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Optimize XTEA encryption (#1143)

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https://dev.to/rsa/making-an-algorithm-15x-faster-without-parallelism-38k5
This commit is contained in:
Ranieri Althoff 2021-04-02 19:48:58 +00:00 committed by GitHub
parent 3600a9b40b
commit 5cc9319a94
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 39 additions and 52 deletions
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85
src/framework/net/protocol.cpp
View File

@ -144,29 +144,35 @@ void Protocol::internalRecvData(uint8* buffer, uint16 size)
void Protocol::generateXteaKey()
{
std::mt19937 eng(std::time(nullptr));
std::uniform_int_distribution<uint32> unif(0, 0xFFFFFFFF);
m_xteaKey[0] = unif(eng);
m_xteaKey[1] = unif(eng);
m_xteaKey[2] = unif(eng);
m_xteaKey[3] = unif(eng);
std::random_device rd;
std::uniform_int_distribution<uint32> unif;
std::generate(m_xteaKey.begin(), m_xteaKey.end(), [&]() { return unif(rd); });
}
void Protocol::setXteaKey(uint32 a, uint32 b, uint32 c, uint32 d)
namespace {
constexpr uint32_t delta = 0x9E3779B9;
template<typename Round>
void apply_rounds(uint8_t* data, size_t length, Round round)
{
m_xteaKey[0] = a;
m_xteaKey[1] = b;
m_xteaKey[2] = c;
m_xteaKey[3] = d;
for (auto j = 0u; j < length; j += 8) {
uint32_t left = data[j+0] | data[j+1] << 8u | data[j+2] << 16u | data[j+3] << 24u,
right = data[j+4] | data[j+5] << 8u | data[j+6] << 16u | data[j+7] << 24u;
round(left, right);
data[j] = static_cast<uint8_t>(left);
data[j+1] = static_cast<uint8_t>(left >> 8u);
data[j+2] = static_cast<uint8_t>(left >> 16u);
data[j+3] = static_cast<uint8_t>(left >> 24u);
data[j+4] = static_cast<uint8_t>(right);
data[j+5] = static_cast<uint8_t>(right >> 8u);
data[j+6] = static_cast<uint8_t>(right >> 16u);
data[j+7] = static_cast<uint8_t>(right >> 24u);
}
}
std::vector<uint32> Protocol::getXteaKey()
{
std::vector<uint32> xteaKey;
xteaKey.resize(4);
for(int i = 0; i < 4; ++i)
xteaKey[i] = m_xteaKey[i];
return xteaKey;
}
bool Protocol::xteaDecrypt(const InputMessagePtr& inputMessage)
@ -177,22 +183,12 @@ bool Protocol::xteaDecrypt(const InputMessagePtr& inputMessage)
return false;
}
uint32 *buffer = (uint32*)(inputMessage->getReadBuffer());
int readPos = 0;
while(readPos < encryptedSize/4) {
uint32 v0 = buffer[readPos], v1 = buffer[readPos + 1];
uint32 delta = 0x61C88647;
uint32 sum = 0xC6EF3720;
for(int32 i = 0; i < 32; i++) {
v1 -= ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + m_xteaKey[sum>>11 & 3]);
sum += delta;
v0 -= ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + m_xteaKey[sum & 3]);
}
buffer[readPos] = v0; buffer[readPos + 1] = v1;
readPos = readPos + 2;
}
for (uint32_t i = 0, sum = delta << 5, next_sum = sum - delta; i < 32; ++i, sum = next_sum, next_sum -= delta) {
apply_rounds(inputMessage->getReadBuffer(), encryptedSize, [&](uint32_t& left, uint32_t& right) {
right -= ((left << 4 ^ left >> 5) + left) ^ (sum + m_xteaKey[(sum >> 11) & 3]);
left -= ((right << 4 ^ right >> 5) + right) ^ (next_sum + m_xteaKey[next_sum & 3]);
});
};
uint16 decryptedSize = inputMessage->getU16() + 2;
int sizeDelta = decryptedSize - encryptedSize;
@ -217,21 +213,12 @@ void Protocol::xteaEncrypt(const OutputMessagePtr& outputMessage)
encryptedSize += n;
}
int readPos = 0;
uint32 *buffer = (uint32*)(outputMessage->getDataBuffer() - 2);
while(readPos < encryptedSize / 4) {
uint32 v0 = buffer[readPos], v1 = buffer[readPos + 1];
uint32 delta = 0x61C88647;
uint32 sum = 0;
for(int32 i = 0; i < 32; i++) {
v0 += ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + m_xteaKey[sum & 3]);
sum -= delta;
v1 += ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + m_xteaKey[sum>>11 & 3]);
}
buffer[readPos] = v0; buffer[readPos + 1] = v1;
readPos = readPos + 2;
}
for (uint32_t i = 0, sum = 0, next_sum = sum + delta; i < 32; ++i, sum = next_sum, next_sum += delta) {
apply_rounds(outputMessage->getDataBuffer() - 2, encryptedSize, [&](uint32_t& left, uint32_t& right) {
left += ((right << 4 ^ right >> 5) + right) ^ (sum + m_xteaKey[sum & 3]);
right += ((left << 4 ^ left >> 5) + left) ^ (next_sum + m_xteaKey[(next_sum >> 11) & 3]);
});
};
}
void Protocol::onConnect()

6
src/framework/net/protocol.h
View File

@ -48,8 +48,8 @@ public:
void setConnection(const ConnectionPtr& connection) { m_connection = connection; }
void generateXteaKey();
void setXteaKey(uint32 a, uint32 b, uint32 c, uint32 d);
std::vector<uint32> getXteaKey();
void setXteaKey(uint32 a, uint32 b, uint32 c, uint32 d) { m_xteaKey = {a, b, c, d}; }
std::vector<uint32> getXteaKey() { return {m_xteaKey.begin(), m_xteaKey.end()}; }
void enableXteaEncryption() { m_xteaEncryptionEnabled = true; }
void enableChecksum() { m_checksumEnabled = true; }
@ -64,7 +64,7 @@ protected:
virtual void onRecv(const InputMessagePtr& inputMessage);
virtual void onError(const boost::system::error_code& err);
uint32 m_xteaKey[4];
std::array<uint32, 4> m_xteaKey;
private:
void internalRecvHeader(uint8* buffer, uint16 size);