1 files changed, 95 insertions, 0 deletions

diff --git a/src/core/hw/aes/ccm.cpp b/src/core/hw/aes/ccm.cpp
new file mode 100644
index 000000000..dc7035ab6
--- /dev/null
+++ b/src/core/hw/aes/ccm.cpp
@@ -0,0 +1,95 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <algorithm>
+#include <cryptopp/aes.h>
+#include <cryptopp/ccm.h>
+#include <cryptopp/cryptlib.h>
+#include <cryptopp/filters.h>
+#include "common/alignment.h"
+#include "common/logging/log.h"
+#include "core/hw/aes/ccm.h"
+#include "core/hw/aes/key.h"
+
+namespace HW {
+namespace AES {
+
+namespace {
+
+// 3DS uses a non-standard AES-CCM algorithm, so we need to derive a sub class from the standard one
+// and override with the non-standard part.
+using CryptoPP::lword;
+using CryptoPP::AES;
+using CryptoPP::CCM_Final;
+using CryptoPP::CCM_Base;
+template <bool T_IsEncryption>
+class CCM_3DSVariant_Final : public CCM_Final<AES, CCM_MAC_SIZE, T_IsEncryption> {
+public:
+    void UncheckedSpecifyDataLengths(lword header_length, lword message_length,
+                                     lword footer_length) override {
+        // 3DS uses the aligned size to generate B0 for authentication, instead of the original size
+        lword aligned_message_length = Common::AlignUp(message_length, AES_BLOCK_SIZE);
+        CCM_Base::UncheckedSpecifyDataLengths(header_length, aligned_message_length, footer_length);
+        CCM_Base::m_messageLength = message_length; // restore the actual message size
+    }
+};
+
+class CCM_3DSVariant {
+public:
+    using Encryption = CCM_3DSVariant_Final<true>;
+    using Decryption = CCM_3DSVariant_Final<false>;
+};
+
+} // namespace
+
+std::vector<u8> EncryptSignCCM(const std::vector<u8>& pdata, const CCMNonce& nonce,
+                               size_t slot_id) {
+    if (!IsNormalKeyAvailable(slot_id)) {
+        LOG_ERROR(HW_AES, "Key slot %d not available. Will use zero key.", slot_id);
+    }
+    const AESKey normal = GetNormalKey(slot_id);
+    std::vector<u8> cipher(pdata.size() + CCM_MAC_SIZE);
+
+    try {
+        CCM_3DSVariant::Encryption e;
+        e.SetKeyWithIV(normal.data(), AES_BLOCK_SIZE, nonce.data(), CCM_NONCE_SIZE);
+        e.SpecifyDataLengths(0, pdata.size(), 0);
+        CryptoPP::ArraySource as(pdata.data(), pdata.size(), true,
+                                 new CryptoPP::AuthenticatedEncryptionFilter(
+                                     e, new CryptoPP::ArraySink(cipher.data(), cipher.size())));
+    } catch (const CryptoPP::Exception& e) {
+        LOG_ERROR(HW_AES, "FAILED with: %s", e.what());
+    }
+    return cipher;
+}
+
+std::vector<u8> DecryptVerifyCCM(const std::vector<u8>& cipher, const CCMNonce& nonce,
+                                 size_t slot_id) {
+    if (!IsNormalKeyAvailable(slot_id)) {
+        LOG_ERROR(HW_AES, "Key slot %d not available. Will use zero key.", slot_id);
+    }
+    const AESKey normal = GetNormalKey(slot_id);
+    const std::size_t pdata_size = cipher.size() - CCM_MAC_SIZE;
+    std::vector<u8> pdata(pdata_size);
+
+    try {
+        CCM_3DSVariant::Decryption d;
+        d.SetKeyWithIV(normal.data(), AES_BLOCK_SIZE, nonce.data(), CCM_NONCE_SIZE);
+        d.SpecifyDataLengths(0, pdata_size, 0);
+        CryptoPP::AuthenticatedDecryptionFilter df(
+            d, new CryptoPP::ArraySink(pdata.data(), pdata_size));
+        CryptoPP::ArraySource as(cipher.data(), cipher.size(), true, new CryptoPP::Redirector(df));
+        if (!df.GetLastResult()) {
+            LOG_ERROR(HW_AES, "FAILED");
+            return {};
+        }
+    } catch (const CryptoPP::Exception& e) {
+        LOG_ERROR(HW_AES, "FAILED with: %s", e.what());
+        return {};
+    }
+    return pdata;
+}
+
+} // namespace AES
+} // namespace HW