82 lines
1.7 KiB
C++
82 lines
1.7 KiB
C++
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/*
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* This file is part of Codecrypt.
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*
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* Codecrypt is free software: you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or (at
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* your option) any later version.
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*
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* Codecrypt is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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* License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with Codecrypt. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef _ccr_rc4_h_
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#define _ccr_rc4_h_
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#include <vector>
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#include <sys/types.h>
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template<class inttype> class arcfour
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{
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std::vector<inttype> S;
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inttype I, J;
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inttype mask;
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public:
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bool init (unsigned bits) {
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if (bits > 8 * sizeof (inttype) ) return false;
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I = J = 0;
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S.resize (1 << bits);
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mask = ~ (inttype) 0;
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if ( (inttype) (1 << bits) ) mask %= 1 << bits;
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for (size_t i = 0; i < (1 << bits); ++i) S[i] = i;
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return true;
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}
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void clear() {
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I = J = 0;
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mask = 0;
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S.clear();
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}
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void load_key (const std::vector<inttype>&K) {
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inttype j = 0, t;
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for (size_t i = 0; i <= mask; ++i) {
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j = (j + S[i] + K[i % K.size()]) & mask;
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t = S[j];
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S[j] = S[i];
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S[i] = t;
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}
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}
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inttype gen() {
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I = (I + 1) & mask;
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J = (J + S[I]) & mask;
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register inttype t;
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t = S[J];
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S[J] = S[I];
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S[I] = t;
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return S[ (S[I] + S[J]) & mask];
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}
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void discard (size_t n) {
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for (size_t i = 0; i < n; ++i) gen();
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}
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void gen (size_t n, std::vector<inttype>&out) {
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out.resize (n);
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for (size_t i = 0; i < n; ++i) out[i] = gen();
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}
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};
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#endif
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