD}<&-

config/includes.chroot/usr/lib/live/boot/0030-ciss-verify-checksums

@@ -89,9 +89,20 @@ Verify_checksums() {
 
   _KEYFILE=""
 
+  _MANIFEST_FOUND="false"
+
   _MP=""
 
+  _RETURN_PGP=""
+
+  _RETURN_SHA=""
+
+  _VERIFICATION_EXECUTED="false"
+
+  _VERIFICATION_SUCCEEDED="false"
+
   ### Parse commandline arguments ----------------------------------------------------------------------------------------------
+  # shellcheck disable=SC2154
   for _PARAMETER in ${LIVE_BOOT_CMDLINE}; do
 
     case "${_PARAMETER}" in
@@ -244,10 +255,12 @@ Verify_checksums() {
 
       if [ -e "${_CHECKSUM}" ]; then
 
+        _MANIFEST_FOUND="true"
         log_in "Found: [${_CHECKSUM}] ..."
 
         if [ -e "/usr/bin/${_DIGEST}sum" ]; then
 
+          _VERIFICATION_EXECUTED="true"
           log_in "Found: [/usr/bin/${_DIGEST}sum] ..."
 
           if [ "${LIVE_VERIFY_CHECKSUMS_SIGNATURES}" = "true" ]; then
@@ -279,6 +292,7 @@ Verify_checksums() {
           if grep -v '^#' "${_CHECKSUM}" | LC_ALL=C /usr/bin/"${_DIGEST}"sum -c > "${_CHECKSUM_LOG}" 2>&1; then
 
             _RETURN_SHA="${?}"
+            _VERIFICATION_SUCCEEDED="true"
             cat "${_CHECKSUM_LOG}" > "${_TTY}"
             log_ok "Found: [/usr/bin/${_DIGEST}sum] successful verified: [${_CHECKSUM}]"
 
@@ -313,6 +327,33 @@ Verify_checksums() {
   log_end_msg
   printf "\n"
 
+  if [ "${_MANIFEST_FOUND}" != "true" ]; then
+
+    log_er "No supported checksum manifest found."
+    sleep 8
+    panic  "No supported checksum manifest found."
+    return 1
+
+  fi
+
+  if [ "${_VERIFICATION_EXECUTED}" != "true" ]; then
+
+    log_er "No supported checksum verification tool was available."
+    sleep 8
+    panic  "No supported checksum verification tool was available."
+    return 1
+
+  fi
+
+  if [ "${_VERIFICATION_SUCCEEDED}" != "true" ]; then
+
+    log_er "No supported checksum manifest was verified successfully."
+    sleep 8
+    panic  "No supported checksum manifest was verified successfully."
+    return 1
+
+  fi
+
   case "${_RETURN_PGP},${_RETURN_SHA}" in
 
     "0,0")
@@ -331,18 +372,28 @@ Verify_checksums() {
       log_er "Verification of [GPG signature] file successful, while verification of [sha checksum] file failed."
       sleep 8
       panic  "Verification of [GPG signature] file successful, while verification of [sha checksum] file failed."
+      return 1
       ;;
 
     *",0")
       log_er "Verification of [GPG signature] file failed, while verification of [sha checksum] file successful."
       sleep 8
       panic  "Verification of [GPG signature] file failed, while verification of [sha checksum] file successful."
+      return 1
       ;;
 
     "na,"*)
       log_er "Verification of [sha checksum] file failed."
       sleep 8
       panic  "Verification of [sha checksum] file failed."
+      return 1
+      ;;
+
+    *)
+      log_er "Checksum verification ended in an unsupported state."
+      sleep 8
+      panic  "Checksum verification ended in an unsupported state."
+      return 1
       ;;
 
   esac

config/includes.chroot/usr/lib/live/boot/0042_ciss_post_decrypt_attest

@@ -15,14 +15,11 @@
 # SPDX-Security-Contact: security@coresecret.eu
 
 # Module summary:
-# - Runs after the encrypted live root filesystem has been decrypted.
+# - Runs after the encrypted live root filesystem has been decrypted and selected for the SquashFS root mount.
-# - Requires the pinned public key, attestation hash file, and detached signature to exist as readable, non-empty regular files
+# - Requires the pinned public key and the signed decrypted-mapper SHA-512 manifest from the mounted live medium.
-#   inside the decrypted rootfs.
+# - Verifies the manifest signature and pinned signer fingerprint, then verifies the complete selected decrypted mapper against
-# - Verifies the attestation signature with gpgv against the pinned key material.
+#   the manifest.
-# - Confirms that the signature fingerprint matches the build-time expected rootfs fingerprint and panics on missing, malformed,
+# - Panics on missing, malformed, mismatched, or unverifiable evidence.
-#   or mismatched evidence.
-
-_SAVED_SET_OPTS="$(set +o)"
 
 set -eu
 
@@ -37,9 +34,12 @@ export CDLB_EXP_CA_FPR="@EXP_CA_FPR@"
 ### Name of the top-level dm-crypt mapping (e.g., cryptsetup --label): zzzz_ciss_crypt_squash.hook.binary ----------------------
 export CDLB_MAPPER_NAME="${CDLB_MAPPER_NAME:-crypt_liveiso}"
 
-### Attestation file locations inside decrypted rootfs. ------------------------------------------------------------------------
+### Rootfs selection and attestation file locations. ---------------------------------------------------------------------------
-CDLB_ATTEST_FPR_SHA="${CDLB_ATTEST_FPR_SHA:-/root/root/.ciss/attestation/${CDLB_EXP_FPR}.gpg.sha512sum.txt}"
+CDLB_LUKS_FS="${CDLB_LUKS_FS:-/live/ciss_rootfs.crypt}"
-CDLB_ATTEST_FPR_SIG="${CDLB_ATTEST_FPR_SIG:-/root/root/.ciss/attestation/${CDLB_EXP_FPR}.gpg.sha512sum.txt.sig}"
+CDLB_MAPPER_DEV="${CDLB_MAPPER_DEV:-/dev/mapper/${CDLB_MAPPER_NAME}}"
+CDLB_MNT_MEDIUM="${CDLB_MNT_MEDIUM:-/run/live/medium}"
+CDLB_ATTEST_ROOTFS_SHA="${CDLB_ATTEST_ROOTFS_SHA:-${CDLB_MNT_MEDIUM}${CDLB_LUKS_FS}.decrypted.sha512sum.txt}"
+CDLB_ATTEST_ROOTFS_SIG="${CDLB_ATTEST_ROOTFS_SIG:-${CDLB_ATTEST_ROOTFS_SHA}.sig}"
 CDLB_KEY_DIR="${CDLB_KEY_DIR:-/etc/ciss/keys}"
 
 ### Declare functions ----------------------------------------------------------------------------------------------------------
@@ -91,11 +91,13 @@ require_attestation_file() {
 
       log_er "0042()              : ${artifact_label} is a broken symlink, not a regular file: [${artifact_path}]"
       panic  "0042()              : ${artifact_label} is a broken symlink, not a regular file: [${artifact_path}]"
+      return 1
 
     fi
 
     log_er "0042()              : ${artifact_label} missing: [${artifact_path}]"
     panic  "0042()              : ${artifact_label} missing: [${artifact_path}]"
+    return 1
 
   fi
 
@@ -103,6 +105,7 @@ require_attestation_file() {
 
     log_er "0042()              : ${artifact_label} is not a regular file: [${artifact_path}]"
     panic  "0042()              : ${artifact_label} is not a regular file: [${artifact_path}]"
+    return 1
 
   fi
 
@@ -110,6 +113,7 @@ require_attestation_file() {
 
     log_er "0042()              : ${artifact_label} is empty: [${artifact_path}]"
     panic  "0042()              : ${artifact_label} is empty: [${artifact_path}]"
+    return 1
 
   fi
 
@@ -117,23 +121,56 @@ require_attestation_file() {
 
     log_er "0042()              : ${artifact_label} is not readable: [${artifact_path}]"
     panic  "0042()              : ${artifact_label} is not readable: [${artifact_path}]"
+    return 1
 
   fi
 
   return 0
 }
 
-HASH_FILE="${CDLB_ATTEST_FPR_SHA}"
+#######################################
-SIGN_FILE="${CDLB_ATTEST_FPR_SIG}"
+# Validate the selected decrypted rootfs payload.
+# Globals:
+#   None
+# Arguments:
+#   1: Absolute payload path
+# Returns:
+#   0: on success
+#######################################
+require_rootfs_payload() {
+  payload_path="${1}"
+
+  if [ ! -b "${payload_path}" ]; then
+
+    log_er "0042()              : Selected rootfs payload is not a block device: [${payload_path}]"
+    panic  "0042()              : Selected rootfs payload is not a block device: [${payload_path}]"
+    return 1
+
+  fi
+
+  if [ ! -r "${payload_path}" ]; then
+
+    log_er "0042()              : Selected rootfs payload is not readable: [${payload_path}]"
+    panic  "0042()              : Selected rootfs payload is not readable: [${payload_path}]"
+    return 1
+
+  fi
+
+  return 0
+}
+
+HASH_FILE="${CDLB_ATTEST_ROOTFS_SHA}"
+SIGN_FILE="${CDLB_ATTEST_ROOTFS_SIG}"
 KEYFILE="${CDLB_KEY_DIR}/${CDLB_EXP_FPR}.gpg"
 
 require_attestation_file "Public key"            "${KEYFILE}"
-require_attestation_file "Attestation data"      "${HASH_FILE}"
+require_attestation_file "Rootfs attestation manifest"  "${HASH_FILE}"
-require_attestation_file "Attestation signature" "${SIGN_FILE}"
+require_attestation_file "Rootfs attestation signature" "${SIGN_FILE}"
+require_rootfs_payload "${CDLB_MAPPER_DEV}"
 
-log_in "0042()               : Verifying rootfs attestation with 'gpgv' and inside LUKS encrypted rootfs pinned GPG FPR."
+log_in "0042()               : Verifying signed rootfs attestation manifest with pinned GPG FPR."
 
-if ! _STATUS="$(/usr/bin/gpgv --keyring "${KEYFILE}" --status-fd 1 "${SIGN_FILE}" "${HASH_FILE}" 2>&1)"; then
+if ! _STATUS="$(/usr/bin/gpgv --no-default-keyring --keyring "${KEYFILE}" --status-fd 1 "${SIGN_FILE}" "${HASH_FILE}" 2>&1)"; then
 
   log_er "0042()              : gpgv verification failed for signature: [${SIGN_FILE}]"
 
@@ -145,6 +182,7 @@ if ! _STATUS="$(/usr/bin/gpgv --keyring "${KEYFILE}" --status-fd 1 "${SIGN_FILE}
 
   sleep 8
   panic  "0042()              : gpgv verification failed for signature: [${SIGN_FILE}]"
+  exit 1
 
 fi
 
@@ -160,10 +198,51 @@ else
   log_er "0042()              : Signature FPR mismatch: got: [${_CDLB_SIG_FILE_FPR}] expected: [${CDLB_EXP_FPR}]"
   sleep 8
   panic "[FATAL] Signature FPR mismatch: got: [${_CDLB_SIG_FILE_FPR}] expected: [${CDLB_EXP_FPR}]."
+  exit 1
 
 fi
 
-eval "${_SAVED_SET_OPTS}"
+_ATTEST_RECORD_COUNT="$(awk 'NF && $1 !~ /^#/ { count++ } END { print count + 0 }' "${HASH_FILE}")"
+
+if [ "${_ATTEST_RECORD_COUNT}" -ne 1 ]; then
+
+  log_er "0042()              : Rootfs attestation manifest must contain exactly one checksum record: [${HASH_FILE}]"
+  sleep 8
+  panic  "0042()              : Rootfs attestation manifest must contain exactly one checksum record: [${HASH_FILE}]"
+  exit 1
+
+fi
+
+_ATTESTED_PAYLOAD="$(awk 'NF && $1 !~ /^#/ { print $2; exit }' "${HASH_FILE}")"
+
+if [ "${_ATTESTED_PAYLOAD}" != "${CDLB_MAPPER_DEV}" ]; then
+
+  log_er "0042()              : Rootfs attestation manifest targets [${_ATTESTED_PAYLOAD}], expected selected payload [${CDLB_MAPPER_DEV}]"
+  sleep 8
+  panic  "0042()              : Rootfs attestation manifest does not target the selected rootfs payload."
+  exit 1
+
+fi
+
+log_in "0042()               : Verifying selected decrypted rootfs mapper content: [${CDLB_MAPPER_DEV}]"
+
+if ! _CHECKSUM_STATUS="$(cd / && LC_ALL=C /usr/bin/sha512sum -c --strict --quiet "${HASH_FILE}" 2>&1)"; then
+
+  log_er "0042()              : Rootfs payload checksum verification failed: [${CDLB_MAPPER_DEV}]"
+
+  if [ -n "${_CHECKSUM_STATUS}" ]; then
+
+    printf '%s\n' "${_CHECKSUM_STATUS}" >&2
+
+  fi
+
+  sleep 8
+  panic  "0042()              : Rootfs payload checksum verification failed: [${CDLB_MAPPER_DEV}]"
+  exit 1
+
+fi
+
+log_ok "0042()               : Rootfs payload checksum verification successful: [${CDLB_MAPPER_DEV}]"
 
 printf "\e[92m[INFO] Successfully applied : [/usr/lib/live/boot/0042_ciss_post_decrypt_attest] \n\e[0m"
 

docs/MAN_CISS_ISO_BOOT_CHAIN.md

@@ -12,19 +12,24 @@ include_toc: true
 
 # 2. CISS.debian.live.builder – Boot & Trust Chain (Technical Documentation)
 
-**Status:** 2025-11-12<br>
+**Status:** 2026-06-10<br>
 **Audience:** CICA CISO, CISS staff, technically proficient administrators<br>
-**Summary:** The **CISS.debian.live.builder** Live-ISO establishes a two-stage verification chain around the live root: 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)`. UEFI Secure Boot can use either the default Microsoft/Debian shim chain, or a CISS-signed UKI chain for systems that trust the CISS Secure Boot key material.<br>
+**Summary:** The **CISS.debian.live.builder** Live-ISO establishes a two-stage verification chain around the live root: an
+ISO-edge checksum-manifest check and a late attestation of the complete selected decrypted rootfs mapper. The late check verifies
+both the signed SHA-512 manifest and the mapper bytes before boot continues. `dm-integrity` separately provides sector-integrity
+protection and is not a substitute for origin-bound signature and checksum attestation. UEFI Secure Boot can use either the
+default Microsoft/Debian shim chain, or a CISS-signed UKI chain for systems that trust the CISS Secure Boot key material.<br>
 
 # 3. Overview
 
 * **Trust anchor:** Pinned fingerprint (FPR) of the signing key embedded at build time in initramfs hooks.
 * **Integrity & authenticity verification:**
 
-  1. **Early:** Verify `sha512sum.txt` at the ISO edge using `gpgv` and FPR pin.
+  1. **ISO edge:** Verify one supported checksum manifest using `gpgv`, FPR pinning, and the matching checksum tool.
-  2. **Late:** Verify an attestation hash list inside the decrypted root FS using `gpgv` and FPR pin.
+  2. **Late rootfs attestation:** Verify the signed mapper manifest and the complete selected decrypted mapper
+     `/dev/mapper/crypt_liveiso` with `sha512sum -c`.
 
-* **Storage-level AEAD (functional):** `dm-crypt` (AES-XTS-512) and `dm-integrity` (HMAC-SHA-512, 4 KiB).
+* **Storage-level protection:** `dm-crypt` (AES-XTS-512) and, outside runner builds, `dm-integrity` (HMAC-SHA-512, 4 KiB).
 * **Remotely unlock:** CISS hardened and build dropbear, modern primitives only, no passwords, no agent/forwarding.
 
 # 3.1. Secure Boot Profiles
@@ -52,11 +57,11 @@ private Secure Boot key names are detected in those paths before live-build chec
 | Component    | Primitive / Parameter                                     | Purpose                                                |
 |--------------|-----------------------------------------------------------|--------------------------------------------------------|
 | LUKS2        | `aes-xts-plain64`, `--key-size 512`, `--sector-size 4096` | Confidentiality (2×256-bit XTS)                        |
-| dm-integrity | `hmac-sha512` (keyed), journal                            | Adversary-resistant per-sector integrity, authenticity |
+| dm-integrity | `hmac-sha512` (keyed), journal                            | Per-sector integrity inside the LUKS mapping; not origin attestation |
 | PBKDF        | `argon2id`, `--iter-time 1000` ms                         | Key derivation, hardware-agnostic                      |
 | Signatures   | Ed25519 or RSA-4096 (FPR pinned)                          | Public verifiability, non-repudiation                  |
 | Verification | `gpgv --no-default-keyring`                               | No agent dependency in initramfs                       |
-| Hash lists   | `sha512sum` format                                        | Deterministic content verification                     |
+| Hash lists   | `sha512sum` format                                        | Deterministic ISO-edge and decrypted-mapper verification |
 | Dropbear     | Modern KEX/AEAD (per `localoptions.h`)                    | Minimal attack surface, remote unlock                  |
 
 # 5. Diagram: CISS Live ISO Boot Flow
@@ -150,7 +155,8 @@ flowchart TD
 
 ```
 
-**Note:** Encrypt-then-MAC at the block layer (functionally AEAD-equivalent). Any manipulation ⇒ hard I/O error.
+**Note:** `dm-integrity` detects sector corruption within its keyed mapping. The signed SHA-512 mapper manifest independently
+binds the selected decrypted rootfs payload to the signing key. Neither property substitutes for the other.
 
 # 7. CISS Live ISO LUKS Build-Time Core Steps
 ```sh
@@ -172,16 +178,24 @@ cryptsetup luksFormat \
   "${LUKSFS}"
 ```
 
+After `filesystem.squashfs` is copied to `/dev/mapper/crypt_liveiso`, the binary hook hashes the complete decrypted mapper,
+including the mapper padding after the SquashFS image. It writes
+`binary/live/ciss_rootfs.crypt.decrypted.sha512sum.txt`, signs that manifest with the existing artifact-signing key, verifies the
+signature and checksum locally, and only then closes the mapping and removes the plaintext `filesystem.squashfs`.
+
 **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).
 
 # 8. Early ISO-Edge Verification (CISS modified hook 0030-ciss-verify-checksums, live-bottom)
 
-**Goal:** Before consuming any medium content, verify:
+**Goal:** During live-boot, require one supported ISO-edge checksum manifest to be successfully verified:
 
 1. **Detached signature of `sha512sum.txt`** using `gpgv` against the embedded public key.
 2. **FPR pinning:** Parse `VALIDSIG` and require exact match with the build-time pinned FPR.
 3. **Optional:** *Script self-IA* – hash the executed hook and compare against the signed list (drift/bitrot detector).
 
+Verification is fail-closed. Boot panics if no supported manifest is present, no matching checksum tool is available, checksum
+verification does not succeed, signature verification fails when requested, or verification ends in an unknown state.
+
 **Core call (initramfs):**
 
 ```sh
@@ -189,12 +203,16 @@ cryptsetup luksFormat \
 # parse [GNUPG:] VALIDSIG ... <FPR> ...
 ```
 
-# 9. Late Root-FS Attestation and dmsetup Health (CISS hook 0042_ciss_post_decrypt_attest, called by 9990-overlay.sh)
+# 9. Late Root-FS Payload Attestation (CISS hook 0042_ciss_post_decrypt_attest, called by 9990-overlay.sh)
 
-**Goal:** After LUKS unlock, validate the **decrypted** contents and the **actual** mapping topology.
+**Goal:** After LUKS unlock and rootfs selection, verify the authenticity of the manifest and the content of the actual selected
+decrypted rootfs payload.
 
-* **Attestation files:** `/root/.ciss/attestation/<FPR>.sha512sum.txt[.sig]`
+* **Exact attested boundary:** the complete `/dev/mapper/crypt_liveiso` block payload selected by `9990-overlay.sh` and mounted
-* **Key source:** `/etc/ciss/keys/*.gpg` (accepted only if FPR == build-pin)
+  read-only as SquashFS, including mapper padding after the SquashFS image.
+* **Attestation files:** `/run/live/medium/live/ciss_rootfs.crypt.decrypted.sha512sum.txt[.sig]`
+* **Key source:** `/etc/ciss/keys/<FPR>.gpg` in the initramfs; the valid signature FPR must equal the build-time pin.
+* **Manifest constraint:** exactly one checksum record is accepted, and it must target the selected mapper path.
 
 **Core calls (initramfs):**
 
@@ -202,13 +220,20 @@ cryptsetup luksFormat \
 # 1) Signature and FPR pin (no agent)
 /usr/bin/gpgv --no-default-keyring --keyring "$KEYFILE" --status-fd 1 --verify "$SIG" "$DATA"
 
-# 2) Optional: Content hash verification
+# 2) Required selected-payload verification
-( cd "$ROOTMP" && /usr/bin/sha512sum -c --strict --quiet "$DATA" )
+( cd / && /usr/bin/sha512sum -c --strict --quiet "$DATA" )
 ```
 
+The signed manifest alone is not sufficient: boot continues only after the selected decrypted mapper content matches it.
+This boundary does not individually attest the mounted file tree, OverlayFS upper layer, runtime mutations, or secrets after
+unlock.
+
 # 10. Failure Policy (fail-closed, deterministic)
 
-* **Abort** on: missing `VALIDSIG`, FPR mismatch, missing key / signature.
+* **ISO-edge abort:** no supported manifest, no supported verification tool, failed checksum, failed requested signature, or
+  unknown verification state.
+* **Rootfs-attestation abort:** missing or malformed manifest/signature/key, missing `VALIDSIG`, FPR mismatch, manifest target
+  mismatch, unreadable or non-block selected mapper, or mapper checksum mismatch.
 
 # 11. CISS hardened and built dropbear
 
@@ -251,17 +276,19 @@ flowchart TD
   subgraph ISO Build Time
     A["Embed and pin GPG FPR (into ISO & RootFS as needed)"] e00@--> B["Generate ISO-edge sha512sum.txt and .sig"];
     B e01@--> C["Build filesystem.squashfs and wrap it into ciss_rootfs.crypt"];
+    C e01a@--> C2["Hash complete decrypted mapper and sign rootfs manifest"];
     e00@{ animation: fast }
     e01@{ animation: fast }
+    e01a@{ animation: fast }
   end
 
   subgraph ISO Boot Time
-    C e02@--> D["0024 LUKS2, dm-integrity HMAC-SHA512"];
+    C2 e02@--> D["0024 LUKS2, dm-integrity HMAC-SHA512"];
     D e03@-->|SUCCESSFUL| E["ciss_rootfs.crypt opened"];
     E e04@--> F["Mounting RootFS"];
     F e05@--> G["0030 verification of authenticity and integrity via embedded and pinned GPG of ISO edge"];
     G e06@-->|SUCCESSFUL| H["ISO edge verified"];
-    H e07@--> I["0042 post-decrypt-attestation of RootFS"];
+    H e07@--> I["0042 verifies signed manifest and selected decrypted mapper"];
     I e08@-->|SUCCESSFUL| J["RootFS attestation successful"];
     e02@{ animation: fast }
     e03@{ animation: fast }
@@ -285,7 +312,9 @@ I -- FAIL --> X;
 
 # 14. Closing Remarks
 
-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 make the state transparent and deterministic.
+The verification path is fail-closed and binds the selected decrypted rootfs mapper to the pinned signing key. `dm-integrity`
+adds a separate sector-integrity property where enabled. The implemented attestation does not cover runtime OverlayFS changes,
+post-unlock secrets, or an individually enumerated mounted file tree.
 
 ---
 **[no tracking | no logging | no advertising | no profiling | no bullshit](https://coresecret.eu/)**

lib/lib_ciss_upgrades_boot.sh

@@ -9,12 +9,12 @@
 # SPDX-LicenseComment: This file is part of the CISS.debian.installer.secure framework.
 # SPDX-PackageName: CISS.debian.live.builder
 # SPDX-Security-Contact: security@coresecret.eu
+# shellcheck disable=SC2154
 
 guard_sourcing || return "${ERR_GUARD_SRCE}"
 
 #######################################
 # Integrates and generates sha512sum and GPG signatures on CISS specific LIVE boot artifacts:
-#  - /root/.ciss/attestation/VAR_SIGNING_KEY_FPR.*
 #  - /etc/initramfs-tools/files/unlock_wrapper.sh
 #  - /usr/lib/live/boot/0030-ciss-verify-checksums
 # Globals:
@@ -31,10 +31,7 @@ guard_sourcing || return "${ERR_GUARD_SRCE}"
 ciss_upgrades_boot() {
   printf "\e[95m🧪 %s starting ... \e[0m\n" "${BASH_SOURCE[0]}"
 
-  gpg --batch --yes --export "${VAR_SIGNING_KEY_FPR}" >| "${VAR_HANDLER_BUILD_DIR}/config/includes.chroot/root/.ciss/attestation/${VAR_SIGNING_KEY_FPR}.gpg"
-
   declare -ar _ary_target=(
-    "/root/.ciss/attestation/${VAR_SIGNING_KEY_FPR}.gpg"
     "/etc/initramfs-tools/files/unlock_wrapper.sh"
     "/usr/lib/live/boot/0030-ciss-verify-checksums"
   )

scripts/usr/lib/live/boot/0030-ciss-verify-checksums

@@ -48,9 +48,20 @@ Verify_checksums() {
 
   _KEYFILE=""
 
+  _MANIFEST_FOUND="false"
+
   _MP=""
 
+  _RETURN_PGP=""
+
+  _RETURN_SHA=""
+
+  _VERIFICATION_EXECUTED="false"
+
+  _VERIFICATION_SUCCEEDED="false"
+
   ### Parse commandline arguments ----------------------------------------------------------------------------------------------
+  # shellcheck disable=SC2154
   for _PARAMETER in ${LIVE_BOOT_CMDLINE}; do
 
     case "${_PARAMETER}" in
@@ -203,10 +214,12 @@ Verify_checksums() {
 
       if [ -e "${_CHECKSUM}" ]; then
 
+        _MANIFEST_FOUND="true"
         printf "\e[95m[INFO] Found: [%s] ... \n\e[0m" "${_CHECKSUM}"
 
         if [ -e "/usr/bin/${_DIGEST}sum" ]; then
 
+          _VERIFICATION_EXECUTED="true"
           printf "\e[95m[INFO] Found: [%s] ... \n\e[0m" "/usr/bin/${_DIGEST}sum"
 
           if [ "${LIVE_VERIFY_CHECKSUMS_SIGNATURES}" = "true" ]; then
@@ -237,6 +250,7 @@ Verify_checksums() {
           if grep -v '^#' "${_CHECKSUM}" | /usr/bin/"${_DIGEST}"sum -c > "${_TTY}"; then
 
             _RETURN_SHA="${?}"
+            _VERIFICATION_SUCCEEDED="true"
             printf "\e[92m[INFO] Found: [%s] successful verified: [%s] \n\e[0m" "/usr/bin/${_DIGEST}sum" "${_CHECKSUM}"
 
           else
@@ -265,6 +279,33 @@ Verify_checksums() {
   log_end_msg
   printf "\n"
 
+  if [ "${_MANIFEST_FOUND}" != "true" ]; then
+
+    printf "\e[91m[FATAL] No supported checksum manifest found. \n\e[0m"
+    sleep 8
+    panic "No supported checksum manifest found."
+    return 1
+
+  fi
+
+  if [ "${_VERIFICATION_EXECUTED}" != "true" ]; then
+
+    printf "\e[91m[FATAL] No supported checksum verification tool was available. \n\e[0m"
+    sleep 8
+    panic "No supported checksum verification tool was available."
+    return 1
+
+  fi
+
+  if [ "${_VERIFICATION_SUCCEEDED}" != "true" ]; then
+
+    printf "\e[91m[FATAL] No supported checksum manifest was verified successfully. \n\e[0m"
+    sleep 8
+    panic "No supported checksum manifest was verified successfully."
+    return 1
+
+  fi
+
   case "${_RETURN_PGP},${_RETURN_SHA}" in
 
     "0,0")
@@ -288,6 +329,7 @@ Verify_checksums() {
       printf "\e[91m[FATAL] CDLB modified: [%s] done. \n\e[0m" "${CDLB_SCRIPT_FULL}"
       sleep 8
       panic "Verification of [GPG signature] file successful, while verification of [sha checksum] file failed."
+      return 1
       ;;
 
     *",0")
@@ -295,6 +337,7 @@ Verify_checksums() {
       printf "\e[91m[FATAL] CDLB modified: [%s] done. \n\e[0m" "${CDLB_SCRIPT_FULL}"
       sleep 8
       panic "Verification of [GPG signature] file failed, while verification of [sha checksum] file successful."
+      return 1
       ;;
 
     "na,"*)
@@ -302,6 +345,14 @@ Verify_checksums() {
       printf "\e[91m[FATAL] CDLB modified: [%s] done. \n\e[0m" "${CDLB_SCRIPT_FULL}"
       sleep 8
       panic "Verification of checksum file failed."
+      return 1
+      ;;
+
+    *)
+      printf "\e[91m[FATAL] Checksum verification ended in an unsupported state. \n\e[0m"
+      sleep 8
+      panic "Checksum verification ended in an unsupported state."
+      return 1
       ;;
 
   esac

tests/test_boot_attestation.sh

@@ -0,0 +1,228 @@
+#!/bin/bash
+# SPDX-Version: 3.0
+# SPDX-FileCopyrightText: 2026; WEIDNER, Marc S.; <msw@coresecret.dev>
+# SPDX-FileType: SOURCE
+# SPDX-License-Identifier: LicenseRef-CNCL-1.1 OR LicenseRef-CCLA-1.1
+# SPDX-PackageName: CISS.debian.live.builder
+
+set -Ceuo pipefail
+
+declare ROOT_DIR=""
+declare SHA512SUM=""
+declare SHASUM=""
+declare TMP_BASE=""
+declare TMP_ROOT=""
+
+ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+SHA512SUM="$(command -v sha512sum)"
+SHASUM="$(command -v shasum || true)"
+TMP_BASE="${TMPDIR:-/tmp}"
+TMP_BASE="${TMP_BASE%/}"
+TMP_ROOT="$(mktemp -d "${TMP_BASE}/ciss-boot-attestation.XXXXXXXX")"
+
+cleanup() {
+  case "${TMP_ROOT}" in
+    "${TMP_BASE}/ciss-boot-attestation."*)
+      rm -rf -- "${TMP_ROOT}"
+      ;;
+    *)
+      printf 'Refusing to clean unexpected test path: %s\n' "${TMP_ROOT}" >&2
+      return 1
+      ;;
+  esac
+}
+trap cleanup EXIT
+
+fail() {
+  printf 'FAIL: %s\n' "${1}" >&2
+  exit 1
+}
+
+prepare_checksum_hook() {
+  declare source_hook="${1}"
+  declare target_hook="${2}"
+  declare fault_mode="${3}"
+  declare test_bin="${4}"
+  declare test_tty="${5}"
+  declare test_runtime=""
+
+  test_runtime="$(dirname "${test_tty}")"
+  sed \
+    -e "s|/usr/bin/|${test_bin}/|g" \
+    -e "s|/run/ciss-|${test_runtime}/ciss-|g" \
+    -e "s|_TTY=\"/dev/tty8\"|_TTY=\"${test_tty}\"|" \
+    "${source_hook}" > "${target_hook}"
+
+  if [[ "${fault_mode}" == "unknown-state" ]]; then
+    sed \
+      -e 's/_RETURN_PGP="na"/_RETURN_PGP="unknown"/' \
+      -e 's/_RETURN_SHA="${?}"/_RETURN_SHA="unknown"/g' \
+      "${target_hook}" > "${target_hook}.new"
+    mv "${target_hook}.new" "${target_hook}"
+  fi
+}
+
+install_test_sha512sum() {
+  declare test_bin="${1}"
+
+  if printf '' | "${SHA512SUM}" -c >/dev/null 2>&1; then
+    ln -s "${SHA512SUM}" "${test_bin}/sha512sum"
+  elif [[ -n "${SHASUM}" ]]; then
+    printf '#!/bin/sh\nexec "%s" -a 512 "$@"\n' "${SHASUM}" > "${test_bin}/sha512sum"
+    chmod 0755 "${test_bin}/sha512sum"
+  else
+    fail "No SHA-512 tool with checksum verification support is available."
+  fi
+}
+
+run_checksum_case() {
+  declare source_hook="${1}"
+  declare case_name="${2}"
+  declare expected_status="${3}"
+  declare expected_message="${4}"
+  declare case_dir=""
+  declare hook_copy=""
+  declare output_file=""
+  declare test_bin=""
+  declare test_tty=""
+  declare source_id=""
+  declare fault_mode=""
+  declare panic_returns="false"
+  declare status=0
+
+  source_id="$(printf '%s' "${source_hook#"${ROOT_DIR}"/}" | tr '/' '_')"
+  case_dir="${TMP_ROOT}/${source_id}-${case_name}"
+  hook_copy="${case_dir}/0030-ciss-verify-checksums"
+  output_file="${case_dir}/output.log"
+  test_bin="${case_dir}/bin"
+  test_tty="${case_dir}/tty.log"
+
+  mkdir -p "${case_dir}" "${test_bin}"
+  : >| "${test_tty}"
+
+  case "${case_name}" in
+    valid)
+      install_test_sha512sum "${test_bin}"
+      printf 'trusted rootfs payload\n' > "${case_dir}/payload"
+      (cd "${case_dir}" && "${test_bin}/sha512sum" payload > sha512sum.txt)
+      ;;
+    missing-manifest)
+      install_test_sha512sum "${test_bin}"
+      ;;
+    unsupported-manifest)
+      install_test_sha512sum "${test_bin}"
+      printf 'unsupported\n' > "${case_dir}/md5sum.txt"
+      ;;
+    failed-checksum)
+      install_test_sha512sum "${test_bin}"
+      printf 'trusted rootfs payload\n' > "${case_dir}/payload"
+      (cd "${case_dir}" && "${test_bin}/sha512sum" payload > sha512sum.txt)
+      printf 'tampered rootfs payload\n' >| "${case_dir}/payload"
+      ;;
+    missing-tool)
+      install_test_sha512sum "${test_bin}"
+      printf 'trusted rootfs payload\n' > "${case_dir}/payload"
+      (cd "${case_dir}" && "${test_bin}/sha512sum" payload > sha512sum.txt)
+      rm -f "${test_bin}/sha512sum"
+      ;;
+    unknown-state)
+      fault_mode="unknown-state"
+      panic_returns="true"
+      install_test_sha512sum "${test_bin}"
+      printf 'trusted rootfs payload\n' > "${case_dir}/payload"
+      (cd "${case_dir}" && "${test_bin}/sha512sum" payload > sha512sum.txt)
+      ;;
+    *)
+      fail "Unknown checksum test case: ${case_name}"
+      ;;
+  esac
+
+  prepare_checksum_hook "${source_hook}" "${hook_copy}" "${fault_mode}" "${test_bin}" "${test_tty}"
+
+  set +e
+  # shellcheck disable=SC2034,SC2329
+  (
+    set +C
+    CDLB_SCRIPT_FULL="${hook_copy}"
+    LIVE_BOOT_CMDLINE="verify-checksums=sha512"
+    LIVE_VERIFY_CHECKSUMS=""
+
+    log_begin_msg() { :; }
+    log_end_msg() { :; }
+    log_success_msg() { :; }
+    panic() {
+      printf 'PANIC: %s\n' "${1}" >&2
+      if [[ "${panic_returns}" == "true" ]]; then
+        return 0
+      fi
+      exit 97
+    }
+    sleep() { :; }
+
+    # shellcheck source=/dev/null
+    . "${hook_copy}"
+    Verify_checksums "${case_dir}"
+  ) > "${output_file}" 2>&1
+  status="${?}"
+  set -e
+
+  [[ "${status}" -eq "${expected_status}" ]] || {
+    cat "${output_file}" >&2
+    fail "${source_hook} ${case_name}: expected status ${expected_status}, got ${status}"
+  }
+
+  grep -Fq "${expected_message}" "${output_file}" || {
+    cat "${output_file}" >&2
+    fail "${source_hook} ${case_name}: missing expected message '${expected_message}'"
+  }
+}
+
+test_rootfs_payload_tamper() {
+  declare case_dir="${TMP_ROOT}/rootfs-payload-tamper"
+  declare test_bin="${case_dir}/bin"
+  declare payload="${case_dir}/crypt_liveiso"
+  declare manifest="${case_dir}/ciss_rootfs.crypt.decrypted.sha512sum.txt"
+  declare build_hook="${ROOT_DIR}/config/hooks/live/zzzz_ciss_crypt_squash.hook.binary"
+  declare boot_hook="${ROOT_DIR}/config/includes.chroot/usr/lib/live/boot/0042_ciss_post_decrypt_attest"
+
+  mkdir -p "${case_dir}" "${test_bin}"
+  install_test_sha512sum "${test_bin}"
+
+  printf 'trusted selected rootfs mapper payload\n' > "${payload}"
+  "${test_bin}/sha512sum" "${payload}" > "${manifest}"
+  "${test_bin}/sha512sum" -c --strict --quiet "${manifest}"
+
+  printf 'tampered selected rootfs mapper payload\n' >> "${payload}"
+  if "${test_bin}/sha512sum" -c --strict --quiet "${manifest}" >/dev/null 2>&1; then
+    fail "Modified selected rootfs payload unexpectedly passed checksum verification."
+  fi
+
+  # shellcheck disable=SC2016
+  grep -Fq 'sha512sum "${MAPPER_DEV}" >| "${ROOTFS_ATTESTATION}"' "${build_hook}" || \
+    fail "Build hook does not generate the attestation from the decrypted mapper."
+  # shellcheck disable=SC2016
+  grep -Fq '/usr/bin/sha512sum -c --strict --quiet "${HASH_FILE}"' "${boot_hook}" || \
+    fail "Boot hook does not verify the selected rootfs payload with sha512sum -c."
+  # shellcheck disable=SC2016
+  grep -Fq '[ "${_ATTESTED_PAYLOAD}" != "${CDLB_MAPPER_DEV}" ]' "${boot_hook}" || \
+    fail "Boot hook does not require the manifest to target the selected rootfs payload."
+}
+
+declare -a CHECKSUM_HOOKS=(
+  "${ROOT_DIR}/config/includes.chroot/usr/lib/live/boot/0030-ciss-verify-checksums"
+  "${ROOT_DIR}/scripts/usr/lib/live/boot/0030-ciss-verify-checksums"
+)
+declare checksum_hook=""
+
+for checksum_hook in "${CHECKSUM_HOOKS[@]}"; do
+  run_checksum_case "${checksum_hook}" "valid"                0  "Verification of [sha checksum] file successful"
+  run_checksum_case "${checksum_hook}" "missing-manifest"     97 "No supported checksum manifest found."
+  run_checksum_case "${checksum_hook}" "unsupported-manifest" 97 "No supported checksum manifest found."
+  run_checksum_case "${checksum_hook}" "failed-checksum"       97 "No supported checksum manifest was verified successfully."
+  run_checksum_case "${checksum_hook}" "missing-tool"          97 "No supported checksum verification tool was available."
+  run_checksum_case "${checksum_hook}" "unknown-state"          1 "Checksum verification ended in an unsupported state."
+done
+
+test_rootfs_payload_tamper
+
+printf 'PASS: checksum verification fails closed and modified rootfs payloads fail attestation.\n'