我在为基于密码的AES加密/解密程序添加MAC时遇到了问题。我正在尝试将MAC＆amp; d明文和salt（与密码一起使用）（两个字节数组）与密文一起添加到最终数组中，然后通过读取密文文件并将其拆分回来进行解密salt，MAC和密文字节数组。
加密类似乎运行顺利，但解密类没有。我调试了该类，发现它失败了，因为它从未进入if语句，检查计算和恢复的MAC是否相同：
if(Arrays.equals(macBytes, hmac))
在打印出盐，消息和MAC的字节数组之前，我无法找出原因，并发现从加密和解密类打印时它们不匹配。所有数组大小在两个类中匹配，但字节值在某处发生变化。
之前两个类都没有使用MAC，但是我没有将盐直接添加到加密数据中，而是将其写入单独的文件中。将它与加密数据包括在一起使得这对我来说更容易携带，但这样做是不是一个糟糕的选择？将它写入单独的文件更好吗？或者我只是在我的代码中遗漏了一些明显的东西？
这是完整的代码。
加密类
public class AESEncryption
{
private final String ALGORITHM = "AES";
private final String MAC_ALGORITHM = "HmacSHA256";
private final String TRANSFORMATION = "AES/CBC/PKCS5Padding";
private final String KEY_DERIVATION_FUNCTION = "PBKDF2WithHmacSHA1";
private final String PLAINTEXT = "/Volumes/CONNOR P/Unencrypted.txt";
private final String ENCRYPTED = "/Volumes/CONNOR P/Encrypted.txt";
private final String PASSWORD = "javapapers";
private final String LOC = Paths.get(".").toAbsolutePath().normalize().toString();
private static final int SALT_SIZE = 64;
private final int KEY_LENGTH = 128;
private final int ITERATIONS = 100000;
public AESEncryption()
{
try
{
encrypt();
}
catch(Exception ex)
{
JOptionPane.showMessageDialog(null, "Error: " + ex.getClass().getName(), "Error", JOptionPane.ERROR_MESSAGE);
}
}
private void encrypt() throws Exception
{
File encrypted = new File(ENCRYPTED);
File plaintext = new File(PLAINTEXT);
int encryptedSize = (int)encrypted.length();
int plaintextSize = (int)plaintext.length();
BufferedInputStream bufferedInputStream = new BufferedInputStream(new FileInputStream(PLAINTEXT));
BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(new FileOutputStream(ENCRYPTED));
//Create salt
byte[] salt = new byte[SALT_SIZE];
SecureRandom secureRandom = new SecureRandom();
secureRandom.nextBytes(salt);
//Create cipher key
SecretKeyFactory factory = SecretKeyFactory.getInstance(KEY_DERIVATION_FUNCTION);
KeySpec keySpec = new PBEKeySpec(PASSWORD.toCharArray(), salt, ITERATIONS, KEY_LENGTH);
SecretKey secret = new SecretKeySpec(factory.generateSecret(keySpec).getEncoded(), ALGORITHM);
//Create cipher
Cipher cipher = Cipher.getInstance(TRANSFORMATION);
cipher.init(Cipher.ENCRYPT_MODE, secret, new IvParameterSpec(new byte[16]));
//Read plaintext file into byte array
byte[] input = new byte[encryptedSize];
Path path = Paths.get(PLAINTEXT);
input = Files.readAllBytes(path);
byte[] crypt = cipher.doFinal(input);
//Create MAC object and apply to the byte array crypt[] containing the plaintext
KeyGenerator keyGenerator = KeyGenerator.getInstance(MAC_ALGORITHM);
SecretKey macKey = keyGenerator.generateKey();
Mac mac = Mac.getInstance(MAC_ALGORITHM);
mac.init(macKey);
byte[] macBytes = mac.doFinal(crypt);
//Add salt, MAC'd plaintext, and encrypted plaintext to final array
byte[] output = new byte[SALT_SIZE + crypt.length + macBytes.length];
System.arraycopy(salt, 0, output, 0, SALT_SIZE);
System.arraycopy(macBytes, 0, output, SALT_SIZE, macBytes.length);
System.arraycopy(crypt, 0, output, SALT_SIZE + macBytes.length, crypt.length);
//Write array with encrypted data to a new file
bufferedOutputStream.write(output);
bufferedInputStream.close();
bufferedOutputStream.flush();
bufferedOutputStream.close();
}
解密课
public class AESDecryption
{
private final String ALGORITHM = "AES";
private final String MAC_ALGORITHM = "HmacSHA256";
private final String TRANSFORMATION = "AES/CBC/PKCS5Padding";
private final String KEY_DERIVATION_FUNCTION = "PBKDF2WithHmacSHA1";
private final String PLAINTEXT = "/Volumes/CONNOR P/De-Encrypted.txt";
private final String ENCRYPTED = "/Volumes/CONNOR P/Encrypted.txt";
private final String PASSWORD = "javapapers";
private final String LOC = Paths.get(".").toAbsolutePath().normalize().toString();
private final int SALT_SIZE = 64;
private final int IV_SIZE = 16;
private final int KEY_LENGTH = 128;
private final int ITERATIONS = 100000;
public AESDecryption()
{
try
{
decrypt();
}
catch(Exception ex)
{
JOptionPane.showMessageDialog(null, "Error: " + ex.getClass().getName(), "Error", JOptionPane.ERROR_MESSAGE);
}
}
private void decrypt() throws Exception
{
File encrypted = new File(ENCRYPTED);
File plaintext = new File(PLAINTEXT);
int encryptedSize = (int)encrypted.length();
int plaintextSize = (int)plaintext.length();
BufferedInputStream bufferedInputStream = new BufferedInputStream(new FileInputStream(encrypted));
BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(new FileOutputStream(plaintext));
//Read in the encrypted data
byte[] input = new byte[encryptedSize];
Path path = Paths.get(ENCRYPTED);
input = Files.readAllBytes(path);
int increment = (input.length-SALT_SIZE)/2;
if(input.length >= (SALT_SIZE + increment))
{
//Recover salt, MAC, and encrypted data and store in arrays
byte[] salt = Arrays.copyOfRange(input, 0, SALT_SIZE);
byte[] macBytes = Arrays.copyOfRange(input, SALT_SIZE, SALT_SIZE + increment);
byte[] crypt = Arrays.copyOfRange(input, SALT_SIZE + increment, input.length);
//Regenerate original MAC
KeyGenerator keyGenerator = KeyGenerator.getInstance(MAC_ALGORITHM);
SecretKey macKey = keyGenerator.generateKey();
Mac mac = Mac.getInstance(MAC_ALGORITHM);
mac.init(macKey);
byte[] hmac = mac.doFinal(crypt);
if(Arrays.equals(macBytes, hmac)) //This is where it fails, never enters
{
//Regenerate cipher and decrypt data
SecretKeyFactory factory = SecretKeyFactory.getInstance(KEY_DERIVATION_FUNCTION);
KeySpec keySpec = new PBEKeySpec(PASSWORD.toCharArray(), salt, ITERATIONS, KEY_LENGTH);
SecretKey secret = new SecretKeySpec(factory.generateSecret(keySpec).getEncoded(), ALGORITHM);
Cipher cipher = Cipher.getInstance(TRANSFORMATION);
cipher.init(Cipher.DECRYPT_MODE, secret, new IvParameterSpec(new byte[16]));
//Write decrypted data to new text file
byte[] output = cipher.doFinal(crypt);
bufferedOutputStream.write(output);
bufferedInputStream.close();
bufferedOutputStream.flush();
bufferedOutputStream.close();
}
}
}
感谢您的帮助。非常感谢。
答案 0 :(得分：0)
public class AESEncryption
{
private final String ALGORITHM = "AES";
private final String MAC_ALGORITHM = "HmacSHA256";
private final String PRNG_ALGORITHM = "SHA1PRNG";
private final String TRANSFORMATION = "AES/CBC/PKCS5Padding";
private final String PLAINTEXT = "/Volumes/CONNOR P/Unencrypted.txt";
private final String ENCRYPTED = "/Volumes/CONNOR P/Encrypted.txt";
private final String PASSWORD = "javapapers";
private final String IV_FILE_NAME = "iv.enc";
private final String LOC = Paths.get(".").toAbsolutePath().normalize().toString();
private final int SALT_SIZE = 16;
private final int IV_SIZE = 16;
private final int KEY_LENGTH = 128;
private final int ITERATIONS = 100000;
private final int START = 0;
public AESEncryption()
{
try
{
encrypt();
}
catch(Exception ex)
{
JOptionPane.showMessageDialog(null, "Error: " + ex.getClass().getName(), "Error", JOptionPane.ERROR_MESSAGE);
}
}
private void encrypt() throws Exception
{
File encrypted = new File(ENCRYPTED);
File plaintext = new File(PLAINTEXT);
int plaintextSize = (int)plaintext.length();
BufferedInputStream bufferedInputStream = new BufferedInputStream(new FileInputStream(plaintext));
BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(new FileOutputStream(encrypted));
//Create salt for cipher key
byte[] salt = new byte[SALT_SIZE];
SecureRandom saltSecureRandom = SecureRandom.getInstance(PRNG_ALGORITHM);
saltSecureRandom.nextBytes(salt);
//Create cipher key & use to initialize cipher
byte[] keyBytes = PBEKeyFactory.getKey(PASSWORD, salt, ITERATIONS, KEY_LENGTH);
SecretKeySpec secret = new SecretKeySpec(keyBytes, ALGORITHM);
Cipher cipher = Cipher.getInstance(TRANSFORMATION);
cipher.init(Cipher.ENCRYPT_MODE, secret, new IvParameterSpec(new byte[16]));
//Create byte array of encrypted data
byte[] input = new byte[plaintextSize];
Path path = Paths.get(PLAINTEXT);
input = Files.readAllBytes(path);
byte[] crypt = cipher.doFinal(input);
//Create salt for the MAC key for added security
byte[] macsalt = new byte[SALT_SIZE];
SecureRandom macsaltSecureRandom = SecureRandom.getInstance(PRNG_ALGORITHM);
macsaltSecureRandom.nextBytes(macsalt);
//PBEKeyFactory.getKey(password, salt, iterations, keylength)
//returns a byte array representation of a SecretKey.
//Used a SecretKeyFactory instead of a KeyGenerator to make key.
//SecretKeyFactory gives back the same key given the same specifications
//whereas KeyGenerator gives back a new random key each time.
byte[] macPBE = PBEKeyFactory.getKey(PASSWORD, macsalt, ITERATIONS, KEY_LENGTH);
SecretKeySpec macKey = new SecretKeySpec(macPBE, MAC_ALGORITHM);
Mac mac = Mac.getInstance(MAC_ALGORITHM);
mac.init(macKey);
byte[] macBytes = mac.doFinal(crypt);
byte[] output = new byte[SALT_SIZE + SALT_SIZE + crypt.length + macBytes.length];
System.arraycopy(salt, START, output, START, SALT_SIZE);
System.arraycopy(macsalt, START, output, SALT_SIZE, SALT_SIZE);
System.arraycopy(macBytes, START, output, SALT_SIZE + SALT_SIZE, macBytes.length);
System.arraycopy(crypt, START, output, SALT_SIZE + SALT_SIZE + macBytes.length, crypt.length);
bufferedInputStream.close();
bufferedOutputStream.write(output);
bufferedOutputStream.flush();
bufferedOutputStream.close();
}
}
public class AESDecryption
{
private final String ALGORITHM = "AES";
private final String MAC_ALGORITHM = "HmacSHA256";
private final String TRANSFORMATION = "AES/CBC/PKCS5Padding";
private final String PLAINTEXT = "/Volumes/CONNOR P/De-Encrypted.txt";
private final String ENCRYPTED = "/Volumes/CONNOR P/Encrypted.txt";
private final String PASSWORD = "javapapers";
private final String LOC = Paths.get(".").toAbsolutePath().normalize().toString();
private final int SALT_SIZE = 16;
//MAC key size is 256 bits (32 bytes) since it is created with
//the HmacSHA256 algorithm
private final int MAC_SIZE = 32;
private final int IV_SIZE = 16;
private final int START = 0;
private final int KEY_LENGTH = 128;
private final int ITERATIONS = 100000;
public AESDecryption()
{
try
{
decrypt();
}
catch(Exception ex)
{
JOptionPane.showMessageDialog(null, "Error: " + ex.getClass().getName(), "Error", JOptionPane.ERROR_MESSAGE);
}
}
private void decrypt() throws Exception
{
File encrypted = new File(ENCRYPTED);
File plaintext = new File(PLAINTEXT);
int encryptedSize = (int)encrypted.length();
BufferedInputStream bufferedInputStream = new BufferedInputStream(new FileInputStream(encrypted));
BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(new FileOutputStream(plaintext));
//Read in encrypted data
byte[] input = new byte[encryptedSize];
Path path = Paths.get(ENCRYPTED);
input = Files.readAllBytes(path);
if(input.length >= (SALT_SIZE*2 + MAC_SIZE))
{
byte[] cryptSalt = Arrays.copyOfRange(input, START, SALT_SIZE);
byte[] macSalt = Arrays.copyOfRange(input, SALT_SIZE, SALT_SIZE*2);
byte[] macBytes = Arrays.copyOfRange(input, SALT_SIZE*2, (SALT_SIZE*2 + MAC_SIZE));
byte[] cryptBytes = Arrays.copyOfRange(input, (SALT_SIZE*2 + MAC_SIZE), input.length);
//This generates the same MAC key from encryption.
//Before, the KeyGenerator created a new random key
//meaning the derived and computed MAC keys were never the same
byte[] macKeyBytes = PBEKeyFactory.getKey(PASSWORD, macSalt, ITERATIONS, KEY_LENGTH);
SecretKeySpec macKey = new SecretKeySpec(macKeyBytes, MAC_ALGORITHM);
Mac mac = Mac.getInstance(MAC_ALGORITHM);
mac.init(macKey);
byte[] compMacBytes = mac.doFinal(cryptBytes);
//Check if computed and derived MAC's are the same
if(Arrays.equals(macBytes, compMacBytes))
{
//Creates same key from encryption
byte[] cryptKeyBytes = PBEKeyFactory.getKey(PASSWORD, cryptSalt, ITERATIONS, KEY_LENGTH);
SecretKeySpec cryptKey = new SecretKeySpec(cryptKeyBytes, ALGORITHM);
//Creates cipher and reads decrypted data to array
Cipher cipher = Cipher.getInstance(TRANSFORMATION);
cipher.init(Cipher.DECRYPT_MODE, cryptKey, new IvParameterSpec(new byte[16]));
byte[] output = cipher.doFinal(cryptBytes);
bufferedInputStream.close();
bufferedOutputStream.write(output);
bufferedOutputStream.flush();
bufferedOutputStream.close();
}
}
}
}
//This class has only one method, getKey(), which returns a byte array
//of a SecretKey of the corresponding parameters
public class PBEKeyFactory
{
private static final String KEY_DERIVATION_FUNCTION = "PBKDF2WithHmacSHA1";
public static byte[] getKey(String password, byte[] salt, int iterations, int length) throws Exception
{
KeySpec keySpec = new PBEKeySpec(password.toCharArray(), salt, iterations, length);
SecretKeyFactory factory = SecretKeyFactory.getInstance(KEY_DERIVATION_FUNCTION);
return factory.generateSecret(keySpec).getEncoded();
}
}