mirror of
https://github.com/QuasarApp/Qt-AES.git
synced 2025-04-27 06:04:32 +00:00
396 lines
11 KiB
C++
396 lines
11 KiB
C++
#include "qaesencryption.h"
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#include <QDebug>
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/*
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* Static Functions
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* */
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QByteArray QAESEncryption::Crypt(QAESEncryption::AES level, QAESEncryption::MODE mode, const QByteArray rawText, const QByteArray key, const QByteArray iv)
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{
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return QAESEncryption(level, mode).encode(rawText, key, iv);
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}
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QByteArray QAESEncryption::Decrypt(QAESEncryption::AES level, QAESEncryption::MODE mode, const QByteArray rawText, const QByteArray key, const QByteArray iv)
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{
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return QAESEncryption(level, mode).decode(rawText, key, iv);
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}
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QByteArray QAESEncryption::ExpandKey(QAESEncryption::AES level, QAESEncryption::MODE mode, const QByteArray key)
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{
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return QAESEncryption(level, mode).expandKey(key);
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}
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/*
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* End Static function declarations
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* */
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/*
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* Constructor
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* */
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QAESEncryption::QAESEncryption(QAESEncryption::AES level, QAESEncryption::MODE mode) : m_nb(4), m_blocklen(16), m_level(level), m_mode(mode)
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{
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m_state = NULL;
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switch (level)
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{
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case AES_128: {
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AES128 aes;
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m_nk = aes.nk;
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m_keyLen = aes.keylen;
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m_nr = aes.nr;
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m_expandedKey = aes.expandedKey;
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}
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break;
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case AES_192: {
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AES192 aes;
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m_nk = aes.nk;
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m_keyLen = aes.keylen;
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m_nr = aes.nr;
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m_expandedKey = aes.expandedKey;
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}
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break;
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case AES_256: {
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AES256 aes;
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m_nk = aes.nk;
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m_keyLen = aes.keylen;
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m_nr = aes.nr;
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m_expandedKey = aes.expandedKey;
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}
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break;
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default: {
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AES128 aes;
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m_nk = aes.nk;
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m_keyLen = aes.keylen;
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m_nr = aes.nr;
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m_expandedKey = aes.expandedKey;
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qDebug() << "Defaulting to AES128";
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}
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break;
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}
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}
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QByteArray QAESEncryption::expandKey(const QByteArray key)
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{
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int i, k;
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quint8 tempa[4]; // Used for the column/row operations
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QByteArray roundKey(key);
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// The first round key is the key itself.
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// ...
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// All other round keys are found from the previous round keys.
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//i == Nk
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for(i = m_nk; i < m_nb * (m_nr + 1); i++)
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{
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{
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tempa[0] = (quint8) roundKey.at((i-1) * 4 + 0);
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tempa[1] = (quint8) roundKey.at((i-1) * 4 + 1);
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tempa[2] = (quint8) roundKey.at((i-1) * 4 + 2);
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tempa[3] = (quint8) roundKey.at((i-1) * 4 + 3);
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}
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if (i % m_nk == 0)
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{
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// This function shifts the 4 bytes in a word to the left once.
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// [a0,a1,a2,a3] becomes [a1,a2,a3,a0]
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// Function RotWord()
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{
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k = tempa[0];
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tempa[0] = tempa[1];
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tempa[1] = tempa[2];
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tempa[2] = tempa[3];
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tempa[3] = k;
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}
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// SubWord() is a function that takes a four-byte input word and
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// applies the S-box to each of the four bytes to produce an output word.
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// Function Subword()
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{
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tempa[0] = getSBoxValue(tempa[0]);
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tempa[1] = getSBoxValue(tempa[1]);
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tempa[2] = getSBoxValue(tempa[2]);
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tempa[3] = getSBoxValue(tempa[3]);
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}
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tempa[0] = tempa[0] ^ Rcon[i/m_nk];
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}
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if (m_level == AES_256 && i % m_nk == 4)
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{
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// Function Subword()
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{
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tempa[0] = getSBoxValue(tempa[0]);
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tempa[1] = getSBoxValue(tempa[1]);
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tempa[2] = getSBoxValue(tempa[2]);
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tempa[3] = getSBoxValue(tempa[3]);
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}
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}
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roundKey.insert(i * 4 + 0, (quint8) roundKey.at((i - m_nk) * 4 + 0) ^ tempa[0]);
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roundKey.insert(i * 4 + 1, (quint8) roundKey.at((i - m_nk) * 4 + 1) ^ tempa[1]);
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roundKey.insert(i * 4 + 2, (quint8) roundKey.at((i - m_nk) * 4 + 2) ^ tempa[2]);
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roundKey.insert(i * 4 + 3, (quint8) roundKey.at((i - m_nk) * 4 + 3) ^ tempa[3]);
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}
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return roundKey;
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}
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// This function adds the round key to state.
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// The round key is added to the state by an XOR function.
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void QAESEncryption::addRoundKey(const quint8 round, const QByteArray expKey)
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{
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QByteArray::iterator it = m_state->begin();
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for(int i=0; i < 16; ++i) {
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it[i] = (quint8) it[i] ^ (quint8) expKey.at(round * m_nb * 4 + (i/4) * m_nb + (i%4));
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}
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}
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// The SubBytes Function Substitutes the values in the
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// state matrix with values in an S-box.
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void QAESEncryption::subBytes()
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{
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QByteArray::iterator it = m_state->begin();
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for(int i = 0; i < 16; i++)
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it[i] = getSBoxValue((quint8) it[i]);
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}
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// The ShiftRows() function shifts the rows in the state to the left.
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// Each row is shifted with different offset.
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// Offset = Row number. So the first row is not shifted.
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void QAESEncryption::shiftRows()
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{
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QByteArray::iterator it = m_state->begin();
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quint8 temp;
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//Keep in mind that QByteArray is column-driven!!
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//Shift 1 to left
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temp = (quint8)it[1];
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it[1] = (quint8)it[5];
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it[5] = (quint8)it[9];
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it[9] = (quint8)it[13];
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it[13] = (quint8)temp;
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//Shift 2 to left
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temp = (quint8)it[2];
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it[2] = (quint8)it[10];
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it[10] = (quint8)temp;
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temp = (quint8)it[6];
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it[6] = (quint8)it[14];
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it[14] = (quint8)temp;
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//Shift 3 to left
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temp = (quint8)it[3];
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it[3] = (quint8)it[15];
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it[15] = (quint8)it[11];
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it[11] = (quint8)it[7];
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it[7] = (quint8)temp;
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}
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// MixColumns function mixes the columns of the state matrix
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//optimized!!
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void QAESEncryption::mixColumns()
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{
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QByteArray::iterator it = m_state->begin();
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quint8 tmp, tm, t;
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for(int i = 0; i < 16; i += 4)
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{
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t = (quint8)it[i];
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tmp = (quint8)it[i] ^ (quint8)it[i+1] ^ (quint8)it[i+2] ^ (quint8)it[i+3] ;
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tm = xTime( (quint8)it[i] ^ (quint8)it[i+1] );
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it[i] = (quint8)it[i] ^ (quint8)tm ^ (quint8)tmp;
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tm = xTime( (quint8)it[i+1] ^ (quint8)it[i+2]);
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it[i+1] = (quint8)it[i+1] ^ (quint8)tm ^ (quint8)tmp;
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tm = xTime( (quint8)it[i+2] ^ (quint8)it[i+3]);
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it[i+2] =(quint8)it[i+2] ^ (quint8)tm ^ (quint8)tmp;
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tm = xTime((quint8)it[i+3] ^ (quint8)t);
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it[i+3] =(quint8)it[i+3] ^ (quint8)tm ^ (quint8)tmp;
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}
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}
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// MixColumns function mixes the columns of the state matrix.
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// The method used to multiply may be difficult to understand for the inexperienced.
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// Please use the references to gain more information.
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void QAESEncryption::invMixColumns()
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{
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QByteArray::iterator it = m_state->begin();
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quint8 a,b,c,d;
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for(int i = 0; i < 16; i+=4)
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{
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a = (quint8) it[i];
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b = (quint8) it[i+1];
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c = (quint8) it[i+2];
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d = (quint8) it[i+3];
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it[i] = (quint8) (multiply(a, 0x0e) ^ multiply(b, 0x0b) ^ multiply(c, 0x0d) ^ multiply(d, 0x09));
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it[i+1] = (quint8) (multiply(a, 0x09) ^ multiply(b, 0x0e) ^ multiply(c, 0x0b) ^ multiply(d, 0x0d));
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it[i+2] = (quint8) (multiply(a, 0x0d) ^ multiply(b, 0x09) ^ multiply(c, 0x0e) ^ multiply(d, 0x0b));
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it[i+3] = (quint8) (multiply(a, 0x0b) ^ multiply(b, 0x0d) ^ multiply(c, 0x09) ^ multiply(d, 0x0e));
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}
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}
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// The SubBytes Function Substitutes the values in the
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// state matrix with values in an S-box.
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void QAESEncryption::invSubBytes()
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{
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QByteArray::iterator it = m_state->begin();
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for(int i = 0; i < 16; ++i)
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it[i] = getSBoxInvert((quint8) it[i]);
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}
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void QAESEncryption::invShiftRows()
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{
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QByteArray::iterator it = m_state->begin();
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uint8_t temp;
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//Keep in mind that QByteArray is column-driven!!
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//Shift 1 to right
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temp = (quint8)it[13];
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it[13] = (quint8)it[9];
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it[9] = (quint8)it[5];
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it[5] = (quint8)it[1];
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it[1] = (quint8)temp;
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//Shift 2
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temp = (quint8)it[10];
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it[10] = (quint8)it[2];
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it[2] = (quint8)temp;
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temp = (quint8)it[14];
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it[14] = (quint8)it[6];
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it[6] = (quint8)temp;
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//Shift 3
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temp = (quint8)it[15];
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it[15] = (quint8)it[3];
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it[3] = (quint8)it[7];
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it[7] = (quint8)it[11];
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it[11] = (quint8)temp;
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}
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QByteArray QAESEncryption::ivXor(const QByteArray in, const QByteArray iv)
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{
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QByteArray::const_iterator it = in.begin();
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QByteArray::const_iterator it_iv = iv.begin();
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QByteArray ret;
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for(int i = 0; i < m_blocklen; i++)
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ret.insert(i,it[i] ^ it_iv[i]);
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return ret;
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}
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// Cipher is the main function that encrypts the PlainText.
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QByteArray QAESEncryption::cipher(const QByteArray expKey, const QByteArray in)
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{
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//m_state is the input buffer...
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QByteArray output(in);
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m_state = &output;
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// Add the First round key to the state before starting the rounds.
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addRoundKey(0, expKey);
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// There will be Nr rounds.
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// The first Nr-1 rounds are identical.
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// These Nr-1 rounds are executed in the loop below.
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for(quint8 round = 1; round < m_nr; ++round)
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{
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subBytes();
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shiftRows();
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mixColumns();
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addRoundKey(round, expKey);
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}
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// The last round is given below.
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// The MixColumns function is not here in the last round.
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subBytes();
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shiftRows();
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addRoundKey(m_nr, expKey);
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return output;
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}
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QByteArray QAESEncryption::invCipher(const QByteArray expKey, const QByteArray in)
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{
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//m_state is the input buffer.... handle it!
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QByteArray output(in);
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m_state = &output;
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// Add the First round key to the state before starting the rounds.
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addRoundKey(m_nr, expKey);
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// There will be Nr rounds.
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// The first Nr-1 rounds are identical.
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// These Nr-1 rounds are executed in the loop below.
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for(quint8 round=m_nr-1; round>0 ; round--)
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{
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invShiftRows();
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invSubBytes();
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addRoundKey(round, expKey);
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invMixColumns();
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}
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// The last round is given below.
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// The MixColumns function is not here in the last round.
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invShiftRows();
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invSubBytes();
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addRoundKey(0, expKey);
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return output;
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}
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QByteArray QAESEncryption::encode(const QByteArray rawText, const QByteArray key, const QByteArray iv)
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{
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if (m_mode == CBC && (iv.isNull() || iv.size() != m_blocklen))
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return QByteArray();
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QByteArray ret;
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QByteArray expandedKey = expandKey(key);
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QByteArray alignedText(rawText);
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QByteArray ivTemp(iv);
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alignedText.append(getPadding(rawText.size(), m_blocklen), 0); //filling the array with zeros
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for(int i=0; i < alignedText.size(); i+= m_blocklen)
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{
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if (m_mode == CBC)
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alignedText.replace(i, m_blocklen, ivXor(alignedText.mid(i, m_blocklen),ivTemp));
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ret.append(cipher(expandedKey, alignedText.mid(i, m_blocklen)));
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if (m_mode == CBC)
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ivTemp = ret.mid(i, m_blocklen);
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}
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return ret;
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}
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QByteArray QAESEncryption::decode(const QByteArray rawText, const QByteArray key, const QByteArray iv)
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{
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if (m_mode == CBC && (iv.isNull() || iv.size() != m_blocklen))
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return QByteArray();
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QByteArray ret;
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QByteArray expandedKey = expandKey(key);
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QByteArray alignedText(rawText);
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QByteArray ivTemp(iv);
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for(int i=0; i < alignedText.size(); i+= m_blocklen)
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{
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ret.append(invCipher(expandedKey, alignedText.mid(i, m_blocklen)));
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if (m_mode == CBC) {
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ret.replace(i, m_blocklen, ivXor(ret.mid(i, m_blocklen),ivTemp));
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ivTemp = alignedText.mid(i, m_blocklen);
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}
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}
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return ret;
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}
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