diff --git a/newsfragments/4094.feature b/newsfragments/4094.feature
new file mode 100644
index 000000000..85c98f3d5
--- /dev/null
+++ b/newsfragments/4094.feature
@@ -0,0 +1 @@
+Mutable directories can now be created with a pre-determined "signature key" via the web API using the "private-key=..." parameter. The "private-key" value must be a DER-encoded 2048-bit RSA private key in urlsafe base64 encoding.