1 files changed, 58 insertions, 0 deletions
diff --git a/usr.sbin/xntpd/lib/a_md5decrypt.c b/usr.sbin/xntpd/lib/a_md5decrypt.c
new file mode 100644
index 0000000..892e52e
--- /dev/null
+++ b/usr.sbin/xntpd/lib/a_md5decrypt.c
@@ -0,0 +1,58 @@
+/* authmd5decrypt.c,v 3.1 1993/07/06 01:07:53 jbj Exp
+ *  md5crypt - MD5 based authentication routines
+ */
+
+#include "ntp_types.h"
+#include "ntp_string.h"
+#include "md5.h"
+#include "ntp_stdlib.h"
+
+extern U_LONG cache_keyid;
+extern char *cache_key;
+extern int cache_keylen;
+
+/*
+ * Stat counters, imported from data base module
+ */
+extern U_LONG authencryptions;
+extern U_LONG authdecryptions;
+extern U_LONG authkeyuncached;
+extern U_LONG authdecryptok;
+extern U_LONG authnokey;
+
+/*
+ * For our purposes an NTP packet looks like:
+ *
+ *	a variable amount of encrypted data, multiple of 8 bytes, followed by:
+ *	NOCRYPT_OCTETS worth of unencrypted data, followed by:
+ *	BLOCK_OCTETS worth of ciphered checksum.
+ */ 
+#define	NOCRYPT_OCTETS	4
+#define	BLOCK_OCTETS	16
+
+#define	NOCRYPT_LONGS	((NOCRYPT_OCTETS)/sizeof(U_LONG))
+#define	BLOCK_LONGS	((BLOCK_OCTETS)/sizeof(U_LONG))
+
+int
+MD5authdecrypt(keyno, pkt, length)
+    U_LONG keyno;
+    const U_LONG *pkt;
+    int length;		/* length of variable data in octets */
+{
+    MD5_CTX ctx;
+
+    authdecryptions++;
+
+    if (keyno != cache_keyid) {
+	authkeyuncached++;
+	if (!authhavekey(keyno))
+	    return 0;
+    }
+
+    MD5Init(&ctx);
+    MD5Update(&ctx, cache_key, cache_keylen);
+    MD5Update(&ctx, (char *)pkt, length);
+    MD5Final(&ctx);
+
+    return (0 == bcmp((char *)ctx.digest, (char *)pkt + length + 4, BLOCK_OCTETS));
+}