diff --git a/src/base_32.ml b/src/base_32.ml
index 5c111967..bbc96e96 100644
--- a/src/base_32.ml
+++ b/src/base_32.ml
@@ -21,4 +21,6 @@ let decode s =
         | c -> c)
       s
   in
-  Base32.decode ~alphabet ~off:0 ~len:(String.length s) s
+  match Base32.decode ~alphabet ~off:0 ~len:(String.length s) s with
+  | Error (`Msg e) -> Error e
+  | Ok v -> Ok v
diff --git a/src/dune b/src/dune
index c5d29ca9..7c13b657 100644
--- a/src/dune
+++ b/src/dune
@@ -1,13 +1,18 @@
 (executable
  (public_name mte)
  (name mte)
- (modules assets assets_crunch headers mte config util management)
+ (modules mte)
+ (libraries mte))
+
+(library
+ (name mte)
+ (wrapped false)
+ (modules :standard \ mte base_32)
  (libraries
-  json
-  types
-  headers_lib
-  syntax
+  base_32
   ;
+  angstrom
+  zarith ;
   mirage-crypto
   duration
   vif
@@ -15,29 +20,7 @@
   jsont
   cohttp))
 
-(library
- (name json)
- (modules json)
- (libraries jsont jsont.bytesrw fmt syntax types))
-
-(library
- (name types)
- (modules types)
- (libraries
-  angstrom
-  zarith ;
-  fmt
-  syntax))
-
-(library
- (name headers_lib)
- (modules headers_lib)
- (libraries fmt syntax))
-
-(library
- (name syntax)
- (modules syntax)
- (libraries))
+; crockford base32, as a lib to use [Base32] by accident *)
 
 (library
  (name base_32)
diff --git a/src/json.ml b/src/json.ml
index 580128df..876d5f5c 100644
--- a/src/json.ml
+++ b/src/json.ml
@@ -75,3 +75,12 @@ end
 
 let amount_jsont =
   Jsont.of_of_string ~kind:"Amount" Amount.of_string ~enc:Amount.to_string
+
+module Eddsa = struct
+  open Eddsa
+
+  let pub_jsont =
+    let dec = Jsont.Base.dec_result pub_of_string in
+    let enc = Jsont.Base.enc pub_to_string in
+    Jsont.Base.string (Jsont.Base.map ~kind:"EddsaPublicKey" ~dec ~enc ())
+end
diff --git a/src/types.ml b/src/types.ml
index d401b9bf..ef08f05f 100644
--- a/src/types.ml
+++ b/src/types.ml
@@ -112,20 +112,39 @@ module Amount = struct
 end
 
 module Eddsa = struct
+  (* TODO test *)
   (* EdDSA and ECDHE public keys always point on Curve25519
      and represented  using the standard 256 bits Ed25519 compact format,
      converted to Crockford Base32. *)
-  type pub = string
-  type priv = string
+  type pub = Mirage_crypto_ec.Ed25519.pub
 
+  let pub_of_string s =
+    let open Mirage_crypto_ec in
+    match Base_32.decode s with
+    | Error _ as err -> err
+    | Ok octets -> (
+        match Ed25519.pub_of_octets octets with
+        | Error e -> Fmt.error "%a" pp_error e
+        | Ok pub -> Ok pub)
+
+  let pub_to_string pub =
+    pub |> Mirage_crypto_ec.Ed25519.pub_to_octets |> Base_32.encode
+
+  (*type priv = string*)
   (* EdDSA signatures are transmitted as 64-bytes base32
    binary-encoded objects with just the R and S values (base32_ binary-only). *)
-  type signature = string
+  (*type signature = string*)
 end
 
 module Rsa = struct
   (* RSA public key converted to Crockford Base32. *)
-  type pub = string
+  type pub = Mirage_crypto_pk.Rsa.pub
+
+  (* TODO
+     how to read/write pub rsa key
+     what format is used? *)
+  let pub_of_string _s = assert false
+  let pub_to_string _pub = assert false
 end
 
 module Hash_code = struct
diff --git a/test/dune b/test/dune
index 6d9fb164..57d2e7e5 100644
--- a/test/dune
+++ b/test/dune
@@ -1,4 +1,4 @@
 (test
  (name test)
  (modules test)
- (libraries types json))
+ (libraries mte fmt))