I first generated IV using this method:
public static String generateRandomIV() {
SecureRandom ranGen = new SecureRandom();
byte[] aesKey = new byte[16];
ranGen.nextBytes(aesKey);
StringBuffer result = new StringBuffer();
for (byte b : aesKey) {
result.append(String.format("%02x", b));
}
if (16 > result.toString().length()) {
return result.toString();
} else {
return result.toString().substring(0, 16);
}
}
And then tried to decrypt a String which was encrypted using IV generated by above method:
private String decrypt(String _inputText, String _encryptionKey,
String _initVector) throws Exception {
String _out = "";
int len = _encryptionKey.getBytes("UTF-8").length;
if (_encryptionKey.getBytes("UTF-8").length >= _key.length) {
len = _key.length;
int ivlen = _initVector.getBytes("UTF-8").length;
if (_initVector.getBytes("UTF-8").length > _iv.length)
ivlen = _iv.length;
System.arraycopy(_encryptionKey.getBytes("UTF-8"), 0, _key, 0, len);
System.arraycopy(_initVector.getBytes("UTF-8"), 0, _iv, 0, ivlen);
SecretKeySpec keySpec = new SecretKeySpec(_key, "AES");
IvParameterSpec ivSpec = new IvParameterSpec(_iv);
//Decryption starts
_cx.init(Cipher.DECRYPT_MODE, keySpec);
byte[] decodeValue = Base64.decode(_inputText.getBytes(), Base64.DEFAULT);
Following Exception is coming at last line of above code snippet:
java.lang.RuntimeException: java.security.InvalidAlgorithmParameterException: IV must be specified in CBC mode
I don't see any use of your IV. Try the following cipher initialization:
_cx.init(Cipher.DECRYPT_MODE, keySpec, ivSpec);
I am trying to decrypt a file using the following code:
Uri targURI = Uri.parse("content://xxxx/yyy.txt");
try {
InputStream content = getContentResolver().openInputStream(targURI);
BufferedReader reader1 = new BufferedReader(new InputStreamReader(content));
String line1;
String text = "";
while ((line1 = reader1.readLine()) != null) {
text+=line1;
}
Log.i("FILE ENCRYPTED", text);
String DECRYPTED = "";
DECRYPTED = decrypt(text);
Log.i("FILE DECRYPTED:", DECRYPTED);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
public String decrypt(String paramString) throws Exception {
String md5_pin1 = "";
String md5_pin = MD5(md5_pin1);
SecretKeySpec keySpec = new SecretKeySpec(md5_pin.getBytes(), "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, keySpec);
byte[] paramString1 = Base64.decode(paramString.getBytes(), 0);
byte[] paramstring2 = cipher.doFinal(paramString1);
String decoded = new String(paramstring2, "UTF-8");
return decoded;
}
#NonNull
public static String MD5(String paramString) throws Exception {
MessageDigest digest = java.security.MessageDigest.getInstance("MD5");
digest.update(paramString.getBytes());
byte messageDigest[] = digest.digest();
StringBuffer hexString = new StringBuffer();
int i=0;
while( i < messageDigest.length) {
String str = Integer.toHexString( messageDigest[i] & 0xFF );
if (str.length() == 1) {
hexString.append("0");
}
hexString.append(str);
i += 1;
}
return hexString.toString();
}
as it is showed the file is accessed using a content provider, and stored in a String variable, and actually the correct string value is stored (encrypted data).
The way to decrypt it is to get a seed (empty space in this case), and then use MD5 digest, then use that value to encrypt/decrypt the cleartext.
However whenever the code reaches: String decoded = new String(paramstring2, "UTF-8"); the error message: pad block corrupted is thrown.
Any ideas what I am doing wrong?
Avoid using default padding for cipher as it may be different on different environment.
Try the following code:
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
Also use the same padding for encrypting the file.
You can use the following methods:
private static byte[] encrypt(byte[] data, byte[] key) throws Exception {
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
byte[] iv = new byte[cipher.getBlockSize()];
IvParameterSpec ivParams = new IvParameterSpec(iv);
cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(key, "AES"), ivParams);
return cipher.doFinal(data);
}
private static byte[] decrypt(byte[] encrypted, byte[] key) throws Exception {
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
byte[] ivByte = new byte[cipher.getBlockSize()];
IvParameterSpec ivParamsSpec = new IvParameterSpec(ivByte);
cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(key, "AES"), ivParamsSpec);
return cipher.doFinal(encrypted);
}
This was not a problem related to coding.
Please disregard this question
I am trying to write a program to encrypt and decrypt files using java, but I get an error on the decrypt function:
Caused by: javax.crypto.BadPaddingException: Given final block not properly padded
here is the code for the encryption:
public static void EncryptFile(String inFile, PublicKey rsaPublicKey) {
AesManaged aesManaged = new AesManaged();
try {
aesManaged.keySize = 256;
aesManaged.blockSize = 128;
aesManaged.mode = "AES/CBC/PKCS5Padding";
byte[] key = generateKey(aesManaged.keySize);
byte[] keyEncrypted = encryptKey(key, rsaPublicKey);
byte[] LenK = new byte[4];
byte[] LenIV = new byte[4];
int lKey = keyEncrypted.length;
LenK = BitConverter.GetBytes(lKey);
int lIV = aesManaged.IV().length;
LenIV = BitConverter.GetBytes(lIV);
// Write the following to the FileStream
// for the encrypted file (outFs):
// - length of the key
// - length of the IV
// - ecrypted key
// - the IV
// - the encrypted cipher content
String outFile = "test.lamar";
ByteArrayOutputStream outFs = new ByteArrayOutputStream();
outFs.write(LenK);
outFs.write(LenIV);
outFs.write(keyEncrypted);
byte[] i = aesManaged.IV();
outFs.write(i);
IvParameterSpec ivspec = new IvParameterSpec(aesManaged.IV());
SecretKeySpec secretKeySpec = new SecretKeySpec(key, "AES");
Cipher cipher = Cipher.getInstance(aesManaged.mode);
cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, ivspec);
FileInputStream fileIn = new FileInputStream(inFile);
CipherOutputStream cipherOut = new CipherOutputStream(outFs, cipher);
int blockSiseByte = aesManaged.blockSize / 8;
byte[] data = new byte[blockSiseByte];
int count;
// Read in the data from the file and encrypt it
while ((count = fileIn.read(data, 0, blockSiseByte)) != -1) {
cipherOut.write(data, 0, count);
}
try (OutputStream outputStream = new FileOutputStream(outFile)) {
outFs.writeTo(outputStream);
}
// Close the encrypted file
fileIn.close();
outFs.close();
cipherOut.close();
} catch (Exception e) {
e.printStackTrace();
}
}
and the code for the decryption:
public static void DecryptFile(String inFile, String outFile,
PrivateKey rsaPrivateKey) {
FileOutputStream outFs = null;
try {
// Create instance of AesManaged for
// symetric decryption of the data.
AesManaged aesManaged = new AesManaged();
{
aesManaged.keySize = 256;
aesManaged.blockSize = 128;
aesManaged.mode = "AES/CBC/PKCS5Padding";
// Create byte arrays to get the length of
// the encrypted key and IV.
// These values were stored as 4 bytes each
// at the beginning of the encrypted package.
byte[] LenK = new byte[4];
byte[] LenIV = new byte[4];
// Use FileStream objects to read the encrypted
// file (inFs) and save the decrypted file (outFs).
{
byte[] fileBytes = FileUtils.readFileToByteArray(new File(inFile));
ByteArrayInputStream inFs = new ByteArrayInputStream(
fileBytes);
;
for (int i = 0; i < LenK.length; i++) {
LenK[i] = (byte) inFs.read();
}
for(int i = 0; i< LenIV.length;i++){
LenIV[i] = (byte)inFs.read();
}
// Convert the lengths to integer values.
int lenK = BitConverter.ToInt32(LenK, 0);
int lenIV = BitConverter.ToInt32(LenIV, 0);
//int startC = lenK + lenIV + 8;
//int lenC = (int) fileBytes.length - startC;
// Create the byte arrays for
// the encrypted AesManaged key,
// the IV, and the cipher text.
byte[] KeyEncrypted = new byte[lenK];
byte[] IV = new byte[lenIV];
// Extract the key and IV
for(int i = 0;i<lenK;i++){
KeyEncrypted[i] = (byte)inFs.read();
}
for(int i =0;i<lenIV;i++){
IV[i] = (byte)inFs.read();
}
// to decrypt the AesManaged key.
byte[] KeyDecrypted = decryptKey(KeyEncrypted,rsaPrivateKey);
Cipher transform = Cipher.getInstance("AES/CBC/PKCS5Padding");
IvParameterSpec ivspec = new IvParameterSpec(IV);
SecretKeySpec secretKeySpec = new SecretKeySpec(KeyDecrypted, "AES");
transform.init(Cipher.DECRYPT_MODE, secretKeySpec, ivspec);
// Decrypt the key.
outFs = new FileOutputStream(outFile);
int count = 0;
int offset = 0;
int blockSizeBytes = aesManaged.blockSize / 8;
byte[] data = new byte[blockSizeBytes];
CipherInputStream cipherIn = new CipherInputStream(
inFs, transform);
while ((count = cipherIn.read(data, 0, blockSizeBytes)) != -1) {
outFs.write(data, 0, count);
}
inFs.close();
cipherIn.close();
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
The error occurred at the line:while ((count = cipherIn.read(data, 0, blockSizeBytes)) != -1) after many iterations.
What am I missing here?
I'm getting a Triple DES decrypted string from the clients server, which has been coded in c# (see below):
using System.IO;
using System;
using System.Security.Cryptography;
using System.Collections;
using System.Text;
class Program
{
static void Main()
{
Console.WriteLine("Hello, World!");
var encryption = TripleDESEncrypt("12345678901234", "C9AF269DF8A78A06D1216BFFF8F0536A");
Console.WriteLine(encryption);
}
public static string TripleDESEncrypt(string strClearText, string strKey)
{
byte[] bytClearText;
byte[] bytClearTextChunk = new byte[8];
byte[] bytEncryptedChunk = new byte[8];
int BytesCount = 0;
int nArrayPosition = 0;
string strEncryptedChar;
string strEncryptedText = "";
ArrayList Input = new ArrayList();
ArrayList Output = new ArrayList();
TripleDESCryptoServiceProvider tdes = (TripleDESCryptoServiceProvider)TripleDESCryptoServiceProvider.Create();
tdes.Key = HexToByteArray(strKey);
tdes.Mode = CipherMode.ECB;
ICryptoTransform tdesEncrypt = tdes.CreateEncryptor();
bytClearText = ASCIIEncoding.ASCII.GetBytes(strClearText);
BytesCount = bytClearText.Length;
for (int i = 0; i < BytesCount; i++)
{
if (nArrayPosition == 8)
{
Input.Add(bytClearTextChunk);
bytClearTextChunk = new byte[8];
nArrayPosition = 0;
}
bytClearTextChunk[nArrayPosition] = bytClearText[i];
nArrayPosition++;
}
if (nArrayPosition != 0)
Input.Add(bytClearTextChunk);
foreach (byte[] Cbyte in Input)
{
tdesEncrypt.TransformBlock(Cbyte, 0, 8, bytEncryptedChunk, 0);
Output.Add(bytEncryptedChunk);
bytEncryptedChunk = null;
bytEncryptedChunk = new byte[8];
}
foreach (byte[] Cbyte in Output)
{
foreach (byte BByte in Cbyte)
{
strEncryptedChar = BByte.ToString("X");
strEncryptedChar = strEncryptedChar.PadLeft(2, Convert.ToChar("0"));
strEncryptedText += strEncryptedChar;
}
}
return strEncryptedText;
}
private static byte[] HexToByteArray(string strHex)
{
byte[] bytArray = new byte[strHex.Length / 2];
int positionCount = 0;
for (int i = 0; i < strHex.Length; i += 2)
{
bytArray[positionCount] = byte.Parse(strHex.Substring(i, 2), System.Globalization.NumberStyles.HexNumber);
positionCount++;
}
return bytArray;
}
}
I am then trying to Triple DES decrypt it in Java using this key: C9AF269DF8A78A06D1216BFFF8F0536A
Here is my code to decrypt:
public String DesDecryptPin(String pin, String encryptKey) throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidKeyException, BadPaddingException, IllegalBlockSizeException, UnsupportedEncodingException {
String UNICODE_FORMAT = "UTF8";
String decryptedPinText = null;
byte[] hexConvert = hexStringtoByteArray(encryptKey);
SecretKey desKey = null;
byte[] tdesKey = new byte[24];
System.arraycopy(hexConvert, 0, tdesKey, 0,16);
System.arraycopy(hexConvert, 0, tdesKey, 0,8);
byte[] encryptKeyBytes = encryptKey.getBytes(UNICODE_FORMAT);
KeySpec desKeySpec = new DESedeKeySpec(tdesKey);
Cipher desCipher;
SecretKeyFactory skf = SecretKeyFactory.getInstance("DESede");
desCipher = Cipher.getInstance("DESede/ECB/NoPadding");
try {
desKey = skf.generateSecret(desKeySpec);
} catch (InvalidKeySpecException e) {
e.printStackTrace();
}
desCipher.init(Cipher.DECRYPT_MODE, desKey);
byte[] decryptPin = desCipher.doFinal(pin.getBytes());
decryptedPinText = new String(decryptPin, "UTF-8");
return decryptedPinText;
}
The sample out put would be input/output would be "12345678901234" however, I'm getting jumbled nonsense returned e.g ��0�8��/0��
So something is getting lost between c# and java...
This is a follow on from a previous question I asked here
I'd appreciate help on this
changes to code
public String DesDecryptPin(String pin, String encryptKey) throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidKeyException, BadPaddingException, IllegalBlockSizeException, UnsupportedEncodingException {
String UNICODE_FORMAT = "UTF8";
String decryptedPinText = null;
SecretKey desKey = null;
byte[] encryptKeyBytes = EncodingUtils.getAsciiBytes(encryptKey);
byte[] tdesKey = new byte[24];
System.arraycopy(encryptKeyBytes, 8, tdesKey, 0, 8);
System.arraycopy(encryptKeyBytes, 0, tdesKey, 8, 16);
KeySpec desKeySpec = new DESedeKeySpec(tdesKey);
Cipher desCipher;
SecretKeyFactory skf = SecretKeyFactory.getInstance("DESede");
desCipher = Cipher.getInstance("DESede/ECB/NoPadding");
try {
desKey = skf.generateSecret(desKeySpec);
} catch (InvalidKeySpecException e) {
e.printStackTrace();
}
desCipher.init(Cipher.DECRYPT_MODE, desKey);
byte[] decryptPin = desCipher.doFinal(EncodingUtils.getAsciiBytes(pin));
decryptedPinText = new String(decryptPin, "ASCII");
return decryptedPinText;
}
c# decrypt code
using System.IO;
using System;
using System.Security.Cryptography;
using System.Collections;
using System.Text;
class Program
{
static void Main()
{
Console.WriteLine("Hello, World!");
var encryption = TripleDESDecrypt("1D30CC3DE1641D7F5E821D13FC1200C3", "C9AF269DF8A78A06D1216BFFF8F0536A");
Console.WriteLine(encryption);
}
public static string TripleDESDecrypt(string strEncryptedText, string strKey)
{
string errorMessage = "";
int errorCode = 0;
string strDecryptedText = "";
try
{
byte[] bytEncryptedChunk = new byte[8];
byte[] bytClearTextChunk = new byte[8];
byte[] _bytesEmpty = new byte[8];
int BytesCount = 0;
int positionCount = 0;
ArrayList Input = new ArrayList();
ArrayList Output = new ArrayList();
TripleDESCryptoServiceProvider tdes = (TripleDESCryptoServiceProvider)TripleDESCryptoServiceProvider.Create();
tdes.Key = HexToByteArray(strKey);
tdes.Mode = CipherMode.ECB;
ICryptoTransform tdesDecrypt = tdes.CreateDecryptor();
BytesCount = strEncryptedText.Length;
for (int i = 0; i < BytesCount; i += 2)
{
if (positionCount == 8)
{
positionCount = 0;
Input.Add(bytEncryptedChunk);
bytEncryptedChunk = new byte[8];
}
bytEncryptedChunk[positionCount] = byte.Parse(strEncryptedText.Substring(i, 2), System.Globalization.NumberStyles.HexNumber);
positionCount++;
}
if (positionCount != 0)
{
Input.Add(bytEncryptedChunk);
}
foreach (byte[] Cbyte in Input)
{
tdesDecrypt.TransformBlock(Cbyte, 0, 8, _bytesEmpty, 0);
tdesDecrypt.TransformBlock(Cbyte, 0, 8, bytClearTextChunk, 0);
Output.Add(bytClearTextChunk);
bytClearTextChunk = null;
bytClearTextChunk = new byte[8];
}
foreach (byte[] Cbyte in Output)
{
strDecryptedText += ASCIIEncoding.ASCII.GetString(Cbyte);
}
}
catch (Exception ex)
{
errorCode = 1;
errorMessage = ex.Message;
}
Console.WriteLine(strDecryptedText);
return strDecryptedText;
}
private static byte[] HexToByteArray(string strHex)
{
byte[] bytArray = new byte[strHex.Length / 2];
int positionCount = 0;
for (int i = 0; i < strHex.Length; i += 2)
{
bytArray[positionCount] = byte.Parse(strHex.Substring(i, 2), System.Globalization.NumberStyles.HexNumber);
positionCount++;
}
return bytArray;
}
}
This returns what is inputting into the encrypt 12345678901234
In your C# code, you use ASCII:
bytClearText = ASCIIEncoding.ASCII.GetBytes(strClearText);
While in Java you use UNICODE:
byte[] encryptKeyBytes = encryptKey.getBytes(UNICODE_FORMAT);
Try to change your C# to use UNICODE or your java code to use ASCII.
Also, since the C# is padding the output :
strEncryptedChar = strEncryptedChar.PadLeft(2, Convert.ToChar("0"));
You probably must check to remove all the '00' in the crypted string, so 1D30CC3DE1641D7F5E821D13FC1200C3 will become 1D30CC3DE1641D7F5E821D13FC12C3
(you must check if it's in the boundaries of an hex expression: 1C01A1 should probably be modified since it got a padding on the second Hexa 1C 01 A1: 1C1A1
acording https://stackoverflow.com/a/33768305/1140304 you can use
unicode instead of UTF-8 in java code
encrypt in c# :
public static string Encrypt2(string clearText,string key)
{
try
{
string encryptedText = "";
MD5 md5 = new MD5CryptoServiceProvider();
TripleDES des = new TripleDESCryptoServiceProvider();
des.KeySize = 128;
des.Mode = CipherMode.CBC;
des.Padding = PaddingMode.PKCS7;
byte[] md5Bytes = md5.ComputeHash(Encoding.Unicode.GetBytes(key));
byte[] ivBytes = new byte[8];
des.Key = md5Bytes;
des.IV = ivBytes;
byte[] clearBytes = Encoding.Unicode.GetBytes(clearText);
ICryptoTransform ct = des.CreateEncryptor();
using (MemoryStream ms = new MemoryStream())
{
using (CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write))
{
cs.Write(clearBytes, 0, clearBytes.Length);
cs.Close();
}
encryptedText = Convert.ToBase64String(ms.ToArray());
}
return encryptedText;
}
catch (Exception exception)
{
return "";
}
}
for decode in c# you can use:
public static string Decrypt2(string cipher,string key)
{
try
{
byte[] clearBytes = Convert.FromBase64String(cipher);
MD5 md5 = new MD5CryptoServiceProvider();
byte[] md5Bytes = md5.ComputeHash(Encoding.Unicode.GetBytes(key));
string encryptedText = "";
TripleDES des = new TripleDESCryptoServiceProvider();
des.KeySize = 128;
des.Mode = CipherMode.CBC;
des.Padding = PaddingMode.PKCS7;
byte[] ivBytes = new byte[8];
des.Key = md5Bytes;
des.IV = ivBytes;
ICryptoTransform ct = des.CreateDecryptor();
byte[] resultArray = ct.TransformFinalBlock(clearBytes, 0, clearBytes.Length);
encryptedText = Encoding.Unicode.GetString(resultArray);
return encryptedText;
}
catch (Exception exception)
{
return "";
}
}
now, for encrypt in java you can use :
private String _encrypt2(String clearText,String key )
{
try
{
/**
* create md5
*/
MessageDigest md = MessageDigest.getInstance("md5");
byte[] digestOfPassword = md.digest(key.getBytes("UTF-16LE"));
byte[] keyBytes = Arrays.copyOf(digestOfPassword, 24);
for (int j = 0, k = 16; j < 8; )
{
keyBytes[k++] = keyBytes[j++];
}
SecretKey secretKey = new SecretKeySpec(keyBytes, 0, 24, "DESede");
IvParameterSpec iv = new IvParameterSpec(new byte[8]);
Cipher cipher = Cipher.getInstance("DESede/CBC/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, secretKey, iv);
byte[] plainTextBytes = clearText.getBytes("UTF-16LE");
byte[] cipherText = cipher.doFinal(plainTextBytes);
String output = Base64.encodeToString(cipherText,Base64.DEFAULT);
return output;
}
catch (Exception ex) {}
return "";
}
and for decrypt in java :
private String _decrypt2(String encryptText,String key)
{
MessageDigest md = null;
byte[] digestOfPassword = null;
try
{
byte[] message = Base64.decode(encryptText.getBytes("UTF-16LE"), Base64.DEFAULT);
/**
* make md5
*/
md = MessageDigest.getInstance("md5");
digestOfPassword = md.digest(key.getBytes("UTF-16LE"));
byte[] keyBytes = Arrays.copyOf(digestOfPassword, 24);
for (int j = 0, k = 16; j < 8; )
{
keyBytes[k++] = keyBytes[j++];
}
SecretKey secretKey = new SecretKeySpec(keyBytes, 0, 24, "DESede");
IvParameterSpec iv = new IvParameterSpec(new byte[8]);
Cipher cipher = Cipher.getInstance("DESede/CBC/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE, secretKey, iv);
byte[] cipherText = cipher.doFinal(message);
return new String(cipherText, "UTF-16LE");
}
catch (NoSuchAlgorithmException e)
{
e.printStackTrace();
}
catch (UnsupportedEncodingException e)
{
e.printStackTrace();
}
catch (InvalidKeyException e)
{
e.printStackTrace();
}
catch (InvalidAlgorithmParameterException e)
{
e.printStackTrace();
}
catch (NoSuchPaddingException e)
{
e.printStackTrace();
}
catch (BadPaddingException e)
{
e.printStackTrace();
}
catch (IllegalBlockSizeException e)
{
e.printStackTrace();
}
return "";
}
If someone find himself/herself in the same problem like I did, here is a java implementation (android) of the same .NET decrypt function:
public static byte[] byteArrayConcat(byte[] array1, byte[] array2) {
byte[] result = new byte[array1.length + array2.length];
System.arraycopy(array1, 0, result, 0, array1.length);
System.arraycopy(array2, 0, result, array1.length, array2.length);
return result;
}
private byte[] fGPKeyTo3DESKey(byte[] GPKey) {
byte[] _3DESKey = new byte[24];
byte[] tmp = new byte[8];
arraycopy(GPKey, 0, tmp, 0, 8);
_3DESKey = DaPlugUtils.byteArrayConcat(GPKey, tmp);
return _3DESKey;
}
private static byte[] hexStringtoByteArray(String hex) {
int len = hex.length();
byte[] data = new byte[len / 2];
for (int i = 0; i < len; i += 2) {
data[i / 2] = (byte) ((Character.digit(hex.charAt(i), 16) << 4) + Character.digit(hex.charAt(i + 1), 16));
}
return data;
}
public String desDecryptPin(String pin, String encryptKey) throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidKeyException, BadPaddingException, IllegalBlockSizeException, InvalidKeySpecException {
int bytesCount = 0;
int positionCount = 0;
byte[] bytEncryptedChunk = new byte[8];
ArrayList<byte[]> Input = new ArrayList();
bytesCount = pin.length();
for (int i = 0; i < bytesCount; i += 2) {
if (positionCount == 8) {
positionCount = 0;
Input.add(bytEncryptedChunk);
bytEncryptedChunk = new byte[8];
}
bytEncryptedChunk[positionCount] = (byte) (Integer.parseInt(pin.substring(i, i + 2), 16));
positionCount++;
}
if (positionCount != 0) {
Input.add(bytEncryptedChunk);
}
byte[] _3DESKey = fGPKeyTo3DESKey(hexStringtoByteArray(encryptKey));
DESedeKeySpec keySpec = new DESedeKeySpec(_3DESKey);
SecretKey k = SecretKeyFactory.getInstance("DESede").generateSecret(keySpec);
Cipher cipher = Cipher.getInstance("DESede/ECB/NoPadding");
cipher.init(Cipher.DECRYPT_MODE, k);
String res = "";
for (byte[] bs : Input) {
byte[] decryptPin = cipher.doFinal(bs);
String a = new String(decryptPin, StandardCharsets.US_ASCII);
res += a;
}
return res.trim();
}
I wrote 2 functions in Java to encrypt and decrypt the message. I chose AES/CBC/PKCS7Padding as parameter. while encryption, my function can't add the right padding(as PKCS7Padding, it shouldn't add 0 to pad my message), so while decryption i can't remove the 0 at the end of the message.
with code, my problem will be more clair
public static byte[] encryptStringToData(String message, String key){
// transform the message from string to bytes
byte[] array_to_encrypt, bkey;
try {
array_to_encrypt = message.getBytes("UTF8");
bkey = key.getBytes("UTF8");
} catch (UnsupportedEncodingException e1) {
array_to_encrypt = null;
bkey = null;
return null;
}
bkey = Arrays.copyOf(bkey, 32);
BlockCipher engine = new AESEngine();
engine.init(true, new KeyParameter(bkey, 0, 32));
PKCS7Padding pad = new PKCS7Padding() ;
BufferedBlockCipher c = new PaddedBufferedBlockCipher(new CBCBlockCipher(engine),pad);
c.init(true, new ParametersWithIV(new KeyParameter(bkey), new byte[16]));
byte[] encrypted_array = new byte[c.getOutputSize(array_to_encrypt.length)];
int outputLen = c.processBytes(array_to_encrypt, 0, array_to_encrypt.length, encrypted_array, 0);
try
{
c.doFinal(encrypted_array, outputLen);
}
catch (CryptoException ce)
{
System.err.println(ce);
System.exit(1);
}
return encrypted_array;
}
public static String decryptDataToString(byte[] message, String key){
Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
String decrypted ="";
try {
byte[] keyBytes = key.getBytes("UTF8");
BlockCipher engine = new AESEngine();
BufferedBlockCipher c = new PaddedBufferedBlockCipher(new CBCBlockCipher(engine));
keyBytes = Arrays.copyOf(keyBytes, 32); // use only first 256 bit
c.init(false, new ParametersWithIV(new KeyParameter(keyBytes), new byte[16]));
byte[] cipherText = new byte[c.getOutputSize(message.length)];
int outputLen = c.processBytes(message, 0, message.length, cipherText, 0);
c.doFinal(cipherText, outputLen);
decrypted = new String(cipherText,"UTF8");
}
catch (CryptoException ce)
{
System.err.println(ce);
System.exit(1);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
return decrypted;
}
result (hex output)
clair message :3132333435 size: 5
encrypted message:561dd9f43ec183fe351776a46276991c size: 16
decrypted message:31323334350000000000000000000000 size: 16
You should check How do I get started using BouncyCastle?
The code for removing extra bytes is:
if (outputLength == output.length) {
return output;
} else {
byte[] truncatedOutput = new byte[outputLength];
System.arraycopy(
output, 0,
truncatedOutput, 0,
outputLength
);
return truncatedOutput;
}
and in your code traslates to:
outputLen += c.doFinal(cipherText, outputLen);
if (outputLen == cipherText.length) {
decrypted = new String(cipherText,"UTF8");
} else {
byte[] truncatedOutput = new byte[outputLen];
System.arraycopy(
cipherText, 0,
truncatedOutput, 0,
outputLen
);
decrypted = new String(truncatedOutput,"UTF8");
}