Add cryptography

Example/src/main/java/me/braydon/example/LicenseClient.java

@@ -1,13 +1,15 @@
+/*
+ * Copyright (c) 2023 Braydon (Rainnny). All rights reserved.
+ *
+ * For inquiries, please contact braydonrainnny@gmail.com
+ */
 package me.braydon.example;
 
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
-import lombok.AllArgsConstructor;
+import lombok.*;
-import lombok.Getter;
-import lombok.NonNull;
-import lombok.ToString;
 import okhttp3.*;
 import oshi.SystemInfo;
 import oshi.hardware.CentralProcessor;
@@ -15,9 +17,18 @@ import oshi.hardware.ComputerSystem;
 import oshi.hardware.HardwareAbstractionLayer;
 import oshi.software.os.OperatingSystem;
 
+import javax.crypto.Cipher;
+import java.io.File;
+import java.io.FileOutputStream;
 import java.io.IOException;
+import java.nio.file.Files;
+import java.security.KeyFactory;
+import java.security.PrivateKey;
+import java.security.PublicKey;
+import java.security.spec.X509EncodedKeySpec;
 import java.time.OffsetDateTime;
 import java.time.format.DateTimeFormatter;
+import java.util.Base64;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.Map;
@@ -32,51 +43,93 @@ import java.util.Map;
  * @author Braydon
  * @see <a href="https://git.rainnny.club/Rainnny/LicenseServer">License Server</a>
  */
-public final class LicenseExample {
+public final class LicenseClient {
+    private static final String ALGORITHM = "RSA"; // The crypto algorithm to use
+    
+    /**
+     * The endpoint to use for downloading the {@link PublicKey}.
+     */
+    private static final String PUBLIC_KEY_ENDPOINT = "/crypto/pub";
+    
     /**
      * The endpoint to check licenses at.
      */
-    private static final String CHECK_ENDPOINT = "http://localhost:7500/check";
+    private static final String CHECK_ENDPOINT = "/check";
     
     /**
      * The {@link Gson} instance to use.
      */
-    private static final Gson GSON = new GsonBuilder()
+    private static final Gson GSON = new GsonBuilder().serializeNulls().create();
-                                         .serializeNulls()
+    
-                                         .create();
+    /**
+     * The URL of the license server to make requests to.
+     */
+    @NonNull private final String appUrl;
+    
+    /**
+     * The product to use for client.
+     */
+    @NonNull private final String product;
+    
+    /**
+     * The {@link OkHttpClient} to use for requests.
+     */
+    @NonNull private final OkHttpClient httpClient;
+    
+    /**
+     * The {@link PublicKey} to use for encryption.
+     */
+    @NonNull private final PublicKey publicKey;
+    
+    public LicenseClient(@NonNull String appUrl, @NonNull String product, @NonNull File publicKeyFile) {
+        this.appUrl = appUrl;
+        this.product = product;
+        httpClient = new OkHttpClient(); // Create a new http client
+        publicKey = fetchPublicKey(publicKeyFile); // Fetch our public key
+    }
+    
+    /**
+     * Read the public key from the given bytes.
+     *
+     * @param bytes the bytes of the public key
+     * @return the public key
+     * @see PrivateKey for public key
+     */
+    @SneakyThrows
+    private static PublicKey readPublicKey(byte[] bytes) {
+        return KeyFactory.getInstance(ALGORITHM).generatePublic(new X509EncodedKeySpec(bytes));
+    }
     
     /**
      * Check the license with the given
      * key for the given product.
      *
      * @param key     the key to check
-     * @param product the product the key belongs to
      * @return the license response
      * @see LicenseResponse for response
      */
     @NonNull
-    public static LicenseResponse check(@NonNull String key, @NonNull String product) {
+    public LicenseResponse check(@NonNull String key) {
         String hardwareId = getHardwareId(); // Get the hardware id of the machine
         
         // Build the json body
         Map<String, Object> body = new HashMap<>();
-        body.put("key", key);
+        body.put("key", encrypt(key));
         body.put("product", product);
-        body.put("hwid", hardwareId);
+        body.put("hwid", encrypt(hardwareId));
         String bodyJson = GSON.toJson(body); // The json body
         
-        OkHttpClient client = new OkHttpClient(); // Create a new http client
         MediaType mediaType = MediaType.parse("application/json"); // Ensure the media type is json
-        RequestBody requestBody = RequestBody.create(bodyJson, mediaType); // Build the request body
+        RequestBody requestBody = RequestBody.create(mediaType, bodyJson); // Build the request body
         Request request = new Request.Builder()
-                              .url(CHECK_ENDPOINT)
+                              .url(appUrl + CHECK_ENDPOINT)
                               .post(requestBody)
                               .build(); // Build the POST request
         
         Response response = null; // The response of the request
         int responseCode = -1; // The response code of the request
         try { // Attempt to execute the request
-            response = client.newCall(request).execute();
+            response = httpClient.newCall(request).execute();
             responseCode = response.code();
             
             // If the response is successful, we can parse the response
@@ -127,6 +180,43 @@ public final class LicenseExample {
         return new LicenseResponse(responseCode, "An unknown error occurred");
     }
     
+    /**
+     * Fetch the public key.
+     * <p>
+     * If the public key is not already present, we
+     * fetch it from the server. Otherwise, the public
+     * key is loaded from the file.
+     * </p>
+     *
+     * @param publicKeyFile the public key file
+     * @return the public key
+     * @see PublicKey for public key
+     */
+    @SneakyThrows
+    private PublicKey fetchPublicKey(@NonNull File publicKeyFile) {
+        byte[] publicKey;
+        if (publicKeyFile.exists()) { // Public key exists, use it
+            publicKey = Files.readAllBytes(publicKeyFile.toPath());
+        } else {
+            Request request = new Request.Builder()
+                                  .url(appUrl + PUBLIC_KEY_ENDPOINT)
+                                  .build(); // Build the GET request
+            @Cleanup Response response = httpClient.newCall(request).execute(); // Make the request
+            if (!response.isSuccessful()) { // Response wasn't successful
+                throw new IOException("Failed to download the public key, got response " + response.code());
+            }
+            ResponseBody body = response.body(); // Get the response body
+            assert body != null; // We need a response body
+            publicKey = body.bytes(); // Read our public key
+            
+            // Write the response to the public key file
+            try (FileOutputStream outputStream = new FileOutputStream(publicKeyFile)) {
+                outputStream.write(publicKey);
+            }
+        }
+        return readPublicKey(publicKey);
+    }
+    
     /**
      * Get the unique hardware
      * identifier of this machine.
@@ -134,7 +224,7 @@ public final class LicenseExample {
      * @return the hardware id
      */
     @NonNull
-    private static String getHardwareId() {
+    private String getHardwareId() {
         SystemInfo systemInfo = new SystemInfo();
         OperatingSystem operatingSystem = systemInfo.getOperatingSystem();
         HardwareAbstractionLayer hardwareAbstractionLayer = systemInfo.getHardware();
@@ -155,9 +245,25 @@ public final class LicenseExample {
                    + String.format("%08x", processorIdentifier.hashCode()) + "-" + processors;
     }
     
-    @AllArgsConstructor
+    /**
-    @Getter
+     * Encrypt the given input.
-    @ToString
+     *
+     * @param input the encrypted input
+     * @return the encrypted result
+     */
+    @SneakyThrows @NonNull
+    private String encrypt(@NonNull String input) {
+        Cipher cipher = Cipher.getInstance(ALGORITHM); // Create our cipher
+        cipher.init(Cipher.ENCRYPT_MODE, publicKey); // Set our mode and public key
+        return Base64.getEncoder().encodeToString(cipher.doFinal(input.getBytes())); // Return our encrypted result
+    }
+    
+    /**
+     * The response of a license check.
+     *
+     * @see #check(String)
+     */
+    @AllArgsConstructor @Getter @ToString
     public static class LicenseResponse {
         /**
          * The status code of the response.

Example/src/main/java/me/braydon/example/Main.java

@@ -1,11 +1,19 @@
+/*
+ * Copyright (c) 2023 Braydon (Rainnny). All rights reserved.
+ *
+ * For inquiries, please contact braydonrainnny@gmail.com
+ */
 package me.braydon.example;
 
+import java.io.File;
+
 /**
  * @author Braydon
  */
 public final class Main {
     public static void main(String[] args) {
-        LicenseExample.LicenseResponse response = LicenseExample.check("XXXX-XXXX-XXXX-XXXX", "Example");
+        LicenseClient client = new LicenseClient("http://localhost:7500", "Example", new File("public.key")); // Create the client
+        LicenseClient.LicenseResponse response = client.check("XXXX-XXXX-XXXX-XXXX"); // Check our license
         if (!response.isValid()) { // License isn't valid
             System.err.println("Invalid license: " + response.getError());
             return;

src/main/java/me/braydon/license/LicenseServer.java

@@ -1,3 +1,8 @@
+/*
+ * Copyright (c) 2023 Braydon (Rainnny). All rights reserved.
+ *
+ * For inquiries, please contact braydonrainnny@gmail.com
+ */
 package me.braydon.license;
 
 import com.google.gson.Gson;

src/main/java/me/braydon/license/common/CryptographyUtils.java

@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2023 Braydon (Rainnny). All rights reserved.
+ *
+ * For inquiries, please contact braydonrainnny@gmail.com
+ */
+package me.braydon.license.common;
+
+import lombok.NonNull;
+import lombok.SneakyThrows;
+import lombok.experimental.UtilityClass;
+
+import javax.crypto.Cipher;
+import java.io.File;
+import java.nio.file.Files;
+import java.security.*;
+import java.security.spec.PKCS8EncodedKeySpec;
+import java.security.spec.X509EncodedKeySpec;
+import java.util.Base64;
+
+/**
+ * @author Braydon
+ */
+@UtilityClass
+public final class CryptographyUtils {
+    private static final String ALGORITHM = "RSA"; // The algorithm to use
+    
+    /**
+     * Generate a new key pair.
+     *
+     * @return the key pair
+     * @see KeyPair for key pair
+     */
+    @NonNull @SneakyThrows
+    public static KeyPair generateKeyPair() {
+        KeyPairGenerator generator = KeyPairGenerator.getInstance(ALGORITHM); // Create a generator
+        generator.initialize(2048); // Set the key size
+        return generator.generateKeyPair(); // Return our generated key pair
+    }
+    
+    /**
+     * Read the public key from the given file.
+     *
+     * @param keyFile the key file to read
+     * @return the public key
+     * @see PrivateKey for public key
+     */
+    @SneakyThrows
+    public static PublicKey readPublicKey(@NonNull File keyFile) {
+        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(Files.readAllBytes(keyFile.toPath())); // Get the key spec
+        return KeyFactory.getInstance(ALGORITHM).generatePublic(keySpec); // Return the public key from the key spec
+    }
+    
+    /**
+     * Read the private key from the given file.
+     *
+     * @param keyFile the key file to read
+     * @return the private key
+     * @see PrivateKey for private key
+     */
+    @SneakyThrows
+    public static PrivateKey readPrivateKey(@NonNull File keyFile) {
+        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(Files.readAllBytes(keyFile.toPath())); // Get the key spec
+        return KeyFactory.getInstance(ALGORITHM).generatePrivate(keySpec); // Return the private key from the key spec
+    }
+    
+    /**
+     * Decrypt the given input with
+     * the provided private key.
+     *
+     * @param input      the encrypted input
+     * @param privateKey the private key
+     * @return the decrypted result
+     * @see PrivateKey for private key
+     */
+    @SneakyThrows @NonNull
+    public static String decryptMessage(@NonNull String input, @NonNull PrivateKey privateKey) {
+        Cipher cipher = Cipher.getInstance(ALGORITHM); // Create the cipher
+        cipher.init(Cipher.DECRYPT_MODE, privateKey); // Set our mode and private key
+        return new String(cipher.doFinal(Base64.getDecoder().decode(input))); // Return our decrypted result
+    }
+}

src/main/java/me/braydon/license/common/IPUtils.java

@@ -1,3 +1,8 @@
+/*
+ * Copyright (c) 2023 Braydon (Rainnny). All rights reserved.
+ *
+ * For inquiries, please contact braydonrainnny@gmail.com
+ */
 package me.braydon.license.common;
 
 import jakarta.servlet.http.HttpServletRequest;

src/main/java/me/braydon/license/common/MiscUtils.java

@@ -1,3 +1,8 @@
+/*
+ * Copyright (c) 2023 Braydon (Rainnny). All rights reserved.
+ *
+ * For inquiries, please contact braydonrainnny@gmail.com
+ */
 package me.braydon.license.common;
 
 import lombok.NonNull;

src/main/java/me/braydon/license/common/RandomUtils.java

@@ -1,3 +1,8 @@
+/*
+ * Copyright (c) 2023 Braydon (Rainnny). All rights reserved.
+ *
+ * For inquiries, please contact braydonrainnny@gmail.com
+ */
 package me.braydon.license.common;
 
 import lombok.NonNull;

src/main/java/me/braydon/license/common/TimeUtils.java

@@ -1,3 +1,8 @@
+/*
+ * Copyright (c) 2023 Braydon (Rainnny). All rights reserved.
+ *
+ * For inquiries, please contact braydonrainnny@gmail.com
+ */
 package me.braydon.license.common;
 
 import lombok.NonNull;

src/main/java/me/braydon/license/controller/CryptographyController.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2023 Braydon (Rainnny). All rights reserved.
+ *
+ * For inquiries, please contact braydonrainnny@gmail.com
+ */
+package me.braydon.license.controller;
+
+import lombok.NonNull;
+import me.braydon.license.model.License;
+import me.braydon.license.service.CryptographyService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.core.io.ByteArrayResource;
+import org.springframework.core.io.Resource;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.ResponseBody;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.security.PublicKey;
+
+/**
+ * @author Braydon
+ */
+@RestController
+@RequestMapping(value = "/crypto", produces = MediaType.APPLICATION_JSON_VALUE)
+public final class CryptographyController {
+    /**
+     * The {@link CryptographyService} to use.
+     */
+    @NonNull private final CryptographyService service;
+    
+    @Autowired
+    public CryptographyController(@NonNull CryptographyService service) {
+        this.service = service;
+    }
+    
+    /**
+     * Downloads the public key file.
+     *
+     * @return the response entity
+     * @see PublicKey for public key
+     * @see License for license
+     * @see ResponseEntity for response entity
+     */
+    @GetMapping("/pub")
+    @ResponseBody
+    public ResponseEntity<Resource> publicKey() {
+        byte[] publicKey = service.getKeyPair().getPublic().getEncoded(); // Get the public key
+        String fileName = "public.key"; // The name of the file to download
+        return ResponseEntity.ok()
+                   .contentType(MediaType.APPLICATION_OCTET_STREAM)
+                   .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + fileName + "\"")
+                   .contentLength(publicKey.length)
+                   .body(new ByteArrayResource(publicKey));
+    }
+}

src/main/java/me/braydon/license/controller/LicenseController.java

@@ -1,12 +1,19 @@
+/*
+ * Copyright (c) 2023 Braydon (Rainnny). All rights reserved.
+ *
+ * For inquiries, please contact braydonrainnny@gmail.com
+ */
 package me.braydon.license.controller;
 
 import jakarta.servlet.http.HttpServletRequest;
 import lombok.NonNull;
+import me.braydon.license.common.CryptographyUtils;
 import me.braydon.license.common.IPUtils;
 import me.braydon.license.dto.LicenseCheckBodyDTO;
 import me.braydon.license.dto.LicenseDTO;
 import me.braydon.license.exception.APIException;
 import me.braydon.license.model.License;
+import me.braydon.license.service.CryptographyService;
 import me.braydon.license.service.LicenseService;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.http.HttpStatus;
@@ -14,6 +21,7 @@ import org.springframework.http.MediaType;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.*;
 
+import java.security.PrivateKey;
 import java.util.Map;
 
 /**
@@ -22,14 +30,20 @@ import java.util.Map;
 @RestController
 @RequestMapping(value = "/", produces = MediaType.APPLICATION_JSON_VALUE)
 public final class LicenseController {
+    /**
+     * The {@link CryptographyService} to use.
+     */
+    @NonNull private final CryptographyService cryptographyService;
+    
     /**
      * The {@link LicenseService} to use.
      */
-    @NonNull private final LicenseService service;
+    @NonNull private final LicenseService licenseService;
     
     @Autowired
-    public LicenseController(@NonNull LicenseService service) {
+    public LicenseController(@NonNull CryptographyService cryptographyService, @NonNull LicenseService licenseService) {
-        this.service = service;
+        this.cryptographyService = cryptographyService;
+        this.licenseService = licenseService;
     }
     
     /**
@@ -53,24 +67,34 @@ public final class LicenseController {
             if (IPUtils.getIpType(ip) == -1) {
                 throw new APIException(HttpStatus.BAD_REQUEST, "Invalid IP address");
             }
-            // Ensure the HWID is valid
+            String key;
-            String hwidString = body.getHwid();
+            String hwid;
+            try {
+                PrivateKey privateKey = cryptographyService.getKeyPair().getPrivate(); // Get our private key
+                key = CryptographyUtils.decryptMessage(body.getKey(), privateKey); // Decrypt our license key
+                hwid = CryptographyUtils.decryptMessage(body.getHwid(), privateKey); // Decrypt our hwid
+            } catch (IllegalArgumentException ex) {
+                throw new APIException(HttpStatus.BAD_REQUEST, "Signature Error");
+            }
+            
+            // Validating that the UUID is in the correct format
             boolean invalidHwid = true;
-            if (hwidString.contains("-")) {
+            if (hwid.contains("-")) {
-                int segments = hwidString.substring(0, hwidString.lastIndexOf("-")).split("-").length;
+                int segments = hwid.substring(0, hwid.lastIndexOf("-")).split("-").length;
                 if (segments == 4) {
                     invalidHwid = false;
                 }
             }
-            if (invalidHwid) {
+            if (invalidHwid) { // Invalid HWID
                 throw new APIException(HttpStatus.BAD_REQUEST, "Invalid HWID");
             }
+            
             // Check the license
-            License license = service.check(
+            License license = licenseService.check(
-                body.getKey(),
+                key,
                 body.getProduct(),
                 ip,
-                hwidString
+                hwid
             );
             // Return OK with the license DTO
             return ResponseEntity.ok(new LicenseDTO(

src/main/java/me/braydon/license/dto/LicenseCheckBodyDTO.java

@@ -1,3 +1,8 @@
+/*
+ * Copyright (c) 2023 Braydon (Rainnny). All rights reserved.
+ *
+ * For inquiries, please contact braydonrainnny@gmail.com
+ */
 package me.braydon.license.dto;
 
 import lombok.AllArgsConstructor;

src/main/java/me/braydon/license/dto/LicenseDTO.java

@@ -1,3 +1,8 @@
+/*
+ * Copyright (c) 2023 Braydon (Rainnny). All rights reserved.
+ *
+ * For inquiries, please contact braydonrainnny@gmail.com
+ */
 package me.braydon.license.dto;
 
 import lombok.AllArgsConstructor;

src/main/java/me/braydon/license/exception/APIException.java

@@ -1,3 +1,8 @@
+/*
+ * Copyright (c) 2023 Braydon (Rainnny). All rights reserved.
+ *
+ * For inquiries, please contact braydonrainnny@gmail.com
+ */
 package me.braydon.license.exception;
 
 import lombok.Getter;

src/main/java/me/braydon/license/exception/LicenseExpiredException.java

@@ -1,3 +1,8 @@
+/*
+ * Copyright (c) 2023 Braydon (Rainnny). All rights reserved.
+ *
+ * For inquiries, please contact braydonrainnny@gmail.com
+ */
 package me.braydon.license.exception;
 
 import me.braydon.license.model.License;

src/main/java/me/braydon/license/exception/LicenseHwidLimitExceededException.java

@@ -1,3 +1,8 @@
+/*
+ * Copyright (c) 2023 Braydon (Rainnny). All rights reserved.
+ *
+ * For inquiries, please contact braydonrainnny@gmail.com
+ */
 package me.braydon.license.exception;
 
 import me.braydon.license.model.License;

src/main/java/me/braydon/license/exception/LicenseIpLimitExceededException.java

@@ -1,3 +1,8 @@
+/*
+ * Copyright (c) 2023 Braydon (Rainnny). All rights reserved.
+ *
+ * For inquiries, please contact braydonrainnny@gmail.com
+ */
 package me.braydon.license.exception;
 
 import me.braydon.license.model.License;

src/main/java/me/braydon/license/exception/LicenseNotFoundException.java

@@ -1,3 +1,8 @@
+/*
+ * Copyright (c) 2023 Braydon (Rainnny). All rights reserved.
+ *
+ * For inquiries, please contact braydonrainnny@gmail.com
+ */
 package me.braydon.license.exception;
 
 import me.braydon.license.model.License;

src/main/java/me/braydon/license/model/License.java

@@ -1,3 +1,8 @@
+/*
+ * Copyright (c) 2023 Braydon (Rainnny). All rights reserved.
+ *
+ * For inquiries, please contact braydonrainnny@gmail.com
+ */
 package me.braydon.license.model;
 
 import lombok.Getter;

src/main/java/me/braydon/license/repository/LicenseRepository.java

@@ -1,3 +1,8 @@
+/*
+ * Copyright (c) 2023 Braydon (Rainnny). All rights reserved.
+ *
+ * For inquiries, please contact braydonrainnny@gmail.com
+ */
 package me.braydon.license.repository;
 
 import lombok.NonNull;

src/main/java/me/braydon/license/service/CryptographyService.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2023 Braydon (Rainnny). All rights reserved.
+ *
+ * For inquiries, please contact braydonrainnny@gmail.com
+ */
+package me.braydon.license.service;
+
+import lombok.Getter;
+import lombok.NonNull;
+import lombok.SneakyThrows;
+import lombok.extern.slf4j.Slf4j;
+import me.braydon.license.common.CryptographyUtils;
+import org.springframework.stereotype.Service;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.security.KeyPair;
+import java.util.Base64;
+
+/**
+ * @author Braydon
+ */
+@Service
+@Slf4j(topic = "Cryptography")
+@Getter
+public final class CryptographyService {
+    /**
+     * Our {@link KeyPair}.
+     */
+    @NonNull private final KeyPair keyPair;
+    
+    @SneakyThrows
+    public CryptographyService() {
+        File publicKeyFile = new File("public.key"); // The private key
+        File privateKeyFile = new File("private.key"); // The private key
+        if (!publicKeyFile.exists() || !privateKeyFile.exists()) { // Missing private key, generate new key pair.
+            keyPair = CryptographyUtils.generateKeyPair(); // Generate new key pair
+            writeKey(keyPair.getPublic().getEncoded(), publicKeyFile); // Write our public key
+            writeKey(keyPair.getPrivate().getEncoded(), privateKeyFile); // Write our private key
+            log.info("New key pair has been generated");
+            log.info(Base64.getEncoder().encodeToString(keyPair.getPublic().getEncoded()));
+            return;
+        }
+        // Load our private key from the file
+        keyPair = new KeyPair(CryptographyUtils.readPublicKey(publicKeyFile), CryptographyUtils.readPrivateKey(privateKeyFile));
+        log.info("Loaded private key from file " + privateKeyFile.getPath());
+    }
+    
+    /**
+     * Write the given contents to the provided file.
+     *
+     * @param contents the content bytes to write
+     * @param file     the file to write to
+     */
+    private void writeKey(byte[] contents, @NonNull File file) {
+        try (FileOutputStream outputStream = new FileOutputStream(file)) {
+            outputStream.write(contents);
+        } catch (IOException ex) {
+            ex.printStackTrace();
+        }
+    }
+}

src/main/java/me/braydon/license/service/DiscordService.java

@@ -1,3 +1,8 @@
+/*
+ * Copyright (c) 2023 Braydon (Rainnny). All rights reserved.
+ *
+ * For inquiries, please contact braydonrainnny@gmail.com
+ */
 package me.braydon.license.service;
 
 import com.google.common.cache.Cache;
@@ -33,7 +38,6 @@ import net.dv8tion.jda.api.requests.GatewayIntent;
 import org.mindrot.jbcrypt.BCrypt;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.annotation.Value;
-import org.springframework.boot.info.BuildProperties;
 import org.springframework.stereotype.Service;
 
 import java.awt.*;
@@ -59,7 +63,7 @@ public final class DiscordService {
     /**
      * The version of this Springboot application.
      */
-    @NonNull private final String applicationVersion;
+    @NonNull private String applicationVersion = "n/a";
     
     /**
      * The salt to use for hashing license keys.
@@ -140,9 +144,9 @@ public final class DiscordService {
                                                             .build();
     
     @Autowired
-    public DiscordService(@NonNull LicenseRepository licenseRepository, @NonNull BuildProperties buildProperties) {
+    public DiscordService(@NonNull LicenseRepository licenseRepository/*, @NonNull BuildProperties buildProperties*/) {
         this.licenseRepository = licenseRepository;
-        this.applicationVersion = buildProperties.getVersion();
+        //        this.applicationVersion = buildProperties.getVersion();
     }
     
     @PostConstruct @SneakyThrows

src/main/java/me/braydon/license/service/LicenseService.java

@@ -1,3 +1,8 @@
+/*
+ * Copyright (c) 2023 Braydon (Rainnny). All rights reserved.
+ *
+ * For inquiries, please contact braydonrainnny@gmail.com
+ */
 package me.braydon.license.service;
 
 import jakarta.annotation.PostConstruct;