Hacl: add HMAC_SHA512

vendors/ocaml-hacl/src/hacl.ml

@@ -117,20 +117,22 @@ module Hash = struct
         Bigstring.t -> Bigstring.t -> Bigstring.t -> unit =
         "ml_Hacl_HMAC_SHA2_256_hmac" [@@noalloc]
 
-      let write_hmac ~key ~msg buf =
-        if Bigstring.length buf < 32 then
-          invalid_arg (Printf.sprintf "Hash.write_hmac_sha156: invalid len \
-                                       %d" 32) ;
+      let write ~key ~msg buf =
+        let buflen = Bigstring.length buf in
+        if buflen < 32 then
+          invalid_arg (Printf.sprintf "Hash.SHA256.HMAC.write: invalid \
+                                       len (%d), expected %d" buflen bytes) ;
         hmac buf key msg
 
-      let hmac ~key ~msg =
+      let digest ~key ~msg =
         let buf = Bigstring.create 32 in
-        write_hmac ~key ~msg buf ;
+        write ~key ~msg buf ;
         buf
     end
   end
 
-  module SHA512 = Make(struct
+  module SHA512 = struct
+    module H = Make(struct
         (* state -> unit *)
         external init : Bigstring.t -> unit =
           "ml_Hacl_SHA2_512_init" [@@noalloc]
@@ -151,7 +153,41 @@ module Hash = struct
         let blockbytes = 128
         let statebytes = 169 * 8
       end)
+    include H
 
+    module HMAC = struct
+      let derive_key k =
+        let buf = Bigstring.create blockbytes in
+        Bigstring.fill buf '\x00' ;
+        let keylen = Bigstring.length k in
+        let k, keylen =
+          if keylen > blockbytes then H.digest k, bytes else k, keylen in
+        Bigstring.blit k 0 buf 0 keylen ;
+        buf
+
+      let xor_ipad =
+        Bigstring.map ~f:(fun c -> Char.(chr ((code c) lxor 0x36)))
+      let xor_opad =
+        Bigstring.map ~f:(fun c -> Char.(chr ((code c) lxor 0x5c)))
+
+      let digest ~key ~msg =
+        let key = derive_key key in
+        let preimage =
+          Bigstring.concat "" [
+            xor_opad key ;
+            digest (Bigstring.concat "" [xor_ipad key ; msg])
+          ] in
+        digest preimage
+
+      let write ~key ~msg buf =
+        let buflen = Bigstring.length buf in
+        if buflen < bytes then
+          invalid_arg (Printf.sprintf "Hash.SHA512.HMAC.write: invalid \
+                                       len (%d), expected %d" buflen bytes) ;
+        let d = digest ~key ~msg in
+        Bigstring.blit d 0 buf 0 bytes
+    end
+  end
 end
 
 module Nonce = struct

vendors/ocaml-hacl/src/hacl.mli

@@ -46,11 +46,11 @@ module Hash : sig
     val digest : Bigstring.t -> Bigstring.t
 
     module HMAC : sig
-      val write_hmac :
+      val write :
         key:Bigstring.t -> msg:Bigstring.t -> Bigstring.t -> unit
       (** @raise [Invalid_argument] if argument is less than 32 bytes long *)
 
-      val hmac :
+      val digest :
         key:Bigstring.t -> msg:Bigstring.t -> Bigstring.t
     end
   end
@@ -71,6 +71,15 @@ module Hash : sig
     (** Direct Interface *)
 
     val digest : Bigstring.t -> Bigstring.t
+
+    module HMAC : sig
+      val write :
+        key:Bigstring.t -> msg:Bigstring.t -> Bigstring.t -> unit
+      (** @raise [Invalid_argument] if argument is less than 32 bytes long *)
+
+      val digest :
+        key:Bigstring.t -> msg:Bigstring.t -> Bigstring.t
+    end
   end
 end
 

vendors/ocaml-hacl/test/test.ml

@@ -84,11 +84,26 @@ let hmac_sha256 () =
   let key  = Bigstring.of_string "key" in
   let msg = Bigstring.of_string "The quick brown fox jumps over the lazy dog" in
   let resp = of_hex "f7bc83f430538424b13298e6aa6fb143ef4d59a14946175997479dbc2d1a3cd8" in
-  let digest = Hash.HMAC_SHA256.hmac ~key ~msg in
+  let digest = Hash.SHA256.HMAC.digest ~key ~msg in
   Alcotest.(check bigstring "hmac_sha256" resp digest)
 
+let hmac_sha512 () =
+  let vectors = [
+    Bigstring.of_string "key",
+    Bigstring.of_string "The quick brown fox jumps over the lazy dog",
+    of_hex "b42af09057bac1e2d41708e48a902e09b5ff7f12ab428a4fe86653c73dd248fb82f948a549f7b791a5b41915ee4d1ec3935357e4e2317250d0372afa2ebeeb3a" ;
+    Bigstring.empty,
+    Bigstring.empty,
+    of_hex "b936cee86c9f87aa5d3c6f2e84cb5a4239a5fe50480a6ec66b70ab5b1f4ac6730c6c515421b327ec1d69402e53dfb49ad7381eb067b338fd7b0cb22247225d47" ;
+  ] in
+  List.iter begin fun (key, msg, resp) ->
+    let digest = Hash.SHA512.HMAC.digest ~key ~msg in
+    Alcotest.(check bigstring "hmac_sha512" resp digest)
+  end vectors
+
 let hash = [
   "hmac_sha256", `Quick, hmac_sha256 ;
+  "hmac_sha512", `Quick, hmac_sha512 ;
 
   "sha256", `Quick, sha256 ;
   "sha256_seq", `Quick, sha256_seq ;