68 lines
1.2 KiB
C++
68 lines
1.2 KiB
C++
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// AesCfb128Decryptor.cpp
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// Implements the cAesCfb128Decryptor class decrypting data using AES CFB-128
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#include "Globals.h"
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#include "AesCfb128Decryptor.h"
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cAesCfb128Decryptor::cAesCfb128Decryptor(void) :
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m_IVOffset(0),
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m_IsValid(false)
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{
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}
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cAesCfb128Decryptor::~cAesCfb128Decryptor()
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{
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// Clear the leftover in-memory data, so that they can't be accessed by a backdoor
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memset(&m_Aes, 0, sizeof(m_Aes));
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}
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void cAesCfb128Decryptor::Init(const Byte a_Key[16], const Byte a_IV[16])
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{
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ASSERT(!IsValid()); // Cannot Init twice
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memcpy(m_IV, a_IV, 16);
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aes_setkey_enc(&m_Aes, a_Key, 128);
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m_IsValid = true;
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}
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void cAesCfb128Decryptor::ProcessData(Byte * a_DecryptedOut, const Byte * a_EncryptedIn, size_t a_Length)
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{
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ASSERT(IsValid()); // Must Init() first
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// PolarSSL doesn't support AES-CFB8, need to implement it manually:
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for (size_t i = 0; i < a_Length; i++)
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{
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Byte Buffer[sizeof(m_IV)];
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aes_crypt_ecb(&m_Aes, AES_ENCRYPT, m_IV, Buffer);
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for (size_t idx = 0; idx < sizeof(m_IV) - 1; idx++)
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{
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m_IV[idx] = m_IV[idx + 1];
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}
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m_IV[sizeof(m_IV) - 1] = a_EncryptedIn[i];
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a_DecryptedOut[i] = a_EncryptedIn[i] ^ Buffer[0];
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}
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}
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