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1 files changed, 54 insertions, 0 deletions

diff --git a/tea.cpp b/tea.cpp
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+++ b/tea.cpp
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+// tea.cpp - modified by Wei Dai from code in the original paper
+
+#include "pch.h"
+#include "tea.h"
+#include "misc.h"
+
+NAMESPACE_BEGIN(CryptoPP)
+
+const word32 TEA::Base::DELTA = 0x9e3779b9;
+
+void TEA::Base::UncheckedSetKey(CipherDir direction, const byte *userKey, unsigned int length)
+{
+	AssertValidKeyLength(length);
+
+	GetUserKey(BIG_ENDIAN_ORDER, k.begin(), 4, userKey, KEYLENGTH);
+}
+
+typedef BlockGetAndPut<word32, BigEndian> Block;
+
+void TEA::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
+{
+	word32 y, z;
+	Block::Get(inBlock)(y)(z);
+
+	word32 sum = 0;
+	for (int i=0; i<ROUNDS; i++)
+	{   
+		sum += DELTA;
+		y += (z << 4) + k[0] ^ z + sum ^ (z >> 5) + k[1];
+		z += (y << 4) + k[2] ^ y + sum ^ (y >> 5) + k[3];
+	}
+
+	Block::Put(xorBlock, outBlock)(y)(z);
+}
+
+typedef BlockGetAndPut<word32, BigEndian> Block;
+
+void TEA::Dec::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
+{
+	word32 y, z;
+	Block::Get(inBlock)(y)(z);
+
+	word32 sum = DELTA << LOG_ROUNDS;
+	for (int i=0; i<ROUNDS; i++)
+	{
+		z -= (y << 4) + k[2] ^ y + sum ^ (y >> 5) + k[3]; 
+		y -= (z << 4) + k[0] ^ z + sum ^ (z >> 5) + k[1];
+		sum -= DELTA;
+	}
+
+	Block::Put(xorBlock, outBlock)(y)(z);
+}
+
+NAMESPACE_END