From 1397c0f8327f7f2b7fdace1f222138ec7e6f308d Mon Sep 17 00:00:00 2001
From: Con Kolivas <kernel@kolivas.org>
Date: Sat, 12 Mar 2011 20:31:56 +1100
Subject: [PATCH] Create custom "loop count" system to determine how many times
 to hash a password when encrypting based on the datestamp. This data will be
 stored as a 2 byte entry in the header in the future (b1 and b2).

---
 lrzip.c         | 31 +++++++++++++++++++++++++++++++
 lrzip_private.h |  5 ++++-
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/lrzip.c b/lrzip.c
index f6f4300..a07b986 100644
--- a/lrzip.c
+++ b/lrzip.c
@@ -35,6 +35,7 @@
 #include <errno.h>
 #endif
 #include <sys/time.h>
+#include <math.h>
 
 #include "md5.h"
 #include "rzip.h"
@@ -44,6 +45,36 @@
 
 #define MAGIC_LEN (39)
 
+/* Determine how many times to hash the password when encrypting, based on
+ * the date such that we increase the number of loops according to Moore's
+ * law relative to when the data is encrypted. It is then stored as a two
+ * byte value in the header */
+#define MOORE 1.835          // world constant  [TIMES per YEAR]
+#define ARBITRARY  1000000   // number of sha2 calls per one second in 2011
+#define T_ZERO 1293840000    // seconds since epoch in 2011
+
+#define SECONDS_IN_A_YEAR (365*86400)
+#define MOORE_TIMES_PER_SECOND pow (MOORE, 1.0 / SECONDS_IN_A_YEAR)
+#define ARBITRARY_AT_EPOCH (ARBITRARY * pow (MOORE_TIMES_PER_SECOND, -T_ZERO))
+
+static i64 nloops(i64 seconds, uchar *b1, uchar *b2)
+{
+	i64 nloops_encoded, nloops;
+	int nbits;
+
+	nloops = ARBITRARY_AT_EPOCH * pow(MOORE_TIMES_PER_SECOND, seconds);
+	nbits = log (nloops) / M_LN2;
+	*b1 = nbits - 7;
+	*b2 = nloops >> *b1;
+	nloops_encoded = (i64)*b2 << (i64)*b1;
+	return nloops_encoded;
+}
+
+static i64 enc_loops(uchar b1, uchar b2)
+{
+	return (i64)b2 << (i64)b1;
+}
+
 static char *make_magic(rzip_control *control, int fd_in)
 {
 	struct timeval tv;
diff --git a/lrzip_private.h b/lrzip_private.h
index a9c10cb..8f98f02 100644
--- a/lrzip_private.h
+++ b/lrzip_private.h
@@ -181,7 +181,10 @@ struct rzip_control {
 	i64 st_size;
 	long page_size;
 	int fd_out;
-	int encrypt;
+	char encrypt;
+	i64 encloops;
+	uchar loop_byte1;
+	uchar loop_byte2;
 	i64 secs;
 	i64 usecs;
 	unsigned char eof;