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<h1>rc6.cpp</h1><pre class="fragment"><div>00001 <span class="comment">// rc6.cpp - written and placed in the public domain by Sean Woods</span>
00002 <span class="comment">// based on Wei Dai's RC5 code.</span>
00003
00004 <span class="preprocessor">#include "pch.h"</span>
00005 <span class="preprocessor">#include "<a class="code" href="rc6_8h.html">rc6.h</a>"</span>
00006 <span class="preprocessor">#include "misc.h"</span>
00007
00008 NAMESPACE_BEGIN(CryptoPP)
00009
00010 void <a class="code" href="class_r_c6.html">RC6</a>::Base::UncheckedSetKey(CipherDir direction, const byte *k, <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> keylen, <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> rounds)
00011 {
00012 AssertValidKeyLength(keylen);
00013 AssertValidRounds(rounds);
00014
00015 r = rounds;
00016 sTable.New(2*(r+2));
00017
00018 <span class="keyword">static</span> <span class="keyword">const</span> RC6_WORD MAGIC_P = 0xb7e15163L; <span class="comment">// magic constant P for wordsize</span>
00019 <span class="keyword">static</span> <span class="keyword">const</span> RC6_WORD MAGIC_Q = 0x9e3779b9L; <span class="comment">// magic constant Q for wordsize</span>
00020 <span class="keyword">static</span> <span class="keyword">const</span> <span class="keywordtype">int</span> U=<span class="keyword">sizeof</span>(RC6_WORD);
00021
00022 <span class="keyword">const</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> c = STDMAX((keylen+U-1)/U, 1U); <span class="comment">// RC6 paper says c=1 if keylen==0</span>
00023 <a class="code" href="class_sec_block.html">SecBlock<RC6_WORD></a> l(c);
00024
00025 GetUserKey(LITTLE_ENDIAN_ORDER, l.<a class="code" href="class_sec_block.html#_sec_block_with_hinta9">begin</a>(), c, k, keylen);
00026
00027 sTable[0] = MAGIC_P;
00028 <span class="keywordflow">for</span> (<span class="keywordtype">unsigned</span> j=1; j<sTable.size();j++)
00029 sTable[j] = sTable[j-1] + MAGIC_Q;
00030
00031 RC6_WORD a=0, b=0;
00032 <span class="keyword">const</span> <span class="keywordtype">unsigned</span> n = 3*STDMAX((<span class="keywordtype">unsigned</span> <span class="keywordtype">int</span>)sTable.size(), c);
00033
00034 <span class="keywordflow">for</span> (<span class="keywordtype">unsigned</span> h=0; h < n; h++)
00035 {
00036 a = sTable[h % sTable.size()] = rotlFixed((sTable[h % sTable.size()] + a + b), 3);
00037 b = l[h % c] = rotlMod((l[h % c] + a + b), (a+b));
00038 }
00039 }
00040
00041 <span class="keyword">typedef</span> BlockGetAndPut<RC6::RC6_WORD, LittleEndian> Block;
00042
00043 <span class="keywordtype">void</span> RC6::Enc::ProcessAndXorBlock(<span class="keyword">const</span> byte *inBlock, <span class="keyword">const</span> byte *xorBlock, byte *outBlock)<span class="keyword"> const</span>
00044 <span class="keyword"></span>{
00045 <span class="keyword">const</span> RC6_WORD *sptr = sTable;
00046 RC6_WORD a, b, c, d, t, u;
00047
00048 Block::Get(inBlock)(a)(b)(c)(d);
00049 b += sptr[0];
00050 d += sptr[1];
00051 sptr += 2;
00052
00053 <span class="keywordflow">for</span>(<span class="keywordtype">unsigned</span> i=0; i<r; i++)
00054 {
00055 t = rotlFixed(b*(2*b+1), 5);
00056 u = rotlFixed(d*(2*d+1), 5);
00057 a = rotlMod(a^t,u) + sptr[0];
00058 c = rotlMod(c^u,t) + sptr[1];
00059 t = a; a = b; b = c; c = d; d = t;
00060 sptr += 2;
00061 }
00062
00063 a += sptr[0];
00064 c += sptr[1];
00065
00066 Block::Put(xorBlock, outBlock)(a)(b)(c)(d);
00067 }
00068
00069 <span class="keywordtype">void</span> RC6::Dec::ProcessAndXorBlock(<span class="keyword">const</span> byte *inBlock, <span class="keyword">const</span> byte *xorBlock, byte *outBlock)<span class="keyword"> const</span>
00070 <span class="keyword"></span>{
00071 <span class="keyword">const</span> RC6_WORD *sptr = sTable.end();
00072 RC6_WORD a, b, c, d, t, u;
00073
00074 Block::Get(inBlock)(a)(b)(c)(d);
00075
00076 sptr -= 2;
00077 c -= sptr[1];
00078 a -= sptr[0];
00079
00080 <span class="keywordflow">for</span> (<span class="keywordtype">unsigned</span> i=0; i < r; i++)
00081 {
00082 sptr -= 2;
00083 t = a; a = d; d = c; c = b; b = t;
00084 u = rotlFixed(d*(2*d+1), 5);
00085 t = rotlFixed(b*(2*b+1), 5);
00086 c = rotrMod(c-sptr[1], t) ^ u;
00087 a = rotrMod(a-sptr[0], u) ^ t;
00088 }
00089
00090 sptr -= 2;
00091 d -= sTable[1];
00092 b -= sTable[0];
00093
00094 Block::Put(xorBlock, outBlock)(a)(b)(c)(d);
00095 }
00096
00097 NAMESPACE_END
</div></pre><hr size="1"><address style="align: right;"><small>Generated on Sun Nov 7 08:23:58 2004 for Crypto++ by
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