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Store 3DES in String instead of CipherOutputStream

I'm trying to 3DES encrypt a string and store it in a properties file using this example. The problem I'm having is I do not want to write the contents of encrypt() and decrypt() to a file directly from the methods. I want to store it in a string for use later.
Below are the methods I'm using.
As you can see this uses CipherOutputStream and CipherInputStream. How would I read the result of both encrypt() and decrypt() into a String instead of writing it out to file?
public static void encrypt(SecretKey key, InputStream in, OutputStream out)
throws NoSuchAlgorithmException, InvalidKeyException,
NoSuchPaddingException, IOException {
// Create and initialize the encryption engine
Cipher cipher = Cipher.getInstance("DESede");
cipher.init(Cipher.ENCRYPT_MODE, key);
// Create a special output stream to do the work for us
CipherOutputStream cos = new CipherOutputStream(out, cipher);
// Read from the input and write to the encrypting output stream
byte[] buffer = new byte[2048];
int bytesRead;
while ((bytesRead = in.read(buffer)) != -1) {
cos.write(buffer, 0, bytesRead);
}
cos.close();
// For extra security, don't leave any plaintext hanging around memory.
java.util.Arrays.fill(buffer, (byte) 0);
}
/**
* Use the specified TripleDES key to decrypt bytes ready from the input
* stream and write them to the output stream. This method uses uses Cipher
* directly to show how it can be done without CipherInputStream and
* CipherOutputStream.
*/
public static void decrypt(SecretKey key, InputStream in, OutputStream out)
throws NoSuchAlgorithmException, InvalidKeyException, IOException,
IllegalBlockSizeException, NoSuchPaddingException,
BadPaddingException {
// Create and initialize the decryption engine
Cipher cipher = Cipher.getInstance("DESede");
cipher.init(Cipher.DECRYPT_MODE, key);
// Read bytes, decrypt, and write them out.
byte[] buffer = new byte[2048];
int bytesRead;
while ((bytesRead = in.read(buffer)) != -1) {
out.write(cipher.update(buffer, 0, bytesRead));
}
// Write out the final bunch of decrypted bytes
out.write(cipher.doFinal());
out.flush();
}

Simple: instead of passing a file output stream to these methods - pass a different kind of stream, for example a ByteArrayOutputStream.
Then you can extract the encrypted data as string from that stream.
And to ensure that the final result is reasonable encoded, you should actually use some kind of Base64OutputStream which in turn writes to that ByteArrayOutputStream.

AES File decrypting “given final block not properly padded”

I want to encrypt and then decrypt file use AES. I have read many topics about error "Given final block not properly padded". But i don't find solution for me.
Sorry about specify the language of my code, i don't know write language java
Here is my code :
Variables
// IV, secret, salt in the same time
private byte[] salt = { 'h', 'u', 'n', 'g', 'd', 'h', '9', '4' };
public byte[] iv;
public SecretKey secret;
createSecretKey
public void createSecretKey(String password){
SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
KeySpec spec = new PBEKeySpec(password.toCharArray(), salt, 65536, 256);
SecretKey tmp = factory.generateSecret(spec);
secret = new SecretKeySpec(tmp.getEncoded(), "AES");
}
method Encrypt
public void encrypt(String inputFile){
FileInputStream fis = new FileInputStream(inputFile);
// Save file: inputFile.enc
FileOutputStream fos = new FileOutputStream(inputFile + ".enc");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, secret);
AlgorithmParameters params = cipher.getParameters();
// Gen Initialization Vector
iv = (byte[]) ((IvParameterSpec) params
.getParameterSpec(IvParameterSpec.class)).getIV();
// read from file (plaint text) -----> save with .enc
int readByte;
byte[] buffer = new byte[1024];
while ((readByte = fis.read(buffer)) != -1) {
fos.write(cipher.doFinal(buffer), 0, readByte);
}
fis.close();
fos.flush();
fos.close();
}
method Decrypt
public void decrypt(String inputFile){
FileInputStream fis = new FileInputStream(inputFile);
// Save file: filename.dec
FileOutputStream fos = new FileOutputStream(inputFile.substring(0,
inputFile.length() - 4) + ".dec");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE, secret, new IvParameterSpec(iv));
// Read from file encrypted ---> .dec
int readByte;
byte[] buffer = new byte[1024];
while ((readByte = fis.read(buffer)) != -1) {
fos.write(cipher.doFinal(buffer), 0, readByte);
}
fos.flush();
fos.close();
fis.close();
}
Update
Solution: edit size of buffer is multiples of 16. Use CipherInput/ Output for read/ write file.
Tks Artjom B.

AES is a block cipher and as such only works on blocks of 16 bytes. A mode of operation such as CBC enables you to chain multiple blocks together. A padding such as PKCS#5 padding enables you to encrypt arbitrary length plaintext by filling the plaintext up to the next multiple of the block size.
The problem is that you're encrypting every 1024 bytes separately. Since 1024 divides the block size, the padding adds a full block before encryption. The ciphertext chunks are therefore 1040 bytes long. Then during decryption, you're only reading 1024 missing the padding. Java tries to decrypt it and then tries to remove the padding. If the padding is malformed (because it's not there), then the exception is thrown.
Easy fix
Simply increase your buffer for decryption to 1040 bytes.
Proper fix
Don't encrypt it in separate chunks, but either use Cipher#update(byte[], int, int) instead of Cipher.doFinal to update the ciphertext for every buffer you read or use a CipherInputStream.
Other security considerations:
You're missing a random IV. Without it, it may be possible for an attacker to see that you encrypted the same plaintext under the same key only by observing the ciphertexts.
You're missing ciphertext authentication. Without it, you can't reliably detect (malicious) changes in the ciphertexts and may open your system to attacks such as padding oracle attack. Either use an authenticated mode like GCM or run your created ciphertext through HMAC to create an authentication tag and write it to the end. Then you can verify the tag during/before decryption.

You are under the false assumption that the length of the encrypted data equals the length of the plain data, but the encrypted AES data is always a multiple of the AES block size (16 bytes) and can have an additional full padding block.
The most efficient way of dealing with stream encryption would be to use JCE's CipherOutputStream and CipherInputStream (http://docs.oracle.com/javase/7/docs/api/javax/crypto/CipherInputStream.html). These classes do all the work for you.
Also, make sure you always save the newly generated IV in your encryption method to be able to use it for the decryption.

Java RSA Server Authentication - Is this secure?

I'm slightly new to RSA, and I'm attempting to make a server-client system where the client can only connect to the official server. The way I want to achieve this is with high bit rsa encryption. What I've done is create a random string of bits both from the server and client, combined them together, and had the client encrypt said bytes with the public key. This encrypted data is then sent to the server, for decryption, and after it is encrypted, it will be sent back to the client where it can check it against the original message, assuring that the server is indeed the one it is attempting to communicate with. My question is, is this secure as possible, using the specified bit length? (64 public key, 4096 private)
public static boolean auth(DataInputStream in, DataOutputStream out) throws IOException {
byte[] clientKey = new byte[2048];
new SecureRandom().nextBytes(clientKey);
out.write(clientKey);
out.flush();
byte[] serverKey = new byte[2048];
in.readFully(serverKey);
byte[] plainKey = new byte[4096];
System.arraycopy(clientKey, 0, plainKey, 0, 2048);
System.arraycopy(serverKey, 0, plainKey, 2048, 2048);
byte[] encryptKey = new byte[4096];
toByteArray(new BigInteger(1, plainKey).modPow(RSA_PUBLIC, RSA_MODULUS), encryptKey, 0, 4096);
out.write(encryptKey);
out.flush();
byte[] serverAttempt = encryptKey;
in.readFully(serverAttempt);
return Arrays.equals(plainKey, serverAttempt);
}

Java - Missing final characters when encrypting using blowfish

I am using some java code that encrypts the contents of a text file using Blowfish. When I convert the encrypted file back (i.e. decrypt it) the string is missing a character from the end. Any ideas why? I am very new to Java and have been fiddling with this for hours with no luck.
The file war_and_peace.txt just contains the string "This is some text". decrypted.txt contains "This is some tex" (with no t on the end). Here is the java code:
public static void encrypt(String key, InputStream is, OutputStream os) throws Throwable {
encryptOrDecrypt(key, Cipher.ENCRYPT_MODE, is, os);
}
public static void decrypt(String key, InputStream is, OutputStream os) throws Throwable {
encryptOrDecrypt(key, Cipher.DECRYPT_MODE, is, os);
}
private static byte[] getBytes(String toGet)
{
try
{
byte[] retVal = new byte[toGet.length()];
for (int i = 0; i < toGet.length(); i++)
{
char anychar = toGet.charAt(i);
retVal[i] = (byte)anychar;
}
return retVal;
}catch(Exception e)
{
String errorMsg = "ERROR: getBytes :" + e;
return null;
}
}
public static void encryptOrDecrypt(String key, int mode, InputStream is, OutputStream os) throws Throwable {
String iv = "12345678";
byte[] IVBytes = getBytes(iv);
IvParameterSpec IV = new IvParameterSpec(IVBytes);
byte[] KeyData = key.getBytes();
SecretKeySpec blowKey = new SecretKeySpec(KeyData, "Blowfish");
//Cipher cipher = Cipher.getInstance("Blowfish/CBC/PKCS5Padding");
Cipher cipher = Cipher.getInstance("Blowfish/CBC/NoPadding");
if (mode == Cipher.ENCRYPT_MODE) {
cipher.init(Cipher.ENCRYPT_MODE, blowKey, IV);
CipherInputStream cis = new CipherInputStream(is, cipher);
doCopy(cis, os);
} else if (mode == Cipher.DECRYPT_MODE) {
cipher.init(Cipher.DECRYPT_MODE, blowKey, IV);
CipherOutputStream cos = new CipherOutputStream(os, cipher);
doCopy(is, cos);
}
}
public static void doCopy(InputStream is, OutputStream os) throws IOException {
byte[] bytes = new byte[4096];
//byte[] bytes = new byte[64];
int numBytes;
while ((numBytes = is.read(bytes)) != -1) {
os.write(bytes, 0, numBytes);
}
os.flush();
os.close();
is.close();
}
public static void main(String[] args) {
//Encrypt the reports
try {
String key = "squirrel123";
FileInputStream fis = new FileInputStream("war_and_peace.txt");
FileOutputStream fos = new FileOutputStream("encrypted.txt");
encrypt(key, fis, fos);
FileInputStream fis2 = new FileInputStream("encrypted.txt");
FileOutputStream fos2 = new FileOutputStream("decrypted.txt");
decrypt(key, fis2, fos2);
} catch (Throwable e) {
e.printStackTrace();
}
}
`

There is a couple of things not optimal here.
But let's first solve your problem. The reason why the last portion of your input is somehow missing is the padding you specify: none! Without specifying a padding, the Cipher can just operate on full-length blocks (8 bytes for Blowfish). Excess input that is less than a block long will be silently discarded, and there's your missing text. In detail: "This is some text" is 17 bytes long, so two full blocks will be decrypted, and the final 17th byte, "t", will be discarded.
Always use a padding in combination with symmetric block ciphers, PKCS5Padding is fine.
Next, when operating with Cipher, you don't need to implement your own getBytes() - there's String#getBytes already doing the job for you. Just be sure to operate on the same character encoding when getting the bytes and when reconstructing a String from bytes later on, it's a common source of errors.
You should have a look at the JCE docs, they will help you avoiding some of the common mistakes.
For example, using String keys directly is a no-go for symmetric cryptography, they do not contain enough entropy, which would make it easier to brute-force such a key. The JCE gives you theKeyGenerator class and you should always use it unless you know exactly what you are doing. It generates a securely random key of the appropriate size for you, but in addition, and that is something people tend to forget, it will also ensure that it doesn't create a weak key. For example, there are known weak keys for Blowfish that should be avoided in practical use.
Finally, you shouldn't use a deterministic IV when doing CBC encryption. There are some recent attacks that make it possible to exploit this, resulting in total recovery of the message, and that's obviously not cool. The IV should always be chosen at random (using a SecureRandom) in order to make it unpredictable. Cipher does this for you by default, you can simply obtain the used IV after encryption with Cipher#getIV.
On another note, less security-relevant: you should close streams in a finally block to ensure they're closed at all cost - otherwise you will be left with an open file handle in case of an exception.
Here's an updated version of your code that takes all these aspects into account (had to use Strings instead of files in main, but you can simply replace it with what you had there):
private static final String ALGORITHM = "Blowfish/CBC/PKCS5Padding";
/* now returns the IV that was used */
private static byte[] encrypt(SecretKey key,
InputStream is,
OutputStream os) {
try {
Cipher cipher = Cipher.getInstance(ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE, key);
CipherInputStream cis = new CipherInputStream(is, cipher);
doCopy(cis, os);
return cipher.getIV();
} catch (Exception ex) {
throw new RuntimeException(ex);
}
}
private static void decrypt(SecretKey key,
byte[] iv,
InputStream is,
OutputStream os)
{
try {
Cipher cipher = Cipher.getInstance(ALGORITHM);
IvParameterSpec ivSpec = new IvParameterSpec(iv);
cipher.init(Cipher.DECRYPT_MODE, key, ivSpec);
CipherInputStream cis = new CipherInputStream(is, cipher);
doCopy(cis, os);
} catch (Exception ex) {
throw new RuntimeException(ex);
}
}
private static void doCopy(InputStream is, OutputStream os)
throws IOException {
try {
byte[] bytes = new byte[4096];
int numBytes;
while ((numBytes = is.read(bytes)) != -1) {
os.write(bytes, 0, numBytes);
}
} finally {
is.close();
os.close();
}
}
public static void main(String[] args) {
try {
String plain = "I am very secret. Help!";
KeyGenerator keyGen = KeyGenerator.getInstance("Blowfish");
SecretKey key = keyGen.generateKey();
byte[] iv;
InputStream in = new ByteArrayInputStream(plain.getBytes("UTF-8"));
ByteArrayOutputStream out = new ByteArrayOutputStream();
iv = encrypt(key, in, out);
in = new ByteArrayInputStream(out.toByteArray());
out = new ByteArrayOutputStream();
decrypt(key, iv, in, out);
String result = new String(out.toByteArray(), "UTF-8");
System.out.println(result);
System.out.println(plain.equals(result)); // => true
} catch (Exception e) {
e.printStackTrace();
}
}

You have your CipherInputStream and CipherOutputStream mixed up. To encrypt, you read from a plain inputstream and write to a CipherOutputStream. To decrypt ... you get the idea.
EDIT:
What is happening is that you have specified NOPADDING and you are attempting to encrypt using a CipherInputStream. The first 16 bytes form two valid complete blocks and so are encrypted correctly. Then there is only 1 byte left over, and when the CipherInputStream class receives the end-of-file indication it performs a Cipher.doFinal() on the cipher object and receives an IllegalBlockSizeException. This exception is swallowed, and read returns -1 indicating end-of-file. If however you use PKCS5PADDING everything should work.
EDIT 2:
emboss is correct in that the real issue is simply that it is tricky and error-prone to use the CipherStream classes with the NOPADDING option. In fact, these classes explicitly state that they silently swallow every Security exception thrown by the underlying Cipher instance, so they are perhaps not a good choice for beginners.

Keys are binary, and String is not a container for binary data. Use a byte[].

When I had this problem I had to call doFinal on the cipher:
http://docs.oracle.com/javase/1.4.2/docs/api/javax/crypto/Cipher.html#doFinal()

BadPaddingException: pad block corrupted

I am trying to decrypt a file in Java which was encrypted in C# using Rijndael/CBC/PKCS7. I keep getting the following exception:
javax.crypto.BadPaddingException: pad block corrupted
at org.bouncycastle.jce.provider.JCEBlockCipher.engineDoFinal(Unknown Source)
at javax.crypto.Cipher.doFinal(DashoA13*..)
at AESFileDecrypter.decrypt(AESFileDecrypter.java:57)
when the doFinal(inpbytes) method is called by the web server for the first byte[]. I am guessing this is a problem with the key or IV. I have the encrypted files on my file system for testing. Is there anything that anyone can see glaringly wrong with my code below?
***keyStr is base64 encoded
public AESFileDecrypter(String keyStr){
try {
Security.addProvider(new BouncyCastleProvider());
convertIvParameter();
key = new sun.misc.BASE64Decoder().decodeBuffer(keyStr);
//use the passed in Base64 decoded key to create a key object
decryptKey = new SecretKeySpec(key, "AES");
//specify the encryption algorithm
decryptCipher = Cipher.getInstance("AES/CBC/PKCS7Padding", "BC");
//make a parameter object for the initialization vector(IV)
IvParameterSpec ivs = new IvParameterSpec(_defaultIv);
//initialize the decrypter to the correct mode, key used and IV
decryptCipher.init(Cipher.DECRYPT_MODE, decryptKey, ivs);
}
catch (Exception e) {
e.printStackTrace();
}
}
public void convertIvParameter() {
int[] iv = new int[] {11, 190, 165, 33, 68, 88, 11, 200, 245, 35, 68, 23, 60, 24, 223, 67};
_defaultIv = new byte[16];
for(int x = 0; x < _defaultIv.length; x++) {
_defaultIv[x] = (byte)iv[x];
}
}
public void decryptUpdate(byte[] inpBytes) throws Exception {
//decrypt the byte passed in from the web server
decryptCipher.update(inpBytes);
}
public byte[] decryptFinal() throws Exception {
//decrypt the byte passed in from the web server
return decryptCipher.doFinal();
}
//sends bytes to the client for diaply
private void sendBytes(FileInputStream fis, OutputStream os)throws Exception {
//set the buffer size to send 4k segments of data
aesFileDecrypter = new AESFileDecrypter(<Insert Key string here>);
byte[] buffer = new byte[4096];
int bytes = 0, totalBytes = fis.available();
//while there is still data to be sent keep looping and write the data
//to the output stream as the buffer is filled
try {
while ((bytes = fis.read(buffer)) != -1) {
aesFileDecrypter.decryptUpdate(buffer);
//os.write(buffer, 0, bytes);
}
os.write(aesFileDecrypter.decryptFinal(), 0, totalBytes);
}
catch(Exception e) {
e.printStackTrace();
}
}

Firstly, just to be clear, from comments below, you shouldn't call doFinal() on every block, because doFinal() expects any padding at the end, which obviouslly won't be there in intermediate blocks. Either (a) call update() on intermediate data, then doFinal() at the end, or (b) just arrange to have all your data in one buffer or byte array, and call doFinal() once on the whole job lot.
It's not clear from the code you posted that that's actually what you're doing, but it should be mentioned just in case.
Failing that, then as a first step to debugging, I'd suggest whichever of these two is easier for you:
Decrypting in ECB mode with no padding and seeing what you get. Look at the first block of data this brings back. If you can XOR this with your IV bytes and get the expected decrypted data, you know your key is OK.
Dumping out the actual key bytes from C# before base 64 encoding and Java after decoding and checking they are the same.
As I recall, C# has unsigned bytes (whereas Java signed) so there are a few places where there's room for things subtly going wrong with byte signedness.

I have encountered this problem before.
When I wrote some code to do encryption and decryption like this:
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(sec, "AES"),new IvParameterSpec(new byte[cipher.getBlockSize()]));
byte[] encode = cipher.doFinal(data);
cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(sec, "AES"), new IvParameterSpec(new byte[cipher.getBlockSize()]));
byte[] decode = cipher.doFinal(encode);
I forgot the first IvParameterSpec(new byte[cipher.getBlockSize()]) when encrypting data, then I got an exception "pad block corrupted", so maybe you should check you encryption code.

As far as I know AES is based on Rijndael, but the specification is not exactly the same. I would suggest to check the key and block size you are using to cipher in C# and the sizes being use in Java. (.Net differences between Rijndael and AES).

The doFinal() was the undoing of the code above, and I ended up just using cipher streams instead of the update/doFinal approach. This way I could use the FileInputStream and my cipher as parameters for the CipherInputStream, and then pass the output to the web browser through an OutputStream. Breaking the update and doFinal out into their own method calls made the task much more difficult and both methods were deleted from the decrypter class (leaving a single while loop that read in chunks of data and output it to the browser). The Bouncy Castle Provider was also not needed in this case and PKCS5Padding was enough, which was given by the SunJCE.