diff --git a/hack/util/checkhash.sh b/hack/util/checkhash.sh
new file mode 100755
index 000000000..bd01194ad
--- /dev/null
+++ b/hack/util/checkhash.sh
@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+
+# Copyright 2021 The cert-manager Authors.
+#
+# 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
+#
+#     http://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.
+
+set -eu -o pipefail
+
+# This script takes the hash of its first argument and verifies it against the
+# hex hash given in its second argument
+
+SHASUM=$(./hack/util/hash.sh "$1")
+
+if [ $SHASUM != "$2"  ]; then
+	echo "invalid checksum for \"$1\": wanted \"$2\" but got \"$SHASUM\""
+	exit 1
+fi
diff --git a/hack/util/hash.sh b/hack/util/hash.sh
new file mode 100755
index 000000000..63add1009
--- /dev/null
+++ b/hack/util/hash.sh
@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+
+# Copyright 2021 The cert-manager Authors.
+#
+# 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
+#
+#     http://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.
+
+set -eu -o pipefail
+
+# This script is a wrapper for outputting purely the sha256 hash of the input file,
+# ideally in a portable way.
+
+sha256sum $1 | cut -d" " -f1