diff --git a/source-builder/sha512-base64 b/source-builder/sha512-base64
new file mode 100755
index 0000000..e6c8e1a
--- /dev/null
+++ b/source-builder/sha512-base64
@@ -0,0 +1,2 @@
+#! /bin/sh
+openssl dgst -binary -sha512 $1 | openssl base64 | sed '{N;s/\n//;}'