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97 lines
2.3 KiB
97 lines
2.3 KiB
// rc6.cpp - written and placed in the public domain by Sean Woods |
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// based on Wei Dai's RC5 code. |
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#include "pch.h" |
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#include "rc6.h" |
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#include "misc.h" |
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#include "secblock.h" |
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NAMESPACE_BEGIN(CryptoPP) |
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void RC6::Base::UncheckedSetKey(const byte *k, unsigned int keylen, const NameValuePairs ¶ms) |
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{ |
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AssertValidKeyLength(keylen); |
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r = GetRoundsAndThrowIfInvalid(params, this); |
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sTable.New(2*(r+2)); |
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static const RC6_WORD MAGIC_P = 0xb7e15163L; // magic constant P for wordsize |
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static const RC6_WORD MAGIC_Q = 0x9e3779b9L; // magic constant Q for wordsize |
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static const int U=sizeof(RC6_WORD); |
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const unsigned int c = STDMAX((keylen+U-1)/U, 1U); // RC6 paper says c=1 if keylen==0 |
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SecBlock<RC6_WORD> l(c); |
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GetUserKey(LITTLE_ENDIAN_ORDER, l.begin(), c, k, keylen); |
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sTable[0] = MAGIC_P; |
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for (unsigned j=1; j<sTable.size();j++) |
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sTable[j] = sTable[j-1] + MAGIC_Q; |
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RC6_WORD a=0, b=0; |
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const unsigned n = 3*STDMAX((unsigned int)sTable.size(), c); |
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for (unsigned h=0; h < n; h++) |
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{ |
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a = sTable[h % sTable.size()] = rotlFixed((sTable[h % sTable.size()] + a + b), 3); |
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b = l[h % c] = rotlMod((l[h % c] + a + b), (a+b)); |
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} |
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} |
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typedef BlockGetAndPut<RC6::RC6_WORD, LittleEndian> Block; |
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void RC6::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const |
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{ |
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const RC6_WORD *sptr = sTable; |
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RC6_WORD a, b, c, d, t, u; |
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Block::Get(inBlock)(a)(b)(c)(d); |
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b += sptr[0]; |
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d += sptr[1]; |
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sptr += 2; |
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for(unsigned i=0; i<r; i++) |
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{ |
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t = rotlFixed(b*(2*b+1), 5); |
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u = rotlFixed(d*(2*d+1), 5); |
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a = rotlMod(a^t,u) + sptr[0]; |
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c = rotlMod(c^u,t) + sptr[1]; |
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t = a; a = b; b = c; c = d; d = t; |
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sptr += 2; |
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} |
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a += sptr[0]; |
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c += sptr[1]; |
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Block::Put(xorBlock, outBlock)(a)(b)(c)(d); |
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} |
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void RC6::Dec::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const |
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{ |
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const RC6_WORD *sptr = sTable.end(); |
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RC6_WORD a, b, c, d, t, u; |
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Block::Get(inBlock)(a)(b)(c)(d); |
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sptr -= 2; |
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c -= sptr[1]; |
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a -= sptr[0]; |
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for (unsigned i=0; i < r; i++) |
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{ |
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sptr -= 2; |
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t = a; a = d; d = c; c = b; b = t; |
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u = rotlFixed(d*(2*d+1), 5); |
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t = rotlFixed(b*(2*b+1), 5); |
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c = rotrMod(c-sptr[1], t) ^ u; |
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a = rotrMod(a-sptr[0], u) ^ t; |
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} |
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sptr -= 2; |
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d -= sTable[1]; |
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b -= sTable[0]; |
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Block::Put(xorBlock, outBlock)(a)(b)(c)(d); |
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} |
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NAMESPACE_END
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