--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dcclib/sign.c	Tue Mar 10 13:49:58 2009 +0100
@@ -0,0 +1,80 @@
+/* Distributed Checksum Clearinghouse
+ *
+ * message authentication
+ *
+ * Copyright (c) 2008 by Rhyolite Software, LLC
+ *
+ * This agreement is not applicable to any entity which sells anti-spam
+ * solutions to others or provides an anti-spam solution as part of a
+ * security solution sold to other entities, or to a private network
+ * which employs the DCC or uses data provided by operation of the DCC
+ * but does not provide corresponding data to other users.
+ *
+ * Permission to use, copy, modify, and distribute this software without
+ * changes for any purpose with or without fee is hereby granted, provided
+ * that the above copyright notice and this permission notice appear in all
+ * copies and any distributed versions or copies are either unchanged
+ * or not called anything similar to "DCC" or "Distributed Checksum
+ * Clearinghouse".
+ *
+ * Parties not eligible to receive a license under this agreement can
+ * obtain a commercial license to use DCC by contacting Rhyolite Software
+ * at sales@rhyolite.com.
+ *
+ * A commercial license would be for Distributed Checksum and Reputation
+ * Clearinghouse software.  That software includes additional features.  This
+ * free license for Distributed ChecksumClearinghouse Software does not in any
+ * way grant permision to use Distributed Checksum and Reputation Clearinghouse
+ * software
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND RHYOLITE SOFTWARE, LLC DISCLAIMS ALL
+ * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL RHYOLITE SOFTWARE, LLC
+ * BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES
+ * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
+ * WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
+ * ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
+ * SOFTWARE.
+ *
+ * Rhyolite Software DCC 1.3.103-1.13 $Revision$
+ */
+
+#include "dcc_defs.h"
+#include "dcc_md5.h"
+#include <string.h>
+
+
+/* sign a DCC packet */
+void
+dcc_sign(const char *passwd,
+	 int passwd_len,
+	 void *pkt,
+	 u_int pkt_len)			/* including signature */
+{
+	MD5_CTX ctx;
+
+	MD5Init(&ctx);
+	MD5Update(&ctx, passwd, passwd_len);
+	MD5Update(&ctx, pkt, pkt_len-sizeof(DCC_SIGNATURE));
+	MD5Final(&((u_char*)pkt)[pkt_len-sizeof(DCC_SIGNATURE)], &ctx);
+}
+
+
+
+/* check the signature of a DCC packet */
+u_char					/* 0=forgery, 1=good signature */
+dcc_ck_signature(const char *passwd,
+		 int passwd_len,
+		 const void *pkt,
+		 u_int pkt_len)		/* including signature */
+{
+	MD5_CTX ctx;
+	DCC_SIGNATURE signature;
+
+	MD5Init(&ctx);
+	MD5Update(&ctx, passwd, passwd_len);
+	MD5Update(&ctx, pkt, pkt_len-sizeof(DCC_SIGNATURE));
+	MD5Final(signature, &ctx);
+	return !memcmp(signature, &((char*)pkt)[pkt_len-sizeof(DCC_SIGNATURE)],
+		       sizeof(signature));
+}