move ed_point_add to urcrypt

pkg/urbit/jets/e/ed_point_add.c

@@ -2,64 +2,33 @@
 **
 */
 #include "all.h"
-
-
-#include <ed25519.h>
-#include <ge.h>
+#include <urcrypt.h>
 
 /* functions
 */
+
   u3_noun
   u3qc_point_add(u3_atom a,
                  u3_atom b)
   {
-    c3_y met_w;
+    c3_w ate_w, bet_w;
 
-    met_w = u3r_met(3, a);
-    if (met_w > 32) {
-      return u3m_bail(c3__fail);
+    if ( ((ate_w = u3r_met(3, a)) > 32) ||
+         ((bet_w = u3r_met(3, b)) > 32) ) {
+      return u3_none;
     }
-    c3_y a_y[32];
-    memset(a_y, 0, 32);
-    u3r_bytes(0, met_w, a_y, a);
+    else {
+      c3_y a_y[32], b_y[32], out_y[32];
 
-    met_w = u3r_met(3, b);
-    if (met_w > 32) {
-      return u3m_bail(c3__fail);
+      memset(a_y, 0, 32);
+      memset(b_y, 0, 32);
+      u3r_bytes(0, ate_w, a_y, a);
+      u3r_bytes(0, bet_w, b_y, b);
+
+      return ( 0 == urcrypt_ed_point_add(a_y, b_y, out_y) )
+        ? u3i_bytes(32, out_y)
+        : u3_none;
     }
-    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

pkg/urcrypt/urcrypt.c

@@ -1,5 +1,36 @@
 #include "urcrypt.h"
 
+int
+urcrypt_ed_point_add(uint8_t a[32], uint8_t b[32], uint8_t out[32])
+{
+  ge_p3 A, B;
+  ge_cached b_cached;
+  ge_p1p1 sum;
+  ge_p3 result;
+
+  if ( ge_frombytes_negate_vartime(&A, a) != 0 ) {
+    return -1;
+  }
+
+  if ( ge_frombytes_negate_vartime(&B, b) != 0 ) {
+    return -1;
+  }
+
+  // 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_p3_to_cached(&b_cached, &B);
+  ge_add(&sum, &A, &b_cached);
+  ge_p1p1_to_p3(&result, &sum);
+
+  ge_p3_tobytes(out, &result);
+
+  return 0;
+}
+
 int
 urcrypt_ed_scalarmult(uint8_t a[32], uint8_t b[32], uint8_t out[32])
 {

pkg/urcrypt/urcrypt.h

@@ -6,6 +6,7 @@
 #include <ed25519.h>
 #include <ge-additions.h>
 
+int urcrypt_ed_point_add(uint8_t a[32], uint8_t b[32], uint8_t out[32]);
 int urcrypt_ed_scalarmult(uint8_t a[32], uint8_t b[32], uint8_t out[32]);
 void urcrypt_ed_sign(uint8_t *message,
                      size_t length,