fix secmod + FAT

src/crypto.ml

@@ -238,6 +238,23 @@ module RsaPrivateKey = struct
   let of_octets = Binary_format_rsa.priv_of_octets
   let to_octets = Binary_format_rsa.priv_to_octets
 
+  (* we use Bin.cstring because size of key (~bits) can change depending on section_name
+     we also have to b32 encode/decode our octets because of null-char
+
+     enforce all to be of the same size instead? *)
+  let bin =
+    let of_octets_exn s =
+      let res =
+        let* s = B32.decode s in
+        of_octets s
+      in
+      match res with
+      | Error e -> Fmt.failwith "RsaPrivateKey.bin decoding failure: %s." e
+      | Ok t -> t
+    in
+    let to_octets t = to_octets t |> B32.encode in
+    Bin.map Bin.cstring of_octets_exn to_octets
+
   let jsont =
     let of_b32 s =
       let* s = B32.decode s in