60 lines
1.5 KiB
C++
60 lines
1.5 KiB
C++
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// eax.cpp - written and placed in the public domain by Wei Dai
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#include "pch.h"
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#include "eax.h"
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NAMESPACE_BEGIN(CryptoPP)
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void EAX_Base::SetKeyWithoutResync(const byte *userKey, size_t keylength, const NameValuePairs ¶ms)
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{
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AccessMAC().SetKey(userKey, keylength, params);
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m_buffer.New(2*AccessMAC().TagSize());
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}
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void EAX_Base::Resync(const byte *iv, size_t len)
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{
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MessageAuthenticationCode &mac = AccessMAC();
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unsigned int blockSize = mac.TagSize();
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memset(m_buffer, 0, blockSize);
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mac.Update(m_buffer, blockSize);
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mac.CalculateDigest(m_buffer+blockSize, iv, len);
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m_buffer[blockSize-1] = 1;
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mac.Update(m_buffer, blockSize);
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m_ctr.SetCipherWithIV(AccessMAC().AccessCipher(), m_buffer+blockSize, blockSize);
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}
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size_t EAX_Base::AuthenticateBlocks(const byte *data, size_t len)
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{
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AccessMAC().Update(data, len);
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return 0;
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}
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void EAX_Base::AuthenticateLastHeaderBlock()
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{
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assert(m_bufferedDataLength == 0);
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MessageAuthenticationCode &mac = AccessMAC();
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unsigned int blockSize = mac.TagSize();
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mac.Final(m_buffer);
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xorbuf(m_buffer+blockSize, m_buffer, blockSize);
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memset(m_buffer, 0, blockSize);
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m_buffer[blockSize-1] = 2;
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mac.Update(m_buffer, blockSize);
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}
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void EAX_Base::AuthenticateLastFooterBlock(byte *tag, size_t macSize)
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{
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assert(m_bufferedDataLength == 0);
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MessageAuthenticationCode &mac = AccessMAC();
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unsigned int blockSize = mac.TagSize();
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mac.TruncatedFinal(m_buffer, macSize);
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xorbuf(tag, m_buffer, m_buffer+blockSize, macSize);
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}
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NAMESPACE_END
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