Read and write X25519 and X448 private keys

Signed-off-by: Jethro Beekman <jethro@fortanix.com>
Co-authored-by: Gijs Kwakkel <gijs.kwakkel@fortanix.com>
Signed-off-by: Gijs Kwakkel <gijs.kwakkel@fortanix.com>
diff --git a/ChangeLog.d/rfc8410.txt b/ChangeLog.d/rfc8410.txt
new file mode 100644
index 0000000..e2984ee
--- /dev/null
+++ b/ChangeLog.d/rfc8410.txt
@@ -0,0 +1,3 @@
+Features
+   * Add support for reading and writing X25519 and X448
+     public and private keys in RFC 8410 format using the existing PK APIs.