diff --git a/src/lib_protocol_environment/environment_V8.ml b/src/lib_protocol_environment/environment_V8.ml
index fa3dd867e57b22fb2e2355cde46198e4f0c97558..f1c18d359ba172a15e4cee9a85f795be7350c18c 100644
--- a/src/lib_protocol_environment/environment_V8.ml
+++ b/src/lib_protocol_environment/environment_V8.ml
@@ -1109,9 +1109,6 @@ struct
 
     type reveal_hash = Tezos_scoru_wasm.Wasm_pvm_state.reveal_hash
 
-    let reveal_hash_to_string =
-      Tezos_scoru_wasm.Wasm_pvm_state.reveal_hash_to_string
-
     type reveal = Tezos_scoru_wasm.Wasm_pvm_state.reveal =
       | Reveal_raw_data of reveal_hash
       | Reveal_metadata
diff --git a/src/lib_protocol_environment/sigs/v8.ml b/src/lib_protocol_environment/sigs/v8.ml
index 681cb2e250a354dee9efb0b6297fe29d67d2c3d4..3bb0f6ea81036bf91243fb222a8556dbe9c17a7e 100644
--- a/src/lib_protocol_environment/sigs/v8.ml
+++ b/src/lib_protocol_environment/sigs/v8.ml
@@ -12082,9 +12082,7 @@ type input = {inbox_level : Bounded.Non_negative_int32.t; message_counter : Z.t}
 
 type output = {outbox_level : Bounded.Non_negative_int32.t; message_index : Z.t}
 
-type reveal_hash
-
-val reveal_hash_to_string : reveal_hash -> string
+type reveal_hash = string
 
 type reveal = Reveal_raw_data of reveal_hash | Reveal_metadata
 
diff --git a/src/lib_protocol_environment/sigs/v8/wasm_2_0_0.mli b/src/lib_protocol_environment/sigs/v8/wasm_2_0_0.mli
index c696ead44f0e78028695e828278ff699fec2bddf..8b7062f5a2215d0ce15ef0859ca129dae8f8a465 100644
--- a/src/lib_protocol_environment/sigs/v8/wasm_2_0_0.mli
+++ b/src/lib_protocol_environment/sigs/v8/wasm_2_0_0.mli
@@ -27,9 +27,7 @@ type input = {inbox_level : Bounded.Non_negative_int32.t; message_counter : Z.t}
 
 type output = {outbox_level : Bounded.Non_negative_int32.t; message_index : Z.t}
 
-type reveal_hash
-
-val reveal_hash_to_string : reveal_hash -> string
+type reveal_hash = string
 
 type reveal = Reveal_raw_data of reveal_hash | Reveal_metadata
 
diff --git a/src/lib_scoru_wasm/builtins.ml b/src/lib_scoru_wasm/builtins.ml
index 5e68b4e41e594a05c070d567e08cdf788125b5d9..7b396c777c6ea24b3003f5bddda68be6ee037c0a 100644
--- a/src/lib_scoru_wasm/builtins.ml
+++ b/src/lib_scoru_wasm/builtins.ml
@@ -23,11 +23,9 @@
 (*                                                                           *)
 (*****************************************************************************)
 
-open Tezos_webassembly_interpreter
-
 module type S = sig
-  (** [reveal_preimage hash] reveals the preimage of the given 32-byte hash. *)
-  val reveal_preimage : Reveal.reveal_hash -> string Lwt.t
+  (** [reveal_preimage hash] reveals the preimage of the given hash. *)
+  val reveal_preimage : string -> string Lwt.t
 
   (** [reveal_metadata ()] returns the encoded metadata for the rollup. *)
   val reveal_metadata : unit -> string Lwt.t
diff --git a/src/lib_scoru_wasm/fast/funcs.ml b/src/lib_scoru_wasm/fast/funcs.ml
index baa1c3a292ca4b6c7ab13aa890bce97fbb6a3e18..8fbe864a5f16be78034d5e800844a7bffc89db65 100644
--- a/src/lib_scoru_wasm/fast/funcs.ml
+++ b/src/lib_scoru_wasm/fast/funcs.ml
@@ -272,34 +272,41 @@ let make (module Builtins : Builtins.S) state =
           ~key_offset
           ~key_length)
   in
+  (* TODO: https://gitlab.com/tezos/tezos/-/issues/4369
+     Align failure mode of reveal_* functions in Fast Execution. *)
   let reveal_preimage =
     fn
-      (i32 @-> i32 @-> i32 @-> returning1 i32)
-      (fun hash_addr dest max_bytes ->
+      (i32 @-> i32 @-> i32 @-> i32 @-> returning1 i32)
+      (fun hash_addr hash_size dest max_bytes ->
         let mem = state.retrieve_mem () in
+        let hash_size = Int32.to_int hash_size in
         let hash_addr = Int32.to_int hash_addr in
         let dest = Int32.to_int dest in
         let max_bytes = Int32.to_int max_bytes in
-        let hash =
-          String.init 32 (fun i ->
-              (* XXX: No bounds checks
-                 The "main" reveal function does not deal with out-of-bounds
-                 scenarios. That ultimate means we don't return error codes.
-                 Instead, we just fail with the exception being thrown.
-                 In most cases the Fast Exec mechanism will fall back to another
-                 execution mode to deal with this. *)
-              Memory.get mem (hash_addr + i)
-              |> Unsigned.UInt8.to_int |> Char.chr)
-          |> Tezos_webassembly_interpreter.Reveal.reveal_hash_from_string_exn
-        in
-        let+ payload = Builtins.reveal_preimage hash in
-        let revealed_bytes = min (String.length payload) max_bytes in
-        let payload = String.sub payload 0 revealed_bytes in
-        String.iteri
-          (fun i c ->
-            Char.code c |> Unsigned.UInt8.of_int |> Memory.set mem (dest + i))
-          payload ;
-        Int32.of_int revealed_bytes)
+        (* If hash_size is too large we fail and fallback to another execution
+           mode.*)
+        if hash_size > Host_funcs.Aux.input_output_max_size then
+          raise @@ Invalid_argument "Hash size too large"
+        else
+          let hash =
+            String.init hash_size (fun i ->
+                (* XXX: No bounds checks
+                   The "main" reveal function does not deal with out-of-bounds
+                   scenarios. That ultimate means we don't return error codes.
+                   Instead, we just fail with the exception being thrown.
+                   In most cases the Fast Exec mechanism will fall back to another
+                   execution mode to deal with this. *)
+                Memory.get mem (hash_addr + i)
+                |> Unsigned.UInt8.to_int |> Char.chr)
+          in
+          let+ payload = Builtins.reveal_preimage hash in
+          let revealed_bytes = min (String.length payload) max_bytes in
+          let payload = String.sub payload 0 revealed_bytes in
+          String.iteri
+            (fun i c ->
+              Char.code c |> Unsigned.UInt8.of_int |> Memory.set mem (dest + i))
+            payload ;
+          Int32.of_int revealed_bytes)
   in
   let reveal_metadata =
     fn
diff --git a/src/lib_scoru_wasm/host_funcs.ml b/src/lib_scoru_wasm/host_funcs.ml
index 6a4761b88fd5c2584cce7f6726058860ac3c4894..42e597bfd2692103b7746570b1eb23487b87119b 100644
--- a/src/lib_scoru_wasm/host_funcs.ml
+++ b/src/lib_scoru_wasm/host_funcs.ml
@@ -111,6 +111,9 @@ module Aux = struct
   module type S = sig
     type memory
 
+    (** max size of intputs and outputs. *)
+    val input_output_max_size : int
+
     (** [write_output ~output_buffer ~memory ~src ~num_bytes] reads
      num_bytes from the memory of module_inst starting at src and writes
      this to the output_buffer. It also checks that the input payload is
@@ -893,20 +896,32 @@ let reveal_preimage_name = "tezos_reveal_preimage"
 
 let reveal_preimage_type =
   let input_types =
-    Types.[NumType I32Type; NumType I32Type; NumType I32Type] |> Vector.of_list
+    Types.[NumType I32Type; NumType I32Type; NumType I32Type; NumType I32Type]
+    |> Vector.of_list
   in
   let output_types = Types.[NumType I32Type] |> Vector.of_list in
   Types.FuncType (input_types, output_types)
 
 let reveal_preimage_parse_args memories args =
   match args with
-  | Values.[Num (I32 hash_addr); Num (I32 base); Num (I32 max_bytes)] ->
+  | Values.
+      [
+        Num (I32 hash_addr);
+        Num (I32 hash_size);
+        Num (I32 base);
+        Num (I32 max_bytes);
+      ] ->
       let open Lwt_result_syntax in
       let*! memory = retrieve_memory memories in
-      let*! hash = Memory_access_interpreter.load_bytes memory hash_addr 32 in
-      Lwt_result.return
-        ( Reveal.(Reveal_raw_data (reveal_hash_from_string_exn hash)),
-          Host_funcs.{base; max_bytes} )
+      let hash_size = Int32.to_int hash_size in
+      if hash_size > Aux.input_output_max_size then
+        fail (Error.code Input_output_too_large)
+      else
+        let*! hash =
+          Memory_access_interpreter.load_bytes memory hash_addr hash_size
+        in
+        Lwt_result.return
+          (Host_funcs.(Reveal_raw_data hash), Host_funcs.{base; max_bytes})
   | _ -> raise Bad_input
 
 let reveal_preimage = Host_funcs.Reveal_func reveal_preimage_parse_args
@@ -927,7 +942,8 @@ let reveal_metadata_parse_args _memories args =
   | Values.[Num (I32 base)] ->
       Lwt.return
         (Ok
-           (Reveal.Reveal_metadata, Host_funcs.{base; max_bytes = metadata_size}))
+           ( Host_funcs.Reveal_metadata,
+             Host_funcs.{base; max_bytes = metadata_size} ))
   | _ -> raise Bad_input
 
 let reveal_metadata = Host_funcs.Reveal_func reveal_metadata_parse_args
diff --git a/src/lib_scoru_wasm/host_funcs.mli b/src/lib_scoru_wasm/host_funcs.mli
index f079f7235caa1942ad5496a28b4ef112faf0c6c2..0b9736244b2316bc6075e9abffe4e37d53b5a222 100644
--- a/src/lib_scoru_wasm/host_funcs.mli
+++ b/src/lib_scoru_wasm/host_funcs.mli
@@ -103,6 +103,9 @@ module Aux : sig
   module type S = sig
     type memory
 
+    (** max size of intputs and outputs. *)
+    val input_output_max_size : int
+
     (** [aux_write_output ~input_buffer ~output_buffer ~module_inst ~src
      ~num_bytes] reads num_bytes from the memory of module_inst starting at
      src and writes this to the output_buffer. It also checks that
diff --git a/src/lib_scoru_wasm/test/helpers/ast_generators.ml b/src/lib_scoru_wasm/test/helpers/ast_generators.ml
index af91a202823fb706d1a4ab046f78bf73fafbe603..a98ccad357c66a99dbd13106f7c6fd19a9a2d3e7 100644
--- a/src/lib_scoru_wasm/test/helpers/ast_generators.ml
+++ b/src/lib_scoru_wasm/test/helpers/ast_generators.ml
@@ -758,7 +758,7 @@ let inv_concat_gen ~module_reg =
   Eval.Inv_concat {arity; vs; instructions; inst; func; concat_kont}
 
 let inv_reveal_tick ~module_reg =
-  let* hash = Reveal.reveal_hash_from_string_exn <$> string_size (pure 32) in
+  let* hash = string_small in
   let* base_destination = Int32.of_int <$> small_nat in
   let* max_bytes = Int32.of_int <$> small_nat in
   let* vs = small_vector_gen value_gen in
diff --git a/src/lib_scoru_wasm/test/helpers/ast_printer.ml b/src/lib_scoru_wasm/test/helpers/ast_printer.ml
index e7b5a13bcde509b7f15c44c09585f53436983d7e..9f104dfb2d5ce5ad9e912853eca09cb65e2fcdf2 100644
--- a/src/lib_scoru_wasm/test/helpers/ast_printer.ml
+++ b/src/lib_scoru_wasm/test/helpers/ast_printer.ml
@@ -428,11 +428,8 @@ let pp_concat_kont pp out Eval.{lv; rv; res; offset} =
     offset
 
 let pp_reveal out = function
-  | Reveal.Reveal_raw_data hash ->
-      Format.fprintf
-        out
-        "Reveal_raw_data (%s)"
-        (Reveal.reveal_hash_to_string hash)
+  | Host_funcs.Reveal_raw_data hash ->
+      Format.fprintf out "Reveal_raw_data (%s)" hash
   | Reveal_metadata -> Format.fprintf out "Reveal_metadata"
 
 let pp_invoke_step_kont out = function
diff --git a/src/lib_scoru_wasm/test/test_fast.ml b/src/lib_scoru_wasm/test/test_fast.ml
index 7ad62747c2aea18b651555018a5447acf7176fb8..06de0768be220597d772a116dc5680cc9624d31c 100644
--- a/src/lib_scoru_wasm/test/test_fast.ml
+++ b/src/lib_scoru_wasm/test/test_fast.ml
@@ -24,7 +24,6 @@
 (*****************************************************************************)
 
 open Tztest
-open Tezos_webassembly_interpreter
 module Preimage_map = Map.Make (String)
 open Wasm_utils
 
@@ -33,7 +32,6 @@ let apply_fast ?(images = Preimage_map.empty) counter tree =
   let run_counter = ref 0l in
   let module Builtins = struct
     let reveal_preimage hash =
-      let hash = Reveal.reveal_hash_to_string hash in
       match Preimage_map.find hash images with
       | None -> Stdlib.failwith "Failed to find preimage"
       | Some preimage -> Lwt.return preimage
@@ -78,7 +76,6 @@ and check_reveal ?(images = Preimage_map.empty) tree =
   let* info = Wasm_utils.Wasm.get_info tree in
   match info.input_request with
   | Reveal_required (Reveal_raw_data hash) -> (
-      let hash = Reveal.reveal_hash_to_string hash in
       match Preimage_map.find hash images with
       | None -> Lwt.return tree
       | Some preimage ->
@@ -239,7 +236,7 @@ let test_store_read_write =
   test_against_both ~from_binary:false ~kernel ~messages:(List.repeat 100 "")
 
 let test_reveal_preimage =
-  let example_hash = "this represents the 32-byte hash" in
+  let example_hash = "this represents the 33-byte hash " in
   let example_preimage = "This is the expected preimage" in
   let images = Preimage_map.singleton example_hash example_preimage in
 
@@ -256,12 +253,12 @@ let test_reveal_preimage =
   (import
     "smart_rollup_core"
     "reveal_preimage"
-    (func $reveal_preimage (param i32 i32 i32) (result i32))
+    (func $reveal_preimage (param i32 i32 i32 i32) (result i32))
   )
 
   (memory 1)
-  (export "memory" (memory 0))
 
+  (export "memory" (memory 0))
   (data (i32.const 0) "%s") ;; The hash we want to reveal
   (data (i32.const 100) "/foo")
 
@@ -270,6 +267,8 @@ let test_reveal_preimage =
     (call $reveal_preimage
       ;; Address of the hash
       (i32.const 0)
+      ;; size of the hash
+      (i32.const 33)
       ;; Destination address and length
       (i32.const 1000) (i32.const 1000)
     )
diff --git a/src/lib_scoru_wasm/test/test_reveal.ml b/src/lib_scoru_wasm/test/test_reveal.ml
index 3e79c9d48388f4b19025f98cbe78c60a29de60aa..77304e67f420d46d4b8f52a733001596f648b1a4 100644
--- a/src/lib_scoru_wasm/test/test_reveal.ml
+++ b/src/lib_scoru_wasm/test/test_reveal.ml
@@ -36,21 +36,22 @@ open Tezos_webassembly_interpreter
 open Tezos_scoru_wasm
 open Wasm_utils
 
-let reveal_preimage_module hash_addr preimage_addr max_bytes =
+let reveal_preimage_module hash_addr hash_size preimage_addr max_bytes =
   Format.sprintf
     {|
       (module
         (import "smart_rollup_core" "reveal_preimage"
-          (func $reveal_preimage (param i32 i32 i32) (result i32))
+          (func $reveal_preimage (param i32 i32 i32 i32) (result i32))
         )
         (memory 1)
         (export "mem" (memory 0))
         (func (export "kernel_run")
-          (call $reveal_preimage (i32.const %ld) (i32.const %ld) (i32.const %ld))
+          (call $reveal_preimage (i32.const %ld) (i32.const %ld) (i32.const %ld) (i32.const %ld))
         )
       )
     |}
     hash_addr
+    hash_size
     preimage_addr
     max_bytes
 
@@ -95,7 +96,10 @@ let test_reveal_preimage_gen preimage max_bytes =
   let open Lwt_result_syntax in
   let hash_addr = 120l in
   let preimage_addr = 200l in
-  let modl = reveal_preimage_module hash_addr preimage_addr max_bytes in
+  let hash_size = 33l in
+  let modl =
+    reveal_preimage_module hash_addr hash_size preimage_addr max_bytes
+  in
   let*! state = initial_tree modl in
   let*! state_snapshotted = eval_until_input_requested state in
   let*! state_with_dummy_input = set_empty_inbox_step 0l state_snapshotted in
@@ -109,9 +113,7 @@ let test_reveal_preimage_gen preimage max_bytes =
         (* The PVM has reached a point where it’s asking for some
            preimage. Since the memory is left blank, we are looking
            for the zero hash *)
-        let zero_hash =
-          Reveal.reveal_hash_from_string_exn (String.make 32 '\000')
-        in
+        let zero_hash = String.make (Int32.to_int hash_size) '\000' in
         assert (hash = zero_hash) ;
         return_unit
     | No_input_required | Input_required | Reveal_required _ -> assert false
@@ -218,7 +220,6 @@ let apply_fast ?(images = Preimage_map.empty) tree =
   let run_counter = ref 0l in
   let module Builtins = struct
     let reveal_preimage hash =
-      let hash = Reveal.reveal_hash_to_string hash in
       match Preimage_map.find hash images with
       | None -> Stdlib.failwith "Failed to find preimage"
       | Some preimage -> Lwt.return preimage
@@ -244,7 +245,7 @@ let apply_fast ?(images = Preimage_map.empty) tree =
 
 let test_fast_exec_reveal () =
   let open Lwt.Syntax in
-  let example_hash = "this represents the 32-byte hash" in
+  let example_hash = "this represents the 33-byte hash!" in
   let example_preimage = "This is the expected preimage" in
   let images = Preimage_map.singleton example_hash example_preimage in
 
@@ -261,7 +262,7 @@ let test_fast_exec_reveal () =
   (import
     "smart_rollup_core"
     "reveal_preimage"
-    (func $reveal_preimage (param i32 i32 i32) (result i32))
+    (func $reveal_preimage (param i32 i32 i32 i32) (result i32))
   )
 
   (memory 1)
@@ -275,6 +276,8 @@ let test_fast_exec_reveal () =
     (call $reveal_preimage
       ;; Address of the hash
       (i32.const 0)
+      ;; Size of the hash
+      (i32.const 33)
       ;; Destination address and length
       (i32.const 1000) (i32.const 1000)
     )
diff --git a/src/lib_scoru_wasm/test/test_wasm_pvm.ml b/src/lib_scoru_wasm/test/test_wasm_pvm.ml
index 96ff17748cfc0a8823dc3a2be0386dd9066f3eec..c00b7816fce8a5e34e179ebfb252550cbc4a36fc 100644
--- a/src/lib_scoru_wasm/test/test_wasm_pvm.ml
+++ b/src/lib_scoru_wasm/test/test_wasm_pvm.ml
@@ -912,8 +912,8 @@ let reveal_upgrade_kernel () =
   let path_start = 23 in
   let path_len = String.length path in
   let hash_start = path_start + path_len in
-  let buffer_start = hash_start + 32 in
-  (* 32 bytes for reveal hash *)
+  let buffer_start = hash_start + 33 in
+  (* 33 bytes for reveal hash *)
   Format.sprintf
     {|
 (module
@@ -922,7 +922,7 @@ let reveal_upgrade_kernel () =
   (import "smart_rollup_core" "store_delete"
     (func $store_delete (param i32 i32) (result i32)))
   (import "smart_rollup_core" "reveal_preimage"
-    (func $reveal_preimage (param i32 i32 i32) (result i32)))
+    (func $reveal_preimage (param i32 i32 i32 i32) (result i32)))
   (func (export "kernel_run")
     (local $preimage_size i32)
 
@@ -938,6 +938,7 @@ let reveal_upgrade_kernel () =
 
     (local.set $preimage_size
      (call $reveal_preimage (local.get $hash_start)
+                            (i32.const 33)
                             (local.get $buffer_start)
                             ;; buffer size
                             (i32.const 4096)))
@@ -1016,10 +1017,7 @@ let test_reveal_upgrade_kernel_ok () =
         (* The PVM has reached a point where it’s asking for some
            preimage. Since the memory is left blank, we are looking
            for the zero hash *)
-        let zero_hash =
-          Tezos_webassembly_interpreter.Reveal.reveal_hash_from_string_exn
-            (String.make 32 '\000')
-        in
+        let zero_hash = String.make 33 '\000' in
         assert (hash = zero_hash) ;
         return_unit
     | No_input_required | Input_required | Reveal_required _ -> assert false
@@ -1095,10 +1093,7 @@ let test_reveal_upgrade_kernel_fallsback_on_error ~binary ~error invalid_kernel
         (* The PVM has reached a point where it’s asking for some
            preimage. Since the memory is left blank, we are looking
            for the zero hash *)
-        let zero_hash =
-          Tezos_webassembly_interpreter.Reveal.reveal_hash_from_string_exn
-            (String.make 32 '\000')
-        in
+        let zero_hash = String.make 33 '\000' in
         assert (hash = zero_hash) ;
         return_unit
     | No_input_required | Input_required | Reveal_required _ -> assert false
diff --git a/src/lib_scoru_wasm/wasm_encoding.ml b/src/lib_scoru_wasm/wasm_encoding.ml
index f03ed383edb952f9cc61cc6d9a8447e45b4c286e..5a11d17979c90529537a127a57c465ab44eaf464 100644
--- a/src/lib_scoru_wasm/wasm_encoding.ml
+++ b/src/lib_scoru_wasm/wasm_encoding.ml
@@ -972,11 +972,7 @@ let packed_frame_stack_encoding =
        (scope ["frame"] frame_encoding)
        (scope ["label_kont"] packed_label_kont_encoding))
 
-let reveal_hash_encoding =
-  conv
-    Reveal.reveal_hash_from_string_exn
-    Reveal.reveal_hash_to_string
-    (value [] (Data_encoding.Fixed.string 32))
+let reveal_hash_encoding = value [] (Data_encoding.string' Hex)
 
 let reveal_encoding =
   tagged_union
@@ -985,12 +981,12 @@ let reveal_encoding =
       case
         "Reveal_raw_data"
         reveal_hash_encoding
-        (function Reveal.Reveal_raw_data hash -> Some hash | _ -> None)
+        (function Host_funcs.Reveal_raw_data hash -> Some hash | _ -> None)
         (fun hash -> Reveal_raw_data hash);
       case
         "Reveal_metadata"
         (value [] Data_encoding.unit)
-        (function Reveal.Reveal_metadata -> Some () | _ -> None)
+        (function Host_funcs.Reveal_metadata -> Some () | _ -> None)
         (fun () -> Reveal_metadata);
     ]
 
diff --git a/src/lib_scoru_wasm/wasm_pvm_state.ml b/src/lib_scoru_wasm/wasm_pvm_state.ml
index 06b5b6bcc7963ceb2d154f2c31f5e35f4daf687b..f3316773418133cdb425edfedc51b466095f5030 100644
--- a/src/lib_scoru_wasm/wasm_pvm_state.ml
+++ b/src/lib_scoru_wasm/wasm_pvm_state.ml
@@ -38,13 +38,10 @@ type output_info = {
   message_index : Z.t;  (** The index of the message in the outbox. *)
 }
 
-type reveal_hash = Tezos_webassembly_interpreter.Reveal.reveal_hash
+type reveal_hash = string
 
-let reveal_hash_to_string =
-  Tezos_webassembly_interpreter.Reveal.reveal_hash_to_string
-
-type reveal = Tezos_webassembly_interpreter.Reveal.reveal =
-  | Reveal_raw_data of Tezos_webassembly_interpreter.Reveal.reveal_hash
+type reveal = Tezos_webassembly_interpreter.Host_funcs.reveal =
+  | Reveal_raw_data of reveal_hash
   | Reveal_metadata
 
 (** Represents the state of input requests. *)
diff --git a/src/lib_webassembly/exec/eval.ml b/src/lib_webassembly/exec/eval.ml
index 2b7f063e4f992aaa006522618be8ecfd9aba98cb..ce12de54ec087aa87d2f11a93228858311a95a8c 100644
--- a/src/lib_webassembly/exec/eval.ml
+++ b/src/lib_webassembly/exec/eval.ml
@@ -358,7 +358,7 @@ type invoke_step_kont =
       concat_kont : value concat_kont;
     }
   | Inv_reveal_tick of {
-      reveal : Reveal.reveal;
+      reveal : Host_funcs.reveal;
       base_destination : int32;
       max_bytes : int32;
       code : code;
diff --git a/src/lib_webassembly/exec/eval.mli b/src/lib_webassembly/exec/eval.mli
index f426728dca641cb6ba6749b1c669c46a42dc2b8e..7928fc0c20d3b10f2706d5dfbd708fba28cbeb78 100644
--- a/src/lib_webassembly/exec/eval.mli
+++ b/src/lib_webassembly/exec/eval.mli
@@ -118,7 +118,7 @@ type invoke_step_kont =
       concat_kont : value concat_kont;
     }
   | Inv_reveal_tick of {
-      reveal : Reveal.reveal;
+      reveal : Host_funcs.reveal;
       base_destination : int32;
       max_bytes : int32;
       code : code;
@@ -285,7 +285,7 @@ exception Reveal_error of reveal_error
 (** [is_reveal_tick config] returns [Some hash] if the evalutation is
     in a state expecting the payload of a given hash, and returns [None]
     otherwise. *)
-val is_reveal_tick : config -> Reveal.reveal option
+val is_reveal_tick : config -> Host_funcs.reveal option
 
 (** [reveal_step reveal module_reg payload config] loads [payload] in
     the memory of the module whose function is being evaluated with
diff --git a/src/lib_webassembly/exec/reveal.ml b/src/lib_webassembly/exec/reveal.ml
deleted file mode 100644
index 8eb7ba7d94332854da25a398ce7d6c95c16b9eff..0000000000000000000000000000000000000000
--- a/src/lib_webassembly/exec/reveal.ml
+++ /dev/null
@@ -1,10 +0,0 @@
-exception Invalid_reveal_hash
-
-type reveal_hash = string
-
-let reveal_hash_from_string_exn str =
-  if String.length str = 32 then str else raise Invalid_reveal_hash
-
-let reveal_hash_to_string hash = hash
-
-type reveal = Reveal_raw_data of reveal_hash | Reveal_metadata
diff --git a/src/lib_webassembly/exec/reveal.mli b/src/lib_webassembly/exec/reveal.mli
deleted file mode 100644
index 46da2dbea0844a7f548eb29917316c97bb920120..0000000000000000000000000000000000000000
--- a/src/lib_webassembly/exec/reveal.mli
+++ /dev/null
@@ -1,10 +0,0 @@
-exception Invalid_reveal_hash
-
-type reveal_hash
-
-(** @raise Invalid_reveal_hash *)
-val reveal_hash_from_string_exn : string -> reveal_hash
-
-val reveal_hash_to_string : reveal_hash -> string
-
-type reveal = Reveal_raw_data of reveal_hash | Reveal_metadata
diff --git a/src/lib_webassembly/runtime/host_funcs.ml b/src/lib_webassembly/runtime/host_funcs.ml
index 5e2231b72b66688ca819310ba3d7f90ac19948ab..1275513ffe3edb704f32a4ec834a9692043bb8e5 100644
--- a/src/lib_webassembly/runtime/host_funcs.ml
+++ b/src/lib_webassembly/runtime/host_funcs.ml
@@ -2,12 +2,14 @@ type available_memories =
   | No_memories_during_init
   | Available_memories of Instance.memory_inst Instance.Vector.t
 
+type reveal = Reveal_raw_data of string | Reveal_metadata
+
 type reveal_destination = {base : int32; max_bytes : int32}
 
 type reveal_func =
   available_memories ->
   Values.value list ->
-  (Reveal.reveal * reveal_destination, int32) result Lwt.t
+  (reveal * reveal_destination, int32) result Lwt.t
 
 type host_func =
   | Host_func of
diff --git a/src/lib_webassembly/runtime/host_funcs.mli b/src/lib_webassembly/runtime/host_funcs.mli
index a13263f339c55ba10b6e18206f4f92c84c2a41ed..296be6205998390548dac24f0ae5211cd8a3bb51 100644
--- a/src/lib_webassembly/runtime/host_funcs.mli
+++ b/src/lib_webassembly/runtime/host_funcs.mli
@@ -5,10 +5,12 @@ type available_memories =
 
 type reveal_destination = {base : int32; max_bytes : int32}
 
+type reveal = Reveal_raw_data of string | Reveal_metadata
+
 type reveal_func =
   available_memories ->
   Values.value list ->
-  (Reveal.reveal * reveal_destination, int32) result Lwt.t
+  (reveal * reveal_destination, int32) result Lwt.t
 
 (** The type of a Host function implementation *)
 type host_func =
diff --git a/src/proto_alpha/bin_sc_rollup_node/fueled_pvm.ml b/src/proto_alpha/bin_sc_rollup_node/fueled_pvm.ml
index 6b417e80e94d23b3a6b33471ac0ec3957451d74d..7a83c58f83b0518dc5e6994bda77d9b65a775f63 100644
--- a/src/proto_alpha/bin_sc_rollup_node/fueled_pvm.ml
+++ b/src/proto_alpha/bin_sc_rollup_node/fueled_pvm.ml
@@ -116,10 +116,11 @@ module Make (PVM : Pvm.S) = struct
       let module Builtins = struct
         let reveal_preimage hash =
           let hash =
-            (* The 32-byte payload represents the encoded [Reveal_hash.t]. We must
+            (* The payload represents the encoded [Sc_rollup_reveal_hash.t]. We must
                decode it properly, instead of converting it byte-for-byte. *)
-            Tezos_webassembly_interpreter.Reveal.reveal_hash_to_string hash
-            |> Data_encoding.Binary.of_string_exn Sc_rollup_reveal_hash.encoding
+            Data_encoding.Binary.of_string_exn
+              Sc_rollup_reveal_hash.encoding
+              hash
           in
           let*! data =
             get_reveal ~data_dir:node_ctxt.data_dir reveal_map hash
diff --git a/src/proto_alpha/bin_wasm_repl/commands.ml b/src/proto_alpha/bin_wasm_repl/commands.ml
index 4d030ffe6b5582885c294a57593a8a3733cfea61..dedf6fa13844c97df1fe27ec54a9e1507eb60945 100644
--- a/src/proto_alpha/bin_wasm_repl/commands.ml
+++ b/src/proto_alpha/bin_wasm_repl/commands.ml
@@ -213,10 +213,7 @@ let pp_input_request ppf = function
   | Input_required -> Format.fprintf ppf "Waiting for input"
   | Reveal_required Reveal_metadata -> Format.fprintf ppf "Waiting for metadata"
   | Reveal_required (Reveal_raw_data hash) ->
-      Format.fprintf
-        ppf
-        "Waiting for reveal: %s"
-        (Tezos_webassembly_interpreter.Reveal.reveal_hash_to_string hash)
+      Format.fprintf ppf "Waiting for reveal: %s" hash
 
 (* [show_status tree] show the state of the PVM. *)
 let show_status tree =
diff --git a/src/proto_alpha/lib_dal/test/test_dac_pages_encoding.ml b/src/proto_alpha/lib_dal/test/test_dac_pages_encoding.ml
index 9ba72106cd3218af0097660374e4217e8aefc0c7..0b82b4c87ffa3c9d5b5192047efdb4d7d190d4b5 100644
--- a/src/proto_alpha/lib_dal/test/test_dac_pages_encoding.ml
+++ b/src/proto_alpha/lib_dal/test/test_dac_pages_encoding.ml
@@ -306,13 +306,13 @@ module Merkle_tree = struct
         retrieved_payload
 
     let multiple_pages_roundtrip_heterogeneous_payload () =
-      (* Each page in tests contains at most 70 bytes, of which 5 are reserved
-         for the page prefix. This leaves 65 bytes to store the payload to be
+      (* Each page in tests contains at most 80 bytes, of which 5 are reserved
+         for the page prefix. This leaves 75 bytes to store the payload to be
          serialized in a page. It also means that a `Hashes` page can contain
-         at most 2 hashes of size 32 bytes each. If we try to serialize a
-         payload between 131 and 195 bytes (included), then the serialized
+         at most 2 hashes of size 33 bytes each. If we try to serialize a
+         payload between 151 and 225 bytes (included), then the serialized
          payload should be spread among a total of 6 pages. Of these,
-         195/65 = 3 pages are used to store the payload, ceil(3/2) = 2 pages
+         225/75 = 3 pages are used to store the payload, ceil(3/2) = 2 pages
          are used for storing the 3 hashes of the 3 payload pages, and
          ceil(2/2) = 1 page is used for storing the 2 hashes of the previous
          pages. *)
@@ -322,7 +322,7 @@ module Merkle_tree = struct
          have a fixed size of 32 bytes, and 5 bytes are used for the preamble,
          we need 32 * 2 + 5 = 69 bytes to store two hashes in a page. We round
          this value to 70. *)
-      let max_page_size = 70 in
+      let max_page_size = 80 in
       let payload =
         Bytes.of_string
           "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do \
@@ -349,11 +349,11 @@ module Merkle_tree = struct
         retrieved_payload
 
     let multiple_pages_roundtrip_homogeneous_payload () =
-      (* Each page in tests contains at most 70 bytes, of which 5 are reserved
-         for the page prefix. This leaves 65 bytes to store the contents to be
+      (* Each page in tests contains at most 80 bytes, of which 5 are reserved
+         for the page prefix. This leaves 75 bytes to store the contents to be
          serialized in a page. It also means that a `Hashes` page can contain
          at most 2 hashes of size 32 bytes each. If we try to serialize a
-         payload of 195 repetitions of the same character, then only one
+         payload of 225 repetitions of the same character, then only one
          payload page will be produced. However, the hash of this page will be
          repeated three times across two pages represent nodes of the Merkle
          tree. Finally, another page will be used for storing the Merkle tree
@@ -365,9 +365,9 @@ module Merkle_tree = struct
          have a fixed size of 32 bytes, and 5 bytes are used for the preamble,
          we need 32 * 2 + 5 = 69 bytes to store two hashes in a page. We round
          this value to 70. *)
-      let max_page_size = 70 in
+      let max_page_size = 80 in
       let payload =
-        List.repeat 195 (Bytes.of_string "a") |> Bytes.concat Bytes.empty
+        List.repeat 225 (Bytes.of_string "a") |> Bytes.concat Bytes.empty
       in
       let* hash =
         lift
diff --git a/src/proto_alpha/lib_protocol/sc_rollup_reveal_hash.ml b/src/proto_alpha/lib_protocol/sc_rollup_reveal_hash.ml
index fb378ecc5d026fae52cef5398ce0b68e8bd9b403..c583ff28e2c173ccacb4b27893f2e4fffb1688a5 100644
--- a/src/proto_alpha/lib_protocol/sc_rollup_reveal_hash.ml
+++ b/src/proto_alpha/lib_protocol/sc_rollup_reveal_hash.ml
@@ -36,12 +36,12 @@ module Blake2B = struct
         let title = "A smart contract rollup reveal hash"
 
         let b58check_prefix =
-          "\017\144\121\209\203" (* "scrrh1(54)" decoded from Base58. *)
+          "\230\206\128\200\196" (* "scrrh1(56)" decoded from Base58. *)
 
-        let size = Some 31
+        let size = Some 32
       end)
 
-  let () = Base58.check_encoded_prefix b58check_encoding "scrrh1" 54
+  let () = Base58.check_encoded_prefix b58check_encoding "scrrh1" 56
 end
 
 type supported_hashes = Blake2B
diff --git a/src/proto_alpha/lib_protocol/sc_rollup_wasm.ml b/src/proto_alpha/lib_protocol/sc_rollup_wasm.ml
index 3bb09f0016f2fa2621f40d4e56a451fd5c2bed52..c32116b216a3765597198ea67a8f967d9de584fb 100644
--- a/src/proto_alpha/lib_protocol/sc_rollup_wasm.ml
+++ b/src/proto_alpha/lib_protocol/sc_rollup_wasm.ml
@@ -300,7 +300,7 @@ module V2_0_0 = struct
           match
             Data_encoding.Binary.of_string_opt
               Sc_rollup_reveal_hash.encoding
-              (Wasm_2_0_0.reveal_hash_to_string hash)
+              hash
           with
           | Some hash -> Waiting_for_reveal (Reveal_raw_data hash)
           | None ->
diff --git a/tezt/tests/dal.ml b/tezt/tests/dal.ml
index 0e5583a2dc3e7f64e5689acd0dfd2e897a5c927a..b217be2d8cfcff64b71fdcf16b84c09688dbf8e9 100644
--- a/tezt/tests/dal.ml
+++ b/tezt/tests/dal.ml
@@ -1382,7 +1382,9 @@ let test_dal_node_handles_dac_store_preimage_merkle_V0 _protocol dal_node
   (* Expected reveal hash equals to the result of
      [Tezos_dal_alpha.Dac_pages_encoding.Merkle_tree.V0.serialize_payload "test"].
   *)
-  let expected_rh = "scrrh1Y5hijnFNJPb96EFTY9SjZ4epyaYF9xU3Eid9KCj9vda25H8W" in
+  let expected_rh =
+    "scrrh13xwafZc5revvm5mittZFsBWb8ynFdH7ZRwpgUzCbtCCZo2orjs"
+  in
   check_valid_root_hash expected_rh actual_rh ;
   let filename =
     Filename.concat
@@ -1419,7 +1421,9 @@ let test_dal_node_handles_dac_store_preimage_hash_chain_V0 _protocol dal_node
   (* Expected reveal hash equals to the result of
      [Tezos_dal_alpha.Dac_pages_encoding.Hash_chain.V0.serialize_payload "test"].
   *)
-  let expected_rh = "scrrh1hYNyzXmagRDi22knBt5dhMMi6Sivdo1ztf5wXiectRnzbSyX" in
+  let expected_rh =
+    "scrrh13qW2L3g9ubEMjvWj5Rk2eqknXDsvnkZKVErFsavKTaFLgRgsXe"
+  in
   check_valid_root_hash expected_rh actual_rh ;
   let filename =
     Filename.concat
@@ -1468,7 +1472,9 @@ let test_rollup_arith_uses_reveals _protocol dal_node sc_rollup_node
          ~payload
          ~pagination_scheme:"Hash_chain_V0")
   in
-  let expected_rh = "scrrh1bZAo4kfAohhKcvgKc4yLHYN49EPuHezNXgFraa1mEbKSTCwf" in
+  let expected_rh =
+    "scrrh144gSwSgX2cSw3v8p9h5rf6L6Ryvx4ewEhBDhkz7ErY9EChS47a"
+  in
   check_valid_root_hash expected_rh actual_rh ;
   let* () =
     send_messages
@@ -1509,7 +1515,7 @@ let test_reveals_fails_on_wrong_hash _protocol dal_node sc_rollup_node
          ~pagination_scheme:"Hash_chain_V0")
   in
   let errorneous_hash =
-    "scrrh1kXE3tnCVTJ21aDNVeaV86e8rS6jtiMEDpjZJtDnLXRThQdmy"
+    "scrrh144gSwSgX2cSw3v8p9h5rf6L6Ryvx4ewEhBDhkz7ErY9EChS47a"
   in
   let* genesis_info =
     RPC.Client.call ~hooks client
diff --git a/tezt/tests/expected/dal.ml/Alpha- Testing DAL rollup and node with L1 (dac_rollup_arith_uses_reveals).out b/tezt/tests/expected/dal.ml/Alpha- Testing DAL rollup and node with L1 (dac_rollup_arith_uses_reveals).out
index 021bdfbd7b4064941c2ee821b1db299b939d3c26..57b53f64ff9d86c5bf843e10250e4de8bea11fbb 100644
--- a/tezt/tests/expected/dal.ml/Alpha- Testing DAL rollup and node with L1 (dac_rollup_arith_uses_reveals).out	
+++ b/tezt/tests/expected/dal.ml/Alpha- Testing DAL rollup and node with L1 (dac_rollup_arith_uses_reveals).out	
@@ -37,9 +37,9 @@ This sequence of operations was run:
 { "level": 2,
   "commitment_hash": "[SC_ROLLUP_COMMITMENT_HASH]" }
 
-./octez-client --wait none send sc rollup message 'text:["hash:scrrh1bZAo4kfAohhKcvgKc4yLHYN49EPuHezNXgFraa1mEbKSTCwf"]' from bootstrap2
+./octez-client --wait none send sc rollup message 'text:["hash:scrrh144gSwSgX2cSw3v8p9h5rf6L6Ryvx4ewEhBDhkz7ErY9EChS47a"]' from bootstrap2
 Node is bootstrapped.
-Estimated gas: 1001.463 units (will add 100 for safety)
+Estimated gas: 1001.497 units (will add 100 for safety)
 Estimated storage: no bytes added
 Operation successfully injected in the node.
 Operation hash is '[OPERATION_HASH]'
@@ -50,16 +50,16 @@ and/or an external block explorer to make sure that it has been included.
 This sequence of operations was run:
   Manager signed operations:
     From: [PUBLIC_KEY_HASH]
-    Fee to the baker: ꜩ0.000402
+    Fee to the baker: ꜩ0.000404
     Expected counter: 1
     Gas limit: 1102
     Storage limit: 0 bytes
     Balance updates:
-      [PUBLIC_KEY_HASH] ... -ꜩ0.000402
-      payload fees(the block proposer) ....... +ꜩ0.000402
+      [PUBLIC_KEY_HASH] ... -ꜩ0.000404
+      payload fees(the block proposer) ....... +ꜩ0.000404
     Smart contract rollup messages submission
       This smart contract rollup messages submission was successfully applied
-      Consumed gas: 1001.463
+      Consumed gas: 1001.497
       Resulting inbox state: { level = 3
                                current messages hash  = hash: [SC_ROLLUP_INBOX_LEVEL_TREE_HASH]
                                level: 3 nb_messages_in_commitment_period = 9
diff --git a/tezt/tests/expected/dal.ml/Alpha- Testing DAL rollup and node with L1 (dac_rollup_arith_wrong_hash).out b/tezt/tests/expected/dal.ml/Alpha- Testing DAL rollup and node with L1 (dac_rollup_arith_wrong_hash).out
index 3c13b62c32e851a513fde916df8a811beae261a2..fe0be78705b9ae77abd511666b50ee66ae1be22a 100644
--- a/tezt/tests/expected/dal.ml/Alpha- Testing DAL rollup and node with L1 (dac_rollup_arith_wrong_hash).out	
+++ b/tezt/tests/expected/dal.ml/Alpha- Testing DAL rollup and node with L1 (dac_rollup_arith_wrong_hash).out	
@@ -37,9 +37,9 @@ This sequence of operations was run:
 { "level": 2,
   "commitment_hash": "[SC_ROLLUP_COMMITMENT_HASH]" }
 
-./octez-client --wait none send sc rollup message 'text:["hash:scrrh1kXE3tnCVTJ21aDNVeaV86e8rS6jtiMEDpjZJtDnLXRThQdmy"]' from bootstrap2
+./octez-client --wait none send sc rollup message 'text:["hash:scrrh144gSwSgX2cSw3v8p9h5rf6L6Ryvx4ewEhBDhkz7ErY9EChS47a"]' from bootstrap2
 Node is bootstrapped.
-Estimated gas: 1001.463 units (will add 100 for safety)
+Estimated gas: 1001.497 units (will add 100 for safety)
 Estimated storage: no bytes added
 Operation successfully injected in the node.
 Operation hash is '[OPERATION_HASH]'
@@ -50,16 +50,16 @@ and/or an external block explorer to make sure that it has been included.
 This sequence of operations was run:
   Manager signed operations:
     From: [PUBLIC_KEY_HASH]
-    Fee to the baker: ꜩ0.000402
+    Fee to the baker: ꜩ0.000404
     Expected counter: 1
     Gas limit: 1102
     Storage limit: 0 bytes
     Balance updates:
-      [PUBLIC_KEY_HASH] ... -ꜩ0.000402
-      payload fees(the block proposer) ....... +ꜩ0.000402
+      [PUBLIC_KEY_HASH] ... -ꜩ0.000404
+      payload fees(the block proposer) ....... +ꜩ0.000404
     Smart contract rollup messages submission
       This smart contract rollup messages submission was successfully applied
-      Consumed gas: 1001.463
+      Consumed gas: 1001.497
       Resulting inbox state: { level = 3
                                current messages hash  = hash: [SC_ROLLUP_INBOX_LEVEL_TREE_HASH]
                                level: 3 nb_messages_in_commitment_period = 9
diff --git a/tezt/tests/sc_rollup.ml b/tezt/tests/sc_rollup.ml
index facbfdb55b377c203b226760f4e340d424d73b5c..58c42864cc4634fb2e0b805602e7d552e58e1dd5 100644
--- a/tezt/tests/sc_rollup.ml
+++ b/tezt/tests/sc_rollup.ml
@@ -2461,8 +2461,8 @@ let test_reveals_fails_on_wrong_hash ~kind =
     }
   @@ fun sc_rollup_node _sc_rollup_client sc_rollup _node client ->
   (* This value has been obtained from the logs of the test
-     scrrh1kXE3tnCVTJ21aDNVeaV86e8rS6jtiMEDpjZJtDnLXRThQdmy. *)
-  let hash = "scrrh1kXE3tnCVTJ21aDNVeaV86e8rS6jtiMEDpjZJtDnLXRThQdmy" in
+     "Alpha: arith - rollup node correctly handles reveals." *)
+  let hash = "scrrh13sj3sMk3Ne75xd4dnYGH4TF4dHzAcmXpEPkdJrQ3fBEGN4jtoF" in
   let pvm_dir =
     Filename.concat (Sc_rollup_node.data_dir sc_rollup_node) "arith"
   in