Jet for +add:ed:crypto

include/jets/w.h

@@ -155,6 +155,7 @@
     u3_noun u3wee_sign(u3_noun);
     u3_noun u3wee_veri(u3_noun);
     u3_noun u3wee_shar(u3_noun);
+    u3_noun u3wee_point_add(u3_noun);
     u3_noun u3wee_double_scalarmult(u3_noun);
     u3_noun u3wee_scalarmult_base(u3_noun);
 

jets/e/ed_point_add.c

@@ -0,0 +1,79 @@
+/* gen164/5/ed_point_add.c
+**
+*/
+#include "all.h"
+
+
+#include <ed25519.h>
+#include <ge.h>
+
+/* functions
+*/
+  u3_noun
+  u3qc_point_add(u3_atom a,
+                 u3_atom b)
+  {
+    c3_y met_w;
+
+    met_w = u3r_met(3, a);
+    if (met_w > 32) {
+      return u3m_bail(c3__exit);
+    }
+    c3_y a_y[32];
+    memset(a_y, 0, 32);
+    u3r_bytes(0, met_w, a_y, a);
+
+    met_w = u3r_met(3, b);
+    if (met_w > 32) {
+      return u3m_bail(c3__exit);
+    }
+    c3_y b_y[32];
+    memset(b_y, 0, 32);
+    u3r_bytes(0, met_w, b_y, b);
+
+    ge_p3 A;
+    if (ge_frombytes_negate_vartime(&A, a_y) != 0) {
+      return u3m_bail(c3__exit);
+    }
+
+    ge_p3 B;
+    if (ge_frombytes_negate_vartime(&B, b_y) != 0) {
+      return u3m_bail(c3__exit);
+    }
+
+    // Undo the negation from above. See add_scalar.c in the ed25519 distro.
+    fe_neg(A.X, A.X);
+    fe_neg(A.T, A.T);
+    fe_neg(B.X, B.X);
+    fe_neg(B.T, B.T);
+
+    ge_cached b_cached;
+    ge_p3_to_cached(&b_cached, &B);
+
+    ge_p1p1 sum;
+    ge_add(&sum, &A, &b_cached);
+
+    ge_p3 result;
+    ge_p1p1_to_p3(&result, &sum);
+
+    c3_y output_y[32];
+    ge_p3_tobytes(output_y, &result);
+
+    return u3i_bytes(32, output_y);
+  }
+
+  u3_noun
+  u3wee_point_add(u3_noun cor)
+  {
+    u3_noun a, b;
+
+    if ( (c3n == u3r_mean(cor, u3x_sam_2, &a,
+                               u3x_sam_3, &b, 0)) ||
+         (c3n == u3ud(a)) ||
+         (c3n == u3ud(b)) )
+    {
+      return u3m_bail(c3__exit);
+    } else {
+      return u3qc_point_add(a, b);
+    }
+  }

jets/tree.c

@@ -175,6 +175,9 @@ static c3_c* _141_hex_coed__ed_shar_ha[] = {
   0
 };
 
+static u3j_harm _141_hex_coed__ed_add_a[] =
+    {{".2", u3wee_point_add}, {}};
+
 static u3j_harm _141_hex_coed__ed_double_scalarmult_a[] =
     {{".2", u3wee_double_scalarmult}, {}};
 
@@ -186,6 +189,7 @@ static u3j_core _141_hex_coed__ed_d[] =
     { "puck", 7, _141_hex_coed__ed_puck_a, 0, _141_hex_coed__ed_puck_ha },
     { "veri", 7, _141_hex_coed__ed_veri_a, 0, _141_hex_coed__ed_veri_ha },
     { "shar", 7, _141_hex_coed__ed_shar_a, 0, _141_hex_coed__ed_shar_ha },
+    { "add", 7, _141_hex_coed__ed_add_a, 0, 0 },
     { "scalarmult-base", 7, _141_hex_coed__ed_scalarmult_a, 0, 0 },
     { "double-scalarmult", 7, _141_hex_coed__ed_double_scalarmult_a, 0, 0 },
     {}

meson.build

@@ -137,6 +137,7 @@ jets_e_ed_src = [
 'jets/e/ed_sign.c',
 'jets/e/ed_veri.c',
 'jets/e/ed_shar.c',
+'jets/e/ed_point_add.c',
 'jets/e/ed_scalarmult_base.c',
 'jets/e/ed_double_scalarmult.c'
 ]