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1 files changed, 174 insertions, 0 deletions

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+// square.cpp - written and placed in the public domain by Wei Dai
+// Based on Paulo S.L.M. Barreto's public domain implementation
+
+#include "pch.h"
+#include "square.h"
+#include "misc.h"
+#include "gf256.h"
+
+NAMESPACE_BEGIN(CryptoPP)
+
+// apply theta to a roundkey
+static void SquareTransform (word32 in[4], word32 out[4])
+{
+	static const byte G[4][4] = 
+	{
+		0x02U, 0x01U, 0x01U, 0x03U, 
+		0x03U, 0x02U, 0x01U, 0x01U, 
+		0x01U, 0x03U, 0x02U, 0x01U, 
+		0x01U, 0x01U, 0x03U, 0x02U
+	};
+
+	GF256 gf256(0xf5);
+
+	for (int i = 0; i < 4; i++)
+	{
+		word32 temp = 0;
+		for (int j = 0; j < 4; j++)
+			for (int k = 0; k < 4; k++)
+				temp ^= (word32)gf256.Multiply(GETBYTE(in[i], 3-k), G[k][j]) << ((3-j)*8);
+		out[i] = temp;
+	}
+}
+
+void Square::Base::UncheckedSetKey(CipherDir dir, const byte *userKey, unsigned int length)
+{
+	AssertValidKeyLength(length);
+
+	static const word32 offset[ROUNDS] = {
+	0x01000000UL, 0x02000000UL, 0x04000000UL, 0x08000000UL,
+	0x10000000UL, 0x20000000UL, 0x40000000UL, 0x80000000UL,
+	};
+
+	GetUserKey(BIG_ENDIAN_ORDER, roundkeys[0], KEYLENGTH/4, userKey, KEYLENGTH);
+
+	/* apply the key evolution function */
+	for (int i = 1; i < ROUNDS+1; i++)
+	{
+		roundkeys[i][0] = roundkeys[i-1][0] ^ rotlFixed(roundkeys[i-1][3], 8U) ^ offset[i-1];
+		roundkeys[i][1] = roundkeys[i-1][1] ^ roundkeys[i][0];
+		roundkeys[i][2] = roundkeys[i-1][2] ^ roundkeys[i][1];
+		roundkeys[i][3] = roundkeys[i-1][3] ^ roundkeys[i][2];
+	}  
+
+	/* produce the round keys */
+	if (dir == ENCRYPTION)
+	{
+		for (int i = 0; i < ROUNDS; i++)
+			SquareTransform (roundkeys[i], roundkeys[i]);
+	}
+	else
+	{
+		for (int i = 0; i < ROUNDS/2; i++)
+			for (int j = 0; j < 4; j++)
+				std::swap(roundkeys[i][j], roundkeys[ROUNDS-i][j]);
+		SquareTransform (roundkeys[ROUNDS], roundkeys[ROUNDS]);
+	}
+}
+
+#define MSB(x) (((x) >> 24) & 0xffU)	/* most  significant byte */
+#define SSB(x) (((x) >> 16) & 0xffU)	/* second in significance */
+#define TSB(x) (((x) >>  8) & 0xffU)	/* third  in significance */
+#define LSB(x) (((x)      ) & 0xffU)	/* least significant byte */
+
+#define squareRound(text, temp, T0, T1, T2, T3, roundkey) \
+{ \
+	temp[0] = T0[MSB (text[0])] \
+			^ T1[MSB (text[1])] \
+			^ T2[MSB (text[2])] \
+			^ T3[MSB (text[3])] \
+			^ roundkey[0]; \
+	temp[1] = T0[SSB (text[0])] \
+			^ T1[SSB (text[1])] \
+			^ T2[SSB (text[2])] \
+			^ T3[SSB (text[3])] \
+			^ roundkey[1]; \
+	temp[2] = T0[TSB (text[0])] \
+			^ T1[TSB (text[1])] \
+			^ T2[TSB (text[2])] \
+			^ T3[TSB (text[3])] \
+			^ roundkey[2]; \
+	temp[3] = T0[LSB (text[0])] \
+			^ T1[LSB (text[1])] \
+			^ T2[LSB (text[2])] \
+			^ T3[LSB (text[3])] \
+			^ roundkey[3]; \
+} /* squareRound */
+
+#define squareFinal(text, temp, S, roundkey) \
+{ \
+	text[0] = ((word32) (S[MSB (temp[0])]) << 24) \
+			^ ((word32) (S[MSB (temp[1])]) << 16) \
+			^ ((word32) (S[MSB (temp[2])]) <<  8) \
+			^  (word32) (S[MSB (temp[3])]) \
+			^ roundkey[0]; \
+	text[1] = ((word32) (S[SSB (temp[0])]) << 24) \
+			^ ((word32) (S[SSB (temp[1])]) << 16) \
+			^ ((word32) (S[SSB (temp[2])]) <<  8) \
+			^  (word32) (S[SSB (temp[3])]) \
+			^ roundkey[1]; \
+	text[2] = ((word32) (S[TSB (temp[0])]) << 24) \
+			^ ((word32) (S[TSB (temp[1])]) << 16) \
+			^ ((word32) (S[TSB (temp[2])]) <<  8) \
+			^  (word32) (S[TSB (temp[3])]) \
+			^ roundkey[2]; \
+	text[3] = ((word32) (S[LSB (temp[0])]) << 24) \
+			^ ((word32) (S[LSB (temp[1])]) << 16) \
+			^ ((word32) (S[LSB (temp[2])]) <<  8) \
+			^  (word32) (S[LSB (temp[3])]) \
+			^ roundkey[3]; \
+} /* squareFinal */
+
+typedef BlockGetAndPut<word32, BigEndian> Block;
+
+void Square::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
+{
+	word32 text[4], temp[4];
+	Block::Get(inBlock)(text[0])(text[1])(text[2])(text[3]);
+   
+	/* initial key addition */
+	text[0] ^= roundkeys[0][0];
+	text[1] ^= roundkeys[0][1];
+	text[2] ^= roundkeys[0][2];
+	text[3] ^= roundkeys[0][3];
+ 
+	/* ROUNDS - 1 full rounds */
+	for (int i=1; i+1<ROUNDS; i+=2)
+	{
+		squareRound (text, temp, Te[0], Te[1], Te[2], Te[3], roundkeys[i]);
+		squareRound (temp, text, Te[0], Te[1], Te[2], Te[3], roundkeys[i+1]);
+	}
+	squareRound (text, temp, Te[0], Te[1], Te[2], Te[3], roundkeys[ROUNDS-1]);
+
+	/* last round (diffusion becomes only transposition) */
+	squareFinal (text, temp, Se, roundkeys[ROUNDS]);
+
+	Block::Put(xorBlock, outBlock)(text[0])(text[1])(text[2])(text[3]);
+}
+
+void Square::Dec::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
+{
+	word32 text[4], temp[4];
+	Block::Get(inBlock)(text[0])(text[1])(text[2])(text[3]);
+   
+	/* initial key addition */
+	text[0] ^= roundkeys[0][0];
+	text[1] ^= roundkeys[0][1];
+	text[2] ^= roundkeys[0][2];
+	text[3] ^= roundkeys[0][3];
+ 
+	/* ROUNDS - 1 full rounds */
+	for (int i=1; i+1<ROUNDS; i+=2)
+	{
+		squareRound (text, temp, Td[0], Td[1], Td[2], Td[3], roundkeys[i]);
+		squareRound (temp, text, Td[0], Td[1], Td[2], Td[3], roundkeys[i+1]);
+	}
+	squareRound (text, temp, Td[0], Td[1], Td[2], Td[3], roundkeys[ROUNDS-1]);
+
+	/* last round (diffusion becomes only transposition) */
+	squareFinal (text, temp, Sd, roundkeys[ROUNDS]);
+
+	Block::Put(xorBlock, outBlock)(text[0])(text[1])(text[2])(text[3]);
+}
+
+NAMESPACE_END