00001
00002
00003 #include "pch.h"
00004 #include "rc5.h"
00005 #include "misc.h"
00006
00007 NAMESPACE_BEGIN(CryptoPP)
00008
00009 void RC5::Base::UncheckedSetKey(const byte *k, unsigned int keylen, const NameValuePairs ¶ms)
00010 {
00011 AssertValidKeyLength(keylen);
00012
00013 r = GetRoundsAndThrowIfInvalid(params, this);
00014 sTable.New(2*(r+1));
00015
00016 static const RC5_WORD MAGIC_P = 0xb7e15163L;
00017 static const RC5_WORD MAGIC_Q = 0x9e3779b9L;
00018 static const int U=sizeof(RC5_WORD);
00019
00020 const unsigned int c = STDMAX((keylen+U-1)/U, 1U);
00021 SecBlock<RC5_WORD> l(c);
00022
00023 GetUserKey(LITTLE_ENDIAN_ORDER, l.begin(), c, k, keylen);
00024
00025 sTable[0] = MAGIC_P;
00026 for (unsigned j=1; j<sTable.size();j++)
00027 sTable[j] = sTable[j-1] + MAGIC_Q;
00028
00029 RC5_WORD a=0, b=0;
00030 const unsigned n = 3*STDMAX((unsigned int)sTable.size(), c);
00031
00032 for (unsigned h=0; h < n; h++)
00033 {
00034 a = sTable[h % sTable.size()] = rotlFixed((sTable[h % sTable.size()] + a + b), 3);
00035 b = l[h % c] = rotlMod((l[h % c] + a + b), (a+b));
00036 }
00037 }
00038
00039 typedef BlockGetAndPut<RC5::RC5_WORD, LittleEndian> Block;
00040
00041 void RC5::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
00042 {
00043 const RC5_WORD *sptr = sTable;
00044 RC5_WORD a, b;
00045
00046 Block::Get(inBlock)(a)(b);
00047 a += sptr[0];
00048 b += sptr[1];
00049 sptr += 2;
00050
00051 for(unsigned i=0; i<r; i++)
00052 {
00053 a = rotlMod(a^b,b) + sptr[2*i+0];
00054 b = rotlMod(a^b,a) + sptr[2*i+1];
00055 }
00056
00057 Block::Put(xorBlock, outBlock)(a)(b);
00058 }
00059
00060 void RC5::Dec::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
00061 {
00062 const RC5_WORD *sptr = sTable.end();
00063 RC5_WORD a, b;
00064
00065 Block::Get(inBlock)(a)(b);
00066
00067 for (unsigned i=0; i<r; i++)
00068 {
00069 sptr-=2;
00070 b = rotrMod(b-sptr[1], a) ^ a;
00071 a = rotrMod(a-sptr[0], b) ^ b;
00072 }
00073 b -= sTable[1];
00074 a -= sTable[0];
00075
00076 Block::Put(xorBlock, outBlock)(a)(b);
00077 }
00078
00079 NAMESPACE_END