X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/ba6e6b64033b1f9de49feccb5c9cd438354481f7..0f00dc4c8eb47e67bc0f148c2dd109f73a451e0a:/math/buf.c

diff --git a/math/buf.c b/math/buf.c
new file mode 100644
index 0000000..01b6a35
--- /dev/null
+++ b/math/buf.c
@@ -0,0 +1,127 @@
+/* -*-c-*-
+ *
+ * Buffer handling
+ *
+ * (c) 2001 Straylight/Edgeware
+ */
+
+/*----- Licensing notice --------------------------------------------------*
+ *
+ * This file is part of Catacomb.
+ *
+ * Catacomb is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Library General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * Catacomb 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 Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with Catacomb; if not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <string.h>
+
+#include "mp.h"
+#include "ec.h"
+#include "buf.h"
+
+/*----- Main code ---------------------------------------------------------*/
+
+/* --- @buf_getmp@ --- *
+ *
+ * Arguments:	@buf *b@ = pointer to a buffer block
+ *
+ * Returns:	A multiprecision integer, or null if there wasn't one there.
+ *
+ * Use:		Gets a multiprecision integer from a buffer.
+ */
+
+mp *buf_getmp(buf *b)
+{
+  uint16 sz;
+  size_t n;
+  mp *m;
+  if (buf_getu16(b, &sz) || buf_ensure(b, sz))
+    return (0);
+  m = mp_loadb(MP_NEW, BCUR(b), sz);
+  n = mp_octets(m);
+  if (n != sz && n != 0 && sz != 1) {
+    mp_drop(m);
+    return (0);
+  }
+  BSTEP(b, sz);
+  return (m);
+}
+
+/* --- @buf_putmp@ --- *
+ *
+ * Arguments:	@buf *b@ = pointer to a buffer block
+ *		@mp *m@ = a multiprecision integer
+ *
+ * Returns:	Zero if it worked, nonzero if there wasn't enough space.
+ *
+ * Use:		Puts a multiprecision integer to a buffer.
+ */
+
+int buf_putmp(buf *b, mp *m)
+{
+  size_t sz = mp_octets(m);
+  assert(sz < MASK16);
+  if (!sz) sz = 1;
+  if (buf_putu16(b, sz) || buf_ensure(b, sz))
+    return (-1);
+  mp_storeb(m, BCUR(b), sz);
+  BSTEP(b, sz);
+  return (0);
+}
+
+/* --- @buf_getec@ --- *
+ *
+ * Arguments:	@buf *b@ = pointer to a buffer block
+ *		@ec *p@ = where to put the point
+ *
+ * Returns:	Zero if it worked, nonzero if it failed.
+ *
+ * Use:		Gets a multiprecision integer from a buffer.  The point must
+ *		be initialized.
+ */
+
+int buf_getec(buf *b, ec *p)
+{
+  mp *x = 0, *y = 0;
+  uint16 n;
+  if (buf_ensure(b, 2)) return (-1);
+  n = LOAD16(BCUR(b)); if (!n) { BSTEP(b, 2); EC_SETINF(p); return (0); }
+  if ((x = buf_getmp(b)) == 0 || (y = buf_getmp(b)) == 0) {
+    mp_drop(x); mp_drop(y); return (-1);
+  }
+  EC_DESTROY(p); p->x = x; p->y = y; p->z = 0;
+  return (0);
+}
+
+/* --- @buf_putec@ --- *
+ *
+ * Arguments:	@buf *b@ = pointer to a buffer block
+ *		@ec *p@ = an elliptic curve point
+ *
+ * Returns:	Zero if it worked, nonzero if there wasn't enough space.
+ *
+ * Use:		Puts an elliptic curve point to a buffer.
+ */
+
+int buf_putec(buf *b, ec *p)
+{
+  if (EC_ATINF(p)) return (buf_putu16(b, 0));
+  if (buf_putmp(b, p->x) || buf_putmp(b, p->y)) return (-1);
+  return (0);
+}
+
+/*----- That's all, folks -------------------------------------------------*/