fp12_tower.c: add blst_bendian_from_fp12.

bindings/blst.hpp

@@ -808,6 +808,8 @@ class PT {
     PT* mul(const PT& p)    { blst_fp12_mul(&value, &value, p); return this; }
     PT* final_exp()         { blst_final_exp(&value, &value);   return this; }
     bool in_group() const   { return blst_fp12_in_group(&value); }
+    void to_bendian(byte out[48*12]) const
+    {   blst_bendian_from_fp12(out, &value);   }
 
     static bool finalverify(const PT& gt1, const PT& gt2)
     {   return blst_fp12_finalverify(gt1, gt2);   }

bindings/blst_aux.h

@@ -75,5 +75,6 @@ void blst_p2_unchecked_mult(blst_p2 *out, const blst_p2 *p, const byte *scalar,
 void blst_pairing_raw_aggregate(blst_pairing *ctx, const blst_p2_affine *q,
                                                    const blst_p1_affine *p);
 blst_fp12 *blst_pairing_as_fp12(blst_pairing *ctx);
+void blst_bendian_from_fp12(byte out[48*12], const blst_fp12 *a);
 
 #endif

bindings/go/blst.go

@@ -207,6 +207,12 @@ func (pt *Fp12) InGroup() bool {
 	return bool(C.blst_fp12_in_group(pt))
 }
 
+func (pt *Fp12) ToBendian() []byte {
+	var out [BLST_FP_BYTES * 12]byte
+	C.blst_bendian_from_fp12((*C.byte)(&out[0]), pt)
+	return out[:]
+}
+
 //
 // MIN-PK
 //

bindings/go/blst.tgo

@@ -196,3 +196,9 @@ func (pt *Fp12) FinalExp() {
 func (pt *Fp12) InGroup() bool {
     return bool(C.blst_fp12_in_group(pt))
 }
+
+func (pt *Fp12) ToBendian() []byte {
+    var out [BLST_FP_BYTES*12]byte
+    C.blst_bendian_from_fp12((*C.byte)(&out[0]), pt)
+    return out[:]
+}

bindings/rust/src/bindings.rs

@@ -7,7 +7,7 @@ macro_rules! offsetof {
         }
     };
 }
-/* automatically generated by rust-bindgen 0.59.1 */
+/* automatically generated by rust-bindgen 0.59.2 */
 
 #[repr(u32)]
 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
@@ -1293,3 +1293,6 @@ extern "C" {
 extern "C" {
     pub fn blst_pairing_as_fp12(ctx: *mut blst_pairing) -> *mut blst_fp12;
 }
+extern "C" {
+    pub fn blst_bendian_from_fp12(out: *mut byte, a: *const blst_fp12);
+}

bindings/rust/src/lib.rs

@@ -156,6 +156,14 @@ impl blst_fp12 {
     pub fn finalverify(a: &Self, b: &Self) -> bool {
         unsafe { blst_fp12_finalverify(a, b) }
     }
+
+    pub fn to_bendian(&self) -> [u8; 48 * 12] {
+        let mut out = MaybeUninit::<[u8; 48 * 12]>::uninit();
+        unsafe {
+            blst_bendian_from_fp12(out.as_mut_ptr() as *mut u8, self);
+            out.assume_init()
+        }
+    }
 }
 
 impl blst_scalar {

build/win64/blst.def

@@ -200,4 +200,5 @@ EXPORTS
 	blst_p2_unchecked_mult
 	blst_pairing_raw_aggregate
 	blst_pairing_as_fp12
+	blst_bendian_from_fp12
 

src/fp12_tower.c

@@ -769,3 +769,18 @@ int blst_fp12_is_one(const vec384fp12 a)
 
 const vec384fp12 *blst_fp12_one(void)
 {   return (const vec384fp12 *)BLS12_381_Rx.p12;   }
+
+void blst_bendian_from_fp12(unsigned char ret[48*12], const vec384fp12 a)
+{
+    size_t i, j;
+    vec384 out;
+
+    for (i = 0; i < 3; i++) {
+        for (j = 0; j < 2; j++) {
+            from_fp(out, a[j][i][0]);
+            be_bytes_from_limbs(ret, out, sizeof(vec384));  ret += 48;
+            from_fp(out, a[j][i][1]);
+            be_bytes_from_limbs(ret, out, sizeof(vec384));  ret += 48;
+        }
+    }
+}