diff --git a/src/binary_formats.ml b/src/binary_formats.ml
index 369908ec..502d0c3f 100644
--- a/src/binary_formats.ml
+++ b/src/binary_formats.ml
@@ -2,6 +2,13 @@
 
    - numeric values are in network byte order (big endian) *)
 
+(* TODO
+   use Bin.seq instead of Bin.bytes?
+   less boilerplate (just make type t abstract)?
+   padding issues?
+   how to encode union?
+   test *)
+
 (* -- Time -- *)
 
 module Time = struct
@@ -181,32 +188,91 @@ module Master_public_key_p = MAKE_EDDSA_PUB ()
 module Master_private_key_p = MAKE_EDDSA_PRIV ()
 module Master_signature_p = MAKE_EDDSA_SIG ()
 
+module Wire_transfert_identifier_raw_p = struct
+  (* uint8_t raw[32]; *)
+  type t = { raw: string }
+
+  let bin =
+    let open Bin in
+    record (fun raw -> { raw }) |+ field (bytes 32) (fun t -> t.raw) |> sealr
+end
+
+module UUID = struct
+  (* uint32_t value[4]; *)
+  type t = { value: string }
+
+  let bin =
+    let open Bin in
+    record (fun value -> { value })
+    |+ field (bytes (4 * 4)) (fun t -> t.value)
+    |> sealr
+end
+
+module Wad_id = struct
+  (* uint32_t value[6]; *)
+  type t = { raw: string }
+
+  let bin =
+    let open Bin in
+    record (fun raw -> { raw })
+    |+ field (bytes (4 * 6)) (fun t -> t.raw)
+    |> sealr
+end
+
+(* TODO not sure what to do of unions *)
+(*
+union TALER_CoinSpendPublicKeyP {
+  uint8_t eddsa_pub[32];
+  uint8_t ecdhe_pub[32];
+};
+union TALER_CoinSpendPrivateKeyP {
+  uint8_t eddsa_priv[32];
+  uint8_t ecdhe_priv[32];
+};
+*)
+
+module Coin_spend_signature_p = MAKE_EDDSA_SIG ()
+
+(* TODO padding: sizeof used here (assume no padding for now) *)
+(*
+struct TALER_TransferSecretP {
+  uint8_t key[sizeof (struct GNUNET_HashCode)];
+};
+  uint8_t key[sizeof (struct GNUNET_HashCode)];
+};
+struct TALER_EncryptedLinkSecretP {
+  uint8_t enc[sizeof (struct TALER_LinkSecretP)];
+};
+*)
+module Transfert_secret_p = MAKE_H (Hash_code)
+module Link_secret_p = MAKE_H (Hash_code)
+module Encrypted_link_secret_p = MAKE_H (Hash_code)
+
+(*
+union TALER_TokenPublicKeyP {
+  uint8_t eddsa_pub[32];
+  uint8_t ecdhe_pub[32];
+};
+*)
+
 (* -- Signatures -- *)
 
-module Purpose = struct
-  (* defined in gnunet_crypto_lib.h *)
+module Ecc_signature_purpose = struct
   type t = {
     (* This field equals the number of bytes being signed,
        namely 'sizeof (struct Data)'. *)
-    size: int32; (* = uint32_t *)
+    size: int32;
     (* This field is used to express the context in
        which the signature is made, ensuring that a
        signature cannot be lifted from one part of the protocol
        to another. *)
-    purpose: int32; (* = uint32_t *)
+    purpose: int32;
   }
 
-  let t_bin =
+  let bin =
     let open Bin in
     record (fun size purpose -> { size; purpose })
     |+ field beint32 (fun t -> t.size)
     |+ field beint32 (fun t -> t.purpose)
     |> sealr
 end
-
-module Data = struct
-  type t = {
-    purpose: Purpose.t;
-    payloads: string list;
-  }
-end