service: nfp: Add plain amiibo support

src/core/hle/service/nfp/amiibo_crypto.cpp

@@ -70,6 +70,10 @@ bool IsAmiiboValid(const EncryptedNTAG215File& ntag_file) {
     return true;
 }
 
+bool IsAmiiboValid(const NTAG215File& ntag_file) {
+    return IsAmiiboValid(EncodedDataToNfcData(ntag_file));
+}
+
 NTAG215File NfcDataToEncodedData(const EncryptedNTAG215File& nfc_data) {
     NTAG215File encoded_data{};
 

src/core/hle/service/nfp/amiibo_crypto.h

@@ -60,6 +60,9 @@ static_assert(sizeof(DerivedKeys) == 0x30, "DerivedKeys is an invalid size");
 /// Validates that the amiibo file is not corrupted
 bool IsAmiiboValid(const EncryptedNTAG215File& ntag_file);
 
+/// Validates that the amiibo file is not corrupted
+bool IsAmiiboValid(const NTAG215File& ntag_file);
+
 /// Converts from encrypted file format to encoded file format
 NTAG215File NfcDataToEncodedData(const EncryptedNTAG215File& nfc_data);
 

src/core/hle/service/nfp/nfp_device.cpp

@@ -121,7 +121,16 @@ bool NfpDevice::LoadAmiibo(std::span<const u8> data) {
 
     // TODO: Filter by allowed_protocols here
 
+    memcpy(&tag_data, data.data(), sizeof(EncryptedNTAG215File));
+    is_plain_amiibo = AmiiboCrypto::IsAmiiboValid(tag_data);
+
+    if (is_plain_amiibo) {
+        encrypted_tag_data = AmiiboCrypto::EncodedDataToNfcData(tag_data);
+        LOG_INFO(Service_NFP, "Using plain amiibo");
+    } else {
+        tag_data = {};
         memcpy(&encrypted_tag_data, data.data(), sizeof(EncryptedNTAG215File));
+    }
 
     device_state = DeviceState::TagFound;
     deactivate_event->GetReadableEvent().Clear();
@@ -232,13 +241,17 @@ Result NfpDevice::Flush() {
 
     tag_data.write_counter++;
 
+    std::vector<u8> data(sizeof(EncryptedNTAG215File));
+    if (is_plain_amiibo) {
+        memcpy(data.data(), &tag_data, sizeof(tag_data));
+    } else {
         if (!AmiiboCrypto::EncodeAmiibo(tag_data, encrypted_tag_data)) {
             LOG_ERROR(Service_NFP, "Failed to encode data");
             return WriteAmiiboFailed;
         }
 
-    std::vector<u8> data(sizeof(encrypted_tag_data));
         memcpy(data.data(), &encrypted_tag_data, sizeof(encrypted_tag_data));
+    }
 
     if (!npad_device->WriteNfc(data)) {
         LOG_ERROR(Service_NFP, "Error writing to file");
@@ -256,6 +269,13 @@ Result NfpDevice::Mount(MountTarget mount_target_) {
         return WrongDeviceState;
     }
 
+    // The loaded amiibo is not encrypted
+    if (is_plain_amiibo) {
+        device_state = DeviceState::TagMounted;
+        mount_target = mount_target_;
+        return ResultSuccess;
+    }
+
     if (!AmiiboCrypto::IsAmiiboValid(encrypted_tag_data)) {
         LOG_ERROR(Service_NFP, "Not an amiibo");
         return NotAnAmiibo;

src/core/hle/service/nfp/nfp_device.h

@@ -95,6 +95,7 @@ private:
     bool is_initalized{};
     bool is_data_moddified{};
     bool is_app_area_open{};
+    bool is_plain_amiibo{};
     TagProtocol allowed_protocols{};
     s64 current_posix_time{};
     MountTarget mount_target{MountTarget::None};

src/core/hle/service/nfp/nfp_types.h

@@ -309,7 +309,8 @@ struct EncryptedNTAG215File {
     u32 CFG1;                        // Defines number of verification attempts
     NTAG215Password password;        // Password data
 };
-static_assert(sizeof(EncryptedNTAG215File) == 0x21C, "EncryptedNTAG215File is an invalid size");
+static_assert(sizeof(EncryptedNTAG215File) == sizeof(NTAG215File),
+              "EncryptedNTAG215File is an invalid size");
 static_assert(std::is_trivially_copyable_v<EncryptedNTAG215File>,
               "EncryptedNTAG215File must be trivially copyable.");