diff --git a/src/lib_crypto/blake2B.ml b/src/lib_crypto/blake2B.ml
index 2d763d33c..5c9aa05b5 100644
--- a/src/lib_crypto/blake2B.ml
+++ b/src/lib_crypto/blake2B.ml
@@ -38,7 +38,7 @@ module Make_minimal (K : Name) = struct
     if String.length s <> size then
       None
     else
-      Some (Blake2b.Hash (Cstruct.of_string s))
+      Some (Blake2b.Hash (MBytes.of_string s))
   let of_string s =
     match of_string_opt s with
     | None ->
@@ -52,7 +52,7 @@ module Make_minimal (K : Name) = struct
           "%s.of_string: wrong string size (%d)"
           K.name (String.length s)
     | Some h -> h
-  let to_string (Blake2b.Hash h) = Cstruct.to_string h
+  let to_string (Blake2b.Hash h) = MBytes.to_string h
 
   let of_hex s = of_string (Hex.to_string s)
   let of_hex_opt s = of_string_opt (Hex.to_string s)
@@ -70,7 +70,7 @@ module Make_minimal (K : Name) = struct
     if MBytes.length b <> size then
       None
     else
-      Some (Blake2b.Hash (Cstruct.of_bigarray b))
+      Some (Blake2b.Hash b)
   let of_bytes_exn b =
     match of_bytes_opt b with
     | None ->
@@ -84,21 +84,20 @@ module Make_minimal (K : Name) = struct
     | Some x -> Ok x
     | None ->
         generic_error "Failed to deserialize a hash (%s)" K.name
-  let to_bytes (Blake2b.Hash h) = Cstruct.to_bigarray h
+  let to_bytes (Blake2b.Hash h) = h
 
   (* let read src off = of_bytes_exn @@ MBytes.sub src off size *)
   (* let write dst off h = MBytes.blit (to_bytes h) 0 dst off size *)
 
   let hash_bytes ?key l =
-    let key = Option.map ~f:Cstruct.of_bigarray key in
     let state = Blake2b.init ?key size in
-    List.iter (fun b -> Blake2b.update state (Cstruct.of_bigarray b)) l ;
+    List.iter (fun b -> Blake2b.update state b) l ;
     Blake2b.final state
 
   let hash_string ?key l =
-    let key = Option.map ~f:Cstruct.of_string key in
+    let key = Option.map ~f:Bigstring.of_string key in
     let state = Blake2b.init ?key size in
-    List.iter (fun s -> Blake2b.update state (Cstruct.of_string s)) l ;
+    List.iter (fun s -> Blake2b.update state (MBytes.of_string s)) l ;
     Blake2b.final state
 
   let path_length = 6
@@ -129,7 +128,7 @@ module Make_minimal (K : Name) = struct
 
   include Compare.Make(struct
       type nonrec t = t
-      let compare (Blake2b.Hash h1) (Blake2b.Hash h2) = Cstruct.compare h1 h2
+      let compare (Blake2b.Hash h1) (Blake2b.Hash h2) = MBytes.compare h1 h2
     end)
 
 end
diff --git a/src/lib_crypto/s.ml b/src/lib_crypto/s.ml
index 62b2cca47..20982a5e2 100644
--- a/src/lib_crypto/s.ml
+++ b/src/lib_crypto/s.ml
@@ -29,7 +29,7 @@ module type MINIMAL_HASH = sig
 
   include Compare.S with type t := t
 
-  val hash_bytes: ?key:Cstruct.buffer -> Cstruct.buffer list -> t
+  val hash_bytes: ?key:MBytes.t -> MBytes.t list -> t
   val hash_string: ?key:string -> string list -> t
 
   val zero: t
diff --git a/src/lib_protocol_compiler/compiler.ml b/src/lib_protocol_compiler/compiler.ml
index 15736b0f8..b16e99e22 100644
--- a/src/lib_protocol_compiler/compiler.ml
+++ b/src/lib_protocol_compiler/compiler.ml
@@ -116,25 +116,6 @@ let debug fmt =
   if !debug_flag then Format.eprintf fmt
   else Format.ifprintf Format.err_formatter fmt
 
-let hash_file file =
-  let open Blake2 in
-  let buflen = 8092 in
-  let buf = BytesLabels.create buflen in
-  let fd = Unix.openfile file [Unix.O_RDONLY] 0o600 in
-  let state = Blake2b.init 32 in
-  let loop () =
-    match Unix.read fd buf 0 buflen with
-    | 0 -> ()
-    | nb_read ->
-        Blake2b.update state
-          (Cstruct.of_bytes
-             (if nb_read = buflen then buf else BytesLabels.sub buf ~pos:0 ~len:nb_read))
-  in
-  loop () ;
-  Unix.close fd ;
-  let Blake2b.Hash h = Blake2b.final state in
-  Cstruct.to_string h
-
 let mktemp_dir () =
   Filename.get_temp_dir_name () //
   Printf.sprintf "tezos-protocol-build-%06X" (Random.int 0xFFFFFF)
diff --git a/vendors/ocaml-blake2/blake2.opam b/vendors/ocaml-blake2/blake2.opam
index aba17f1f1..01a0b5c1b 100644
--- a/vendors/ocaml-blake2/blake2.opam
+++ b/vendors/ocaml-blake2/blake2.opam
@@ -16,6 +16,7 @@ build: [ "jbuilder" "build" "-j" jobs "-p" name "@install" ]
 build-test: [ "jbuilder" "runtest" "-p" name "-j" jobs ]
 depends: [
   "jbuilder" {build & >= "1.0+beta16"}
-  "cstruct" {>= "3.2.1"}
+  "bigstring" {>= "0.1.1"}
   "alcotest" { test }
+  "hex" {test & >= "1.2.0"}
 ]
diff --git a/vendors/ocaml-blake2/src/blake2.ml b/vendors/ocaml-blake2/src/blake2.ml
index d3f9bcbe1..56dba1f21 100644
--- a/vendors/ocaml-blake2/src/blake2.ml
+++ b/vendors/ocaml-blake2/src/blake2.ml
@@ -4,32 +4,32 @@
   ---------------------------------------------------------------------------*)
 
 module Blake2b = struct
-  type t = Cstruct.t
+  type t = Bigstring.t
 
   external sizeof_state : unit -> int =
     "sizeof_blake2b_state" [@@noalloc]
 
   let bytes = sizeof_state ()
 
-  external init : Cstruct.buffer -> int -> int =
+  external init : Bigstring.t -> int -> int =
     "ml_blake2b_init" [@@noalloc]
 
-  external outlen : Cstruct.buffer -> int =
+  external outlen : Bigstring.t -> int =
     "blake2b_state_outlen" [@@noalloc]
 
-  let outlen t = outlen t.Cstruct.buffer
+  let outlen t = outlen t
 
-  external init_key : Cstruct.buffer -> int -> Cstruct.buffer -> int =
+  external init_key : Bigstring.t -> int -> Bigstring.t -> int =
     "ml_blake2b_init_key" [@@noalloc]
 
-  external update : Cstruct.buffer -> Cstruct.buffer -> int =
+  external update : Bigstring.t -> Bigstring.t -> int =
     "ml_blake2b_update" [@@noalloc]
 
-  external final : Cstruct.buffer -> Cstruct.buffer -> int =
+  external final : Bigstring.t -> Bigstring.t -> int =
     "ml_blake2b_final" [@@noalloc]
 
   external direct :
-    Cstruct.buffer -> Cstruct.buffer -> Cstruct.buffer -> int =
+    Bigstring.t -> Bigstring.t -> Bigstring.t -> int =
     "ml_blake2b" [@@noalloc]
 
   let or_fail ~msg f =
@@ -40,37 +40,33 @@ module Blake2b = struct
   let init ?key size =
     if size < 1 || size > 64 then
       invalid_arg "Blake2b.init: size must be between 1 and 64" ;
-    let t = Cstruct.create_unsafe bytes in
+    let t = Bigstring.create bytes in
     begin match key with
       | Some key ->
           or_fail ~msg:"Blake2b.init"
-            (fun () -> init_key t.buffer size key.Cstruct.buffer)
+            (fun () -> init_key t size key)
       | None ->
           or_fail ~msg:"Blake2b.init"
-            (fun () -> init t.buffer size)
+            (fun () -> init t size)
     end ;
     t
 
   let update t buf =
-    or_fail ~msg:"Blake2b.update"
-      (fun () -> update t.Cstruct.buffer buf.Cstruct.buffer)
+    or_fail ~msg:"Blake2b.update" (fun () -> update t buf)
 
-  type hash = Hash of Cstruct.t
+  type hash = Hash of Bigstring.t
 
   let final t =
     let len = outlen t in
-    let buf = Cstruct.create_unsafe len in
-    or_fail ~msg:"Blake2b.final"
-      (fun () -> final t.Cstruct.buffer buf.Cstruct.buffer) ;
+    let buf = Bigstring.create len in
+    or_fail ~msg:"Blake2b.final" (fun () -> final t buf) ;
     Hash buf
 
-  let direct ?(key=Cstruct.create_unsafe 0) inbuf len =
+  let direct ?(key=Bigstring.create 0) inbuf len =
     if len < 1 || len > 64 then
       invalid_arg "Blake2b.direct: size must be between 1 and 64" ;
-    let outbuf = Cstruct.create len in
-    or_fail ~msg:"Blake2b.direct"
-      (fun () -> direct outbuf.Cstruct.buffer
-          inbuf.Cstruct.buffer key.buffer) ;
+    let outbuf = Bigstring.create len in
+    or_fail ~msg:"Blake2b.direct" (fun () -> direct outbuf inbuf key) ;
     Hash outbuf
 end
 
diff --git a/vendors/ocaml-blake2/src/blake2.mli b/vendors/ocaml-blake2/src/blake2.mli
index 9cda35b60..7c47e8b19 100644
--- a/vendors/ocaml-blake2/src/blake2.mli
+++ b/vendors/ocaml-blake2/src/blake2.mli
@@ -5,20 +5,20 @@
 
 module Blake2b : sig
   type t
-  type hash = Hash of Cstruct.t
+  type hash = Hash of Bigstring.t
 
-  val init : ?key:Cstruct.t -> int -> t
+  val init : ?key:Bigstring.t -> int -> t
   (** [init ?key size] is a blake2b context for hashes of size [size],
       using [key] if present. *)
 
-  val update : t -> Cstruct.t -> unit
+  val update : t -> Bigstring.t -> unit
   (** [update t buf] updates [t] with the data in [buf]. *)
 
   val final : t -> hash
   (** [final t] is the blake2b hash of all data updated in [t] so
       far. *)
 
-  val direct : ?key:Cstruct.t -> Cstruct.t -> int -> hash
+  val direct : ?key:Bigstring.t -> Bigstring.t -> int -> hash
   (** [direct ?key inbuf len] is the blake2b hash of length [len],
       using [key] is present. *)
 end
diff --git a/vendors/ocaml-blake2/src/jbuild b/vendors/ocaml-blake2/src/jbuild
index 6ce592cfd..8d1a727f6 100644
--- a/vendors/ocaml-blake2/src/jbuild
+++ b/vendors/ocaml-blake2/src/jbuild
@@ -3,5 +3,6 @@
 (library
  ((name            blake2)
   (public_name     blake2)
-  (libraries       (cstruct))
-  (c_names         (blake2b-ref))))
+  (libraries       (bigstring))
+  (c_names         (blake2b-ref))
+  (c_flags         (-O3))))
diff --git a/vendors/ocaml-blake2/test/jbuild b/vendors/ocaml-blake2/test/jbuild
index 42fe2a4a7..68230860f 100644
--- a/vendors/ocaml-blake2/test/jbuild
+++ b/vendors/ocaml-blake2/test/jbuild
@@ -2,7 +2,7 @@
 
 (executable
  ((name test)
-  (libraries (blake2 alcotest))))
+  (libraries (blake2 hex alcotest))))
 
 (alias
  ((name    runtest-blake2)
diff --git a/vendors/ocaml-blake2/test/test.ml b/vendors/ocaml-blake2/test/test.ml
index 2670bbe1a..6c715520e 100644
--- a/vendors/ocaml-blake2/test/test.ml
+++ b/vendors/ocaml-blake2/test/test.ml
@@ -2,44 +2,40 @@
 open Blake2
 
 type vector = {
-  data_in : string list ;
-  data_key : string option ;
-  data_out : string ;
+  data_in : Bigstring.t list ;
+  data_key : Bigstring.t option ;
+  data_out : Bigstring.t ;
 }
 
+let hex s =
+  Cstruct.to_bigarray (Hex.to_cstruct (`Hex s))
+
 let vectors = [
-  { data_in = [ "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f" ] ;
+  { data_in = [ hex "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f" ] ;
     data_key = None ;
-    data_out = "1c077e279de6548523502b6df800ffdab5e2c3e9442eb838f58c295f3b147cef9d701c41c321283f00c71affa0619310399126295b78dd4d1a74572ef9ed5135" ;
+    data_out = hex "1c077e279de6548523502b6df800ffdab5e2c3e9442eb838f58c295f3b147cef9d701c41c321283f00c71affa0619310399126295b78dd4d1a74572ef9ed5135" ;
   } ;
-  { data_in = [ "000102030405060708090a0b0c0d0e0f101112131415" ; "161718"; "191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f" ] ;
+  { data_in = [ hex "000102030405060708090a0b0c0d0e0f101112131415" ; hex "161718"; hex "191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f" ] ;
     data_key = None ;
-    data_out = "1c077e279de6548523502b6df800ffdab5e2c3e9442eb838f58c295f3b147cef9d701c41c321283f00c71affa0619310399126295b78dd4d1a74572ef9ed5135" ;
+    data_out = hex "1c077e279de6548523502b6df800ffdab5e2c3e9442eb838f58c295f3b147cef9d701c41c321283f00c71affa0619310399126295b78dd4d1a74572ef9ed5135" ;
   } ;
-  { data_in = [ "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3" ] ;
-    data_key = Some ("000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f") ;
-    data_out = "b39614268fdd8781515e2cfebf89b4d5402bab10c226e6344e6b9ae000fb0d6c79cb2f3ec80e80eaeb1980d2f8698916bd2e9f747236655116649cd3ca23a837" ;
+  { data_in = [ hex "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3" ] ;
+    data_key = Some (hex "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f") ;
+    data_out = hex "b39614268fdd8781515e2cfebf89b4d5402bab10c226e6344e6b9ae000fb0d6c79cb2f3ec80e80eaeb1980d2f8698916bd2e9f747236655116649cd3ca23a837" ;
   } ;
 ]
 
 let test_update { data_in ; data_key ; data_out } =
-  let key =
-    match data_key with None -> None | Some s -> Some (Cstruct.of_hex s) in
-  let data_out = Cstruct.of_hex data_out in
-  let d = Blake2b.init ?key (Cstruct.len data_out) in
-  List.iter (fun s -> Blake2b.update d (Cstruct.of_hex s)) data_in ;
+  let d = Blake2b.init ?key:data_key (Bigstring.length data_out) in
+  List.iter (Blake2b.update d) data_in ;
   let Blake2b.Hash h = Blake2b.final d in
-  assert Cstruct.(equal data_out h)
+  assert Bigstring.(equal data_out h)
 
 let test_direct { data_in ; data_key ; data_out } =
-  let key =
-    match data_key with None -> None | Some s -> Some (Cstruct.of_hex s) in
-  let data_out = Cstruct.of_hex data_out in
   let Blake2b.Hash h =
-    Blake2b.direct ?key
-      (Cstruct.of_hex (String.concat "" data_in))
-      (Cstruct.len data_out) in
-  assert Cstruct.(equal data_out h)
+    Blake2b.direct ?key:data_key
+      (Bigstring.concat "" data_in) (Bigstring.length data_out) in
+  assert Bigstring.(equal data_out h)
 
 let update_tests =
   List.mapi