From 4a9d61607fa7025bffc449cc2212cf03e5ad902c Mon Sep 17 00:00:00 2001
From: Raymond Pasco <ray@the.ug>
Date: Tue, 24 May 2016 12:00:35 -0400
Subject: [PATCH] Jet shar:ed curve25519 shared secret arm

---
 Makefile         |  3 ++-
 include/jets/w.h |  1 +
 jets/e/ed_shar.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 jets/tree.c      |  3 +++
 4 files changed, 53 insertions(+), 1 deletion(-)
 create mode 100644 jets/e/ed_shar.c

diff --git a/Makefile b/Makefile
index 83ea4eb0e..57658c7c4 100644
--- a/Makefile
+++ b/Makefile
@@ -268,7 +268,8 @@ J_E_OFILES=\
 J_E_OFILES_ED=\
        jets/e/ed_puck.o \
        jets/e/ed_sign.o \
-       jets/e/ed_veri.o
+       jets/e/ed_veri.o \
+       jets/e/ed_shar.o
 
 J_F_OFILES=\
        jets/f/al.o \
diff --git a/include/jets/w.h b/include/jets/w.h
index ebe70213f..7075c6047 100644
--- a/include/jets/w.h
+++ b/include/jets/w.h
@@ -132,6 +132,7 @@
     u3_noun u3wee_puck(u3_noun);
     u3_noun u3wee_sign(u3_noun);
     u3_noun u3wee_veri(u3_noun);
+    u3_noun u3wee_shar(u3_noun);
 
     u3_noun u3we_bend_fun(u3_noun);
     u3_noun u3we_cold_fun(u3_noun);
diff --git a/jets/e/ed_shar.c b/jets/e/ed_shar.c
new file mode 100644
index 000000000..d67110699
--- /dev/null
+++ b/jets/e/ed_shar.c
@@ -0,0 +1,47 @@
+/* j/5/shar.c
+**
+*/
+#include "all.h"
+
+#include <ed25519.h>
+
+  u3_noun
+  u3qee_shar(u3_atom pub, u3_atom sek)
+  {
+    c3_y pub_y[32], sek_y[32], self_y[32], exp_y[64], shr_y[32];
+    c3_w met_pub_w, met_sek_w;
+
+    met_pub_w = u3r_met(3, pub);
+    met_sek_w = u3r_met(3, sek);
+
+    if ( (met_pub_w > 32) || (met_sek_w > 32) ) {
+      return u3m_bail(c3__exit);
+    }
+
+    u3r_bytes(0, 32, pub_y, pub);
+    u3r_bytes(0, 32, sek_y, sek);
+
+    memset(self_y, 0, 32);
+    memset(exp_y, 0, 64);
+    memset(shr_y, 0, 32);
+
+    ed25519_create_keypair(self_y, exp_y, sek_y);
+    ed25519_key_exchange(shr_y, pub_y, exp_y);
+
+    return u3i_bytes(32, shr_y);
+  }
+
+  u3_noun
+  u3wee_shar(u3_noun cor)
+  {
+    u3_noun pub, sek;
+
+    if ( (c3n == u3r_mean(cor, u3x_sam_2, &pub, u3x_sam_3, &sek, 0)) ||
+         (c3n == u3ud(pub)) ||
+         (c3n == u3ud(sek)) )
+    {
+      return u3m_bail(c3__exit);
+    } else {
+      return u3qee_shar(pub, sek);
+    }
+  }
diff --git a/jets/tree.c b/jets/tree.c
index 1f9bc6b96..d7bb3a6b4 100644
--- a/jets/tree.c
+++ b/jets/tree.c
@@ -300,10 +300,13 @@ static u3j_core _mood__hoon__rq_d[] =
 static u3j_harm _mood__hoon__coed__ed_puck_a[] = {{".2", u3wee_puck}, {}};
 static u3j_harm _mood__hoon__coed__ed_sign_a[] = {{".2", u3wee_sign}, {}};
 static u3j_harm _mood__hoon__coed__ed_veri_a[] = {{".2", u3wee_veri}, {}};
+static u3j_harm _mood__hoon__coed__ed_shar_a[] = {{".2", u3wee_shar}, {}};
+
 static u3j_core _mood__hoon__coed__ed_d[] =
   { { "sign", _mood__hoon__coed__ed_sign_a },
     { "puck", _mood__hoon__coed__ed_puck_a },
     { "veri", _mood__hoon__coed__ed_veri_a },
+    { "shar", _mood__hoon__coed__ed_shar_a },
     {}
   };
 static u3j_core _mood__hoon__coed_d[] =