From eb8aa4ec8ea84c76dcf06d1647fce1b237cec313 Mon Sep 17 00:00:00 2001
Message-Id: <eb8aa4ec8ea84c76dcf06d1647fce1b237cec313.1716251081.git.mdw@distorted.org.uk>
From: Mark Wooding <mdw@chiark.greenend.org.uk>
Date: Wed, 26 Apr 2017 11:53:05 +0100
Subject: [PATCH] pubkey.c, catacomb/__init__.py: Add bindings for Hamburg's
 X448.
Organization: Straylight/Edgeware

From: Mark Wooding <mdw@distorted.org.uk>

---
 catacomb-python.h    |  1 +
 catacomb.c           |  1 +
 catacomb/__init__.py | 15 ++++++++++++++-
 pubkey.c             | 20 +++++++++++++++++++-
 4 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/catacomb-python.h b/catacomb-python.h
index 41c5292..d7e2543 100644
--- a/catacomb-python.h
+++ b/catacomb-python.h
@@ -88,6 +88,7 @@
 #include <catacomb/bintab.h>
 #include <catacomb/dsa.h>
 #include <catacomb/x25519.h>
+#include <catacomb/x448.h>
 #include <catacomb/ed25519.h>
 
 #include <catacomb/gf.h>
diff --git a/catacomb.c b/catacomb.c
index d64a16e..9c83c9d 100644
--- a/catacomb.c
+++ b/catacomb.c
@@ -46,6 +46,7 @@ static const struct nameval consts[] = {
   C(KF_BURN), C(KF_OPT),
   C(EC_XONLY), C(EC_YBIT), C(EC_LSB), C(EC_CMPR), C(EC_EXPLY), C(EC_SORT),
   C(X25519_KEYSZ), C(X25519_PUBSZ), C(X25519_OUTSZ),
+  C(X448_KEYSZ), C(X448_PUBSZ), C(X448_OUTSZ),
   C(ED25519_KEYSZ), C(ED25519_PUBSZ), C(ED25519_SIGSZ),
 #define ENTRY(tag, val, str) C(KERR_##tag),
   KEY_ERRORS(ENTRY)
diff --git a/catacomb/__init__.py b/catacomb/__init__.py
index 9522528..4c225e7 100644
--- a/catacomb/__init__.py
+++ b/catacomb/__init__.py
@@ -459,11 +459,15 @@ class _tmp:
 _augment(RSAPriv, _tmp)
 
 ###--------------------------------------------------------------------------
-### Bernstein's elliptic curve crypto.
+### Bernstein's elliptic curve crypto and related schemes.
 
 X25519_BASE = \
   bytes('0900000000000000000000000000000000000000000000000000000000000000')
 
+X448_BASE = \
+  bytes('05000000000000000000000000000000000000000000000000000000'
+        '00000000000000000000000000000000000000000000000000000000')
+
 Z128 = bytes('00000000000000000000000000000000')
 
 class _BoxyPub (object):
@@ -495,6 +499,15 @@ class X25519Priv (_BoxyPriv, X25519Pub):
   def _op(me, k, X): return x25519(k, X)
   def _hashkey(me, z): return hsalsa20_prf(z, Z128)
 
+class X448Pub (_BoxyPub):
+  _PUBSZ = X448_PUBSZ
+  _BASE = X448_BASE
+
+class X448Priv (_BoxyPriv, X448Pub):
+  _KEYSZ = X448_KEYSZ
+  def _op(me, k, X): return x448(k, X)
+  ##def _hashkey(me, z): return ???
+
 class Ed25519Pub (object):
   def __init__(me, pub):
     me.pub = pub
diff --git a/pubkey.c b/pubkey.c
index 391db31..5292717 100644
--- a/pubkey.c
+++ b/pubkey.c
@@ -1118,7 +1118,7 @@ end:
   return (rc);
 }
 
-/*----- X25519 ------------------------------------------------------------*/
+/*----- X25519 and related algorithms -------------------------------------*/
 
 static PyObject *meth_x25519(PyObject *me, PyObject *arg)
 {
@@ -1136,6 +1136,22 @@ end:
   return (0);
 }
 
+static PyObject *meth_x448(PyObject *me, PyObject *arg)
+{
+  const char *k, *p;
+  Py_ssize_t ksz, psz;
+  PyObject *rc = 0;
+  if (!PyArg_ParseTuple(arg, "s#s#:x448", &k, &ksz, &p, &psz)) goto end;
+  if (ksz != X448_KEYSZ) VALERR("bad key length");
+  if (psz != X448_PUBSZ) VALERR("bad public length");
+  rc = bytestring_pywrap(0, X448_OUTSZ);
+  x448((octet *)PyString_AS_STRING(rc),
+       (const octet *)k, (const octet *)p);
+  return (rc);
+end:
+  return (0);
+}
+
 /*----- Ed25519 -----------------------------------------------------------*/
 
 static PyObject *meth_ed25519_pubkey(PyObject *me, PyObject *arg)
@@ -1203,6 +1219,8 @@ static PyMethodDef methods[] = {
 generate(NBITS, [event = pgen_nullev, rng = rand, nsteps = 0]) -> R")
   METH  (x25519,			"\
 x25519(KEY, PUBLIC) -> SHARED")
+  METH  (x448,				"\
+x448(KEY, PUBLIC) -> SHARED")
   METH  (ed25519_pubkey,		"\
 ed25519_pubkey(KEY) -> PUBLIC")
   KWMETH(ed25519_sign,			"\
-- 
[mdw]