Add script to sign arbitrary files using the key stored in Secrets Manager

sign.sh

@@ -0,0 +1,41 @@
+#!/bin/bash
+set -euo pipefail
+
+if [[ "${2:-}" == "" ]]; then
+    echo "Usage: sign.sh ARTIFACTTYPE FILE [FILE...]" >&2
+    echo "">&2
+    echo "Creates detached signature as FILE.sig." >&2
+    exit 1
+fi
+
+tmpdir=$(mktemp -d)
+trap "shred $tmpdir/* && rm -rf $tmpdir" EXIT
+
+SECRET=CDK/$1/SigningKey
+
+# Use secrets manager to obtain the key and passphrase into a JSON file
+echo "Retrieving key $SECRET..." >&2
+aws secretsmanager get-secret-value --secret-id "$SECRET" --output text --query SecretString > $tmpdir/secret.txt
+
+value-from-secret() {
+    node -e "console.log(JSON.parse(require('fs').readFileSync('$tmpdir/secret.txt', { encoding: 'utf-8' })).$1)"
+}
+
+passphrase=$(value-from-secret Passphrase)
+
+echo "Importing key..." >&2
+gpg --homedir $tmpdir --import <(value-from-secret PrivateKey)
+
+while [[ "${2:-}" != "" ]]; do
+    echo "Signing $2..." >&2
+    echo $passphrase | gpg \
+        --homedir $tmpdir \
+        --local-user [email protected] \
+        --batch --yes \
+        --passphrase-fd 0 \
+        --output $2.sig \
+        --detach-sign $2
+    shift
+done
+
+echo "Done!" >&2