1// shark.cpp - written and placed in the public domain by Wei Dai
2
3#include "pch.h"
4#include "shark.h"
5#include "misc.h"
6#include "modes.h"
7#include "gf256.h"
8
9NAMESPACE_BEGIN(CryptoPP)
10
11static word64 SHARKTransform(word64 a)
12{
13	static const byte iG[8][8] = {
14		0xe7, 0x30, 0x90, 0x85, 0xd0, 0x4b, 0x91, 0x41,
15		0x53, 0x95, 0x9b, 0xa5, 0x96, 0xbc, 0xa1, 0x68,
16		0x02, 0x45, 0xf7, 0x65, 0x5c, 0x1f, 0xb6, 0x52,
17		0xa2, 0xca, 0x22, 0x94, 0x44, 0x63, 0x2a, 0xa2,
18		0xfc, 0x67, 0x8e, 0x10, 0x29, 0x75, 0x85, 0x71,
19		0x24, 0x45, 0xa2, 0xcf, 0x2f, 0x22, 0xc1, 0x0e,
20		0xa1, 0xf1, 0x71, 0x40, 0x91, 0x27, 0x18, 0xa5,
21		0x56, 0xf4, 0xaf, 0x32, 0xd2, 0xa4, 0xdc, 0x71,
22	};
23
24	word64 result=0;
25	GF256 gf256(0xf5);
26	for (unsigned int i=0; i<8; i++)
27		for(unsigned int j=0; j<8; j++)
28			result ^= word64(gf256.Multiply(iG[i][j], GF256::Element(a>>(56-8*j)))) << (56-8*i);
29	return result;
30}
31
32void SHARK::Base::UncheckedSetKey(const byte *key, unsigned int keyLen, const NameValuePairs &params)
33{
34	AssertValidKeyLength(keyLen);
35
36	m_rounds = GetRoundsAndThrowIfInvalid(params, this);
37	m_roundKeys.New(m_rounds+1);
38
39	// concatenate key enought times to fill a
40	for (unsigned int i=0; i<(m_rounds+1)*8; i++)
41		((byte *)m_roundKeys.begin())[i] = key[i%keyLen];
42
43	SHARK::Encryption e;
44	e.InitForKeySetup();
45	byte IV[8] = {0,0,0,0,0,0,0,0};
46	CFB_Mode_ExternalCipher::Encryption cfb(e, IV);
47
48	cfb.ProcessString((byte *)m_roundKeys.begin(), (m_rounds+1)*8);
49
50	ConditionalByteReverse(BIG_ENDIAN_ORDER, m_roundKeys.begin(), m_roundKeys.begin(), (m_rounds+1)*8);
51
52	m_roundKeys[m_rounds] = SHARKTransform(m_roundKeys[m_rounds]);
53
54	if (!IsForwardTransformation())
55	{
56		unsigned int i;
57
58		// transform encryption round keys into decryption round keys
59		for (i=0; i<m_rounds/2; i++)
60			std::swap(m_roundKeys[i], m_roundKeys[m_rounds-i]);
61
62		for (i=1; i<m_rounds; i++)
63			m_roundKeys[i] = SHARKTransform(m_roundKeys[i]);
64	}
65
66#ifdef IS_LITTLE_ENDIAN
67	m_roundKeys[0] = ByteReverse(m_roundKeys[0]);
68	m_roundKeys[m_rounds] = ByteReverse(m_roundKeys[m_rounds]);
69#endif
70}
71
72// construct an SHARK_Enc object with fixed round keys, to be used to initialize actual round keys
73void SHARK::Enc::InitForKeySetup()
74{
75	m_rounds = DEFAULT_ROUNDS;
76	m_roundKeys.New(DEFAULT_ROUNDS+1);
77
78	for (unsigned int i=0; i<DEFAULT_ROUNDS; i++)
79		m_roundKeys[i] = cbox[0][i];
80
81	m_roundKeys[DEFAULT_ROUNDS] = SHARKTransform(cbox[0][DEFAULT_ROUNDS]);
82
83#ifdef IS_LITTLE_ENDIAN
84	m_roundKeys[0] = ByteReverse(m_roundKeys[0]);
85	m_roundKeys[m_rounds] = ByteReverse(m_roundKeys[m_rounds]);
86#endif
87}
88
89typedef word64 ArrayOf256Word64s[256];
90
91template <const byte *sbox, const ArrayOf256Word64s *cbox>
92struct SharkProcessAndXorBlock{		// VC60 workaround: problem with template functions
93inline SharkProcessAndXorBlock(const word64 *roundKeys, unsigned int rounds, const byte *inBlock, const byte *xorBlock, byte *outBlock)
94{
95	word64 tmp = *(word64 *)inBlock ^ roundKeys[0];
96
97	ByteOrder order = GetNativeByteOrder();
98	tmp = cbox[0][GetByte(order, tmp, 0)] ^ cbox[1][GetByte(order, tmp, 1)]
99		^ cbox[2][GetByte(order, tmp, 2)] ^ cbox[3][GetByte(order, tmp, 3)]
100		^ cbox[4][GetByte(order, tmp, 4)] ^ cbox[5][GetByte(order, tmp, 5)]
101		^ cbox[6][GetByte(order, tmp, 6)] ^ cbox[7][GetByte(order, tmp, 7)]
102		^ roundKeys[1];
103
104	for(unsigned int i=2; i<rounds; i++)
105	{
106		tmp = cbox[0][GETBYTE(tmp, 7)] ^ cbox[1][GETBYTE(tmp, 6)]
107			^ cbox[2][GETBYTE(tmp, 5)] ^ cbox[3][GETBYTE(tmp, 4)]
108			^ cbox[4][GETBYTE(tmp, 3)] ^ cbox[5][GETBYTE(tmp, 2)]
109			^ cbox[6][GETBYTE(tmp, 1)] ^ cbox[7][GETBYTE(tmp, 0)]
110			^ roundKeys[i];
111	}
112
113	PutBlock<byte, BigEndian>(xorBlock, outBlock)
114		(sbox[GETBYTE(tmp, 7)])
115		(sbox[GETBYTE(tmp, 6)])
116		(sbox[GETBYTE(tmp, 5)])
117		(sbox[GETBYTE(tmp, 4)])
118		(sbox[GETBYTE(tmp, 3)])
119		(sbox[GETBYTE(tmp, 2)])
120		(sbox[GETBYTE(tmp, 1)])
121		(sbox[GETBYTE(tmp, 0)]);
122
123	*(word64 *)outBlock ^= roundKeys[rounds];
124}};
125
126void SHARK::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
127{
128	SharkProcessAndXorBlock<sbox, cbox>(m_roundKeys, m_rounds, inBlock, xorBlock, outBlock);
129}
130
131void SHARK::Dec::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
132{
133	SharkProcessAndXorBlock<sbox, cbox>(m_roundKeys, m_rounds, inBlock, xorBlock, outBlock);
134}
135
136NAMESPACE_END
137