ec 25519: less arguments (offset being always 0)

Author: hannesm

ec/mirage_crypto_ec.ml

@@ -926,14 +926,13 @@ end
 
 module X25519 = struct
   (* RFC 7748 *)
-  external x25519_scalar_mult_generic : bytes -> bytes -> int -> bytes -> int -> unit = "mc_x25519_scalar_mult_generic" [@@noalloc]
+  external x25519_scalar_mult_generic : bytes -> bytes -> bytes -> unit = "mc_x25519_scalar_mult_generic" [@@noalloc]
 
   let key_len = 32
 
   let scalar_mult in_ base =
     let out = Bytes.make key_len '\000' in
-    x25519_scalar_mult_generic out
-      in_ 0 base 0;
+    x25519_scalar_mult_generic out in_ base;
     out
 
   type secret = bytes
@@ -985,7 +984,7 @@ module Ed25519 = struct
   external scalar_mult_base_to_bytes : bytes -> bytes -> unit = "mc_25519_scalar_mult_base" [@@noalloc]
   external reduce_l : bytes -> unit = "mc_25519_reduce_l" [@@noalloc]
   external muladd : bytes -> bytes -> bytes -> bytes -> unit = "mc_25519_muladd" [@@noalloc]
-  external double_scalar_mult : bytes -> bytes -> bytes -> bytes -> int -> bool = "mc_25519_double_scalar_mult" [@@noalloc]
+  external double_scalar_mult : bytes -> bytes -> bytes -> bytes -> bool = "mc_25519_double_scalar_mult" [@@noalloc]
   external pub_ok : bytes -> bool = "mc_25519_pub_ok" [@@noalloc]
 
   type pub = bytes
@@ -1081,7 +1080,7 @@ module Ed25519 = struct
         let k = Cstruct.to_bytes k in
         reduce_l k;
         let r' = Bytes.make key_len '\000' in
-        let success = double_scalar_mult r' k key s 0 in
+        let success = double_scalar_mult r' k key s in
         success && Bytes.equal r r'
       end else
         false

ec/native/curve25519_stubs.c

@@ -1803,12 +1803,11 @@ static void sc_muladd(uint8_t *s, const uint8_t *a, const uint8_t *b,
 }
 
 #include <caml/memory.h>
-#define _st_uint8_off(st, off) ((uint8_t*) String_val (st) + Long_val (off))
 
-CAMLprim value mc_x25519_scalar_mult_generic(value out, value scalar, value soff, value point, value poff)
+CAMLprim value mc_x25519_scalar_mult_generic(value out, value scalar, value point)
 {
-  CAMLparam5(out, scalar, soff, point, poff);
-  x25519_scalar_mult_generic(Bytes_val(out), _st_uint8_off(scalar, soff), _st_uint8_off(point, poff));
+  CAMLparam3(out, scalar, point);
+  x25519_scalar_mult_generic(Bytes_val(out), Bytes_val(scalar), Bytes_val(point));
   CAMLreturn(Val_unit);
 }
 
@@ -1836,9 +1835,9 @@ CAMLprim value mc_25519_muladd(value out, value a, value b, value c)
   CAMLreturn(Val_unit);
 }
 
-CAMLprim value mc_25519_double_scalar_mult(value out, value k, value key, value c, value coff)
+CAMLprim value mc_25519_double_scalar_mult(value out, value k, value key, value c)
 {
-  CAMLparam5(out, k, key, c, coff);
+  CAMLparam4(out, k, key, c);
   ge_p2 R;
   ge_p3 B;
   fe_loose t;
@@ -1848,7 +1847,7 @@ CAMLprim value mc_25519_double_scalar_mult(value out, value k, value key, value
   fe_carry(&B.X, &t);
   fe_neg(&t, &B.T);
   fe_carry(&B.T, &t);
-  ge_double_scalarmult_vartime(&R, Bytes_val(k), &B, _st_uint8_off(c, coff));
+  ge_double_scalarmult_vartime(&R, Bytes_val(k), &B, Bytes_val(c));
   x25519_ge_tobytes(Bytes_val(out), &R);
   CAMLreturn(Val_bool(success));
 }