diff --git a/src/proto/alpha/TEZOS_PROTOCOL b/src/proto/alpha/TEZOS_PROTOCOL
index 6064904f2..21c25a9b6 100644
--- a/src/proto/alpha/TEZOS_PROTOCOL
+++ b/src/proto/alpha/TEZOS_PROTOCOL
@@ -23,6 +23,7 @@
         "Roll_repr",
         "Vote_repr",
         "Operation_repr",
+        "Manager_repr",
         "Block_header_repr",
 
         "Storage_sigs",
diff --git a/src/proto/alpha/apply.ml b/src/proto/alpha/apply.ml
index c4f2856a7..9933e97da 100644
--- a/src/proto/alpha/apply.ml
+++ b/src/proto/alpha/apply.ml
@@ -149,28 +149,15 @@ let apply_manager_operation_content
       Contract.set_delegate ctxt source delegate >>=? fun ctxt ->
       return (ctxt, origination_nonce, None)
 
-let check_signature_and_update_public_key ctxt id public_key op =
-  begin
-    match public_key with
-    | None -> return ctxt
-    | Some public_key ->
-        Public_key.reveal ctxt id public_key
-  end >>=? fun ctxt ->
-  Public_key.get ctxt id >>=? fun public_key ->
-  Operation.check_signature public_key op >>=? fun () ->
-  return ctxt
-
 let apply_sourced_operation
     ctxt baker_contract pred_block block_prio
     operation origination_nonce ops =
   match ops with
   | Manager_operations { source ; public_key ; fee ; counter ; operations = contents } ->
       Contract.must_exist ctxt source >>=? fun () ->
-      Contract.get_manager ctxt source >>=? fun manager ->
-      check_signature_and_update_public_key
-        ctxt manager public_key operation >>=? fun ctxt ->
-      Contract.check_counter_increment
-        ctxt source counter >>=? fun () ->
+      Contract.update_manager_key ctxt source public_key >>=? fun (ctxt,public_key) ->
+      Operation.check_signature public_key operation >>=? fun () ->
+      Contract.check_counter_increment ctxt source counter >>=? fun () ->
       Contract.increment_counter ctxt source >>=? fun ctxt ->
       Contract.spend ctxt source fee >>=? fun ctxt ->
       (match baker_contract with
@@ -187,10 +174,10 @@ let apply_sourced_operation
         (ctxt, origination_nonce, None) contents
   | Delegate_operations { source ; operations = contents } ->
       let delegate = Ed25519.Public_key.hash source in
-      check_signature_and_update_public_key
-        ctxt delegate (Some source) operation >>=? fun ctxt ->
+      Public_key.reveal ctxt delegate source >>=? fun ctxt ->
+      Operation.check_signature source operation >>=? fun () ->
       (* TODO, see how to extract the public key hash after this operation to
-         pass it to apply_delegate_operation_content *)
+       pass it to apply_delegate_operation_content *)
       fold_left_s (fun ctxt content ->
           apply_delegate_operation_content
             ctxt delegate pred_block block_prio content)
diff --git a/src/proto/alpha/contract_storage.ml b/src/proto/alpha/contract_storage.ml
index c3603b5b9..f530826c7 100644
--- a/src/proto/alpha/contract_storage.ml
+++ b/src/proto/alpha/contract_storage.ml
@@ -16,6 +16,9 @@ type error +=
   | Unspendable_contract of Contract_repr.contract (* `Permanent *)
   | Non_existing_contract of Contract_repr.contract (* `Temporary *)
   | Non_delegatable_contract of Contract_repr.contract (* `Permanent *)
+  | Inconsistent_hash of Ed25519.Public_key.t * Ed25519.Public_key_hash.t * Ed25519.Public_key_hash.t (* `Permanent *)
+  | Inconsistent_public_key of Ed25519.Public_key.t * Ed25519.Public_key.t (* `Permanent *)
+  | Missing_public_key of Ed25519.Public_key_hash.t (* `Permanent *)
   | Failure of string (* `Permanent *)
 
 let () =
@@ -129,6 +132,47 @@ let () =
     Data_encoding.(obj1 (req "contract" Contract_repr.encoding))
     (function Non_delegatable_contract c -> Some c | _ -> None)
     (fun c -> Non_delegatable_contract c) ;
+  register_error_kind
+    `Permanent
+    ~id:"contract.manager.inconsistent_hash"
+    ~title:"Inconsistent public key hash"
+    ~description:"A revealed manager public key is inconsistent with the announced hash"
+    ~pp:(fun ppf (k, eh, ph) ->
+        Format.fprintf ppf "The hash of the manager public key %s is not %a as announced but %a"
+          (Ed25519.Public_key.to_b58check k)
+          Ed25519.Public_key_hash.pp ph
+          Ed25519.Public_key_hash.pp eh)
+    Data_encoding.(obj3
+                     (req "public_key" Ed25519.Public_key.encoding)
+                     (req "expected_hash" Ed25519.Public_key_hash.encoding)
+                     (req "provided_hash" Ed25519.Public_key_hash.encoding))
+    (function Inconsistent_hash (k, eh, ph) -> Some (k, eh, ph) | _ -> None)
+    (fun (k, eh, ph) -> Inconsistent_hash (k, eh, ph)) ;
+  register_error_kind
+    `Permanent
+    ~id:"contract.manager.inconsistent_public_key"
+    ~title:"Inconsistent public key"
+    ~description:"A provided manager public key is different with the public key stored in the contract"
+    ~pp:(fun ppf (eh, ph) ->
+        Format.fprintf ppf "Expected manager public key %s but %s was provided"
+          (Ed25519.Public_key.to_b58check ph)
+          (Ed25519.Public_key.to_b58check eh))
+    Data_encoding.(obj2
+                     (req "public_key" Ed25519.Public_key.encoding)
+                     (req "expected_public_key" Ed25519.Public_key.encoding))
+    (function Inconsistent_public_key (eh, ph) -> Some (eh, ph) | _ -> None)
+    (fun (eh, ph) -> Inconsistent_public_key (eh, ph)) ;
+  register_error_kind
+    `Permanent
+    ~id:"contract.manager.missing_public_key"
+    ~title:"Missing public key"
+    ~description:"The manager public key must be provided to execute the current operation"
+    ~pp:(fun ppf (k) ->
+        Format.fprintf ppf "The manager public key ( with hash %a ) is missing"
+          Ed25519.Public_key_hash.pp k)
+    Data_encoding.(obj1 (req "hash" Ed25519.Public_key_hash.encoding))
+    (function Missing_public_key (k) -> Some (k) | _ -> None)
+    (fun (k) -> Missing_public_key (k)) ;
   register_error_kind
     `Permanent
     ~id:"contract.failure"
@@ -138,7 +182,7 @@ let () =
     Data_encoding.(obj1 (req "message" string))
     (function Failure s -> Some s | _ -> None)
     (fun s -> Failure s)
-
+ 
 let failwith msg = fail (Failure msg)
 
 let create_base c contract ~balance ~manager ~delegate ?script ~spendable ~delegatable =
@@ -146,7 +190,7 @@ let create_base c contract ~balance ~manager ~delegate ?script ~spendable ~deleg
    | None -> return 0l
    | Some _ -> Storage.Contract.Global_counter.get c) >>=? fun counter ->
   Storage.Contract.Balance.init c contract balance >>=? fun c ->
-  Storage.Contract.Manager.init c contract manager >>=? fun c ->
+  Storage.Contract.Manager.init c contract (Manager_repr.hash manager) >>=? fun c ->
   begin
     match delegate with
     | None -> return c
@@ -254,7 +298,28 @@ let get_manager c contract =
       | Some manager -> return manager
       | None -> failwith "get_manager"
     end
-  | Some v -> return v
+  | Some (Manager_repr.Hash v) -> return v
+  | Some (Manager_repr.Public_key v) -> return (Ed25519.Public_key.hash v)
+
+let update_manager_key c contract = function
+  | Some public_key ->
+    begin Storage.Contract.Manager.get c contract >>=? function
+    | (Manager_repr.Public_key v) -> (* key revealed for the second time *)
+        if Ed25519.Public_key.(v = public_key) then return (c,v)
+        else fail (Inconsistent_public_key (v,public_key))
+    | (Manager_repr.Hash v) ->
+        let actual_hash = Ed25519.Public_key.hash public_key in
+        if (Ed25519.Public_key_hash.equal actual_hash v) then
+          let v = (Manager_repr.public_key public_key) in
+          Storage.Contract.Manager.set c contract v >>=? fun c ->
+          return (c,public_key) (* reveal and update key *)
+        else fail (Inconsistent_hash (public_key,v,actual_hash))
+    end
+  | None -> 
+    begin Storage.Contract.Manager.get c contract >>=? function
+    | (Manager_repr.Public_key v) -> return (c,v) (* already revealed *)
+    | (Manager_repr.Hash v) -> fail (Missing_public_key (v))
+    end
 
 let get_delegate_opt = Roll_storage.get_contract_delegate
 
diff --git a/src/proto/alpha/contract_storage.mli b/src/proto/alpha/contract_storage.mli
index 15609fb1d..465bc79e5 100644
--- a/src/proto/alpha/contract_storage.mli
+++ b/src/proto/alpha/contract_storage.mli
@@ -16,6 +16,9 @@ type error +=
   | Unspendable_contract of Contract_repr.contract (* `Permanent *)
   | Non_existing_contract of Contract_repr.contract (* `Temporary *)
   | Non_delegatable_contract of Contract_repr.contract (* `Permanent *)
+  | Inconsistent_hash of Ed25519.Public_key.t * Ed25519.Public_key_hash.t * Ed25519.Public_key_hash.t (* `Permanent *)
+  | Inconsistent_public_key of Ed25519.Public_key.t * Ed25519.Public_key.t (* `Permanent *)
+  | Missing_public_key of Ed25519.Public_key_hash.t (* `Permanent *)
   | Failure of string (* `Permanent *)
 
 val delete : Storage.t -> Contract_repr.t -> Storage.t tzresult Lwt.t
@@ -32,6 +35,10 @@ val is_delegatable : Storage.t -> Contract_repr.t -> bool tzresult Lwt.t
 val is_spendable : Storage.t -> Contract_repr.t -> bool tzresult Lwt.t
 
 val get_manager: Storage.t -> Contract_repr.t -> Ed25519.Public_key_hash.t tzresult Lwt.t
+val update_manager_key:
+  Storage.t -> Contract_repr.t -> Ed25519.Public_key.t option ->
+    (Storage.t * Ed25519.Public_key.t) tzresult Lwt.t
+
 val get_delegate_opt: Storage.t -> Contract_repr.t -> Ed25519.Public_key_hash.t option tzresult Lwt.t
 val get_balance: Storage.t -> Contract_repr.t -> Tez_repr.t tzresult Lwt.t
 val get_counter: Storage.t -> Contract_repr.t -> int32 tzresult Lwt.t
diff --git a/src/proto/alpha/manager_repr.ml b/src/proto/alpha/manager_repr.ml
new file mode 100644
index 000000000..8fe03f252
--- /dev/null
+++ b/src/proto/alpha/manager_repr.ml
@@ -0,0 +1,53 @@
+(**************************************************************************)
+(*                                                                        *)
+(*    Copyright (c) 2014 - 2016.                                          *)
+(*    Dynamic Ledger Solutions, Inc. <contact@tezos.com>                  *)
+(*                                                                        *)
+(*    All rights reserved. No warranty, explicit or implicit, provided.   *)
+(*                                                                        *)
+(**************************************************************************)
+
+(* Tezos Protocol Implementation - Low level Repr. of Managers' keys *)
+
+type manager_key =
+  | Hash of Ed25519.Public_key_hash.t
+  | Public_key of Ed25519.Public_key.t
+
+type t = manager_key
+
+let hash hash = Hash hash
+let public_key hash = Public_key hash
+
+open Data_encoding
+
+let hash_encoding =
+  (obj1
+    (req "hash" Ed25519.Public_key_hash.encoding)
+  )
+
+let pubkey_encoding =
+  (obj1
+    (req "public_key" Ed25519.Public_key.encoding)
+  )
+
+let hash_case tag =
+  case ~tag hash_encoding
+  (function
+    | Hash hash -> Some hash
+    | _ -> None)
+  (fun hash -> Hash hash)
+
+let pubkey_case tag =
+  case ~tag pubkey_encoding
+  (function
+    | Public_key hash -> Some hash
+    | _ -> None)
+  (fun hash -> Public_key hash)
+
+
+let encoding =
+  union [
+    hash_case 0 ;
+    pubkey_case 1 ;
+  ]
+
diff --git a/src/proto/alpha/manager_repr.mli b/src/proto/alpha/manager_repr.mli
new file mode 100644
index 000000000..3607c3a0b
--- /dev/null
+++ b/src/proto/alpha/manager_repr.mli
@@ -0,0 +1,22 @@
+(**************************************************************************)
+(*                                                                        *)
+(*    Copyright (c) 2014 - 2016.                                          *)
+(*    Dynamic Ledger Solutions, Inc. <contact@tezos.com>                  *)
+(*                                                                        *)
+(*    All rights reserved. No warranty, explicit or implicit, provided.   *)
+(*                                                                        *)
+(**************************************************************************)
+
+(* Tezos Protocol Implementation - Low level Repr. of Managers' keys *)
+
+(** The public key of the manager of a contract is reveled only after the
+    first operation. At Origination time, the manager provides only the hash
+    of its public key that is stored in the contract. When the public key
+    is actually reveeld, the public key instead of the hash of the key *)
+type manager_key =
+  | Hash of Ed25519.Public_key_hash.t
+  | Public_key of Ed25519.Public_key.t
+
+type t = manager_key
+
+val encoding : t Data_encoding.encoding
diff --git a/src/proto/alpha/storage.ml b/src/proto/alpha/storage.ml
index 4adf6e3f7..f6f18c584 100644
--- a/src/proto/alpha/storage.ml
+++ b/src/proto/alpha/storage.ml
@@ -295,10 +295,10 @@ module Contract = struct
   module Manager =
     Make_indexed_data_storage(struct
       type key = Contract_repr.t
-      type value = Ed25519.Public_key_hash.t
+      type value = Manager_repr.t
       let name = "contract manager"
       let key = Key.Contract.manager
-      let encoding = Ed25519.Public_key_hash.encoding
+      let encoding = Manager_repr.encoding
     end)
 
   module Spendable =
diff --git a/src/proto/alpha/storage.mli b/src/proto/alpha/storage.mli
index ee4b5f243..554be84c0 100644
--- a/src/proto/alpha/storage.mli
+++ b/src/proto/alpha/storage.mli
@@ -136,7 +136,7 @@ module Contract : sig
   (** The manager of a contract *)
   module Manager : Indexed_data_storage
     with type key = Contract_repr.t
-     and type value = Ed25519.Public_key_hash.t
+     and type value = Manager_repr.t
      and type context := t
 
   (** The delegate of a contract, if any. *)
diff --git a/src/proto/alpha/tezos_context.mli b/src/proto/alpha/tezos_context.mli
index 3131c8aa0..71701c11f 100644
--- a/src/proto/alpha/tezos_context.mli
+++ b/src/proto/alpha/tezos_context.mli
@@ -424,6 +424,9 @@ module Contract : sig
 
   val get_manager:
     context -> contract -> public_key_hash tzresult Lwt.t
+  val update_manager_key:
+    context -> contract -> public_key option -> (context * public_key) tzresult Lwt.t
+
   val get_delegate_opt:
     context -> contract -> public_key_hash option tzresult Lwt.t
   val is_delegatable:
diff --git a/test/proto_alpha/proto_alpha_helpers.ml b/test/proto_alpha/proto_alpha_helpers.ml
index fc4e95643..31c9aedca 100644
--- a/test/proto_alpha/proto_alpha_helpers.ml
+++ b/test/proto_alpha/proto_alpha_helpers.ml
@@ -224,6 +224,7 @@ module Account = struct
   let set_delegate
       ?(block = `Prevalidation)
       ?(fee = 5L)
+      ?src_pk
       ~contract
       ~manager_sk
       delegate_opt =
@@ -234,6 +235,7 @@ module Account = struct
       ~source:contract
       ~manager_sk
       ~fee
+      ?src_pk
       delegate_opt
 
   let balance ?(block = `Prevalidation) (account : t) =
@@ -370,7 +372,19 @@ module Assert = struct
 
   let inconsistent_pkh ~msg =
     Assert.contain_error ~msg ~f:begin ecoproto_error (function
-        | Public_key_storage.Inconsistent_hash _ -> true
+        | Contract_storage.Inconsistent_hash _ -> true
+        | _ -> false)
+    end
+
+  let inconsistent_public_key ~msg =
+    Assert.contain_error ~msg ~f:begin ecoproto_error (function
+        | Contract_storage.Inconsistent_public_key _ -> true
+        | _ -> false)
+    end
+
+  let missing_public_key ~msg =
+    Assert.contain_error ~msg ~f:begin ecoproto_error (function
+        | Contract_storage.Missing_public_key _ -> true
         | _ -> false)
     end
 
diff --git a/test/proto_alpha/proto_alpha_helpers.mli b/test/proto_alpha/proto_alpha_helpers.mli
index 52b4c6452..1a288e0a9 100644
--- a/test/proto_alpha/proto_alpha_helpers.mli
+++ b/test/proto_alpha/proto_alpha_helpers.mli
@@ -78,6 +78,7 @@ module Account : sig
   val set_delegate :
     ?block:Client_proto_rpcs.block ->
     ?fee:int64 ->
+    ?src_pk:public_key ->
     contract:Contract.t ->
     manager_sk:secret_key ->
     public_key_hash option ->
@@ -176,6 +177,8 @@ module Assert : sig
   val balance_too_low : msg:string -> 'a tzresult -> unit
   val non_spendable : msg:string -> 'a tzresult -> unit
   val inconsistent_pkh : msg:string -> 'a tzresult -> unit
+  val inconsistent_public_key : msg:string -> 'a tzresult -> unit
+  val missing_public_key : msg:string -> 'a tzresult -> unit
 
   (** Origination assertions *)
 
diff --git a/test/proto_alpha/test_origination.ml b/test/proto_alpha/test_origination.ml
index eff35d7ae..501a6ada9 100644
--- a/test/proto_alpha/test_origination.ml
+++ b/test/proto_alpha/test_origination.ml
@@ -64,6 +64,7 @@ let run blkid ({ b1 ; b2 ; _ } : Helpers.Account.bootstrap_accounts) =
 
   (* Change delegate of a non-delegatable contract *)
   Helpers.Account.set_delegate
+    ~src_pk:b1.pk
     ~contract:nd_contract
     ~manager_sk:b1.sk
     (Some b2.pkh) >>= fun result ->
@@ -71,6 +72,7 @@ let run blkid ({ b1 ; b2 ; _ } : Helpers.Account.bootstrap_accounts) =
 
   (* Change delegate of a delegatable contract *)
   Helpers.Account.set_delegate
+    ~src_pk:b1.pk
     ~contract:d_contract
     ~manager_sk:b1.sk
     (Some b2.pkh) >>= fun _result ->
diff --git a/test/proto_alpha/test_transaction.ml b/test/proto_alpha/test_transaction.ml
index 71da3c41f..57d2c41a0 100644
--- a/test/proto_alpha/test_transaction.ml
+++ b/test/proto_alpha/test_transaction.ml
@@ -100,7 +100,7 @@ let run blkid ({ b1 ; b2 ; b3 ; _ } : Helpers.Account.bootstrap_accounts) =
     ~account
     ~destination:b2.contract
     ~amount:10_00L () >>= fun result ->
-  Assert.inconsistent_pkh ~msg:__LOC__ result ;
+  Assert.inconsistent_public_key ~msg:__LOC__ result ;
 
   return blkh