Lower Build-Depends on debhelper-compat to version 12 (which should have

debian/changelog

@@ -0,0 +1,5 @@
+exim-encrypt-dlfunc (0.2.0) unstable; urgency=medium
+
+  * Initial Release.
+
+ -- Heiko Reese <heiko.reese@kit.edu>  Sun, 22 Aug 2021 20:00:57 +0000

debian/control

@@ -0,0 +1,19 @@
+Source: exim-encrypt-dlfunc
+Priority: optional
+Maintainer: Heiko Reese <heiko.reese@kit.edu>
+Build-Depends: debhelper-compat (= 12), build-essential, exim4-dev, libsodium-dev, meson, pkg-config, openssl, python3-pip
+Standards-Version: 4.5.1
+Section: libs
+Homepage: https://git.scc.kit.edu/mail/exim-encrypt-dlfunc
+Vcs-Browser: https://git.scc.kit.edu/mail/exim-encrypt-dlfunc
+Vcs-Git: https://git.scc.kit.edu/mail/exim-encrypt-dlfunc.git
+Rules-Requires-Root: no
+
+Package: exim-encrypt-dlfunc
+Architecture: any
+Multi-Arch: same
+Depends: ${shlibs:Depends}, ${misc:Depends}, exim4-daemon-heavy
+Description: String encryption library for exim4
+ This library provides functions to encrypt and decrypt strings within exim4
+ using either passwords or public/private key pairs. All cryptographic
+ functionality is provides by libsodium.

debian/copyright

@@ -0,0 +1,29 @@
+Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
+Upstream-Name: exim-encrypt-dlfunc
+Upstream-Contact: Heiko Reese <heiko.reese@kit.edu>
+Source: https://git.scc.kit.edu/mail/exim-encrypt-dlfunc
+
+Files: *
+Copyright: 2021 Heiko Reese <heiko.reese@kit.edu> 
+License: Apache-2.0
+
+Files: debian/*
+Copyright: 2021 Heiko Reese <heiko.reese@kit.edu>
+License: Apache-2.0
+
+License: Apache-2.0
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+ .
+ https://www.apache.org/licenses/LICENSE-2.0
+ .
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+ .
+ On Debian systems, the complete text of the Apache version 2.0 license
+ can be found in "/usr/share/common-licenses/Apache-2.0".
+

debian/rules

@@ -0,0 +1,25 @@
+#!/usr/bin/make -f
+# See debhelper(7) (uncomment to enable)
+# output every command that modifies files on the build system.
+export DH_VERBOSE = 1
+
+
+# see FEATURE AREAS in dpkg-buildflags(1)
+export DEB_BUILD_MAINT_OPTIONS = hardening=+all
+
+# see ENVIRONMENT in dpkg-buildflags(1)
+# package maintainers to append CFLAGS
+#export DEB_CFLAGS_MAINT_APPEND  = -Wall -pedantic
+# package maintainers to append LDFLAGS
+#export DEB_LDFLAGS_MAINT_APPEND = -Wl,--as-needed
+
+
+%:
+	dh $@
+
+
+# dh_make generated override targets
+# This is example for Cmake (See https://bugs.debian.org/641051 )
+#override_dh_auto_configure:
+#	dh_auto_configure -- \
+#	-DCMAKE_LIBRARY_PATH=$(DEB_HOST_MULTIARCH)