diff --git a/.github/workflows/portage-stable-packages-list b/.github/workflows/portage-stable-packages-list
index 7ea7b64a97..f8c6734960 100644
--- a/.github/workflows/portage-stable-packages-list
+++ b/.github/workflows/portage-stable-packages-list
@@ -290,6 +290,7 @@ dev-libs/tree-sitter
 dev-libs/tree-sitter-bash
 dev-libs/userspace-rcu
 dev-libs/xmlsec
+dev-libs/xxhash
 dev-libs/yajl
 
 dev-perl/Parse-Yapp
@@ -666,6 +667,7 @@ sys-fs/btrfs-progs
 sys-fs/cryptsetup
 sys-fs/dosfstools
 sys-fs/e2fsprogs
+sys-fs/erofs-utils
 sys-fs/fuse
 sys-fs/fuse-common
 sys-fs/fuse-overlayfs
diff --git a/build_library/prod_image_util.sh b/build_library/prod_image_util.sh
index d7e77ff3a5..27a6120b4f 100755
--- a/build_library/prod_image_util.sh
+++ b/build_library/prod_image_util.sh
@@ -162,6 +162,10 @@ EOF
   # Remove source locale data, only need to ship the compiled archive.
   sudo rm -rf ${root_fs_dir}/usr/share/i18n/
 
+  # Inject ephemeral sysext signing certificate
+  sudo mkdir -p "${root_fs_dir}/usr/lib/verity.d"
+  sudo cp "${SYSEXT_SIGNING_KEY_DIR}/sysexts.crt" "${root_fs_dir}/usr/lib/verity.d"
+
   # Finish image will move files from /etc to /usr/share/flatcar/etc.
   # Note that image filesystem contents generated by finish_image will not
   # include sysext contents (only the sysext squashfs files themselves).
diff --git a/build_library/sysext_prod_builder b/build_library/sysext_prod_builder
index 8b8f3ddbc2..ab811f2761 100755
--- a/build_library/sysext_prod_builder
+++ b/build_library/sysext_prod_builder
@@ -59,7 +59,7 @@ create_prod_sysext() {
   # Pass the build ID extracted from root FS to build_sysext. This prevents common.sh
   #   in build_sysext to generate a (timestamp based) build ID during a DEV build of a
   #   release tag (which breaks its version check).
-  sudo "FLATCAR_BUILD_ID=$FLATCAR_BUILD_ID" "${SCRIPTS_DIR}/build_sysext" \
+  sudo -E "FLATCAR_BUILD_ID=$FLATCAR_BUILD_ID" "${SCRIPTS_DIR}/build_sysext" \
             --board="${BOARD}" \
             --image_builddir="${workdir}/sysext-build" \
             --squashfs_base="${base_sysext}" \
@@ -94,6 +94,14 @@ sysext_mountdir="${BUILD_DIR}/prod-sysext-work/mounts"
 sysext_base="${sysext_workdir}/base-os.squashfs"
 
 function cleanup() {
+  IFS=':' read -r -a mounted_sysexts <<< "$sysext_lowerdirs"
+  # skip the rootfs
+  mounted_sysexts=("${mounted_sysexts[@]:1}")
+
+  for sysext in "${mounted_sysexts[@]}"; do
+    sudo systemd-dissect --umount --rmdir "$sysext"
+  done
+
   sudo umount "${sysext_mountdir}"/* || true
   rm -rf "${sysext_workdir}" || true
 }
@@ -111,6 +119,7 @@ sudo mksquashfs "${root_fs_dir}" "${sysext_base}" -noappend -xattrs-exclude '^bt
 # for combined overlay later.
 prev_pkginfo=""
 sysext_lowerdirs="${sysext_mountdir}/rootfs-lower"
+mkdir -p "${sysext_mountdir}"
 for sysext in ${sysexts_list//,/ }; do
   # format is "<name>:<group>/<package>"
   name="${sysext%|*}"
@@ -124,12 +133,21 @@ for sysext in ${sysexts_list//,/ }; do
                      "${grp_pkg}" \
                      "${prev_pkginfo}"
 
-  mkdir -p "${sysext_mountdir}/${name}" \
-           "${sysext_mountdir}/${name}_pkginfo"
-  sudo mount -rt squashfs -o loop,nodev "${sysext_output_dir}/${name}.raw" \
-                                    "${sysext_mountdir}/${name}"
-  sudo mount -rt squashfs -o loop,nodev "${sysext_output_dir}/${name}_pkginfo.raw" \
-                                    "${sysext_mountdir}/${name}_pkginfo"
+  sudo systemd-dissect \
+    --read-only \
+    --mount \
+    --mkdir \
+    --image-policy='root=encrypted+unprotected+absent:usr=encrypted+unprotected+absent' \
+    "${sysext_output_dir}/${name}.raw" \
+    "${sysext_mountdir}/${name}"
+
+  sudo systemd-dissect \
+    --read-only \
+    --mount \
+    --mkdir \
+    --image-policy='root=encrypted+unprotected+absent:usr=encrypted+unprotected+absent' \
+    "${sysext_output_dir}/${name}_pkginfo.raw" \
+    "${sysext_mountdir}/${name}_pkginfo"
 
   sysext_lowerdirs="${sysext_lowerdirs}:${sysext_mountdir}/${name}"
   sysext_lowerdirs="${sysext_lowerdirs}:${sysext_mountdir}/${name}_pkginfo"
diff --git a/build_library/vm_image_util.sh b/build_library/vm_image_util.sh
index dce01f9c05..adf5fac405 100644
--- a/build_library/vm_image_util.sh
+++ b/build_library/vm_image_util.sh
@@ -580,7 +580,7 @@ install_oem_sysext() {
     fi
 
     mkdir -p "${built_sysext_dir}"
-    sudo "${build_sysext_env[@]}" "${SCRIPT_ROOT}/build_sysext" "${build_sysext_flags[@]}" "${oem_sysext}"
+    sudo -E "${build_sysext_env[@]}" "${SCRIPT_ROOT}/build_sysext" "${build_sysext_flags[@]}" "${oem_sysext}"
 
     local installed_sysext_oem_dir='/oem/sysext'
     local installed_sysext_file_prefix="${oem_sysext}-${version}"
diff --git a/build_sysext b/build_sysext
index 138d7f8906..44842e8f98 100755
--- a/build_sysext
+++ b/build_sysext
@@ -301,14 +301,25 @@ if [[ -n "${invalid_files}" ]]; then
   die "Invalid file ownership: ${invalid_files}"
 fi
 
-mksquashfs "${BUILD_DIR}/install-root" "${BUILD_DIR}/${SYSEXTNAME}.raw" \
-               -noappend -xattrs-exclude '^btrfs.' -comp "${FLAGS_compression}" ${FLAGS_mksquashfs_opts}
+systemd-repart \
+  --private-key="${SYSEXT_SIGNING_KEY_DIR}/sysexts.key" \
+  --certificate="${SYSEXT_SIGNING_KEY_DIR}/sysexts.crt" \
+  --make-ddi=sysext \
+  --copy-source="${BUILD_DIR}/install-root" \
+  "${BUILD_DIR}/${SYSEXTNAME}.raw"
+
 rm -rf "${BUILD_DIR}"/{fs-root,install-root,workdir}
 
 # Generate reports
 mkdir "${BUILD_DIR}/img-rootfs"
-mount -rt squashfs -o loop,nodev "${BUILD_DIR}/${SYSEXTNAME}.raw" "${BUILD_DIR}/img-rootfs"
+systemd-dissect --read-only \
+  --mount \
+  --mkdir \
+  --image-policy='root=encrypted+unprotected+absent:usr=encrypted+unprotected+absent' \
+  "${BUILD_DIR}/${SYSEXTNAME}.raw" \
+  "${BUILD_DIR}/img-rootfs"
+
 write_contents "${BUILD_DIR}/img-rootfs" "${BUILD_DIR}/${SYSEXTNAME}_contents.txt"
 write_contents_with_technical_details "${BUILD_DIR}/img-rootfs" "${BUILD_DIR}/${SYSEXTNAME}_contents_wtd.txt"
 write_disk_space_usage_in_paths "${BUILD_DIR}/img-rootfs" "${BUILD_DIR}/${SYSEXTNAME}_disk_usage.txt"
-umount "${BUILD_DIR}/img-rootfs"
+systemd-dissect --umount --rmdir "${BUILD_DIR}/img-rootfs"
diff --git a/sdk_container/src/third_party/coreos-overlay/coreos-devel/sdk-depends/sdk-depends-0.0.1.ebuild b/sdk_container/src/third_party/coreos-overlay/coreos-devel/sdk-depends/sdk-depends-0.0.1.ebuild
index 0d8be10a14..f1c57c78dd 100644
--- a/sdk_container/src/third_party/coreos-overlay/coreos-devel/sdk-depends/sdk-depends-0.0.1.ebuild
+++ b/sdk_container/src/third_party/coreos-overlay/coreos-devel/sdk-depends/sdk-depends-0.0.1.ebuild
@@ -46,6 +46,7 @@ DEPEND="
 	sys-firmware/edk2-bin
 	sys-fs/btrfs-progs
 	sys-fs/cryptsetup
+        sys-fs/erofs-utils
 	dev-perl/Parse-Yapp
 	dev-util/pkgcheck
 "
diff --git a/sdk_container/src/third_party/coreos-overlay/profiles/coreos/targets/sdk/make.defaults b/sdk_container/src/third_party/coreos-overlay/profiles/coreos/targets/sdk/make.defaults
index b55f758adf..232dcb4910 100644
--- a/sdk_container/src/third_party/coreos-overlay/profiles/coreos/targets/sdk/make.defaults
+++ b/sdk_container/src/third_party/coreos-overlay/profiles/coreos/targets/sdk/make.defaults
@@ -1,4 +1,5 @@
 USE="cros_host expat man -pam"
+USE="${USE} cryptsetup"
 
 # Used by some old goo in profiles/coreos/base/profile.bashrc
 # TODO: clean up that old goo
diff --git a/sdk_container/src/third_party/coreos-overlay/profiles/coreos/targets/sdk/package.accept_keywords b/sdk_container/src/third_party/coreos-overlay/profiles/coreos/targets/sdk/package.accept_keywords
index 7b5df04972..b5d36edcaa 100644
--- a/sdk_container/src/third_party/coreos-overlay/profiles/coreos/targets/sdk/package.accept_keywords
+++ b/sdk_container/src/third_party/coreos-overlay/profiles/coreos/targets/sdk/package.accept_keywords
@@ -1,2 +1,4 @@
 # Temporarily put the SDK version ahead for sd-json support in Dracut.
 =sys-apps/systemd-257.5 ~amd64 ~arm64
+
+=sys-fs/erofs-utils-1.8.4 ~amd64 ~arm64
diff --git a/sdk_container/src/third_party/coreos-overlay/sys-kernel/coreos-kernel/coreos-kernel-6.12.40.ebuild b/sdk_container/src/third_party/coreos-overlay/sys-kernel/coreos-kernel/coreos-kernel-6.12.40.ebuild
index cea1123a3e..00f8d64b5a 100644
--- a/sdk_container/src/third_party/coreos-overlay/sys-kernel/coreos-kernel/coreos-kernel-6.12.40.ebuild
+++ b/sdk_container/src/third_party/coreos-overlay/sys-kernel/coreos-kernel/coreos-kernel-6.12.40.ebuild
@@ -64,6 +64,7 @@ src_prepare() {
 	validate_sig_key
 
 	config_update 'CONFIG_INITRAMFS_SOURCE="bootengine.cpio"'
+	config_update "CONFIG_SYSTEM_TRUSTED_KEYS=\"/usr/share/sb_keys/shim.pem\""
 
 	# include all intel and amd microcode files, avoiding the signatures
 	local fw_dir="${ESYSROOT}/lib/firmware"
diff --git a/sdk_container/src/third_party/coreos-overlay/sys-kernel/coreos-modules/files/commonconfig-6.12 b/sdk_container/src/third_party/coreos-overlay/sys-kernel/coreos-modules/files/commonconfig-6.12
index 32312c1cba..c9438df8df 100644
--- a/sdk_container/src/third_party/coreos-overlay/sys-kernel/coreos-modules/files/commonconfig-6.12
+++ b/sdk_container/src/third_party/coreos-overlay/sys-kernel/coreos-modules/files/commonconfig-6.12
@@ -166,6 +166,7 @@ CONFIG_DM_SNAPSHOT=m
 CONFIG_DM_THIN_PROVISIONING=m
 CONFIG_DM_UEVENT=y
 CONFIG_DM_VERITY=m
+CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG=y
 CONFIG_DM_ZERO=m
 CONFIG_DNS_RESOLVER=y
 CONFIG_DRM=m
diff --git a/sdk_container/src/third_party/portage-stable/dev-libs/xxhash/Manifest b/sdk_container/src/third_party/portage-stable/dev-libs/xxhash/Manifest
new file mode 100644
index 0000000000..1ea2e70343
--- /dev/null
+++ b/sdk_container/src/third_party/portage-stable/dev-libs/xxhash/Manifest
@@ -0,0 +1,2 @@
+DIST xxhash-0.8.2.tar.gz 1141188 BLAKE2B 735408256240760778fa516e01bed428f04837eb4e059c512e924f13e4a96db6cacbbefb04dea65a37b0f25b52cf13c4927a6e7870dc8c0d45b1b955d4ba3da1 SHA512 3e3eef21432fe88bc4dd9940ccad0308fdea3537b06fa5ac0e74c1bde53413dff29c8b3fc617a8a42b9ce88fcf213311d338a31b1ce73b3729342c9e68f06c78
+DIST xxhash-0.8.3.tar.gz 1147630 BLAKE2B 75923c7c5df3490062791fa02ccddfb7281b3646e2b3e4b4a0c0d611c339e07c8d9cb656777fd0fcec9cda484f7b33edf080116bb011f70d6b8299cda63afa4e SHA512 8b5c8b9aad4e869f28310b12cc314037feda81d92f26c23eaecdb35dc65042ca2e65f2e9606033e62a31bcc737a9a950500ffcbdb8677d6ab20e820ea14f2b79
diff --git a/sdk_container/src/third_party/portage-stable/dev-libs/xxhash/metadata.xml b/sdk_container/src/third_party/portage-stable/dev-libs/xxhash/metadata.xml
new file mode 100644
index 0000000000..63e48a416a
--- /dev/null
+++ b/sdk_container/src/third_party/portage-stable/dev-libs/xxhash/metadata.xml
@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE pkgmetadata SYSTEM "https://www.gentoo.org/dtd/metadata.dtd">
+<pkgmetadata>
+	<maintainer type="person">
+		<email>amadio@gentoo.org</email>
+		<name>Guilherme Amadio</name>
+	</maintainer>
+	<upstream>
+		<remote-id type="github">Cyan4973/xxHash</remote-id>
+		<bugs-to>https://github.com/Cyan4973/xxHash/issues</bugs-to>
+	</upstream>
+</pkgmetadata>
diff --git a/sdk_container/src/third_party/portage-stable/dev-libs/xxhash/xxhash-0.8.2.ebuild b/sdk_container/src/third_party/portage-stable/dev-libs/xxhash/xxhash-0.8.2.ebuild
new file mode 100644
index 0000000000..5cb861b0ad
--- /dev/null
+++ b/sdk_container/src/third_party/portage-stable/dev-libs/xxhash/xxhash-0.8.2.ebuild
@@ -0,0 +1,43 @@
+# Copyright 1999-2023 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+inherit multilib-minimal toolchain-funcs
+
+DESCRIPTION="Extremely fast non-cryptographic hash algorithm"
+HOMEPAGE="https://xxhash.com/"
+SRC_URI="https://github.com/Cyan4973/xxHash/archive/v${PV}.tar.gz -> ${P}.tar.gz"
+S=${WORKDIR}/xxHash-${PV}
+
+LICENSE="BSD-2 GPL-2+"
+# https://abi-laboratory.pro/tracker/timeline/xxhash
+SLOT="0"
+KEYWORDS="~alpha amd64 arm arm64 hppa ~loong ~mips ppc ppc64 ~riscv ~s390 sparc x86 ~x64-macos"
+
+src_prepare() {
+	default
+
+	multilib_copy_sources
+}
+
+multilib_src_compile() {
+	emake AR="$(tc-getAR)" CC="$(tc-getCC)"
+}
+
+multilib_src_test() {
+	emake CC="$(tc-getCC)" check
+}
+
+multilib_src_install() {
+	local emakeargs=(
+		DESTDIR="${D}"
+		PREFIX="${EPREFIX}"/usr
+		LIBDIR="${EPREFIX}"/usr/$(get_libdir)
+	)
+
+	emake "${emakeargs[@]}" install
+	einstalldocs
+
+	rm "${ED}"/usr/$(get_libdir)/libxxhash.a || die
+}
diff --git a/sdk_container/src/third_party/portage-stable/dev-libs/xxhash/xxhash-0.8.3.ebuild b/sdk_container/src/third_party/portage-stable/dev-libs/xxhash/xxhash-0.8.3.ebuild
new file mode 100644
index 0000000000..f37f8df286
--- /dev/null
+++ b/sdk_container/src/third_party/portage-stable/dev-libs/xxhash/xxhash-0.8.3.ebuild
@@ -0,0 +1,42 @@
+# Copyright 1999-2025 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+inherit multilib-minimal toolchain-funcs
+
+DESCRIPTION="Extremely fast non-cryptographic hash algorithm"
+HOMEPAGE="https://xxhash.com/"
+SRC_URI="https://github.com/Cyan4973/xxHash/archive/v${PV}.tar.gz -> ${P}.tar.gz"
+S=${WORKDIR}/xxHash-${PV}
+
+LICENSE="BSD-2 GPL-2+"
+SLOT="0"
+KEYWORDS="~alpha amd64 arm arm64 hppa ~loong ~mips ppc ppc64 ~riscv ~s390 sparc x86 ~x64-macos"
+
+src_prepare() {
+	default
+
+	multilib_copy_sources
+}
+
+multilib_src_compile() {
+	emake AR="$(tc-getAR)" CC="$(tc-getCC)"
+}
+
+multilib_src_test() {
+	emake CC="$(tc-getCC)" check
+}
+
+multilib_src_install() {
+	local emakeargs=(
+		DESTDIR="${D}"
+		PREFIX="${EPREFIX}"/usr
+		LIBDIR="${EPREFIX}"/usr/$(get_libdir)
+	)
+
+	emake "${emakeargs[@]}" install
+	einstalldocs
+
+	rm "${ED}"/usr/$(get_libdir)/libxxhash.a || die
+}
diff --git a/sdk_container/src/third_party/portage-stable/sys-fs/erofs-utils/Manifest b/sdk_container/src/third_party/portage-stable/sys-fs/erofs-utils/Manifest
new file mode 100644
index 0000000000..55cebbc53f
--- /dev/null
+++ b/sdk_container/src/third_party/portage-stable/sys-fs/erofs-utils/Manifest
@@ -0,0 +1 @@
+DIST erofs-utils-1.8.4.tar.gz 187276 BLAKE2B da0d80abbfd9b2d547c30bad7647165a3500f20e5de0b5db4c54efb27ec895fd069be983193b06d35728f5a8e1490e6cd255207c76135d8978d86e1512430755 SHA512 c941b0a2ab6c650a9aa4c9cadeb277ebc87007dc51354ff013c7cb763e6e8c9d44ed9e4791730ed05088faaba8c612198b924e70f5e52019382cfdf6d2e6b677
diff --git a/sdk_container/src/third_party/portage-stable/sys-fs/erofs-utils/erofs-utils-1.8.4.ebuild b/sdk_container/src/third_party/portage-stable/sys-fs/erofs-utils/erofs-utils-1.8.4.ebuild
new file mode 100644
index 0000000000..56cd91d056
--- /dev/null
+++ b/sdk_container/src/third_party/portage-stable/sys-fs/erofs-utils/erofs-utils-1.8.4.ebuild
@@ -0,0 +1,63 @@
+# Copyright 2021-2025 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+inherit autotools
+
+DESCRIPTION="Userspace tools for EROFS"
+HOMEPAGE="https://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs-utils.git"
+
+SRC_URI="https://git.kernel.org/pub/scm/linux/kernel/git/xiang/${PN}.git/snapshot/${P}.tar.gz"
+
+LICENSE="GPL-2+"
+SLOT="0"
+KEYWORDS="~amd64 ~arm64 ~loong"
+
+IUSE="fuse libdeflate +lz4 +lzma selinux static-libs +threads +uuid +zlib +zstd"
+
+RDEPEND="
+	dev-libs/xxhash:0=
+	fuse? ( sys-fs/fuse:0 )
+	lz4? ( app-arch/lz4:0= )
+	lzma? ( >=app-arch/xz-utils-5.4.0:0= )
+	selinux? ( sys-libs/libselinux:0= )
+	uuid? ( sys-apps/util-linux )
+	zlib? (
+		libdeflate? ( app-arch/libdeflate:0= )
+		!libdeflate? ( sys-libs/zlib:0= )
+	)
+	zstd? ( app-arch/zstd:0= )
+"
+DEPEND="${RDEPEND}"
+BDEPEND="virtual/pkgconfig"
+
+PATCHES=(
+)
+
+src_prepare() {
+	default
+	eautoreconf
+}
+
+src_configure() {
+	local myeconfargs=(
+		--disable-werror
+		$(use_enable fuse)
+		$(use_with libdeflate)
+		$(use_enable lz4)
+		$(use_enable lzma)
+		$(use_with selinux)
+		$(use_enable static-libs static-fuse)
+		$(use_enable threads multithreading)
+		$(use_with uuid)
+		$(use_with zlib)
+		$(use_with zstd libzstd)
+		--without-qpl  # not packaged
+		# do not use bundled xxhash; also upstream says "expected to be
+		# faster than the internal one"
+		--with-xxhash
+	)
+
+	econf "${myeconfargs[@]}"
+}
diff --git a/sdk_container/src/third_party/portage-stable/sys-fs/erofs-utils/metadata.xml b/sdk_container/src/third_party/portage-stable/sys-fs/erofs-utils/metadata.xml
new file mode 100644
index 0000000000..eaf0493a83
--- /dev/null
+++ b/sdk_container/src/third_party/portage-stable/sys-fs/erofs-utils/metadata.xml
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE pkgmetadata SYSTEM "https://www.gentoo.org/dtd/metadata.dtd">
+<pkgmetadata>
+	<maintainer type="person">
+		<email>xen0n@gentoo.org</email>
+		<name>WANG Xuerui</name>
+	</maintainer>
+	<use>
+		<flag name="fuse">Builds erofsfuse (requires <pkg>sys-fs/fuse</pkg>).</flag>
+		<flag name="libdeflate">Use <pkg>app-arch/libdeflate</pkg> rather than <pkg>sys-libs/zlib</pkg> for handling deflate compression.</flag>
+		<flag name="uuid">Enables UUID support via <pkg>sys-apps/util-linux</pkg>.</flag>
+	</use>
+</pkgmetadata>
diff --git a/sdk_lib/sdk_entry.sh b/sdk_lib/sdk_entry.sh
index 3c7aaeb356..093eb90825 100755
--- a/sdk_lib/sdk_entry.sh
+++ b/sdk_lib/sdk_entry.sh
@@ -63,6 +63,27 @@ grep -q 'export MODULE_SIGNING_KEY_DIR' /home/sdk/.bashrc || {
     fi
 }
 
+grep -q 'export SYSEXT_SIGNING_KEY_DIR' /home/sdk/.bashrc || {
+    SYSEXT_SIGNING_KEY_DIR=$(su sdk -c "mktemp -d")
+    if [[ ! "$SYSEXT_SIGNING_KEY_DIR" || ! -d "$SYSEXT_SIGNING_KEY_DIR" ]]; then
+        echo "Failed to create temporary directory for secure boot keys."
+    else
+        echo "export SYSEXT_SIGNING_KEY_DIR='$SYSEXT_SIGNING_KEY_DIR'" >> /home/sdk/.bashrc
+    fi
+    pushd "$SYSEXT_SIGNING_KEY_DIR"
+    build_id=$(source "/mnt/host/source/.repo/manifests/version.txt"; echo "$FLATCAR_BUILD_ID")
+    openssl req -new -nodes -utf8 \
+        -x509 -batch -sha256 \
+        -days 36000 \
+        -outform PEM \
+        -out sysexts.crt \
+        -keyout sysexts.key \
+        -newkey 4096 \
+        -subj "/CN=Flatcar $build_id sysext signing key/" \
+          || echo "Generating module signing key failed"
+    popd
+}
+
 # This is ugly.
 #   We need to sudo su - sdk -c so the SDK user gets a fresh login.
 #    'sdk' is member of multiple groups, and plain docker USER only