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85 lines
2.1 KiB
C++
85 lines
2.1 KiB
C++
/*
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* All or portions of this file Copyright (c) Amazon.com, Inc. or its affiliates or
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* its licensors.
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*
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* For complete copyright and license terms please see the LICENSE at the root of this
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* distribution (the "License"). All use of this software is governed by the License,
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* or, if provided, by the license below or the license accompanying this file. Do not
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* remove or modify any license notices. This file is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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*
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*/
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#include "CrySystem_precompiled.h"
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#include "StreamCipher.h"
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StreamCipherState CStreamCipher::BeginCipher(const uint8* pKey, uint32 keyLength)
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{
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StreamCipherState cipher;
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Init(cipher, pKey, keyLength);
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return cipher;
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}
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void CStreamCipher::Init(StreamCipherState& state, const uint8* key, int keyLen)
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{
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int i, j;
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for (i = 0; i < 256; i++)
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{
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state.m_S[i] = i;
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}
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if (key)
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{
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for (i = j = 0; i < 256; i++)
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{
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uint8 temp;
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j = (j + key[i % keyLen] + state.m_S[i]) & 255;
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temp = state.m_S[i];
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state.m_S[i] = state.m_S[j];
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state.m_S[j] = temp;
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}
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}
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state.m_I = state.m_J = 0;
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for (i = 0; i < 1024; i++)
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{
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GetNext(state);
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}
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memcpy(state.m_StartS, state.m_S, sizeof(state.m_StartS));
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state.m_StartI = state.m_I;
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state.m_StartJ = state.m_J;
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}
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uint8 CStreamCipher::GetNext(StreamCipherState& state)
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{
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uint8 tmp;
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state.m_I = (state.m_I + 1) & 0xff;
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state.m_J = (state.m_J + state.m_S[state.m_I]) & 0xff;
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tmp = state.m_S[state.m_J];
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state.m_S[state.m_J] = state.m_S[state.m_I];
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state.m_S[state.m_I] = tmp;
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return state.m_S[(state.m_S[state.m_I] + state.m_S[state.m_J]) & 0xff];
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}
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void CStreamCipher::ProcessBuffer(StreamCipherState& state, const uint8* input, int inputLen, uint8* output, bool resetKey)
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{
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if (resetKey)
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{
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memcpy(state.m_S, state.m_StartS, sizeof(state.m_S));
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state.m_I = state.m_StartI;
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state.m_J = state.m_StartJ;
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}
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for (int i = 0; i < inputLen; i++)
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{
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output[i] = input[i] ^ GetNext(state);
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}
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}
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