From 539364846a89987ac2679988653f50332cb91d26 Mon Sep 17 00:00:00 2001
From: "madmaxoft@gmail.com"
 <madmaxoft@gmail.com@0a769ca7-a7f5-676a-18bf-c427514a06d6>
Date: Thu, 30 Aug 2012 21:06:13 +0000
Subject: Implemented 1.3.2 protocol encryption using CryptoPP, up to Client
 Status packet (http://wiki.vg/Protocol_FAQ step 14)

git-svn-id: http://mc-server.googlecode.com/svn/trunk@808 0a769ca7-a7f5-676a-18bf-c427514a06d6
---
 CryptoPP/blumshub.cpp | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 CryptoPP/blumshub.cpp

(limited to 'CryptoPP/blumshub.cpp')

diff --git a/CryptoPP/blumshub.cpp b/CryptoPP/blumshub.cpp
new file mode 100644
index 000000000..be9b75829
--- /dev/null
+++ b/CryptoPP/blumshub.cpp
@@ -0,0 +1,63 @@
+// blumshub.cpp - written and placed in the public domain by Wei Dai
+
+#include "pch.h"
+#include "blumshub.h"
+
+NAMESPACE_BEGIN(CryptoPP)
+
+PublicBlumBlumShub::PublicBlumBlumShub(const Integer &n, const Integer &seed)
+	: modn(n),
+	  maxBits(BitPrecision(n.BitCount())-1)
+{
+	current = modn.Square(modn.Square(seed));
+	bitsLeft = maxBits;
+}
+
+unsigned int PublicBlumBlumShub::GenerateBit()
+{
+	if (bitsLeft==0)
+	{
+		current = modn.Square(current);
+		bitsLeft = maxBits;
+	}
+
+	return current.GetBit(--bitsLeft);
+}
+
+byte PublicBlumBlumShub::GenerateByte()
+{
+	byte b=0;
+	for (int i=0; i<8; i++)
+		b = (b << 1) | PublicBlumBlumShub::GenerateBit();
+	return b;
+}
+
+void PublicBlumBlumShub::GenerateBlock(byte *output, size_t size)
+{
+	while (size--)
+		*output++ = PublicBlumBlumShub::GenerateByte();
+}
+
+void PublicBlumBlumShub::ProcessData(byte *outString, const byte *inString, size_t length)
+{
+	while (length--)
+		*outString++ = *inString++ ^ PublicBlumBlumShub::GenerateByte();
+}
+
+BlumBlumShub::BlumBlumShub(const Integer &p, const Integer &q, const Integer &seed)
+	: PublicBlumBlumShub(p*q, seed),
+	  p(p), q(q),
+	  x0(modn.Square(seed))
+{
+}
+
+void BlumBlumShub::Seek(lword index)
+{
+	Integer i(Integer::POSITIVE, index);
+	i *= 8;
+	Integer e = a_exp_b_mod_c (2, i / maxBits + 1, (p-1)*(q-1));
+	current = modn.Exponentiate(x0, e);
+	bitsLeft = maxBits - i % maxBits;
+}
+
+NAMESPACE_END
-- 
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