Diff: ctaocrypt/src/dh.c

Revision:

0:714293de3836

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ctaocrypt/src/dh.c	Thu Sep 05 10:33:04 2013 +0000
@@ -0,0 +1,171 @@
+/* dh.c
+ *
+ * Copyright (C) 2006-2013 wolfSSL Inc.
+ *
+ * This file is part of CyaSSL.
+ *
+ * CyaSSL is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * CyaSSL is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ */
+
+#ifdef HAVE_CONFIG_H
+    #include <config.h>
+#endif
+
+#include <cyassl/ctaocrypt/settings.h>
+
+#ifndef NO_DH
+
+#include <cyassl/ctaocrypt/dh.h>
+#include <cyassl/ctaocrypt/ctaoerror2.h>
+
+#ifndef USER_MATH_LIB
+    #include <math.h>
+    #define XPOW(x,y) pow((x),(y))
+    #define XLOG(x)   log((x))
+#else
+    /* user's own math lib */
+#endif
+
+
+#ifndef min
+
+    static INLINE word32 min(word32 a, word32 b)
+    {
+        return a > b ? b : a;
+    }
+
+#endif /* min */
+
+
+void InitDhKey(DhKey* key)
+{
+    (void)key;
+/* TomsFastMath doesn't use memory allocation */
+#ifndef USE_FAST_MATH
+    key->p.dp = 0;
+    key->g.dp = 0;
+#endif
+}
+
+
+void FreeDhKey(DhKey* key)
+{
+    (void)key;
+/* TomsFastMath doesn't use memory allocation */
+#ifndef USE_FAST_MATH
+    mp_clear(&key->p);
+    mp_clear(&key->g);
+#endif
+}
+
+
+static word32 DiscreteLogWorkFactor(word32 n)
+{
+    /* assuming discrete log takes about the same time as factoring */
+    if (n<5)
+        return 0;
+    else
+        return (word32)(2.4 * XPOW((double)n, 1.0/3.0) *
+                XPOW(XLOG((double)n), 2.0/3.0) - 5);
+}
+
+
+static void GeneratePrivate(DhKey* key, RNG* rng, byte* priv, word32* privSz)
+{
+    word32 sz = mp_unsigned_bin_size(&key->p);
+    sz = min(sz, 2 * DiscreteLogWorkFactor(sz * CYASSL_BIT_SIZE) /
+                                           CYASSL_BIT_SIZE + 1);
+    RNG_GenerateBlock(rng, priv, sz);
+    priv[0] |= 0x0C;
+
+    *privSz = sz;
+}
+
+
+static int GeneratePublic(DhKey* key, const byte* priv, word32 privSz,
+                          byte* pub, word32* pubSz)
+{
+    int ret = 0;
+
+    mp_int x; 
+    mp_int y;
+
+    if (mp_init_multi(&x, &y, 0, 0, 0, 0) != MP_OKAY)
+        return MP_INIT_E;
+
+    if (mp_read_unsigned_bin(&x, priv, privSz) != MP_OKAY)
+        ret = MP_READ_E;
+
+    if (ret == 0 && mp_exptmod(&key->g, &x, &key->p, &y) != MP_OKAY)
+        ret = MP_EXPTMOD_E;
+
+    if (ret == 0 && mp_to_unsigned_bin(&y, pub) != MP_OKAY)
+        ret = MP_TO_E;
+
+    if (ret == 0)
+        *pubSz = mp_unsigned_bin_size(&y);
+
+    mp_clear(&y);
+    mp_clear(&x);
+
+    return ret;
+}
+
+
+int DhGenerateKeyPair(DhKey* key, RNG* rng, byte* priv, word32* privSz,
+                      byte* pub, word32* pubSz)
+{
+    GeneratePrivate(key, rng, priv, privSz);
+    return GeneratePublic(key, priv, *privSz, pub, pubSz);
+
+}
+
+int DhAgree(DhKey* key, byte* agree, word32* agreeSz, const byte* priv,
+            word32 privSz, const byte* otherPub, word32 pubSz)
+{
+    int ret = 0;
+
+    mp_int x; 
+    mp_int y;
+    mp_int z;
+
+    if (mp_init_multi(&x, &y, &z, 0, 0, 0) != MP_OKAY)
+        return MP_INIT_E;
+
+    if (mp_read_unsigned_bin(&x, priv, privSz) != MP_OKAY)
+        ret = MP_READ_E;
+
+    if (ret == 0 && mp_read_unsigned_bin(&y, otherPub, pubSz) != MP_OKAY)
+        ret = MP_READ_E;
+
+    if (ret == 0 && mp_exptmod(&y, &x, &key->p, &z) != MP_OKAY)
+        ret = MP_EXPTMOD_E;
+
+    if (ret == 0 && mp_to_unsigned_bin(&z, agree) != MP_OKAY)
+        ret = MP_TO_E;
+
+    if (ret == 0)
+        *agreeSz = mp_unsigned_bin_size(&z);
+
+    mp_clear(&z);
+    mp_clear(&y);
+    mp_clear(&x);
+
+    return ret;
+}
+
+
+#endif /* NO_DH */
+