Develop Reference

Triple Des codes returning cipher with different lengths

I have got this code from Server guys:
public string Encryption(string PlainText)
{
string key = "twelve_digit_key";
TripleDES des = CreateDES(key);
ICryptoTransform ct = des.CreateEncryptor();
byte[] input = Encoding.Unicode.GetBytes(PlainText);
byte[] buffer = ct.TransformFinalBlock(input, 0, input.Length);
return Convert.ToBase64String(buffer);
}
static TripleDES CreateDES(string key)
{
MD5 md5 = new MD5CryptoServiceProvider();
TripleDES des = new TripleDESCryptoServiceProvider();
des.Key = md5.ComputeHash(Encoding.Unicode.GetBytes(key));
des.IV = new byte[des.BlockSize / 8];
return des;
}
This is my code against above :
public String encryptDES(String message) throws Exception {
final MessageDigest md = MessageDigest.getInstance("md5");
final byte[] digestOfPassword = md.digest(getNativeKey3().getBytes("utf-8"));
final byte[] keyBytes = Arrays.copyOf(digestOfPassword, 24);
for (int j = 0, k = 16; j < 8; ) {
keyBytes[k++] = keyBytes[j++];
}
final SecretKey key = new SecretKeySpec(digestOfPassword, "DESede");
final IvParameterSpec iv = new IvParameterSpec(new byte[8]);
final Cipher cipher = Cipher.getInstance("DESede/CBC/PKCS7Padding");
cipher.init(Cipher.ENCRYPT_MODE, key, iv);
final byte[] plainTextBytes = message.getBytes("utf-8");
final byte[] cipherText = cipher.doFinal(plainTextBytes);
return Base64.encodeToString(cipherText, Base64.DEFAULT)
.replace("\n", "")
.replace("\r", "");
}
Problem :
First Code gives below result :
Encrypted Text for 121212 is VvRQkSUj5SQ69mGXsL+h6w==
But Second Code returns this :
Encrypted Text for 121212 is 2STVJSd1mnw=
Observations :
When I increase the plainttext to 10 digits I am getting 24 digit cipher text
Can any one help me in this:
Thanks in Advance

You've been fooled by the badly named Unicode class, which actually specifies UTF-16LE rather than UTF-8.
You can use StandardCharsets.UTF_16LE for specifying the encoding rather than the string; this saves you from one exception to handle.
If there are still issues with the length (test!) then you may have to deal with the Byte Order Mark or BOM - but I don't think so.

Encrypt and decrypt with hex string

I searched a lot but I haven't found a good solution how to solve this. I have an app which has to decrypt a long hex string with AES 256.
In order to test it, I created a test method which encrypts a long text into a hex and then convert it back and decrypt it.
If I run this method, I always get the following error: Given final block not properly padded. I receive this error in the decryption method.
The test method looks like so:
#Test
public void testEncAndDecRequestWithHexString() throws UnsupportedEncodingException {
CryptoHelper cryptoHelper = new CryptoHelper("AES256");
String paramStr = "ABCB28BCEE5947B8AECE3386871EC0DF&{D5CA99D2-506B-4864-8971-E87821D6B105}&7523429";
//encrypt the param string
byte[] paramByteEnc = cryptoHelper.encryptBytesToBytes(paramStr.getBytes("ASCII"), PARAM_KEY, PARAM_IV);
//convert it to hex
String encryptedHexStr = cryptoHelper.byteArrayToHexStr(paramByteEnc);
//convert it back to a byte array
byte[] encryptedHexBytes = cryptoHelper.hexStrToByteArray(encryptedHexStr);
// decrypt it
byte[] paramByteDecrypted = cryptoHelper.decryptBytesToBytes(encryptedHexBytes, encryptedHexBytes.length, PARAM_KEY, PARAM_IV);
String decryptedStr = new String(paramByteDecrypted);
assertEquals("ABCB28BCEE5947B8AECE3386871EC0DF&{D5CA99D2-506B-4864-8971-E87821D6B105}&7523429", decryptedStr);
}
The CryptHelper class has following methods:
#Override
public byte[] encryptBytesToBytes(byte[] plainData, byte[] key, byte[] iv) {
try {
initCipher(Cipher.ENCRYPT_MODE, key, iv);
return aesCipher.doFinal(plainData);
} catch (IllegalBlockSizeException | BadPaddingException e) {
log.severe(e.getMessage());
}
return null;
}
#Override
public byte[] decryptBytesToBytes(byte[] encryptedBytes, int length,
byte[] key, byte[] iv) {
try {
initCipher(Cipher.DECRYPT_MODE, key, iv);
return aesCipher.doFinal(encryptedBytes, 0, length);
} catch (IllegalBlockSizeException | BadPaddingException e) {
e.printStackTrace();
}
return null;
}
private void initCipher(int mode, byte[] keyBytes, byte[] ivBytes) {
try {
// create shared secret and init cipher mode
SecretKeySpec secretKeySpec = new SecretKeySpec(keyBytes, "AES");
aesCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
aesCipher.init(mode == Cipher.ENCRYPT_MODE ? Cipher.ENCRYPT_MODE : Cipher.DECRYPT_MODE, secretKeySpec, new IvParameterSpec(ivBytes));
} catch (InvalidAlgorithmParameterException | NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException e) {
e.printStackTrace();
}
}
public String byteArrayToHexStr(byte[] encrypted) {
StringBuilder hex = new StringBuilder();
for (byte b : encrypted) {
hex.append(String.format("%02X", b));
}
return new String(hex.toString());
}
public byte[] hexStrToByteArray(String hex) {
StringBuilder sb = new StringBuilder();
for (int i = 0; i < hex.length() - 1; i += 2) {
String output = hex.substring(i, (i + 2));
int decimal = Integer.parseInt(output, 16);
sb.append((char) decimal);
}
String temp = sb.toString();
return temp.getBytes();
}
I used the same key and initialization vector for the decryption process so the problem is not the wrong key or initialization vector. I am also sure that every function here is doing their job correctly. If you don't use the functions hexStrToByteArray() and byteArrayToHexStr() and just use the encrypted byte for decrypting, it works no problem. I think there is a encoding/decoding problem but I have no idea how to handle it in java. If I use getBytes("UTF-8") and new String(byte[], "UTF-8") I get an IllegalBlockSizeException.
I hope you can help me finding out if I am on the right way and what I did wrong.

This is a clear indication that you shouldn't write library functions if they have already been defined. Use a hex codec from Bouncy Castle, Guava or Apache codec instead (until Oracle finally sees the light and provides one in a java.util package).
If you do implement it yourself, please don't mistake characters for bytes:
public byte[] hexStrToByteArray(String hex) {
ByteArrayOutputStream baos = new ByteArrayOutputStream(hex.length() / 2);
for (int i = 0; i < hex.length(); i += 2) {
String output = hex.substring(i, i + 2);
int decimal = Integer.parseInt(output, 16);
baos.write(decimal);
}
return baos.toByteArray();
}

Different AES128 with zero padding encryption result between php and java

I have a different result between java and php method in doing AES128 with zero padding and no IV encryption.
Here PHP code :
<?php
$ptaDataString = "secretdata";
$ptaDataString = encryptData($ptaDataString);
$ptaDataString = base64_encode($ptaDataString);
function encryptData($input) {
$ptaKey = 'secret';
$iv = "\0";
$encrypted = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $ptaKey, $input, MCRYPT_MODE_CBC, $iv);
return $encrypted;
}
echo $ptaDataString;
?>
And here is java code:
public static String encrypt() throws Exception {
try {
String data = "secretdata";
String key = "secret0000000000";
String iv = "0000000000000000";
Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
int blockSize = cipher.getBlockSize();
byte[] dataBytes = data.getBytes();
int plaintextLength = dataBytes.length;
if (plaintextLength % blockSize != 0) {
plaintextLength = plaintextLength + (blockSize - (plaintextLength % blockSize));
}
byte[] plaintext = new byte[plaintextLength];
System.arraycopy(dataBytes, 0, plaintext, 0, dataBytes.length);
SecretKeySpec keyspec = new SecretKeySpec(key.getBytes(), "AES");
IvParameterSpec ivspec = new IvParameterSpec(iv.getBytes());
cipher.init(Cipher.ENCRYPT_MODE, keyspec, ivspec);
byte[] encrypted = cipher.doFinal(plaintext);
return new sun.misc.BASE64Encoder().encode(encrypted);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
php resulting : kjgE5p/3qrum6ghdjiVIoA==
Java resulting : zLKhVMksRRr1VHQigmPQ2Q==
Any help would be appreciated,
Thanks

In Java, a zero byte expressed as a string is "\0" not "0". If you correct your example as follows, the results match:
String data = "secretdata";
String key = "secret\0\0\0\0\0\0\0\0\0\0";
String iv = "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0";
In the case of the IV, it's probably just easier to write:
byte[] iv = new byte[<block size>];
In the final line of your code, you access sun.misc.BASE64Encoder(). Accessing anything that starts with sun.* is frowned upon, since these are internal classes. Consider instead using:
return DatatypeConverter.printBase64Binary(encrypted);

PSKC file decryption using java

I am new to encryption and decryption. I was given a PSKC file and asked for decryption. I was given the password for decryption. The PSKC file doenot have initialization vector value.
I wrote the code trying to decrypt it. But i am unsuccessful in achieving the outcome.
below is the PSKC file example
<?xml version="1.0"?>
<pskc:KeyContainer xmlns:ds="http://www.w3.org/2000/09/xmldsig#" xmlns:pkcs5="http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5v2-0#" xmlns:xenc="http://www.w3.org/2001/04/xmlenc#" xmlns:xenc11="http://www.w3.org/2009/xmlenc11#" xmlns:pskc="urn:ietf:params:xml:ns:keyprov:pskc">
<pskc:EncryptionKey>
<xenc11:DerivedKey xmlns:xenc="http://www.w3.org/2001/04/xmlenc#" xmlns:pkcs5="http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5v2-0#" xmlns:pskc="urn:ietf:params:xml:ns:keyprov:pskc" xmlns:ds="http://www.w3.org/2000/09/xmldsig#" xmlns:xenc11="http://www.w3.org/2009/xmlenc11#">
<xenc11:KeyDerivationMethod Algorithm="http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5v2-0#pbkdf2">
<pkcs5:PBKDF2-params xmlns:xenc="http://www.w3.org/2001/04/xmlenc#" xmlns:pskc="urn:ietf:params:xml:ns:keyprov:pskc" xmlns:xenc11="http://www.w3.org/2009/xmlenc11#" xmlns:ds="http://www.w3.org/2000/09/xmldsig#" xmlns:pkcs5="http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5v2-0#">
<Salt>
<Specified>EW0h0yUcDX72WU9UiKiCwDpXsJg=</Specified>
</Salt>
<IterationCount>128</IterationCount>
<KeyLength>16</KeyLength>
<PRF />
</pkcs5:PBKDF2-params>
</xenc11:KeyDerivationMethod>
<xenc:ReferenceList>
<xenc:DataReference URI="#ED" />
</xenc:ReferenceList>
<xenc11:MasterKeyName>Passphrase1</xenc11:MasterKeyName>
</xenc11:DerivedKey>
</pskc:EncryptionKey>
<pskc:MACMethod Algorithm="http://www.w3.org/2000/09/xmldsig#hmac-sha1">
<pskc:MACKey>
<xenc:EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#aes128-cbc" />
<xenc:CipherData>
<xenc:CipherValue>jq/NdikC7AZf0Z+HEL5NrCICV8XW+ttzl/8687hVGHceoyJAaFws+111plQH6Mlg</xenc:CipherValue>
</xenc:CipherData>
</pskc:MACKey>
</pskc:MACMethod>
<pskc:KeyPackage>
<pskc:DeviceInfo>
<pskc:Manufacturer>Gemalto</pskc:Manufacturer>
<pskc:SerialNo>GAKT000047A5</pskc:SerialNo>
</pskc:DeviceInfo>
<pskc:CryptoModuleInfo>
<pskc:Id>CM_ID_007</pskc:Id>
</pskc:CryptoModuleInfo>
<pskc:Key Id="GAKT000047A5" Algorithm="urn:ietf:params:xml:ns:keyprov:pskc:totp">
<pskc:Issuer>Issuer0</pskc:Issuer>
<pskc:AlgorithmParameters>
<pskc:ResponseFormat Encoding="DECIMAL" Length="6" />
</pskc:AlgorithmParameters>
<pskc:Data>
<pskc:Secret>
<pskc:EncryptedValue>
<xenc:EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#aes128-cbc" />
<xenc:CipherData>
<xenc:CipherValue>pM7VB/KomPjq2cKaxPr5cKT1tUZN5tGMI+u1XKJTG1la+ThraPpLKlL2plKk6vQE</xenc:CipherValue>
</xenc:CipherData>
</pskc:EncryptedValue>
<pskc:ValueMAC>lbu+9OcLArnj6mS7KYOKDa4zRU0=</pskc:ValueMAC>
</pskc:Secret>
<pskc:Time>
<pskc:PlainValue>0</pskc:PlainValue>
</pskc:Time>
<pskc:TimeInterval>
<pskc:PlainValue>30</pskc:PlainValue>
</pskc:TimeInterval>
</pskc:Data>
</pskc:Key>
</pskc:KeyPackage>
</pskc:KeyContainer>
below is the java code which i have written for decryption.
import java.security.NoSuchAlgorithmException;
import java.util.HashMap;
import javax.crypto.Cipher;
import javax.crypto.Mac;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import org.apache.commons.codec.binary.Base64;
import org.bouncycastle.crypto.generators.PKCS5S2ParametersGenerator;
import org.bouncycastle.crypto.params.KeyParameter;
import org.bouncycastle.crypto.params.ParametersWithIV;
import com.sun.org.apache.xerces.internal.impl.dv.util.HexBin;
public class test {
/**
* #param args
*/
public static void main(String[] args) {
test te = new test();
try {
te.decryptSeedValue();
} catch (Exception e) {
// TODO Auto-generated catch block
System.out.println(e.getMessage());
e.printStackTrace();
}
// TODO Auto-generated method stub
}
public static HashMap decryptSeedValue()throws Exception{
String password = "G?20R+I+3-/UcWIN";
String pbesalt ="EW0h0yUcDX72WU9UiKiCwDpXsJg=";
String iv = "aaaaaaaaaaaaaaaaaaaaaaaa";
int iteration = 128;
String value = "pM7VB/KomPjq2cKaxPr5cKT1tUZN5tGMI+u1XKJTG1la+ThraPpLKlL2plKk6vQE";
String valueDigest = "lbu+9OcLArnj6mS7KYOKDa4zRU0=";
byte[] cipherText =null;
//some parameters need to decode from Base64 to byte[]
byte[] data = base64Decode(value.getBytes());
//System.out.println("data(hex string) = " + HexBin.encode(data));//debug
byte[] salt = base64Decode(pbesalt.getBytes());
//System.out.println("salt(hex string) = " + HexBin.encode(salt));//debug
byte[] initVec = base64Decode(iv.getBytes());
//System.out.println("iv(hex string) = " + HexBin.encode(initVec));//debug
//perform PBE key generation and AES/CBC/PKCS5Padding decrpyption
HashMap hs = myFunction(data, password, initVec, salt, iteration);
String seedValue = (String)hs.get("DECRYPTED_SEED_VALUE");
byte[] temp = (byte[])hs.get("HASH_OUTPUT");
//System.out.println("hashed output(hex string) = " + HexBin.encode(temp));//debug
//perform Base64 Encode
byte[] out = base64Encode(temp);
String output = new String((out));
System.out.println("output = "+output);
System.out.println("valueD = "+valueDigest);
//System.out.println("hashed output(base64) = " + output);
//compare the result
if(output.equals(valueDigest)){
System.out.println("Hash verification successful for:-->" );
System.out.println("\n");
//hs.put("SEED_VALUE", HexBin.encode(temp));
hs.put("SEED_VALUE", seedValue);
return hs;
}
else{
System.out.println("Hash verification failed for :-->");
return null;
}
}
public static HashMap myFunction(byte[] data, String password, byte[] initVec,
byte[] salt, int iteration) throws Exception{
PKCS5S2ParametersGenerator generator = new PKCS5S2ParametersGenerator();
byte[] pBytes = password.getBytes();
generator.init(pBytes, salt, iteration);
int keysize = 128;//fixed at AES key of 16 bytes
int ivsize = initVec.length;
ParametersWithIV params = (ParametersWithIV) generator.generateDerivedParameters(keysize, ivsize);
KeyParameter keyParam = (KeyParameter) params.getParameters();
//System.out.println("derived key = " + HexBin.encode(keyParam.getKey()));
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
IvParameterSpec paramSpec = new IvParameterSpec(initVec);
SecretKeySpec key = new SecretKeySpec(keyParam.getKey(), "AES");
cipher.init(Cipher.DECRYPT_MODE, key, paramSpec);
//perform decryption
byte[] secret = cipher.doFinal(data);
//display the 20 bytes secret of the token
//System.out.println("token secret(hex string) = " + HexBin.encode(secret));
//perform HMAC-SHA-1
byte[] output = hmac_sha1(secret, keyParam.getKey());
HashMap hs = new HashMap();
hs.put("ENCRYPTION_KEY", HexBin.encode(keyParam.getKey()));
hs.put("HASH_OUTPUT", output);
hs.put("DECRYPTED_SEED_VALUE", HexBin.encode(secret));
return hs;
}
public static byte[] base64Encode(byte[] passwordBytes) throws NoSuchAlgorithmException {
Base64 base64 = new Base64();
byte[] hashBytes2 = base64.encode(passwordBytes);
return hashBytes2;
}
public static byte[] base64Decode(byte[] passwordBytes) throws NoSuchAlgorithmException {
Base64 base64 = new Base64();
byte[] hashBytes2 = base64.decode(passwordBytes);
return hashBytes2;
}
public static byte[] hmac_sha1(byte[] dataByte, byte[] keyByte) throws Exception{
Mac hmacSha1;
hmacSha1 = Mac.getInstance("HmacSHA1");
SecretKeySpec macKey = new SecretKeySpec(keyByte, "HmacSHA1");
hmacSha1.init(macKey);
byte[] result = hmacSha1.doFinal(dataByte);
return result;
}
/**
* Convert a byte array of 8 bit characters into a String.
*
* #param bytes the array containing the characters
* #param length the number of bytes to process
* #return a String representation of bytes
*/
private static String toString(
byte[] bytes,
int length)
{
char[] chars = new char[length];
for (int i = 0; i != chars.length; i++)
{
chars[i] = (char)(bytes[i] & 0xff);
}
return new String(chars);
}
}
it doesn't throw any exception, but it prints "Hash verification failed for" which is defined in my code when decryption fails.
Can some one please help me out.

As per the pskc standard http://www.rfc-editor.org/rfc/rfc6030.txt the IV is prepended to the ciphervalue. This is aes128, so it'll be the first 16 bytes once it's been base64 decoded.

Adding onto what bcharlton is describing; what you are not doing is check the hmac_sha1 for the encrypted data (which has the iv prepended in encrypted form), using the MACKey described in the xml document.
With AES-128 CBC the initialization vector is explicitly defined, and since there is no verification built into it, it uses HMAC for it.
So given your example the following will work:
public static HashMap decryptSeedValue() throws Exception
{
String password = "G?20R+I+3-/UcWIN";
String pbesalt = "EW0h0yUcDX72WU9UiKiCwDpXsJg=";
String iv = "aaaaaaaaaaaaaaaaaaaaaaaa";
int iteration = 128;
String value = "pM7VB/KomPjq2cKaxPr5cKT1tUZN5tGMI+u1XKJTG1la+ThraPpLKlL2plKk6vQE";
String valueDigest = "lbu+9OcLArnj6mS7KYOKDa4zRU0=";
//YOU NEED THIS GUY BELOW TO VERIFY
String macKey = "jq/NdikC7AZf0Z+HEL5NrCICV8XW+ttzl/8687hVGHceoyJAaFws+111plQH6Mlg";
byte[] cipherText = null;
//some parameters need to decode from Base64 to byte[]
byte[] data = base64Decode(value.getBytes());
//System.out.println("data(hex string) = " + HexBin.encode(data));//debug
byte[] salt = base64Decode(pbesalt.getBytes());
//System.out.println("salt(hex string) = " + HexBin.encode(salt));//debug
byte[] initVec = base64Decode(iv.getBytes());
//System.out.println("iv(hex string) = " + HexBin.encode(initVec));//debug
//perform PBE key generation and AES/CBC/PKCS5Padding decrpyption
HashMap hs = myFunction(data, password, base64Decode(macKey.getBytes()), salt, iteration);
String seedValue = (String) hs.get("DECRYPTED_SEED_VALUE");
byte[] temp = (byte[]) hs.get("HASH_OUTPUT");
//System.out.println("hashed output(hex string) = " + HexBin.encode(temp));//debug
//perform Base64 Encode
byte[] out = base64Encode(temp);
String output = new String((out));
System.out.println("output = " + output);
System.out.println("valueD = " + valueDigest);
//System.out.println("hashed output(base64) = " + output);
//compare the result
if (output.equals(valueDigest)) {
System.out.println("Hash verification successful for:-->");
System.out.println("\n");
//hs.put("SEED_VALUE", HexBin.encode(temp));
hs.put("SEED_VALUE", seedValue);
return hs;
} else {
System.out.println("Hash verification failed for :-->");
return null;
}
}
public static HashMap myFunction(byte[] data, String password, byte[] macData,
byte[] salt, int iteration) throws Exception
{
PKCS5S2ParametersGenerator generator = new PKCS5S2ParametersGenerator();
byte[] pBytes = password.getBytes();
generator.init(pBytes, salt, iteration);
byte[] iv = new byte[16];
int ivsize = iv.length;
byte[] encryptedData = new byte[data.length - ivsize];
System.arraycopy(data, 0, iv, 0, iv.length);
System.arraycopy(data, ivsize, encryptedData, 0, encryptedData.length);
byte[] maciv = new byte[16];
byte[] encryptedMac = new byte[macData.length - maciv.length];
System.arraycopy(macData, 0, maciv, 0, maciv.length);
System.arraycopy(macData, maciv.length, encryptedMac, 0, encryptedMac.length);
int keysize = 128;//fixed at AES key of 16 bytes
SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
KeySpec spec = new PBEKeySpec(password.toCharArray(), salt, iteration, keysize);
SecretKey tmp = factory.generateSecret(spec);
SecretKey key = new SecretKeySpec(tmp.getEncoded(), "AES");
Cipher dcipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
dcipher.init(Cipher.DECRYPT_MODE, key, new IvParameterSpec(iv));
byte[] decryptedData = dcipher.doFinal(encryptedData);
// decryptedData is your token value!
dcipher.init(Cipher.DECRYPT_MODE, key, new IvParameterSpec(maciv));
byte[] decryptedMac = dcipher.doFinal(encryptedMac);
//display the 20 bytes secret of the token
//System.out.println("token secret(hex string) = " + HexBin.encode(secret));
//perform HMAC-SHA-1
//Use the decrypted MAC key here for hashing!
byte[] output = hmac_sha1(data, decryptedMac);
HashMap hs = new HashMap();
hs.put("ENCRYPTION_KEY", password);
hs.put("HASH_OUTPUT", output);
hs.put("DECRYPTED_SEED_VALUE", HexBin.encode(decryptedData));
return hs;
}
Keep in mind that as https://www.rfc-editor.org/rfc/rfc6030#section-6.2 describes, a different iv can be used for the MAC and the token key.

javax.crypto.BadPaddingException

I am working on AES algorithm, and I have this exception which I couldn't solve.
javax.crypto.BadPaddingException: Given final block not properly padded
at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..)
at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..)
at com.sun.crypto.provider.AESCipher.engineDoFinal(DashoA13*..)
at javax.crypto.Cipher.doFinal(DashoA13*..)
the exception happens in the decryption part.
I initialize the key in a different place from where the decryption algorithm is
KeyGenerator kgen = KeyGenerator.getInstance("AES");//key generation for AES
kgen.init(128); // 192 and 256 bits may not be available
then I pass it with the cipher text which I read from file to the following method
public String decrypt(String message, SecretKey skey) {
byte[] raw = skey.getEncoded();
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
// Instantiate the cipher
Cipher cipher;
byte[] original = null;
try {
cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
System.out.println("Original string: "
+ message);
original = cipher.doFinal(message.trim().getBytes()); //here where I got the exception
String originalString = new String(original);
}
//catches
EDIT
here's the encryption method.
public String encrypt(String message, SecretKey skey) {
byte[] raw = skey.getEncoded();
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
// Instantiate the cipher
Cipher cipher;
byte[] encrypted = null;
try {
cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
encrypted = cipher.doFinal(message.getBytes());
System.out.println("raw is " + encrypted);
} catches
return asHex(encrypted);
}
and here's the asHex method
public static String asHex(byte buf[]) {
StringBuffer strbuf = new StringBuffer(buf.length * 2);
int i;
for (i = 0; i < buf.length; i++) {
if (((int) buf[i] & 0xff) < 0x10) {
strbuf.append("0");
}
strbuf.append(Long.toString((int) buf[i] & 0xff, 16));
}
return strbuf.toString();
}
Here's where I read the cipher text form the file
static public String readFile(String filePath) {
StringBuilder file = new StringBuilder();
String line = null;
try {
FileReader reader = new FileReader(filePath);
BufferedReader br = new BufferedReader(reader);
if (br != null) {
line = br.readLine();
while (line != null) {
file.append(line);
// System.out.println("line is " + line);
line = br.readLine();
}
}
br.close();
reader.close();
} catch (IOException ex) {
Logger.getLogger(FileManagement.class.getName()).log(Level.SEVERE, null, ex);
}
System.out.println("line is " + file.toString());
return String.valueOf(file);
}
can someone help?

Ok, so the problem is that you are converting the encrypted bytes to a hex string (using the asHex method) but are not converting the hex string back to a byte array correctly for decryption. You can't use getBytes.
You can use the following method to convert a hex string to a byte array:
public static byte[] fromHexString(String s) {
int len = s.length();
byte[] data = new byte[len / 2];
for (int i = 0; i < len; i += 2) {
data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4)
+ Character.digit(s.charAt(i+1), 16));
}
return data;
}
and then change your decrypt method to use:
original = cipher.doFinal(fromHexString(message));

I did have a Bad Padding Exception and have not been able to find on the internet a solution to my problem. Since I found it after some hard-working hours, I give it here.
My problem was, I was reading a file on my hard drive, and encrypting it through a buffer, always calling the doFinal() method instead of update() method. So when decrypting it, I had padding errors
input = new FileInputStream(file);
output = new FileOutputStream(newFile);
Cipher cipher = Cipher.getInstance("DES");
cipher.init(Cipher.ENCRYPT_MODE, mySecretKey);
byte[] buf = new byte[1024];
count = input.read(buf);
while (count >= 0) {
output.write(cipher.update(buf, 0, count)); // HERE I WAS DOING doFinal() method
count = input.read(buf);
}
output.write(cipher.doFinal()); // AND I DID NOT HAD THIS LINE BEFORE
output.flush();
And when decrypting, with the same method, but with a Cipher init with DECRYPT_MODE
input = new FileInputStream(file);
output = new FileOutputStream(newFile);
Cipher cipher = Cipher.getInstance("DES");
cipher.init(Cipher.DECRYPT_MODE, mySecretKey);
byte[] buf = new byte[1024];
count = input.read(buf);
while (count >= 0) {
output.write(cipher.update(buf, 0, count)); // HERE I WAS DOING doFinal() method
//AND HERE WAS THE BadPaddingExceotion -- the first pass in the while structure
count = input.read(buf);
}
output.write(cipher.doFinal()); // AND I DID NOT HAD THIS LINE BEFORE
output.flush();
With the code written, I no longer have any BadPaddingException.
I may precise that this exception only appears when the original clear file length (obtained through file.length()) is bigger than the buffer. Else, we do not need to pass several times in the while structure, and we can encrypt in one pass with a doFinal() call. That justify the random character of the exception following the size of the file you try to encrypt.
I hope you had a good reading!

I guess the expression message.trim().getBytes() does not return the same bytes which are generated when you encrypted the message. Specially the trim() method could delete the bytes which were added as padding in the encrypted message.
Verify that both the returned array of the doFinal() method during the encryption and the returned array of message.trim().getBytes():
got the same number of bytes (array length)
got the same bytes in the array

KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
kpg.initialize(512);
KeyPair rsaKeyPair = kpg.genKeyPair();
byte[] txt = "This is a secret message.".getBytes();
System.out.println("Original clear message: " + new String(txt));
// encrypt
Cipher cipher;
try
{
cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.ENCRYPT_MODE, rsaKeyPair.getPublic());
txt = cipher.doFinal(txt);
}
catch (Throwable e)
{
e.printStackTrace();
return;
}
System.out.println("Encrypted message: " + new String(txt));
// decrypt
try
{
cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.DECRYPT_MODE, rsaKeyPair.getPrivate());
txt = cipher.doFinal(txt);
}
catch (Throwable e)
{
e.printStackTrace();
return;
}
System.out.println("Decrypted message: " + new String(txt));

Here is a solution I was able to piece together using a jks keystore with RSA encryption
import javax.crypto.Cipher;
import javax.xml.bind.DatatypeConverter;
import java.security.Key;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.KeyStore;
import java.security.cert.Certificate;
public class Main {
public static void main(String[] args) {
byte[] txt = "This is a secret message for your own eyes only".getBytes();
byte[] encText;
try{
// Load the keystore
KeyStore ks = KeyStore.getInstance(KeyStore.getDefaultType());
char[] password = "keystorePassword".toCharArray();
java.io.FileInputStream fis = new java.io.FileInputStream("/path/to/keystore/myKeyStore.jks");
ks.load(fis, password);
fis.close();
Key rsakey = ks.getKey("mykeyalias", password);
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
// Encrypt
Certificate cert = ks.getCertificate("mykeyalias");
try
{
cipher.init(Cipher.ENCRYPT_MODE, cert.getPublicKey());
encText = cipher.doFinal(txt);
System.out.println(encText.toString());
}
catch (Throwable e)
{
e.printStackTrace();
return;
}
// Decrypt
cipher.init(Cipher.DECRYPT_MODE, rsakey);
String decrypted = new String(cipher.doFinal(encText));
System.out.println(decrypted);
} catch (Exception e) {
System.out.println("error" + e);
}
}