diff --git a/src/proto_alpha/lib_protocol/contract_repr.ml b/src/proto_alpha/lib_protocol/contract_repr.ml
index e7befb910d8a6f93d0e1b2ff18aa0a0a7461f3cf..3f4dc97444d614f83c42aa62893bbea93f0bde16 100644
--- a/src/proto_alpha/lib_protocol/contract_repr.ml
+++ b/src/proto_alpha/lib_protocol/contract_repr.ml
@@ -59,18 +59,35 @@ let to_b58check = function
   | Implicit pbk -> Signature.Public_key_hash.to_b58check pbk
   | Originated h -> Contract_hash.to_b58check h
 
-let of_b58check s =
+let implicit_of_b58data : Base58.data -> Signature.public_key_hash option =
+  function
+  | Ed25519.Public_key_hash.Data h -> Some (Signature.Ed25519 h)
+  | Secp256k1.Public_key_hash.Data h -> Some (Signature.Secp256k1 h)
+  | P256.Public_key_hash.Data h -> Some (Signature.P256 h)
+  | _ -> None
+
+let originated_of_b58data = function
+  | Contract_hash.Data h -> Some h
+  | _ -> None
+
+let contract_of_b58data data =
+  match implicit_of_b58data data with
+  | Some pkh -> Some (Implicit pkh)
+  | None -> (
+      match originated_of_b58data data with
+      | Some contract_hash -> Some (Originated contract_hash)
+      | None -> None)
+
+let of_b58check_gen ~of_b58data s =
   match Base58.decode s with
   | Some data -> (
-      match data with
-      | Ed25519.Public_key_hash.Data h -> ok (Implicit (Signature.Ed25519 h))
-      | Secp256k1.Public_key_hash.Data h ->
-          ok (Implicit (Signature.Secp256k1 h))
-      | P256.Public_key_hash.Data h -> ok (Implicit (Signature.P256 h))
-      | Contract_hash.Data h -> ok (Originated h)
-      | _ -> error (Invalid_contract_notation s))
+      match of_b58data data with
+      | Some c -> ok c
+      | None -> error (Invalid_contract_notation s))
   | None -> error (Invalid_contract_notation s)
 
+let of_b58check = of_b58check_gen ~of_b58data:contract_of_b58data
+
 let pp ppf = function
   | Implicit pbk -> Signature.Public_key_hash.pp ppf pbk
   | Originated h -> Contract_hash.pp ppf h
@@ -79,44 +96,78 @@ let pp_short ppf = function
   | Implicit pbk -> Signature.Public_key_hash.pp_short ppf pbk
   | Originated h -> Contract_hash.pp_short ppf h
 
-let cases is_contract to_contract =
-  Data_encoding.
-    [
-      case
-        (Tag 0)
-        ~title:"Implicit"
-        Signature.Public_key_hash.encoding
-        (fun k ->
-          match is_contract k with Some (Implicit k) -> Some k | _ -> None)
-        (fun k -> to_contract (Implicit k));
-      case
-        (Tag 1)
-        (Fixed.add_padding Contract_hash.encoding 1)
-        ~title:"Originated"
-        (fun k ->
-          match is_contract k with Some (Originated k) -> Some k | _ -> None)
-        (fun k -> to_contract (Originated k));
-    ]
+let implicit_case ~proj ~inj =
+  let open Data_encoding in
+  case (Tag 0) ~title:"Implicit" Signature.Public_key_hash.encoding proj inj
 
-let encoding =
+let originated_case ~proj ~inj =
+  let open Data_encoding in
+  case
+    (Tag 1)
+    (Fixed.add_padding Contract_hash.encoding 1)
+    ~title:"Originated"
+    proj
+    inj
+
+let cases is_contract to_contract =
+  [
+    implicit_case
+      ~proj:(fun k ->
+        match is_contract k with Some (Implicit k) -> Some k | _ -> None)
+      ~inj:(fun k -> to_contract (Implicit k));
+    originated_case
+      ~proj:(fun k ->
+        match is_contract k with Some (Originated k) -> Some k | _ -> None)
+      ~inj:(fun k -> to_contract (Originated k));
+  ]
+
+let encoding_gen ~id_extra ~title_extra ~can_be ~cases ~to_b58check ~of_b58data
+    =
   let open Data_encoding in
   def
-    "contract_id"
-    ~title:"A contract handle"
+    ("contract_id" ^ id_extra)
+    ~title:("A contract handle" ^ title_extra)
     ~description:
-      "A contract notation as given to an RPC or inside scripts. Can be a \
-       base58 implicit contract hash or a base58 originated contract hash."
+      ("A contract notation as given to an RPC or inside scripts. Can be a \
+        base58 " ^ can_be)
   @@ splitted
        ~binary:(union ~tag_size:`Uint8 @@ cases (fun x -> Some x) (fun x -> x))
        ~json:
          (conv
             to_b58check
             (fun s ->
-              match of_b58check s with
+              match of_b58check_gen ~of_b58data s with
               | Ok s -> s
               | Error _ -> Json.cannot_destruct "Invalid contract notation.")
             string)
 
+let encoding =
+  encoding_gen
+    ~id_extra:""
+    ~title_extra:""
+    ~can_be:"implicit contract hash or a base58 originated contract hash."
+    ~cases
+    ~to_b58check
+    ~of_b58data:contract_of_b58data
+
+let implicit_encoding =
+  encoding_gen
+    ~id_extra:".implicit"
+    ~title_extra:" -- implicit account"
+    ~can_be:"implicit contract hash."
+    ~cases:(fun proj inj -> [implicit_case ~proj ~inj])
+    ~to_b58check:Signature.Public_key_hash.to_b58check
+    ~of_b58data:implicit_of_b58data
+
+let originated_encoding =
+  encoding_gen
+    ~id_extra:".originated"
+    ~title_extra:" -- originated account"
+    ~can_be:"originated contract hash."
+    ~cases:(fun proj inj -> [originated_case ~proj ~inj])
+    ~to_b58check:Contract_hash.to_b58check
+    ~of_b58data:originated_of_b58data
+
 let () =
   let open Data_encoding in
   register_error_kind
diff --git a/src/proto_alpha/lib_protocol/contract_repr.mli b/src/proto_alpha/lib_protocol/contract_repr.mli
index a818e5654e774b2117fb33eefbb495dcb448fa0e..ac3695a6f81b37a1d16862bb9f2ceba988288a89 100644
--- a/src/proto_alpha/lib_protocol/contract_repr.mli
+++ b/src/proto_alpha/lib_protocol/contract_repr.mli
@@ -75,6 +75,14 @@ val pp_short : Format.formatter -> t -> unit
 
 val encoding : t Data_encoding.t
 
+(** [implicit_encoding] is an encoding for public key hashes that is
+    compatible with the [encoding] of contracts for implicit accounts. *)
+val implicit_encoding : Signature.Public_key_hash.t Data_encoding.t
+
+(** [originated_encoding] is an encoding for contract hashes that is
+    compatible with the [encoding] of contracts for originated accounts. *)
+val originated_encoding : Contract_hash.t Data_encoding.t
+
 (** [cases f g] exports the {!Data_encoding.cases} used to define {!encoding}.
 
     The only reason why we export that is to let {!Destination_repr.encoding}