With inner thinking, here are a few steps to protect your process:
The first step is to change your password processing from String to character array .
The reason for this is that String is an immutable object, and therefore its data will not be cleared immediately, even if this object is set to null ; Instead, the data is set up to collect garbage, and this creates a security problem because malware can access this String data (password) before it is cleared.
This is the main reason why the getText() method of Swing JPasswordField is deprecated, and why getPassword() uses character arrays .
The second step is to encrypt your credentials, only temporarily decrypting them during the authentication process.
This, like the first step, ensures that the time of your vulnerability is as short as possible.
It is recommended that your credentials not be hard-coded and instead store them in a centralized, customizable, and easy-to-maintain way, such as a configuration or properties file.
You must encrypt your credentials before saving the file, and in addition, you can apply a second encryption to the file itself (two-level encryption for the credentials and 1-layer encryption to the other contents of the file).
Please note that each of the two encryption processes mentioned above can be multi-level. Each encryption can be a separate application of the standard triple data encryption (AKA TDES and 3DES) as a conceptual example.
After your local environment is properly secured (but remember that it will never be “secure”!), The third step is to apply basic protection to your transfer process using TLS (Transport Layer Security) or SSL (Secure Sockets Layer) .
The fourth step is to apply other protection methods.
For example, applying obfuscation techniques to your “used” compiler to avoid (even soon) the impact of your security measures if your program is received by Ms. Eva, Mr. Mallory or someone else (bad guys) and decompiled .
UPDATE 1:
For @ Damien.Bell, here is an example that covers the first and second steps:
//These will be used as the source of the configuration file stored attributes. private static final Map<String, String> COMMON_ATTRIBUTES = new HashMap<String, String>(); private static final Map<String, char[]> SECURE_ATTRIBUTES = new HashMap<String, char[]>(); //Ciphering (encryption and decryption) password/key. private static final char[] PASSWORD = "Unauthorized_Personel_Is_Unauthorized".toCharArray(); //Cipher salt. private static final byte[] SALT = { (byte) 0xde, (byte) 0x33, (byte) 0x10, (byte) 0x12, (byte) 0xde, (byte) 0x33, (byte) 0x10, (byte) 0x12,}; //Desktop dir: private static final File DESKTOP = new File(System.getProperty("user.home") + "/Desktop"); //File names: private static final String NO_ENCRYPTION = "no_layers.txt"; private static final String SINGLE_LAYER = "single_layer.txt"; private static final String DOUBLE_LAYER = "double_layer.txt"; /** * @param args the command line arguments */ public static void main(String[] args) throws GeneralSecurityException, FileNotFoundException, IOException { //Set common attributes. COMMON_ATTRIBUTES.put("Gender", "Male"); COMMON_ATTRIBUTES.put("Age", "21"); COMMON_ATTRIBUTES.put("Name", "Hypot Hetical"); COMMON_ATTRIBUTES.put("Nickname", "HH"); /* * Set secure attributes. * NOTE: Ignore the use of Strings here, it being used for convenience only. * In real implementations, JPasswordField.getPassword() would send the arrays directly. */ SECURE_ATTRIBUTES.put("Username", "Hypothetical".toCharArray()); SECURE_ATTRIBUTES.put("Password", "LetMePass_Word".toCharArray()); /* * For demosntration purposes, I make the three encryption layer-levels I mention. * To leave no doubt the code works, I use real file IO. */ //File without encryption. create_EncryptedFile(NO_ENCRYPTION, COMMON_ATTRIBUTES, SECURE_ATTRIBUTES, 0); //File with encryption to secure attributes only. create_EncryptedFile(SINGLE_LAYER, COMMON_ATTRIBUTES, SECURE_ATTRIBUTES, 1); //File completely encrypted, including re-encryption of secure attributes. create_EncryptedFile(DOUBLE_LAYER, COMMON_ATTRIBUTES, SECURE_ATTRIBUTES, 2); /* * Show contents of all three encryption levels, from file. */ System.out.println("NO ENCRYPTION: \n" + readFile_NoDecryption(NO_ENCRYPTION) + "\n\n\n"); System.out.println("SINGLE LAYER ENCRYPTION: \n" + readFile_NoDecryption(SINGLE_LAYER) + "\n\n\n"); System.out.println("DOUBLE LAYER ENCRYPTION: \n" + readFile_NoDecryption(DOUBLE_LAYER) + "\n\n\n"); /* * Decryption is demonstrated with the Double-Layer encryption file. */ //Descrypt first layer. (file content) (REMEMBER: Layers are in reverse order from writing). String decryptedContent = readFile_ApplyDecryption(DOUBLE_LAYER); System.out.println("READ: [first layer decrypted]\n" + decryptedContent + "\n\n\n"); //Decrypt second layer (secure data). for (String line : decryptedContent.split("\n")) { String[] pair = line.split(": ", 2); if (pair[0].equalsIgnoreCase("Username") || pair[0].equalsIgnoreCase("Password")) { System.out.println("Decrypted: " + pair[0] + ": " + decrypt(pair[1])); } } } private static String encrypt(byte[] property) throws GeneralSecurityException { SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBEWithMD5AndDES"); SecretKey key = keyFactory.generateSecret(new PBEKeySpec(PASSWORD)); Cipher pbeCipher = Cipher.getInstance("PBEWithMD5AndDES"); pbeCipher.init(Cipher.ENCRYPT_MODE, key, new PBEParameterSpec(SALT, 20)); //Encrypt and save to temporary storage. String encrypted = Base64.encodeBytes(pbeCipher.doFinal(property)); //Cleanup data-sources - Leave no traces behind. for (int i = 0; i < property.length; i++) { property[i] = 0; } property = null; System.gc(); //Return encryption result. return encrypted; } private static String encrypt(char[] property) throws GeneralSecurityException { //Prepare and encrypt. byte[] bytes = new byte[property.length]; for (int i = 0; i < property.length; i++) { bytes[i] = (byte) property[i]; } String encrypted = encrypt(bytes); /* * Cleanup property here. (child data-source 'bytes' is cleaned inside 'encrypt(byte[])'). * It not being done because the sources are being used multiple times for the different layer samples. */ // for (int i = 0; i < property.length; i++) { //cleanup allocated data. // property[i] = 0; // } // property = null; //de-allocate data (set for GC). // System.gc(); //Attempt triggering garbage-collection. return encrypted; } private static String encrypt(String property) throws GeneralSecurityException { String encrypted = encrypt(property.getBytes()); /* * Strings can't really have their allocated data cleaned before CG, * that why secure data should be handled with char[] or byte[]. * Still, don't forget to set for GC, even for data of sesser importancy; * You are making everything safer still, and freeing up memory as bonus. */ property = null; return encrypted; } private static String decrypt(String property) throws GeneralSecurityException, IOException { SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBEWithMD5AndDES"); SecretKey key = keyFactory.generateSecret(new PBEKeySpec(PASSWORD)); Cipher pbeCipher = Cipher.getInstance("PBEWithMD5AndDES"); pbeCipher.init(Cipher.DECRYPT_MODE, key, new PBEParameterSpec(SALT, 20)); return new String(pbeCipher.doFinal(Base64.decode(property))); } private static void create_EncryptedFile( String fileName, Map<String, String> commonAttributes, Map<String, char[]> secureAttributes, int layers) throws GeneralSecurityException, FileNotFoundException, IOException { StringBuilder sb = new StringBuilder(); for (String k : commonAttributes.keySet()) { sb.append(k).append(": ").append(commonAttributes.get(k)).append(System.lineSeparator()); } //First encryption layer. Encrypts secure attribute values only. for (String k : secureAttributes.keySet()) { String encryptedValue; if (layers >= 1) { encryptedValue = encrypt(secureAttributes.get(k)); } else { encryptedValue = new String(secureAttributes.get(k)); } sb.append(k).append(": ").append(encryptedValue).append(System.lineSeparator()); } //Prepare file and file-writing process. File f = new File(DESKTOP, fileName); if (!f.getParentFile().exists()) { f.getParentFile().mkdirs(); } else if (f.exists()) { f.delete(); } BufferedWriter bw = new BufferedWriter(new FileWriter(f)); //Second encryption layer. Encrypts whole file content including previously encrypted stuff. if (layers >= 2) { bw.append(encrypt(sb.toString().trim())); } else { bw.append(sb.toString().trim()); } bw.flush(); bw.close(); } private static String readFile_NoDecryption(String fileName) throws FileNotFoundException, IOException, GeneralSecurityException { File f = new File(DESKTOP, fileName); BufferedReader br = new BufferedReader(new FileReader(f)); StringBuilder sb = new StringBuilder(); while (br.ready()) { sb.append(br.readLine()).append(System.lineSeparator()); } return sb.toString(); } private static String readFile_ApplyDecryption(String fileName) throws FileNotFoundException, IOException, GeneralSecurityException { File f = new File(DESKTOP, fileName); BufferedReader br = new BufferedReader(new FileReader(f)); StringBuilder sb = new StringBuilder(); while (br.ready()) { sb.append(br.readLine()).append(System.lineSeparator()); } return decrypt(sb.toString()); }
A complete example regarding each step of the defense would far exceed what I consider to be reasonable for this question, since it is about "what are the steps" and not "how to apply them."
This would greatly overestimate my answer (finally, the sample), while the other questions here about SO are already focused on the “How” on these steps, being much more appropriate and offering a much better explanation and sample on the implementation of each individual step.