fix currency bin encoding

src/crypto.ml

@@ -113,17 +113,19 @@ module RsaPublicKey = struct
       String.sub src pos len |> rev_string len |> Z.of_bits
 
     let to_octets ({ n; e } : Mirage_crypto_pk.Rsa.pub) =
-      let n_len = Z.size n in
-      let e_len = Z.size e in
+      let n = Z.to_bits n in
+      let e = Z.to_bits e in
+      let n_len = String.length n in
+      let e_len = String.length e in
       let len = 4 + n_len + e_len in
       let b = Bytes.make len '\x00' in
       Bytes.set_uint16_be b 0 n_len;
       Bytes.set_uint16_be b 2 e_len;
-      let n = Z.to_bits n |> rev_string n_len in
-      let e = Z.to_bits e |> rev_string e_len in
+      let n = rev_string n_len n in
+      let e = rev_string e_len e in
       Bytes.blit_string n 0 b 4 n_len;
       Bytes.blit_string e 0 b (4 + n_len) e_len;
-      Bytes.unsafe_to_string b
+      Bytes.to_string b
 
     let of_octets =
       let check = function
@@ -131,8 +133,6 @@ module RsaPublicKey = struct
         | true -> Ok ()
       in
       fun s ->
-        Result.get_ok
-        @@
         let open Syntax in
         let len = String.length s in
         let* () = check (len >= 4) in
@@ -142,6 +142,11 @@ module RsaPublicKey = struct
         let n = z_of_bits_be s 4 n_len in
         let e = z_of_bits_be s (4 + n_len) e_len in
         Mirage_crypto_pk.Rsa.pub ~n ~e |> unwrap_err_msg
+
+    let of_octets s =
+      match of_octets s with
+      | Error e -> Fmt.failwith "RsaPublicKey.of_octets failure: %s@." e
+      | Ok v -> v
   end
 
   include Binary