add call-ec_p256k1

src/call-ec.c

@@ -0,0 +1,86 @@
+/*
+ * call-ec.c - interface between Gnuk and Elliptic curve over GF(prime)
+ *
+ * Copyright (C) 2013 Free Software Initiative of Japan
+ * Author: NIIBE Yutaka <gniibe@fsij.org>
+ *
+ * This file is a part of Gnuk, a GnuPG USB Token implementation.
+ *
+ * Gnuk 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 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Gnuk 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "field-group-select.h"
+
+/* We are little endian.  */
+
+#define ECDSA_BYTE_SIZE 32
+
+int
+FUNC(ecdsa_sign) (const uint8_t *hash, uint8_t *output,
+		  const uint8_t *key_data)
+{
+  int i;
+  bn256 r[1], s[1], z[1], d[1];
+  uint8_t *p;
+
+  p = (uint8_t *)d;
+  for (i = 0; i < ECDSA_BYTE_SIZE; i++)
+    p[ECDSA_BYTE_SIZE - i - 1] = key_data[i];
+
+  p = (uint8_t *)z;
+  for (i = 0; i < ECDSA_BYTE_SIZE; i++)
+    p[ECDSA_BYTE_SIZE - i - 1] = hash[i];
+
+  FUNC(ecdsa) (r, s, z, d);
+  p = (uint8_t *)r;
+  for (i = 0; i < ECDSA_BYTE_SIZE; i++)
+    *output++ = p[ECDSA_BYTE_SIZE - i - 1];
+  p = (uint8_t *)s;
+  for (i = 0; i < ECDSA_BYTE_SIZE; i++)
+    *output++ = p[ECDSA_BYTE_SIZE - i - 1];
+  return 0;
+}
+
+uint8_t *
+FUNC(ecdsa_compute_public) (const uint8_t *key_data)
+{
+  uint8_t *p0, *p, *p1;
+  ac q[1];
+  bn256 k[1];
+  int i;
+
+  p0 = (uint8_t *)malloc (ECDSA_BYTE_SIZE * 2);
+  if (p0 == NULL)
+    return NULL;
+
+  p = (uint8_t *)k;
+  for (i = 0; i < ECDSA_BYTE_SIZE; i++)
+    p[ECDSA_BYTE_SIZE - i - 1] = key_data[i];
+  if (FUNC(compute_kG) (q, k) < 0)
+    {
+      free (p0);
+      return NULL;
+    }
+
+  p = p0;
+  p1 = (uint8_t *)q->x;
+  for (i = 0; i < ECDSA_BYTE_SIZE; i++)
+    *p++ = p1[ECDSA_BYTE_SIZE - i - 1];
+  p1 = (uint8_t *)q->y;
+  for (i = 0; i < ECDSA_BYTE_SIZE; i++)
+    *p++ = p1[ECDSA_BYTE_SIZE - i - 1];
+
+  return p0;
+}