From 7c546425d20ace8020b05050f558107589bd5faf Mon Sep 17 00:00:00 2001
From: Vincent Bernardoff <vb@luminar.eu.org>
Date: Tue, 17 Apr 2018 11:44:01 +0200
Subject: [PATCH] Vendors/tweetnacl: use bigstring

---
 src/lib_crypto/crypto_box.ml                  |  54 +--
 src/lib_crypto/ed25519.ml                     |  39 +-
 src/lib_crypto/rand.ml                        |   8 +-
 src/lib_crypto/secp256k1.ml                   |   2 +-
 vendors/ocaml-tweetnacl/src/jbuild            |   5 +-
 vendors/ocaml-tweetnacl/src/tweetnacl.ml      | 436 +++++++++---------
 vendors/ocaml-tweetnacl/src/tweetnacl.mli     |  92 ++--
 vendors/ocaml-tweetnacl/src/tweetnacl_stubs.c |  14 +-
 vendors/ocaml-tweetnacl/test/test.ml          |  84 ++--
 vendors/ocaml-tweetnacl/tweetnacl.opam        |   9 +-
 10 files changed, 350 insertions(+), 393 deletions(-)

diff --git a/src/lib_crypto/crypto_box.ml b/src/lib_crypto/crypto_box.ml
index cf5edcc47..d43686534 100644
--- a/src/lib_crypto/crypto_box.ml
+++ b/src/lib_crypto/crypto_box.ml
@@ -20,26 +20,14 @@ type target = Z.t
 module Secretbox = struct
   include Secretbox
 
-  let of_bytes bytes =
-    of_cstruct (Cstruct.of_bigarray bytes)
+  let box key msg nonce = box ~key ~msg ~nonce
 
-  let of_bytes_exn bytes =
-    of_cstruct_exn (Cstruct.of_bigarray bytes)
-
-  let box key msg nonce =
-    let msg = Cstruct.of_bigarray msg in
-    Cstruct.to_bigarray (box ~key ~msg ~nonce)
-
-  let box_open key cmsg nonce =
-    let cmsg = Cstruct.of_bigarray cmsg in
-    Option.map ~f:Cstruct.to_bigarray (box_open ~key ~cmsg ~nonce)
+  let box_open key cmsg nonce = box_open ~key ~cmsg ~nonce
 
   let box_noalloc key nonce msg =
-    let msg = Cstruct.of_bigarray msg in
     box_noalloc ~key ~nonce ~msg
 
   let box_open_noalloc key nonce cmsg =
-    let cmsg = Cstruct.of_bigarray cmsg in
     box_open_noalloc ~key ~nonce ~cmsg
 end
 
@@ -54,7 +42,7 @@ let () =
   Base58.check_encoded_prefix Public_key_hash.b58check_encoding "id" 30
 
 let hash pk =
-  Public_key_hash.hash_bytes [Cstruct.to_bigarray (Box.to_cstruct pk)]
+  Public_key_hash.hash_bytes [Box.to_bytes pk]
 
 let zerobytes = Box.zerobytes
 let boxzerobytes = Box.boxzerobytes
@@ -63,42 +51,32 @@ let random_keypair () =
   let pk, sk = Box.keypair () in
   sk, pk, hash pk
 
-let zero_nonce = Tweetnacl.Nonce.(of_cstruct_exn (Cstruct.create bytes))
+let zero_nonce = Tweetnacl.Nonce.(of_bytes_exn (MBytes.init bytes '\x00'))
 let random_nonce = Nonce.gen
 let increment_nonce = Nonce.increment
 
-let box sk pk msg nonce =
-  let msg = Cstruct.of_bigarray msg in
-  Cstruct.to_bigarray (Box.box ~sk ~pk ~msg ~nonce)
+let box sk pk msg nonce = Box.box ~sk ~pk ~msg ~nonce
 
-let box_open sk pk cmsg nonce =
-  let cmsg = Cstruct.of_bigarray cmsg in
-  Option.map ~f:Cstruct.to_bigarray (Box.box_open ~sk ~pk ~cmsg ~nonce)
+let box_open sk pk cmsg nonce = Box.box_open ~sk ~pk ~cmsg ~nonce
 
 let box_noalloc sk pk nonce msg =
-  let msg = Cstruct.of_bigarray msg in
   Box.box_noalloc ~sk ~pk ~nonce ~msg
 
 let box_open_noalloc sk pk nonce cmsg =
-  let cmsg = Cstruct.of_bigarray cmsg in
   Box.box_open_noalloc ~sk ~pk ~nonce ~cmsg
 
 let precompute sk pk = Box.combine pk sk
 
 let fast_box k msg nonce =
-  let msg = Cstruct.of_bigarray msg in
-  Cstruct.to_bigarray (Box.box_combined ~k ~msg ~nonce)
+  Box.box_combined ~k ~msg ~nonce
 
 let fast_box_open k cmsg nonce =
-  let cmsg = Cstruct.of_bigarray cmsg in
-  Option.map ~f:Cstruct.to_bigarray (Box.box_open_combined ~k ~cmsg ~nonce)
+  Box.box_open_combined ~k ~cmsg ~nonce
 
 let fast_box_noalloc k nonce msg =
-  let msg = Cstruct.of_bigarray msg in
   Box.box_combined_noalloc ~k ~nonce ~msg
 
 let fast_box_open_noalloc k nonce cmsg =
-  let cmsg = Cstruct.of_bigarray cmsg in
   Box.box_open_combined_noalloc ~k ~nonce ~cmsg
 
 let compare_target hash target =
@@ -128,8 +106,8 @@ let default_target = make_target 24.
 let check_proof_of_work pk nonce target =
   let hash =
     Blake2B.hash_bytes [
-      Cstruct.to_bigarray (Box.to_cstruct pk) ;
-      Cstruct.to_bigarray (Nonce.to_cstruct nonce) ;
+      Box.to_bytes pk ;
+      Nonce.to_bytes nonce ;
     ] in
   compare_target hash target
 
@@ -146,16 +124,16 @@ let generate_proof_of_work ?max pk target =
       loop (Nonce.increment nonce) (cpt + 1) in
   loop (random_nonce ()) 0
 
-let public_key_to_bigarray x = Cstruct.to_bigarray (Box.to_cstruct x)
-let public_key_of_bigarray x = Box.pk_of_cstruct_exn (Cstruct.of_bigarray x)
+let public_key_to_bigarray = Box.to_bytes
+let public_key_of_bigarray = Box.pk_of_bytes_exn
 let public_key_size = Box.pkbytes
 
-let secret_key_to_bigarray x = Cstruct.to_bigarray (Box.to_cstruct x)
-let secret_key_of_bigarray x = Box.sk_of_cstruct_exn (Cstruct.of_bigarray x)
+let secret_key_to_bigarray = Box.to_bytes
+let secret_key_of_bigarray = Box.sk_of_bytes_exn
 let secret_key_size = Box.skbytes
 
-let nonce_to_bigarray x = Cstruct.to_bigarray (Nonce.to_cstruct x)
-let nonce_of_bigarray x = Nonce.of_cstruct_exn (Cstruct.of_bigarray x)
+let nonce_to_bigarray = Nonce.to_bytes
+let nonce_of_bigarray = Nonce.of_bytes_exn
 let nonce_size = Nonce.bytes
 
 let public_key_encoding =
diff --git a/src/lib_crypto/ed25519.ml b/src/lib_crypto/ed25519.ml
index dd6b024d9..6df75db65 100644
--- a/src/lib_crypto/ed25519.ml
+++ b/src/lib_crypto/ed25519.ml
@@ -28,11 +28,11 @@ module Public_key = struct
   let name = "Ed25519.Public_key"
   let title = "Ed25519 public key"
 
-  let to_string s = Cstruct.to_string (Sign.to_cstruct s)
-  let of_string_opt s = Sign.pk_of_cstruct (Cstruct.of_string s)
+  let to_string s = MBytes.to_string (Sign.to_bytes s)
+  let of_string_opt s = Sign.pk_of_bytes (MBytes.of_string s)
 
-  let to_bytes pk = Cstruct.to_bigarray (Sign.to_cstruct pk)
-  let of_bytes_opt s = Sign.pk_of_cstruct (Cstruct.of_bigarray s)
+  let to_bytes = Sign.to_bytes
+  let of_bytes_opt = Sign.pk_of_bytes
 
   let size = Sign.pkbytes
 
@@ -51,13 +51,12 @@ module Public_key = struct
     Base58.check_encoded_prefix b58check_encoding "edpk" 54
 
   let hash v =
-    Public_key_hash.hash_bytes
-      [ Cstruct.to_bigarray (Sign.to_cstruct v) ]
+    Public_key_hash.hash_bytes [ Sign.to_bytes v ]
 
   include Compare.Make(struct
       type nonrec t = t
       let compare a b =
-        Cstruct.compare (Sign.to_cstruct a) (Sign.to_cstruct b)
+        MBytes.compare (Sign.to_bytes a) (Sign.to_bytes b)
     end)
 
   include Helpers.MakeRaw(struct
@@ -102,12 +101,11 @@ module Secret_key = struct
 
   let size = Sign.seedbytes
 
-  let to_bytes x = Cstruct.to_bigarray (Sign.seed x)
+  let to_bytes = Sign.seed
   let of_bytes_opt s =
-    let s = Cstruct.of_bigarray s in
-    match Cstruct.len s with
+    match MBytes.length s with
     | 32 -> let _pk, sk = Sign.keypair ~seed:s () in Some sk
-    | 64 -> Sign.sk_of_cstruct s
+    | 64 -> Sign.sk_of_bytes s
     | _ -> None
 
   let to_string s = MBytes.to_string (to_bytes s)
@@ -122,9 +120,9 @@ module Secret_key = struct
     Base58.register_encoding
       ~prefix: Base58.Prefix.ed25519_seed
       ~length: size
-      ~to_raw: (fun sk -> Cstruct.to_string (Sign.seed sk))
+      ~to_raw: (fun sk -> MBytes.to_string (Sign.seed sk))
       ~of_raw: (fun buf ->
-          let seed = Cstruct.of_string buf in
+          let seed = MBytes.of_string buf in
           match Sign.keypair ~seed () with
           | exception _ -> None
           | _pk, sk -> Some sk)
@@ -134,8 +132,8 @@ module Secret_key = struct
     Base58.register_encoding
       ~prefix: Base58.Prefix.ed25519_secret_key
       ~length: Sign.skbytes
-      ~to_raw: (fun sk -> Cstruct.to_string (Sign.to_cstruct sk))
-      ~of_raw: (fun buf -> Sign.sk_of_cstruct (Cstruct.of_string buf))
+      ~to_raw: (fun sk -> MBytes.to_string (Sign.to_bytes sk))
+      ~of_raw: (fun buf -> Sign.sk_of_bytes (MBytes.of_string buf))
       ~wrap: (fun x -> Data x)
 
   let of_b58check_opt s =
@@ -167,7 +165,7 @@ module Secret_key = struct
   include Compare.Make(struct
       type nonrec t = t
       let compare a b =
-        Cstruct.compare (Sign.to_cstruct a) (Sign.to_cstruct b)
+        MBytes.compare (Sign.to_bytes a) (Sign.to_bytes b)
     end)
 
   include Helpers.MakeRaw(struct
@@ -262,13 +260,10 @@ let pp ppf t = Format.fprintf ppf "%s" (to_b58check t)
 
 let zero = MBytes.init size '\000'
 
-let sign key msg =
-  Cstruct.(to_bigarray (Sign.detached ~key (of_bigarray msg)))
+let sign key msg = Sign.detached ~key msg
 
 let check public_key signature msg =
-  Sign.verify_detached ~key:public_key
-    ~signature:(Cstruct.of_bigarray signature)
-    (Cstruct.of_bigarray msg)
+  Sign.verify_detached ~key:public_key ~signature msg
 
 let append key msg =
   MBytes.concat msg (sign key msg)
@@ -278,7 +273,7 @@ let concat msg signature =
 
 module Seed = struct
 
-  type t = Cstruct.t
+  type t = Bigstring.t
 
   let generate () = Rand.gen 32
   let extract = Sign.seed
diff --git a/src/lib_crypto/rand.ml b/src/lib_crypto/rand.ml
index 746bcd086..5c4a7f3ca 100644
--- a/src/lib_crypto/rand.ml
+++ b/src/lib_crypto/rand.ml
@@ -7,8 +7,7 @@
 (*                                                                        *)
 (**************************************************************************)
 
-let generate len =
-  Cstruct.to_bigarray (Tweetnacl.Rand.gen len)
+let generate = Tweetnacl.Rand.gen
 
 let generate_into ?(pos=0) ?len buf =
   let buflen = MBytes.length buf in
@@ -18,6 +17,5 @@ let generate_into ?(pos=0) ?len buf =
   if pos < 0 || len < 0 || pos + len > buflen then
     invalid_arg (Printf.sprintf "Rand.generate_into: \
                                  invalid slice (pos=%d len=%d)" pos len) ;
-  let cs = Cstruct.of_bigarray buf in
-  let cs = Cstruct.sub cs pos len in
-  Tweetnacl.Rand.write cs
+  let buf = MBytes.sub buf pos len in
+  Tweetnacl.Rand.write buf
diff --git a/src/lib_crypto/secp256k1.ml b/src/lib_crypto/secp256k1.ml
index f18e354ec..118b2441b 100644
--- a/src/lib_crypto/secp256k1.ml
+++ b/src/lib_crypto/secp256k1.ml
@@ -264,7 +264,7 @@ let append key msg =
   concat msg signature
 
 let generate_key () =
-  let sk = Key.read_sk_exn context (Cstruct.to_bigarray (Tweetnacl.Rand.gen 32)) in
+  let sk = Key.read_sk_exn context (Tweetnacl.Rand.gen 32) in
   let pk = Key.neuterize_exn context sk in
   let pkh = Public_key.hash pk in
   (pkh, pk, sk)
diff --git a/vendors/ocaml-tweetnacl/src/jbuild b/vendors/ocaml-tweetnacl/src/jbuild
index 6aff84f95..ab0bf36c2 100644
--- a/vendors/ocaml-tweetnacl/src/jbuild
+++ b/vendors/ocaml-tweetnacl/src/jbuild
@@ -3,5 +3,6 @@
 (library
  ((name            tweetnacl)
   (public_name     tweetnacl)
-  (libraries       (hex cstruct zarith))
-  (c_names         (tweetnacl_stubs))))
+  (libraries       (bigstring ocplib-endian.bigstring zarith))
+  (c_names         (tweetnacl_stubs))
+  (c_flags         (-O3))))
diff --git a/vendors/ocaml-tweetnacl/src/tweetnacl.ml b/vendors/ocaml-tweetnacl/src/tweetnacl.ml
index 1d386aee9..0200fc77a 100644
--- a/vendors/ocaml-tweetnacl/src/tweetnacl.ml
+++ b/vendors/ocaml-tweetnacl/src/tweetnacl.ml
@@ -3,74 +3,76 @@
    Distributed under the ISC license, see terms at the end of the file.
   ---------------------------------------------------------------------------*)
 
+open EndianBigstring
+
 module Rand = struct
-  external randombytes : Cstruct.buffer -> int -> unit =
+  external randombytes : Bigstring.t -> int -> unit =
     "ml_randombytes" [@@noalloc]
 
   let gen sz =
-    let cs = Cstruct.create_unsafe sz in
-    randombytes (Cstruct.to_bigarray cs) sz ;
-    cs
+    let buf = Bigstring.create sz in
+    randombytes buf sz ;
+    buf
 
-  let write cs =
-    Cstruct.(randombytes (to_bigarray cs) (len cs))
+  let write buf =
+    randombytes buf (Bigstring.length buf)
 end
 
 module Hash = struct
   let bytes = 64
 
   external sha512 :
-    Cstruct.buffer -> Cstruct.buffer -> int -> unit =
+    Bigstring.t -> Bigstring.t -> int -> unit =
     "ml_crypto_hash" [@@noalloc]
 
   let sha512 msg =
-    let q = Cstruct.create_unsafe bytes in
-    sha512 q.buffer msg.Cstruct.buffer (Cstruct.len msg) ;
+    let q = Bigstring.create bytes in
+    sha512 q msg (Bigstring.length msg) ;
     q
 end
 
-let cs_of_z cs z =
-  Cstruct.memset cs 0 ;
+let buf_of_z buf z =
+  Bigstring.fill buf '\x00' ;
   let bits = Z.to_bits z in
-  Cstruct.blit_from_string bits 0 cs 0 (String.length bits)
+  Bigstring.blit_of_string bits 0 buf 0 (String.length bits)
 
-let unopt_invalid_arg1 ~msg f cs =
-  match f cs with
+let unopt_invalid_arg1 ~msg f buf =
+  match f buf with
   | Some v -> v
   | None -> invalid_arg msg
 
 module Nonce = struct
-  type t = Cstruct.t
+  type t = Bigstring.t
   let bytes = 24
 
   let gen () =
     Rand.gen bytes
 
   let rec incr_byte b step byteno =
-    let res = Cstruct.BE.get_uint16 b byteno + step in
+    let res = BigEndian.get_uint16 b byteno + step in
     let lo = res land 0xffff in
     let hi = res asr 16 in
-    Cstruct.BE.set_uint16 b byteno lo ;
+    BigEndian.set_int16 b byteno lo ;
     if hi = 0 || byteno = 0 then ()
     else incr_byte b hi (byteno - 2)
 
   let increment ?(step = 1) nonce =
-    let new_nonce = Cstruct.create_unsafe 24 in
-    Cstruct.blit nonce 0 new_nonce 0 24 ;
+    let new_nonce = Bigstring.create 24 in
+    Bigstring.blit nonce 0 new_nonce 0 24 ;
     incr_byte new_nonce step 22 ;
     new_nonce
 
-  let of_cstruct cs =
-    try Some (Cstruct.sub cs 0 bytes) with _ -> None
+  let of_bytes buf =
+    try Some (Bigstring.sub buf 0 bytes) with _ -> None
 
-  let of_cstruct_exn =
-    unopt_invalid_arg1 ~msg:"Box.Nonce.of_cstruct_exn" of_cstruct
+  let of_bytes_exn =
+    unopt_invalid_arg1 ~msg:"Box.Nonce.of_bytes_exn" of_bytes
 
-  let to_cstruct nonce = nonce
+  let to_bytes nonce = nonce
 end
 
 module Secretbox = struct
-  type key = Cstruct.t
+  type key = Bigstring.t
 
   let keybytes = 32
   let zerobytes = 32
@@ -79,46 +81,44 @@ module Secretbox = struct
   let genkey () =
     Rand.gen 32
 
-  let of_cstruct cs =
-    if Cstruct.len cs < keybytes then None
-    else Some (Cstruct.sub cs 0 keybytes)
+  let of_bytes buf =
+    if Bigstring.length buf < keybytes then None
+    else Some (Bigstring.sub buf 0 keybytes)
 
-  let of_cstruct_exn =
-    unopt_invalid_arg1 ~msg:"Secret_box.of_cstruct_exn" of_cstruct
+  let of_bytes_exn =
+    unopt_invalid_arg1 ~msg:"Secret_box.of_bytes_exn" of_bytes
 
   external secretbox :
-    Cstruct.buffer -> Cstruct.buffer ->
-    Cstruct.buffer -> Cstruct.buffer -> unit = "ml_secretbox" [@@noalloc]
+    Bigstring.t -> Bigstring.t ->
+    Bigstring.t -> Bigstring.t -> unit = "ml_secretbox" [@@noalloc]
 
   external secretbox_open :
-    Cstruct.buffer -> Cstruct.buffer ->
-    Cstruct.buffer -> Cstruct.buffer -> int = "ml_secretbox_open" [@@noalloc]
+    Bigstring.t -> Bigstring.t ->
+    Bigstring.t -> Bigstring.t -> int = "ml_secretbox_open" [@@noalloc]
 
   let box ~key ~nonce ~msg =
-    let msglen = Cstruct.len msg in
+    let msglen = Bigstring.length msg in
     let buflen = msglen + zerobytes in
-    let buf = Cstruct.create buflen in
-    Cstruct.blit msg 0 buf zerobytes msglen ;
-    secretbox
-      buf.buffer buf.buffer nonce.Cstruct.buffer key.Cstruct.buffer ;
-    Cstruct.sub buf boxzerobytes (buflen - boxzerobytes)
+    let buf = Bigstring.create buflen in
+    Bigstring.fill buf '\x00' ;
+    Bigstring.blit msg 0 buf zerobytes msglen ;
+    secretbox buf buf nonce key ;
+    Bigstring.sub buf boxzerobytes (buflen - boxzerobytes)
 
   let box_noalloc ~key ~nonce ~msg =
-    secretbox
-      msg.Cstruct.buffer msg.buffer nonce.Cstruct.buffer key.Cstruct.buffer
+    secretbox msg msg nonce key
 
   let box_open ~key ~nonce ~cmsg =
-    let msglen = Cstruct.len cmsg - boxzerobytes in
-    let buf = Cstruct.create (zerobytes + msglen) in
-    Cstruct.blit cmsg 0 buf boxzerobytes (msglen + boxzerobytes) ;
-    match secretbox_open buf.buffer buf.buffer
-            nonce.Cstruct.buffer key.Cstruct.buffer with
-    | 0 -> Some (Cstruct.sub buf zerobytes msglen)
+    let msglen = Bigstring.length cmsg - boxzerobytes in
+    let buf = Bigstring.create (zerobytes + msglen) in
+    Bigstring.fill buf '\x00' ;
+    Bigstring.blit cmsg 0 buf boxzerobytes (msglen + boxzerobytes) ;
+    match secretbox_open buf buf nonce key with
+    | 0 -> Some (Bigstring.sub buf zerobytes msglen)
     | _ -> None
 
   let box_open_noalloc ~key ~nonce ~cmsg =
-    match secretbox_open cmsg.Cstruct.buffer cmsg.buffer
-            nonce.Cstruct.buffer key.Cstruct.buffer with
+    match secretbox_open cmsg cmsg nonce key with
     | 0 -> true
     | _ -> false
 end
@@ -128,9 +128,9 @@ module Box = struct
   type public
   type combined
   type _ key =
-    | Sk : Cstruct.t -> secret key
-    | Pk : Cstruct.t -> public key
-    | Ck : Cstruct.t -> combined key
+    | Sk : Bigstring.t -> secret key
+    | Pk : Bigstring.t -> public key
+    | Ck : Bigstring.t -> combined key
 
   let skbytes = 32
   let pkbytes = 32
@@ -138,136 +138,127 @@ module Box = struct
   let zerobytes = 32
   let boxzerobytes = 16
 
-  let to_cstruct : type a. a key -> Cstruct.t = function
-    | Pk cs -> cs
-    | Sk cs -> cs
-    | Ck cs -> cs
+  let to_bytes : type a. a key -> Bigstring.t = function
+    | Pk buf -> buf
+    | Sk buf -> buf
+    | Ck buf -> buf
 
-  let blit_to_cstruct :
-    type a. a key -> ?pos:int -> Cstruct.t -> unit = fun key ?(pos=0) cs ->
+  let blit_to_bytes :
+    type a. a key -> ?pos:int -> Bigstring.t -> unit = fun key ?(pos=0) buf ->
     match key with
-    | Pk pk -> Cstruct.blit pk 0 cs pos pkbytes
-    | Sk sk -> Cstruct.blit sk 0 cs pos skbytes
-    | Ck ck -> Cstruct.blit ck 0 cs pos beforenmbytes
-
-  let pp : type a. Format.formatter -> a key -> unit = fun ppf -> function
-    | Pk cs -> Format.fprintf ppf "P %a" Hex.pp (Hex.of_cstruct cs)
-    | Sk cs -> Format.fprintf ppf "S %a" Hex.pp (Hex.of_cstruct cs)
-    | Ck cs -> Format.fprintf ppf "C %a" Hex.pp (Hex.of_cstruct cs)
-
-  let show t = Format.asprintf "%a" pp t
+    | Pk pk -> Bigstring.blit pk 0 buf pos pkbytes
+    | Sk sk -> Bigstring.blit sk 0 buf pos skbytes
+    | Ck ck -> Bigstring.blit ck 0 buf pos beforenmbytes
 
   let equal :
     type a. a key -> a key -> bool = fun a b -> match a, b with
-    | Pk a, Pk b -> Cstruct.equal a b
-    | Sk a, Sk b -> Cstruct.equal a b
-    | Ck a, Ck b -> Cstruct.equal a b
+    | Pk a, Pk b -> Bigstring.equal a b
+    | Sk a, Sk b -> Bigstring.equal a b
+    | Ck a, Ck b -> Bigstring.equal a b
 
-  let sk_of_cstruct cs =
-    try Some (Sk (Cstruct.sub cs 0 skbytes)) with _ -> None
-  let pk_of_cstruct cs =
-    try Some (Pk (Cstruct.sub cs 0 pkbytes)) with _ -> None
-  let ck_of_cstruct cs =
-    try Some (Ck (Cstruct.sub cs 0 beforenmbytes)) with _ -> None
+  let sk_of_bytes buf =
+    try Some (Sk (Bigstring.sub buf 0 skbytes)) with _ -> None
+  let pk_of_bytes buf =
+    try Some (Pk (Bigstring.sub buf 0 pkbytes)) with _ -> None
+  let ck_of_bytes buf =
+    try Some (Ck (Bigstring.sub buf 0 beforenmbytes)) with _ -> None
 
-  let sk_of_cstruct_exn =
-    unopt_invalid_arg1 ~msg:"Box.sk_of_cstruct_exn" sk_of_cstruct
-  let pk_of_cstruct_exn =
-    unopt_invalid_arg1 ~msg:"Box.pk_of_cstruct_exn" pk_of_cstruct
-  let ck_of_cstruct_exn =
-    unopt_invalid_arg1 ~msg:"Box.ck_of_cstruct_exn" ck_of_cstruct
+  let sk_of_bytes_exn =
+    unopt_invalid_arg1 ~msg:"Box.sk_of_bytes_exn" sk_of_bytes
+  let pk_of_bytes_exn =
+    unopt_invalid_arg1 ~msg:"Box.pk_of_bytes_exn" pk_of_bytes
+  let ck_of_bytes_exn =
+    unopt_invalid_arg1 ~msg:"Box.ck_of_bytes_exn" ck_of_bytes
 
   external keypair :
-    Cstruct.buffer -> Cstruct.buffer -> unit =
+    Bigstring.t -> Bigstring.t -> unit =
     "ml_crypto_box_keypair" [@@noalloc]
 
   let keypair () =
-    let sk = Cstruct.create skbytes in
-    let pk = Cstruct.create pkbytes in
-    keypair pk.buffer sk.buffer ;
+    let sk = Bigstring.create skbytes in
+    let pk = Bigstring.create pkbytes in
+    keypair pk sk ;
     Pk pk, Sk sk
 
   external box_stub :
-    Cstruct.buffer -> Cstruct.buffer -> Cstruct.buffer ->
-    Cstruct.buffer -> Cstruct.buffer -> unit =
+    Bigstring.t -> Bigstring.t -> Bigstring.t ->
+    Bigstring.t -> Bigstring.t -> unit =
     "ml_crypto_box" [@@noalloc]
 
   let box ~pk:(Pk pk) ~sk:(Sk sk) ~nonce ~msg =
-    let msglen = Cstruct.len msg in
+    let msglen = Bigstring.length msg in
     let buflen = msglen + zerobytes in
-    let buf = Cstruct.create buflen in
-    Cstruct.blit msg 0 buf zerobytes msglen ;
-    box_stub
-      buf.buffer buf.buffer nonce.Cstruct.buffer pk.buffer sk.buffer ;
-    Cstruct.sub buf boxzerobytes (buflen - boxzerobytes)
+    let buf = Bigstring.create buflen in
+    Bigstring.fill buf '\x00' ;
+    Bigstring.blit msg 0 buf zerobytes msglen ;
+    box_stub buf buf nonce pk sk ;
+    Bigstring.sub buf boxzerobytes (buflen - boxzerobytes)
 
   let box_noalloc ~pk:(Pk pk) ~sk:(Sk sk) ~nonce ~msg =
-    box_stub
-      msg.Cstruct.buffer msg.buffer nonce.Cstruct.buffer pk.buffer sk.buffer
+    box_stub msg msg nonce pk sk
 
   external box_open_stub :
-    Cstruct.buffer -> Cstruct.buffer -> Cstruct.buffer ->
-    Cstruct.buffer -> Cstruct.buffer -> int =
+    Bigstring.t -> Bigstring.t -> Bigstring.t ->
+    Bigstring.t -> Bigstring.t -> int =
     "ml_crypto_box_open" [@@noalloc]
 
   let box_open ~pk:(Pk pk) ~sk:(Sk sk) ~nonce ~cmsg =
-    let msglen = Cstruct.len cmsg - boxzerobytes in
-    let buf = Cstruct.create (zerobytes + msglen) in
-    Cstruct.blit cmsg 0 buf boxzerobytes (msglen + boxzerobytes) ;
-    match box_open_stub buf.buffer buf.buffer
-            nonce.Cstruct.buffer pk.buffer sk.buffer with
-    | 0 -> Some (Cstruct.sub buf zerobytes msglen)
+    let msglen = Bigstring.length cmsg - boxzerobytes in
+    let buf = Bigstring.create (zerobytes + msglen) in
+    Bigstring.fill buf '\x00' ;
+    Bigstring.blit cmsg 0 buf boxzerobytes (msglen + boxzerobytes) ;
+    match box_open_stub buf buf nonce pk sk with
+    | 0 -> Some (Bigstring.sub buf zerobytes msglen)
     | _ -> None
 
   let box_open_noalloc ~pk:(Pk pk) ~sk:(Sk sk) ~nonce ~cmsg =
-    match box_open_stub cmsg.Cstruct.buffer cmsg.buffer
-            nonce.Cstruct.buffer pk.buffer sk.buffer with
+    match box_open_stub cmsg cmsg nonce pk sk with
     | 0 -> true
     | _ -> false
 
   external box_beforenm :
-    Cstruct.buffer -> Cstruct.buffer -> Cstruct.buffer -> unit =
+    Bigstring.t -> Bigstring.t -> Bigstring.t -> unit =
     "ml_crypto_box_beforenm" [@@noalloc]
 
   let combine (Pk pk) (Sk sk) =
-    let combined = Cstruct.create_unsafe beforenmbytes in
-    box_beforenm combined.buffer pk.buffer sk.buffer ;
+    let combined = Bigstring.create beforenmbytes in
+    box_beforenm combined pk sk ;
     Ck combined
 
   external box_afternm :
-    Cstruct.buffer -> Cstruct.buffer ->
-    Cstruct.buffer -> Cstruct.buffer -> unit =
+    Bigstring.t -> Bigstring.t ->
+    Bigstring.t -> Bigstring.t -> unit =
     "ml_crypto_box_afternm" [@@noalloc]
 
   let box_combined ~k:(Ck k) ~nonce ~msg =
-    let msglen = Cstruct.len msg in
+    let msglen = Bigstring.length msg in
     let buflen = msglen + zerobytes in
-    let buf = Cstruct.create buflen in
-    Cstruct.blit msg 0 buf zerobytes msglen ;
-    box_afternm buf.buffer buf.buffer nonce.Cstruct.buffer k.buffer ;
-    Cstruct.sub buf boxzerobytes (buflen - boxzerobytes)
+    let buf = Bigstring.create buflen in
+    Bigstring.fill buf '\x00' ;
+    Bigstring.blit msg 0 buf zerobytes msglen ;
+    box_afternm buf buf nonce k ;
+    Bigstring.sub buf boxzerobytes (buflen - boxzerobytes)
 
   let box_combined_noalloc ~k:(Ck k) ~nonce ~msg =
-    box_afternm msg.Cstruct.buffer msg.buffer nonce.Cstruct.buffer k.buffer
+    box_afternm msg msg nonce k
 
   external box_open_afternm :
-    Cstruct.buffer -> Cstruct.buffer ->
-    Cstruct.buffer -> Cstruct.buffer -> int =
+    Bigstring.t -> Bigstring.t ->
+    Bigstring.t -> Bigstring.t -> int =
     "ml_crypto_box_open_afternm" [@@noalloc]
 
   let box_open_combined ~k:(Ck k) ~nonce ~cmsg =
-    let msglen = Cstruct.len cmsg - boxzerobytes in
+    let msglen = Bigstring.length cmsg - boxzerobytes in
     let buflen = msglen + zerobytes in
-    let buf = Cstruct.create buflen in
-    Cstruct.blit cmsg 0 buf boxzerobytes (msglen + boxzerobytes) ;
-    match box_open_afternm buf.buffer buf.buffer
-            nonce.Cstruct.buffer k.buffer with
-    | 0 -> Some (Cstruct.sub buf zerobytes msglen)
+    let buf = Bigstring.create buflen in
+    Bigstring.fill buf '\x00' ;
+    Bigstring.blit cmsg 0 buf boxzerobytes (msglen + boxzerobytes) ;
+    match box_open_afternm buf buf nonce k with
+    | 0 -> Some (Bigstring.sub buf zerobytes msglen)
     | _ -> None
 
   let box_open_combined_noalloc ~k:(Ck k) ~nonce ~cmsg =
-    match box_open_afternm cmsg.Cstruct.buffer cmsg.buffer
-            nonce.Cstruct.buffer k.buffer with
+    match box_open_afternm cmsg cmsg nonce k with
     | 0 -> true
     | _ -> false
 end
@@ -277,9 +268,9 @@ module Sign = struct
   type extended
   type public
   type _ key =
-    | Sk : Cstruct.t -> secret key
-    | Ek : Cstruct.t -> extended key
-    | Pk : Cstruct.t -> public key
+    | Sk : Bigstring.t -> secret key
+    | Ek : Bigstring.t -> extended key
+    | Pk : Bigstring.t -> public key
 
   let bytes = 64
   let pkbytes = 32
@@ -287,169 +278,156 @@ module Sign = struct
   let ekbytes = 64
   let seedbytes = 32
 
-  let sk_of_cstruct cs =
-    try Some (Sk (Cstruct.sub cs 0 skbytes)) with _ -> None
-  let ek_of_cstruct cs =
-    try Some (Ek (Cstruct.sub cs 0 ekbytes)) with _ -> None
-  let pk_of_cstruct cs =
-    try Some (Pk (Cstruct.sub cs 0 pkbytes)) with _ -> None
+  let sk_of_bytes buf =
+    try Some (Sk (Bigstring.sub buf 0 skbytes)) with _ -> None
+  let ek_of_bytes buf =
+    try Some (Ek (Bigstring.sub buf 0 ekbytes)) with _ -> None
+  let pk_of_bytes buf =
+    try Some (Pk (Bigstring.sub buf 0 pkbytes)) with _ -> None
 
-  let sk_of_cstruct_exn =
-    unopt_invalid_arg1 ~msg:"Sign.sk_of_cstruct_exn" sk_of_cstruct
-  let ek_of_cstruct_exn =
-    unopt_invalid_arg1 ~msg:"Sign.ek_of_cstruct_exn" ek_of_cstruct
-  let pk_of_cstruct_exn =
-    unopt_invalid_arg1 ~msg:"Sign.pk_of_cstruct_exn" pk_of_cstruct
+  let sk_of_bytes_exn =
+    unopt_invalid_arg1 ~msg:"Sign.sk_of_bytes_exn" sk_of_bytes
+  let ek_of_bytes_exn =
+    unopt_invalid_arg1 ~msg:"Sign.ek_of_bytes_exn" ek_of_bytes
+  let pk_of_bytes_exn =
+    unopt_invalid_arg1 ~msg:"Sign.pk_of_bytes_exn" pk_of_bytes
 
-  let to_cstruct : type a. a key -> Cstruct.t = function
-    | Pk cs -> cs
-    | Sk cs -> cs
-    | Ek cs -> cs
+  let to_bytes : type a. a key -> Bigstring.t = function
+    | Pk buf -> buf
+    | Sk buf -> buf
+    | Ek buf -> buf
 
-  let seed (Sk cs) = Cstruct.sub cs 0 seedbytes
+  let seed (Sk buf) = Bigstring.sub buf 0 seedbytes
 
-  let blit_to_cstruct :
-    type a. a key -> ?pos:int -> Cstruct.t -> unit = fun key ?(pos=0) cs ->
+  let blit_to_bytes :
+    type a. a key -> ?pos:int -> Bigstring.t -> unit = fun key ?(pos=0) buf ->
     match key with
-    | Pk pk -> Cstruct.blit pk 0 cs pos pkbytes
-    | Sk sk -> Cstruct.blit sk 0 cs pos skbytes
-    | Ek ek -> Cstruct.blit ek 0 cs pos ekbytes
-
-  let pp : type a. Format.formatter -> a key -> unit = fun ppf -> function
-    | Pk cs -> Format.fprintf ppf "P %a" Hex.pp (Hex.of_cstruct cs)
-    | Sk cs -> Format.fprintf ppf "S %a" Hex.pp (Hex.of_cstruct cs)
-    | Ek cs -> Format.fprintf ppf "E %a" Hex.pp (Hex.of_cstruct cs)
-
-  let show t = Format.asprintf "%a" pp t
+    | Pk pk -> Bigstring.blit pk 0 buf pos pkbytes
+    | Sk sk -> Bigstring.blit sk 0 buf pos skbytes
+    | Ek ek -> Bigstring.blit ek 0 buf pos ekbytes
 
   let equal :
     type a. a key -> a key -> bool = fun a b -> match a, b with
-    | Pk a, Pk b -> Cstruct.equal a b
-    | Sk a, Sk b -> Cstruct.equal a b
-    | Ek a, Ek b -> Cstruct.equal a b
+    | Pk a, Pk b -> Bigstring.equal a b
+    | Sk a, Sk b -> Bigstring.equal a b
+    | Ek a, Ek b -> Bigstring.equal a b
 
   external keypair :
-    Cstruct.buffer -> Cstruct.buffer -> unit =
+    Bigstring.t -> Bigstring.t -> unit =
     "ml_crypto_sign_keypair" [@@noalloc]
 
   external keypair_seed :
-    Cstruct.buffer -> Cstruct.buffer -> unit =
+    Bigstring.t -> Bigstring.t -> unit =
     "ml_crypto_sign_keypair_seed" [@@noalloc]
 
   let keypair ?seed () =
-    let pk = Cstruct.create_unsafe pkbytes in
-    let sk = Cstruct.create_unsafe skbytes in
+    let pk = Bigstring.create pkbytes in
+    let sk = Bigstring.create skbytes in
     begin match seed with
-      | None ->
-          Cstruct.(keypair (to_bigarray pk) (to_bigarray sk))
-      | Some cs ->
-          if Cstruct.len cs < seedbytes then
-            invalid_arg "Sign.keypair: seed must be at least 32 bytes long" ;
-          Cstruct.blit cs 0 sk 0 pkbytes ;
-          Cstruct.(keypair_seed (to_bigarray pk) (to_bigarray sk))
+      | None -> keypair pk sk
+      | Some buf ->
+        if Bigstring.length buf < seedbytes then
+          invalid_arg "Sign.keypair: seed must be at least 32 bytes long" ;
+        Bigstring.blit buf 0 sk 0 pkbytes ;
+        keypair_seed pk sk
     end ;
     Pk pk, Sk sk
 
   let extended (Sk sk) =
-    let cs = Hash.sha512 (Cstruct.sub sk 0 pkbytes) in
-    Cstruct.(set_uint8 cs 0 (get_uint8 cs 0 land 248)) ;
-    Cstruct.(set_uint8 cs 31 (get_uint8 cs 31 land 127)) ;
-    Cstruct.(set_uint8 cs 31 (get_uint8 cs 31 lor 64)) ;
-    Ek cs
+    let buf = Hash.sha512 (Bigstring.sub sk 0 pkbytes) in
+    BigEndian.(set_int8 buf 0 (get_uint8 buf 0 land 248)) ;
+    BigEndian.(set_int8 buf 31 (get_uint8 buf 31 land 127)) ;
+    BigEndian.(set_int8 buf 31 (get_uint8 buf 31 lor 64)) ;
+    Ek buf
 
   external sign :
-    Cstruct.buffer -> Cstruct.buffer -> unit =
+    Bigstring.t -> Bigstring.t -> unit =
     "ml_crypto_sign" [@@noalloc]
 
   external sign_extended :
-    Cstruct.buffer -> Cstruct.buffer -> unit =
+    Bigstring.t -> Bigstring.t -> unit =
     "ml_crypto_sign_extended" [@@noalloc]
 
   let sign ~key:(Sk sk) msg =
-    let msglen = Cstruct.len msg in
-    let cs = Cstruct.create_unsafe (bytes + msglen) in
-    Cstruct.blit msg 0 cs bytes msglen ;
-    Cstruct.(sign (to_bigarray cs) (to_bigarray sk)) ;
-    cs
+    let msglen = Bigstring.length msg in
+    let buf = Bigstring.create (bytes + msglen) in
+    Bigstring.blit msg 0 buf bytes msglen ;
+    sign buf sk ;
+    buf
 
   let sign_extended ~key:(Ek ek) msg =
-    let msglen = Cstruct.len msg in
-    let cs = Cstruct.create_unsafe (bytes + msglen) in
-    Cstruct.blit msg 0 cs bytes msglen ;
-    Cstruct.(sign_extended (to_bigarray cs) (to_bigarray ek)) ;
-    cs
+    let msglen = Bigstring.length msg in
+    let buf = Bigstring.create (bytes + msglen) in
+    Bigstring.blit msg 0 buf bytes msglen ;
+    sign_extended buf ek ;
+    buf
 
   let detached ~key msg =
-    Cstruct.sub (sign ~key msg) 0 bytes
+    Bigstring.sub (sign ~key msg) 0 bytes
 
   let detached_extended ~key msg =
-    Cstruct.sub (sign_extended ~key msg) 0 bytes
+    Bigstring.sub (sign_extended ~key msg) 0 bytes
 
   external verify :
-    Cstruct.buffer -> Cstruct.buffer -> Cstruct.buffer -> Cstruct.buffer -> int =
+    Bigstring.t -> Bigstring.t -> Bigstring.t -> int =
     "ml_crypto_sign_open" [@@noalloc]
 
   let verify ~key:(Pk pk) smsg =
-    let mlen = Cstruct.create_unsafe 8 in
-    let msg = Cstruct.(create (len smsg)) in
-    let ret = Cstruct.(verify
-                         (to_bigarray msg) (to_bigarray mlen)
-                         (to_bigarray smsg) (to_bigarray pk)) in
-    match ret with
-    | 0 ->
-        let len = Cstruct.LE.get_uint64 mlen 0 |> Int64.to_int in
-        Some (Cstruct.sub msg 0 len)
-    | _ -> None
+    let msg = Bigstring.(create (length smsg)) in
+    match verify msg smsg pk with
+    | -1 -> None
+    | len -> Some (Bigstring.sub msg 0 len)
 
   let verify_detached ~key ~signature msg =
-    let cs = Cstruct.create_unsafe (bytes + Cstruct.len msg) in
-    Cstruct.blit signature 0 cs 0 bytes ;
-    Cstruct.blit msg 0 cs bytes (Cstruct.len msg) ;
-    match verify ~key cs with
+    let msglen = Bigstring.length msg in
+    let buf = Bigstring.create (bytes + msglen) in
+    Bigstring.blit signature 0 buf 0 bytes ;
+    Bigstring.blit msg 0 buf bytes msglen ;
+    match verify ~key buf with
     | None -> false
     | Some _ -> true
 
   external add :
-    Cstruct.buffer -> Cstruct.buffer -> unit =
+    Bigstring.t -> Bigstring.t -> unit =
     "ml_add" [@@noalloc]
 
   let add (Pk p) (Pk q) =
-    let cs = Cstruct.create_unsafe pkbytes in
-    Cstruct.blit p 0 cs 0 pkbytes ;
-    Cstruct.(add (to_bigarray cs) (to_bigarray q)) ;
-    Pk cs
+    let buf = Bigstring.create pkbytes in
+    Bigstring.blit p 0 buf 0 pkbytes ;
+    add buf q ;
+    Pk buf
 
   external mult :
-    Cstruct.buffer -> Cstruct.buffer -> Cstruct.buffer -> unit =
+    Bigstring.t -> Bigstring.t -> Bigstring.t -> unit =
     "ml_scalarmult" [@@noalloc]
 
   external base :
-    Cstruct.buffer -> Cstruct.buffer -> unit =
+    Bigstring.t -> Bigstring.t -> unit =
     "ml_scalarbase" [@@noalloc]
 
   let mult (Pk q) s =
-    let r = Cstruct.create_unsafe pkbytes in
-    let scalar = Cstruct.create_unsafe pkbytes in
-    cs_of_z scalar s ;
-    Cstruct.(mult (to_bigarray r) (to_bigarray q) (to_bigarray scalar)) ;
+    let r = Bigstring.create pkbytes in
+    let scalar = Bigstring.create pkbytes in
+    buf_of_z scalar s ;
+    mult r q scalar ;
     Pk r
 
   let base_direct s =
-    let cs = Cstruct.create_unsafe pkbytes in
-    Cstruct.(base (to_bigarray cs) (to_bigarray s)) ;
-    cs
+    let buf = Bigstring.create pkbytes in
+    base buf s ;
+    buf
 
   let base s =
-    let r = Cstruct.create_unsafe pkbytes in
-    let scalar = Cstruct.create_unsafe pkbytes in
-    cs_of_z scalar s ;
-    Cstruct.(base (to_bigarray r) (to_bigarray scalar)) ;
+    let r = Bigstring.create pkbytes in
+    let scalar = Bigstring.create pkbytes in
+    buf_of_z scalar s ;
+    base r scalar ;
     Pk r
 
   let public : type a. a key -> public key = function
     | Pk _ as pk -> pk
-    | Sk cs -> Pk (Cstruct.sub cs 32 32)
-    | Ek cs -> Pk (base_direct (Cstruct.sub cs 0 32))
+    | Sk buf -> Pk (Bigstring.sub buf 32 32)
+    | Ek buf  -> Pk (base_direct (Bigstring.sub buf 0 32))
 end
 
 (*---------------------------------------------------------------------------
diff --git a/vendors/ocaml-tweetnacl/src/tweetnacl.mli b/vendors/ocaml-tweetnacl/src/tweetnacl.mli
index 60951fc3e..78b57142c 100644
--- a/vendors/ocaml-tweetnacl/src/tweetnacl.mli
+++ b/vendors/ocaml-tweetnacl/src/tweetnacl.mli
@@ -4,12 +4,12 @@
   ---------------------------------------------------------------------------*)
 
 module Rand : sig
-  val gen : int -> Cstruct.t
-  val write : Cstruct.t -> unit
+  val gen : int -> Bigstring.t
+  val write : Bigstring.t -> unit
 end
 
 module Hash : sig
-  val sha512 : Cstruct.t -> Cstruct.t
+  val sha512 : Bigstring.t -> Bigstring.t
 end
 
 module Nonce : sig
@@ -17,9 +17,9 @@ module Nonce : sig
   val bytes : int
   val gen : unit -> t
   val increment : ?step:int -> t -> t
-  val of_cstruct : Cstruct.t -> t option
-  val of_cstruct_exn : Cstruct.t -> t
-  val to_cstruct : t -> Cstruct.t
+  val of_bytes : Bigstring.t -> t option
+  val of_bytes_exn : Bigstring.t -> t
+  val to_bytes : t -> Bigstring.t
 end
 
 module Secretbox : sig
@@ -30,14 +30,14 @@ module Secretbox : sig
   val boxzerobytes : int
 
   val genkey : unit -> key
-  val of_cstruct : Cstruct.t -> key option
-  val of_cstruct_exn : Cstruct.t -> key
+  val of_bytes : Bigstring.t -> key option
+  val of_bytes_exn : Bigstring.t -> key
 
-  val box : key:key -> nonce:Nonce.t -> msg:Cstruct.t -> Cstruct.t
-  val box_open : key:key -> nonce:Nonce.t -> cmsg:Cstruct.t -> Cstruct.t option
+  val box : key:key -> nonce:Nonce.t -> msg:Bigstring.t -> Bigstring.t
+  val box_open : key:key -> nonce:Nonce.t -> cmsg:Bigstring.t -> Bigstring.t option
 
-  val box_noalloc : key:key -> nonce:Nonce.t -> msg:Cstruct.t -> unit
-  val box_open_noalloc : key:key -> nonce:Nonce.t -> cmsg:Cstruct.t -> bool
+  val box_noalloc : key:key -> nonce:Nonce.t -> msg:Bigstring.t -> unit
+  val box_open_noalloc : key:key -> nonce:Nonce.t -> cmsg:Bigstring.t -> bool
 end
 
 module Box : sig
@@ -53,46 +53,44 @@ module Box : sig
   val zerobytes : int
   val boxzerobytes : int
 
-  val pp : Format.formatter -> _ key -> unit
-  val show : _ key -> string
   val equal : 'a key -> 'a key -> bool
-  val to_cstruct : _ key -> Cstruct.t
-  val blit_to_cstruct : _ key -> ?pos:int -> Cstruct.t -> unit
+  val to_bytes : _ key -> Bigstring.t
+  val blit_to_bytes : _ key -> ?pos:int -> Bigstring.t -> unit
 
-  val sk_of_cstruct : Cstruct.t -> secret key option
-  val pk_of_cstruct : Cstruct.t -> public key option
-  val ck_of_cstruct : Cstruct.t -> combined key option
+  val sk_of_bytes : Bigstring.t -> secret key option
+  val pk_of_bytes : Bigstring.t -> public key option
+  val ck_of_bytes : Bigstring.t -> combined key option
 
-  val sk_of_cstruct_exn : Cstruct.t -> secret key
-  val pk_of_cstruct_exn : Cstruct.t -> public key
-  val ck_of_cstruct_exn : Cstruct.t -> combined key
+  val sk_of_bytes_exn : Bigstring.t -> secret key
+  val pk_of_bytes_exn : Bigstring.t -> public key
+  val ck_of_bytes_exn : Bigstring.t -> combined key
 
   val keypair : unit -> public key * secret key
 
   val box :
     pk:public key -> sk:secret key ->
-    nonce:Nonce.t -> msg:Cstruct.t -> Cstruct.t
+    nonce:Nonce.t -> msg:Bigstring.t -> Bigstring.t
   val box_open :
     pk:public key -> sk:secret key ->
-    nonce:Nonce.t -> cmsg:Cstruct.t -> Cstruct.t option
+    nonce:Nonce.t -> cmsg:Bigstring.t -> Bigstring.t option
 
   val box_noalloc :
     pk:public key -> sk:secret key ->
-    nonce:Nonce.t -> msg:Cstruct.t -> unit
+    nonce:Nonce.t -> msg:Bigstring.t -> unit
   val box_open_noalloc :
     pk:public key -> sk:secret key ->
-    nonce:Nonce.t -> cmsg:Cstruct.t -> bool
+    nonce:Nonce.t -> cmsg:Bigstring.t -> bool
 
   val combine : public key -> secret key -> combined key
   val box_combined :
-    k:combined key -> nonce:Nonce.t -> msg:Cstruct.t -> Cstruct.t
+    k:combined key -> nonce:Nonce.t -> msg:Bigstring.t -> Bigstring.t
   val box_open_combined :
-    k:combined key -> nonce:Nonce.t -> cmsg:Cstruct.t -> Cstruct.t option
+    k:combined key -> nonce:Nonce.t -> cmsg:Bigstring.t -> Bigstring.t option
 
   val box_combined_noalloc :
-    k:combined key -> nonce:Nonce.t -> msg:Cstruct.t -> unit
+    k:combined key -> nonce:Nonce.t -> msg:Bigstring.t -> unit
   val box_open_combined_noalloc :
-    k:combined key -> nonce:Nonce.t -> cmsg:Cstruct.t -> bool
+    k:combined key -> nonce:Nonce.t -> cmsg:Bigstring.t -> bool
 end
 
 module Sign : sig
@@ -107,34 +105,32 @@ module Sign : sig
   val ekbytes : int
   val seedbytes : int
 
-  val pp : Format.formatter -> _ key -> unit
-  val show : _ key -> string
-  val to_cstruct : _ key -> Cstruct.t
-  val blit_to_cstruct : _ key -> ?pos:int -> Cstruct.t -> unit
+  val to_bytes : _ key -> Bigstring.t
+  val blit_to_bytes : _ key -> ?pos:int -> Bigstring.t -> unit
 
-  val sk_of_cstruct : Cstruct.t -> secret key option
-  val ek_of_cstruct : Cstruct.t -> extended key option
-  val pk_of_cstruct : Cstruct.t -> public key option
+  val sk_of_bytes : Bigstring.t -> secret key option
+  val ek_of_bytes : Bigstring.t -> extended key option
+  val pk_of_bytes : Bigstring.t -> public key option
 
-  val sk_of_cstruct_exn : Cstruct.t -> secret key
-  val ek_of_cstruct_exn : Cstruct.t -> extended key
-  val pk_of_cstruct_exn : Cstruct.t -> public key
+  val sk_of_bytes_exn : Bigstring.t -> secret key
+  val ek_of_bytes_exn : Bigstring.t -> extended key
+  val pk_of_bytes_exn : Bigstring.t -> public key
 
-  val keypair : ?seed:Cstruct.t -> unit -> public key * secret key
+  val keypair : ?seed:Bigstring.t -> unit -> public key * secret key
   val equal : 'a key -> 'a key -> bool
 
   val extended : secret key -> extended key
-  val seed : secret key -> Cstruct.t
+  val seed : secret key -> Bigstring.t
   val public : _ key -> public key
 
-  val sign : key:secret key -> Cstruct.t -> Cstruct.t
-  val sign_extended : key:extended key -> Cstruct.t -> Cstruct.t
+  val sign : key:secret key -> Bigstring.t -> Bigstring.t
+  val sign_extended : key:extended key -> Bigstring.t -> Bigstring.t
 
-  val detached : key:secret key -> Cstruct.t -> Cstruct.t
-  val detached_extended : key:extended key -> Cstruct.t -> Cstruct.t
+  val detached : key:secret key -> Bigstring.t -> Bigstring.t
+  val detached_extended : key:extended key -> Bigstring.t -> Bigstring.t
 
-  val verify : key:public key -> Cstruct.t -> Cstruct.t option
-  val verify_detached : key:public key -> signature:Cstruct.t -> Cstruct.t -> bool
+  val verify : key:public key -> Bigstring.t -> Bigstring.t option
+  val verify_detached : key:public key -> signature:Bigstring.t -> Bigstring.t -> bool
 
   val add : public key -> public key -> public key
   val mult : public key -> Z.t -> public key
diff --git a/vendors/ocaml-tweetnacl/src/tweetnacl_stubs.c b/vendors/ocaml-tweetnacl/src/tweetnacl_stubs.c
index cbfb684f0..f961fdad9 100644
--- a/vendors/ocaml-tweetnacl/src/tweetnacl_stubs.c
+++ b/vendors/ocaml-tweetnacl/src/tweetnacl_stubs.c
@@ -1033,12 +1033,14 @@ CAMLprim value ml_crypto_sign_extended(value sm, value d) {
     return Val_unit;
 }
 
-CAMLprim value ml_crypto_sign_open(value m, value mlen, value sm, value pk) {
-    return Val_int(crypto_sign_open(Caml_ba_data_val(m),
-                                    Caml_ba_data_val(mlen),
-                                    Caml_ba_data_val(sm),
-                                    Caml_ba_array_val(sm)->dim[0],
-                                    Caml_ba_data_val(pk)));
+CAMLprim value ml_crypto_sign_open(value m, value sm, value pk) {
+    i64 mlen;
+    int ret = crypto_sign_open(Caml_ba_data_val(m),
+                               &mlen,
+                               Caml_ba_data_val(sm),
+                               Caml_ba_array_val(sm)->dim[0],
+                               Caml_ba_data_val(pk));
+    return (ret == -1 ? Val_long(-1) : Val_long(mlen));
 }
 
 CAMLprim value ml_crypto_sign_keypair(value pk, value sk) {
diff --git a/vendors/ocaml-tweetnacl/test/test.ml b/vendors/ocaml-tweetnacl/test/test.ml
index 4241a1695..b1e72fe7d 100644
--- a/vendors/ocaml-tweetnacl/test/test.ml
+++ b/vendors/ocaml-tweetnacl/test/test.ml
@@ -1,12 +1,17 @@
 open Tweetnacl
 
-let msg = "Voulez-vous coucher avec moi, ce soir ?" |> Cstruct.of_string
-let msglen = Cstruct.len msg
+let pp_bigstring ppf buf =
+  Format.fprintf ppf "%a" Hex.pp (Hex.of_cstruct (Cstruct.of_bigarray buf))
+
+let bigstring = Alcotest.testable pp_bigstring Bigstring.equal
+
+let msg = Bigstring.of_string "Voulez-vous coucher avec moi, ce soir ?"
+let msglen = Bigstring.length msg
 
 let sha512 () =
   let resp = `Hex "7941f442d956f124d77ee1d1f0ba3db100751090462cdce4aed5fcd240529097bc666bf9c424becde760910df652c7aefec50b02d7f6efe666f79e5242fb755b" in
   let digest = Hash.sha512 msg in
-  assert (resp = (Hex.of_cstruct digest))
+  assert (resp = (Hex.of_cstruct (Cstruct.of_bigarray digest)))
 
 let keypair () =
   let seed = Rand.gen 32 in
@@ -19,16 +24,15 @@ let sign () =
   let pk, sk = Sign.keypair () in
   let signed_msg = Sign.sign ~key:sk msg in
   match Sign.verify ~key:pk signed_msg with
-  | None -> failwith "Impossible to verify"
+  | None -> assert false
   | Some verified_msg ->
-      assert (Hex.of_cstruct msg =
-              Hex.of_cstruct (Cstruct.sub verified_msg Sign.bytes msglen))
+    Alcotest.check bigstring "sign" msg verified_msg
 
 let sign_detached () =
   let pk, sk = Sign.keypair () in
   let signature = Sign.detached ~key:sk msg in
   match Sign.verify_detached ~key:pk ~signature msg with
-  | false -> failwith "Impossible to verify"
+  | false -> assert false
   | true -> ()
 
 let sign_extended () =
@@ -36,34 +40,33 @@ let sign_extended () =
   let ek = Sign.extended sk in
   let signed_msg = Sign.sign_extended ~key:ek msg in
   match Sign.verify ~key:pk signed_msg with
-  | None -> failwith "Impossible to verify"
+  | None -> assert false
   | Some verified_msg ->
-      assert (Hex.of_cstruct msg =
-              Hex.of_cstruct (Cstruct.sub verified_msg Sign.bytes msglen))
+    Alcotest.check bigstring "sign_extended" msg verified_msg
 
 let sign_extended_detached () =
   let pk, sk = Sign.keypair () in
   let ek = Sign.extended sk in
   let signature = Sign.detached_extended ~key:ek msg in
   match Sign.verify_detached ~key:pk ~signature msg with
-  | false -> failwith "Impossible to verify"
+  | false -> assert false
   | true -> ()
 
 let public () =
   let pk, sk = Sign.keypair () in
-  let pk' = Sign.to_cstruct pk in
+  let pk' = Sign.to_bytes pk in
   let ek = Sign.extended sk in
-  let ppk = Sign.(public pk |> to_cstruct) in
-  let psk = Sign.(public sk |> to_cstruct) in
-  let pek = Sign.(public ek |> to_cstruct) in
-  assert (Cstruct.equal pk' ppk) ;
-  assert (Cstruct.equal pk' psk) ;
-  assert (Cstruct.equal pk' pek)
+  let ppk = Sign.(to_bytes (public pk)) in
+  let psk = Sign.(to_bytes (public sk)) in
+  let pek = Sign.(to_bytes (public ek)) in
+  Alcotest.check bigstring "public" pk' ppk ;
+  Alcotest.check bigstring "public" pk' psk ;
+  Alcotest.check bigstring "public" pk' pek
 
 let base () =
   let pk, sk = Sign.keypair () in
-  let ek = Sign.(extended sk |> to_cstruct) in
-  let z = Z.of_bits Cstruct.(sub ek 0 32 |> to_string) in
+  let ek = Sign.(to_bytes (extended sk)) in
+  let z = Z.of_bits Bigstring.(to_string (sub ek 0 32)) in
   let pk' = Sign.base z in
   assert (Sign.equal pk pk')
 
@@ -105,23 +108,25 @@ let secretbox () =
   let key = genkey () in
   let nonce = Nonce.gen () in
   let cmsg = box ~key ~nonce ~msg in
-  assert (Cstruct.len cmsg = msglen + boxzerobytes) ;
+  assert (Bigstring.length cmsg = msglen + boxzerobytes) ;
   begin match box_open ~key ~nonce ~cmsg with
     | None -> assert false
-    | Some msg' -> assert Cstruct.(equal msg msg')
+    | Some msg' -> Alcotest.check bigstring "secretbox" msg msg'
   end
 
 let secretbox_noalloc () =
   let open Secretbox in
   let buflen = msglen + zerobytes in
-  let buf = Cstruct.create buflen in
-  Cstruct.blit msg 0 buf zerobytes msglen ;
+  let buf = Bigstring.create buflen in
+  Bigstring.fill buf '\x00' ;
+  Bigstring.blit msg 0 buf zerobytes msglen ;
   let key = genkey () in
   let nonce = Nonce.gen () in
   box_noalloc ~key ~nonce ~msg:buf ;
   let res = box_open_noalloc ~key ~nonce ~cmsg:buf in
   assert res ;
-  assert Cstruct.(equal msg (sub buf zerobytes msglen))
+  Alcotest.check
+    bigstring "secretbox_noalloc" msg (Bigstring.sub buf zerobytes msglen)
 
 let secretbox = [
   "secretbox", `Quick, secretbox ;
@@ -131,36 +136,39 @@ let secretbox = [
 let box () =
   let open Box in
   let pk, sk = keypair () in
-  let ck = combine pk sk in
+  let k = combine pk sk in
   let nonce = Nonce.gen () in
   let cmsg = box ~pk ~sk ~nonce ~msg in
-  assert (Cstruct.len cmsg = msglen + boxzerobytes) ;
+  assert (Bigstring.length cmsg = msglen + boxzerobytes) ;
   begin match box_open ~pk ~sk ~nonce ~cmsg with
     | None -> assert false
-    | Some msg' -> assert Cstruct.(equal msg msg')
+    | Some msg' -> Alcotest.check bigstring "box" msg msg'
   end ;
-  let cmsg = box_combined ~k:ck ~nonce ~msg in
-  begin match box_open_combined ~k:ck ~nonce ~cmsg with
+  let cmsg = box_combined ~k ~nonce ~msg in
+  begin match box_open_combined ~k ~nonce ~cmsg with
     | None -> assert false
-    | Some msg' -> assert Cstruct.(equal msg msg')
+    | Some msg' -> Alcotest.check bigstring "box" msg msg'
   end
 
 let box_noalloc () =
   let open Box in
   let buflen = msglen + zerobytes in
-  let buf = Cstruct.create buflen in
-  Cstruct.blit msg 0 buf zerobytes msglen ;
+  let buf = Bigstring.create buflen in
+  Bigstring.fill buf '\x00' ;
+  Bigstring.blit msg 0 buf zerobytes msglen ;
   let pk, sk = keypair () in
-  let ck = combine pk sk in
+  let k = combine pk sk in
   let nonce = Nonce.gen () in
   box_noalloc ~pk ~sk ~nonce ~msg:buf ;
   let res = box_open_noalloc ~pk ~sk ~nonce ~cmsg:buf in
   assert res ;
-  assert Cstruct.(equal msg (sub buf zerobytes msglen)) ;
-  box_combined_noalloc ~k:ck ~nonce ~msg:buf ;
-  let res = box_open_combined_noalloc ~k:ck ~nonce ~cmsg:buf in
+  Alcotest.check bigstring
+    "box_noalloc" msg (Bigstring.sub buf zerobytes msglen) ;
+  box_combined_noalloc ~k ~nonce ~msg:buf ;
+  let res = box_open_combined_noalloc ~k ~nonce ~cmsg:buf in
   assert res ;
-  assert Cstruct.(equal msg (sub buf zerobytes msglen))
+  Alcotest.check bigstring
+    "box_noalloc" msg (Bigstring.sub buf zerobytes msglen)
 
 let box = [
   "box", `Quick, box ;
diff --git a/vendors/ocaml-tweetnacl/tweetnacl.opam b/vendors/ocaml-tweetnacl/tweetnacl.opam
index ce275756c..a5f3adeb4 100644
--- a/vendors/ocaml-tweetnacl/tweetnacl.opam
+++ b/vendors/ocaml-tweetnacl/tweetnacl.opam
@@ -16,8 +16,9 @@ build: [ "jbuilder" "build" "-j" jobs "-p" name "@install" ]
 build-test: [ "jbuilder" "runtest" "-p" name "-j" jobs ]
 depends: [
   "jbuilder" {build & >= "1.0+beta16"}
-  "hex" {>= "1.2.0"}
-  "cstruct" {>= "3.2.1"}
-  "zarith" {>= "1.7" }
-  "alcotest" { test }
+  "bigstring" {>= "0.1.1"}
+  "ocplib-endian" {>= "1.0"}
+  "zarith" {>= "1.7"}
+  "alcotest" {test & >= "0.8.1"}
+  "hex" {test & >= "1.2.0"}
 ]