Move XChunk processors to ZoneCommon

src/ZoneCommon/Zone/XChunk/XChunkProcessorSalsa20Decryption.cpp

@@ -0,0 +1,44 @@
+#include "XChunkProcessorSalsa20Decryption.h"
+
+#include <cassert>
+
+#include "Crypto.h"
+#include "AbstractSalsa20Processor.h"
+
+XChunkProcessorSalsa20Decryption::XChunkProcessorSalsa20Decryption(const int streamCount, std::string& zoneName, const uint8_t* salsa20Key, size_t keySize)
+    : AbstractSalsa20Processor(streamCount, zoneName, salsa20Key, keySize)
+{
+}
+
+size_t XChunkProcessorSalsa20Decryption::Process(const int streamNumber, const uint8_t* input, const size_t inputLength, uint8_t* output, const size_t outputBufferSize)
+{
+    assert(streamNumber >= 0 && streamNumber < m_stream_count);
+    assert(input != nullptr);
+    assert(output != nullptr);
+    assert(inputLength <= outputBufferSize);
+
+    auto& streamContext = m_stream_contexts[streamNumber];
+
+    // Initialize Salsa20 with an IV of the first 8 bytes of the current hash block
+    streamContext.m_salsa20->SetIV(GetHashBlock(streamNumber), SALSA20_IV_SIZE);
+    streamContext.m_salsa20->Process(input, output, inputLength);
+
+    // Hash decrypted XChunk
+    uint8_t blockSha1Hash[SHA1_HASH_SIZE];
+    streamContext.m_sha1->Init();
+    streamContext.m_sha1->Process(output, inputLength);
+    streamContext.m_sha1->Finish(&blockSha1Hash);
+
+    // Advance index to next hash block
+    m_stream_block_indices[streamNumber] = (m_stream_block_indices[streamNumber] + 1) % BLOCK_HASHES_COUNT;
+
+    auto* nextHashBlock = GetHashBlock(streamNumber);
+
+    // XOR the upcoming hash block with the hash of the XChunk utilizing the previous hash block
+    for (unsigned int hashOffset = 0; hashOffset < sizeof(blockSha1Hash); hashOffset++)
+    {
+        nextHashBlock[hashOffset] ^= blockSha1Hash[hashOffset];
+    }
+
+    return inputLength;
+}