Remove ppx_expect dependency (#43)

ppx_expect is in theory usable in Mirage since it strips the code in the released binaries; but for now it causes some cross-compilation issues because of C stubs that rely on POSIX APIs. So for now let's do without it!

See janestreet/ppx_expect#15

fiat-p256.opam

@@ -25,10 +25,8 @@ depends: [
  "cstruct" {>= "3.5.0"}
  "dune" {build & >= "1.6.0"}
  "hex"
- "hex" {with-test}
  "ppx_deriving_yojson" {with-test}
  "rresult" {with-test}
- "ppx_expect"
  "yojson" {with-test & >= "1.6.0"}
 ]
 synopsis: "Primitives for Elliptic Curve Cryptography taken from Fiat"

p256/cstruct_util.ml

@@ -1,10 +1,3 @@
-let pp_hex_le fmt cs =
- let n = Cstruct.len cs in
- for i = n - 1 downto 0 do
- let byte = Cstruct.get_uint8 cs i in
- Format.fprintf fmt "%02x" byte
- done
-
 let compare_be a b =
  let first_diff = ref None in
  let a_len = Cstruct.len a in
@@ -24,15 +17,3 @@ let compare_be a b =
  0
  | Some d ->
  d
-
-let%expect_test "compare_be" =
- let test a b = print_int (compare_be a b) in
- test (Cstruct.of_string "aa") (Cstruct.of_string "ab");
- [%expect {| -1 |}];
- test (Cstruct.of_string "ab") (Cstruct.of_string "aa");
- [%expect {| 1 |}];
- test (Cstruct.of_string "aa") (Cstruct.of_string "aa");
- [%expect {| 0 |}];
- test (Cstruct.of_string "abx") (Cstruct.of_string "aaz");
- [%expect {| 1 |}];
- ()

p256/cstruct_util.mli

@@ -1,7 +1,3 @@
-val pp_hex_le : Format.formatter -> Cstruct.t -> unit
-(** Display the contents of a cstruct as hex data, seen as a little endian
- number. *)
-
 val compare_be : Cstruct.t -> Cstruct.t -> int
 (** Compare two cstructs, interpreting them as big endian numbers.
  Raises [Invalid_argument _] if they have a different length. *)

p256/dune

@@ -4,8 +4,6 @@
  (libraries bigarray-compat cstruct hex)
  (c_names p256_stubs)
  (c_flags (:include discover/cflags.sexp))
- (preprocess (pps ppx_expect))
- (inline_tests)
 )
 
 (rule

p256/fiat_p256.ml

@@ -1,38 +1,7 @@
 let dh ~scalar ~point =
  Point.x_of_finite_point (Montgomery_ladder.scalar_mult scalar point)
 
-let base_point = Point.of_hex_exn Parameters.g
-
-let public scalar = Montgomery_ladder.scalar_mult scalar base_point
-
-let%expect_test "dh" =
- let test d p =
- Format.printf "%a\n" Cstruct_util.pp_hex_le (dh ~scalar:d ~point:p)
- in
- let d_a =
- Scalar.of_hex_exn
- (`Hex
- "200102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f")
- in
- let d_b =
- Scalar.of_hex_exn
- (`Hex
- "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f")
- in
- let p_a = public d_a in
- let p_b = public d_b in
- test d_b p_a;
- [%expect
- {| 2e3e4065a62a7f425aaf8aae3d158f367c733300b5002e0b62f4bc6260789e1b |}];
- test d_a p_b;
- [%expect
- {| 2e3e4065a62a7f425aaf8aae3d158f367c733300b5002e0b62f4bc6260789e1b |}];
- test d_a p_a;
- [%expect
- {| 2ea4e810837da217a5bfd05f01d12459eeda830b6e0dec7f8afa425c5b55c507 |}];
- test d_b p_b;
- [%expect
- {| a7666bcc3818472194460f7df22d80a5886da0e1679eac930175ce1ff733c7ca |}]
+let public scalar = Montgomery_ladder.scalar_mult scalar Point.params_g
 
 type error = Error.point_error
 
@@ -73,7 +42,6 @@ let gen_key ~rng =
 
 let key_exchange secret received =
  match point_of_cs received with
- | Error _ as err ->
- err
+ | Error _ as err -> err
  | Ok other_party_public_key ->
  Ok (dh ~scalar:secret ~point:other_party_public_key)

p256/montgomery_ladder.ml

@@ -10,63 +10,3 @@ let scalar_mult d p =
  r0 := Point.double !r0 )
  done;
  !r0
-
-let%expect_test "scalar mult" =
- let test ~scalar ~point =
- let scalar = Scalar.of_hex_exn scalar in
- let point = Point.of_hex_exn point in
- let res = scalar_mult scalar point in
- Format.printf "%a\n" Point.pp res
- in
- let point =
- `Hex
- "046B17D1F2E12C4247F8BCE6E563A440F277037D812DEB33A0F4A13945D898C2964FE342E2FE1A7F9B8EE7EB4A7C0F9E162BCE33576B315ECECBB6406837BF51F5"
- in
- test
- ~scalar:
- (`Hex
- "0000000000000000000000000000000000000000000000000000000000000001")
- ~point;
- [%expect
- {| 046b17d1f2e12c4247f8bce6e563a440f277037d812deb33a0f4a13945d898c2964fe342e2fe1a7f9b8ee7eb4a7c0f9e162bce33576b315ececbb6406837bf51f5 |}];
- test
- ~scalar:
- (`Hex
- "0000000000000000000000000000000000000000000000000000000000000002")
- ~point;
- [%expect
- {| 047cf27b188d034f7e8a52380304b51ac3c08969e277f21b35a60b48fc4766997807775510db8ed040293d9ac69f7430dbba7dade63ce982299e04b79d227873d1 |}];
- test
- ~scalar:
- (`Hex
- "0000000000000000000000000000000000000000000000000000000000000004")
- ~point;
- [%expect
- {| 04e2534a3532d08fbba02dde659ee62bd0031fe2db785596ef509302446b030852e0f1575a4c633cc719dfee5fda862d764efc96c3f30ee0055c42c23f184ed8c6 |}];
- test
- ~scalar:
- (`Hex
- "0612465c89a023ab17855b0a6bcebfd3febb53aef84138647b5352e02c10c346")
- ~point:
- (`Hex
- "0462d5bd3372af75fe85a040715d0f502428e07046868b0bfdfa61d731afe44f26ac333a93a9e70a81cd5a95b5bf8d13990eb741c8c38872b4a07d275a014e30cf");
- [%expect
- {| 0453020d908b0219328b658b525f26780e3ae12bcd952bb25a93bc0895e1714285b2ba871dd1652c3f467df15c6b70647efbcbbab5cbf7f55e6ff336f843d628a1 |}];
- test
- ~scalar:
- (`Hex
- "0a0d622a47e48f6bc1038ace438c6f528aa00ad2bd1da5f13ee46bf5f633d71a")
- ~point:
- (`Hex
- "043cbc1b31b43f17dc200dd70c2944c04c6cb1b082820c234a300b05b7763844c74fde0a4ef93887469793270eb2ff148287da9265b0334f9e2609aac16e8ad503");
- [%expect
- {| 047fffffffffffffffffffffffeecf2230ffffffffffffffffffffffffffffffff00000001c7c30643abed0af0a49fe352cb483ff9b97dccdf427c658e8793240d |}];
- test
- ~scalar:
- (`Hex
- "55d55f11bb8da1ea318bca7266f0376662441ea87270aa2077f1b770c4854a48")
- ~point:
- (`Hex
- "04000000000000000000000000000000000000000000000000000000000000000066485c780e2f83d72433bd5d84a06bb6541c2af31dae871728bf856a174f93f4");
- [%expect
- {| 04cfe4077c8730b1c9384581d36bff5542bc417c9eff5c2afcb98cc8829b2ce8487764c65671a66a3ecf1ec63cf49b5c36119162ace73f8d8be270e27cdaf4677c |}]

p256/parameters.ml

@@ -4,9 +4,11 @@ let a =
 let b =
  `Hex "5AC635D8AA3A93E7B3EBBD55769886BC651D06B0CC53B0F63BCE3C3E27D2604B"
 
-let g =
- `Hex
- "046B17D1F2E12C4247F8BCE6E563A440F277037D812DEB33A0F4A13945D898C2964FE342E2FE1A7F9B8EE7EB4A7C0F9E162BCE33576B315ECECBB6406837BF51F5"
+let g_x =
+ `Hex "6B17D1F2E12C4247F8BCE6E563A440F277037D812DEB33A0F4A13945D898C296"
+
+let g_y =
+ `Hex "4FE342E2FE1A7F9B8EE7EB4A7C0F9E162BCE33576B315ECECBB6406837BF51F5"
 
 let p =
  `Hex "FFFFFFFF00000001000000000000000000000000FFFFFFFFFFFFFFFFFFFFFFFF"

p256/parameters.mli

@@ -6,8 +6,11 @@ val a : Hex.t
 
 val b : Hex.t
 
-val g : Hex.t
-(** The base point, in uncompressed form. *)
+val g_x : Hex.t
+(** The base point's x coordinate. *)
+
+val g_y : Hex.t
+(** The base point's y coordinate. *)
 
 val p : Hex.t
 (** The prime number corresponding to [Fe]. *)