I want to decrypt and encrypt a string using chacha20
BouncyCastleProvider is using chacha20 technique. So I included it jar. and tried the code but not able to work.
PBE.java
public class PBE extends AppCompatActivity {
private static final String salt = "A long, but constant phrase that will be used each time as the salt.";
private static final int iterations = 2000;
private static final int keyLength = 256;
private static final SecureRandom random = new SecureRandom();
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.pbe);
try {
Security.insertProviderAt(new BouncyCastleProvider(), 1);
//Security.addProvider(new BouncyCastleProvider());
String passphrase = "The quick brown fox jumped over the lazy brown dog";
String plaintext = "Hello";
byte [] ciphertext = encrypt(passphrase, plaintext);
String recoveredPlaintext = decrypt(passphrase, ciphertext);
TextView decryptedTv = (TextView) findViewById(R.id.tv_decrypt);
decryptedTv.setText(recoveredPlaintext);
System.out.println(recoveredPlaintext);
}catch (Exception e){
e.printStackTrace();
}
}
private static byte [] encrypt(String passphrase, String plaintext) throws Exception {
SecretKey key = generateKey(passphrase);
Cipher cipher = Cipher.getInstance("AES/CTR/NOPADDING");//,new BouncyCastleProvider());
cipher.init(Cipher.ENCRYPT_MODE, key, generateIV(cipher), random);
return cipher.doFinal(plaintext.getBytes());
}
private static String decrypt(String passphrase, byte [] ciphertext) throws Exception {
SecretKey key = generateKey(passphrase);
Cipher cipher = Cipher.getInstance("AES/CTR/NOPADDING");// , new BouncyCastleProvider());
cipher.init(Cipher.DECRYPT_MODE, key, generateIV(cipher), random);
return new String(cipher.doFinal(ciphertext));
}
private static SecretKey generateKey(String passphrase) throws Exception {
PBEKeySpec keySpec = new PBEKeySpec(passphrase.toCharArray(), salt.getBytes(), iterations, keyLength);
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBEWITHSHA256AND256BITAES-CBC-BC");
return keyFactory.generateSecret(keySpec);
}
private static IvParameterSpec generateIV(Cipher cipher) throws Exception {
byte [] ivBytes = new byte[cipher.getBlockSize()];
random.nextBytes(ivBytes);
return new IvParameterSpec(ivBytes);
}
}
But it is not giving me proper result..
Edit and Updated Code
public class ChaCha20Encryptor implements Encryptor {
private final byte randomIvBytes[] = {0, 1, 2, 3, 4, 5, 6, 7};
static {
Security.addProvider(new BouncyCastleProvider());
}
@Override
public byte[] encrypt(byte[] data, byte[] randomKeyBytes) throws IOException, InvalidKeyException,
InvalidAlgorithmParameterException, InvalidCipherTextException {
ChaChaEngine cipher = new ChaChaEngine();
CipherParameters cp = new KeyParameter(getMyKey(randomKeyBytes));
cipher.init(true, new ParametersWithIV(cp , randomIvBytes));
//cipher.init(true, new ParametersWithIV(new KeyParameter(randomKeyBytes), randomIvBytes));
byte[] result = new byte[data.length];
cipher.processBytes(data, 0, data.length, result, 0);
return result;
}
@Override
public byte[] decrypt(byte[] data, byte[] randomKeyBytes)
throws InvalidKeyException, InvalidAlgorithmParameterException, IOException,
IllegalStateException, InvalidCipherTextException {
ChaChaEngine cipher = new ChaChaEngine();
CipherParameters cp = new KeyParameter(getMyKey(randomKeyBytes));
cipher.init(false, new ParametersWithIV(cp , randomIvBytes));
//cipher.init(false, new ParametersWithIV(new KeyParameter(randomKeyBytes), randomIvBytes));
byte[] result = new byte[data.length];
cipher.processBytes(data, 0, data.length, result, 0);
return result;
}
@Override
public int getKeyLength() {
return 32;
}
@Override
public String toString() {
return "ChaCha20()";
}
private static byte[] getMyKey(byte[] key){
try {
//byte[] key = encodekey.getBytes("UTF-8");
MessageDigest sha = MessageDigest.getInstance("SHA-1");
key = sha.digest(key);
key = Arrays.copyOf(key, 16); // use only first 128 bit
}
catch (NoSuchAlgorithmException e){
e.printStackTrace();
}
return key;
}
}
Now I have only problem decrypting. It shows an error that key must be 128 or 256 bits. What am I doing wrong.
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