I am working on AES encryption and decryption in Android, I post request using below Android code snippet.
Request Post
String urlParameters = "username=abc&password=abc";
String request = "http://abcd.co.uk/data_abc.php?";
String passkey = "mysecretkey";
URL url;
HttpURLConnection connection = null;
try {
//Create connection
url = new URL(request);
connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-Type",
"application/x-www-form-urlencoded");
connection.setRequestProperty("Content-Length", "" +
Integer.toString(urlParameters.getBytes().length));
connection.setRequestProperty("Content-Language", "en-US");
connection.setUseCaches(false);
connection.setDoInput(true);
connection.setDoOutput(true);
//Send request
DataOutputStream wr = new DataOutputStream(
connection.getOutputStream());
wr.writeBytes(urlParameters);
wr.flush();
wr.close();
//Get Response
InputStream is = connection.getInputStream();
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
String line;
StringBuffer response = new StringBuffer();
while ((line = rd.readLine()) != null) {
response.append(line);
response.append('\r');
}
rd.close();
return response.toString();
} catch (Exception e) {
e.printStackTrace();
return null;
} finally {
if (connection != null) {
connection.disconnect();
}
}
And I successfully got Base64 Encrypted response string from the above request but when I try to decrypt the response string using following code snippet, It return unreadable string like characters and boxes.
Decryption
String strDecriptedValue = decrypt(passkey, responseBase64);
public static String decrypt(String seed, String encrypted)
throws Exception {
byte[] rawKey = getRawKey(seed.getBytes());
byte[] enc = Base64.decode(encrypted.getBytes(), Base64.DEFAULT);
byte[] result = decrypt(rawKey, enc);
return new String(result);
}
private static byte[] getRawKey(byte[] seed) throws Exception {
KeyGenerator keygen = KeyGenerator.getInstance("AES");
SecureRandom random = SecureRandom.getInstance("SHA1PRNG");
random.setSeed(seed);
keygen.init(128, random);
SecretKey key = keygen.generateKey();
byte[] raw = key.getEncoded();
return raw;
}
private static byte[] decrypt(byte[] raw, byte[] encrypted)
throws Exception {
SecretKeySpec keySpec = new SecretKeySpec(raw, "AES");
Cipher cipher = Cipher.getInstance("AES/ECB/NoPadding");
cipher.init(Cipher.DECRYPT_MODE, keySpec);
byte[] decrypted = cipher.doFinal(encrypted);
return decrypted;
}
Decrypted Output
��]ة*�]��O��Z���Q2�_
The response should be in JSON format but actual output is like above.
Please share the snippet which is used to decrypt the data with AES 256 bit, secure key using Base 64.
And also I tried using AES/CBC/NoPadding , AES/CBC/PKCS5Padding etc., but its not getting work.
You are using SecureRandom random to generated key using passed seed value.
But the actual implementation of SecureRandom on the server and the one used by your Android code be different (you are using some PHP code it seems) so the generated key value would be different.
Also you mentioned the 256 bit key but your code is using 128 instead: keygen.init(128, random);
So make sure that your are using the same keys on both side. You should try your code first with the 'fixed' key on both side and check if it works, otherwise you may still have bugs in your decryption/encryption process. You included only half of the process code in your question.
Related
I need to encrypt a set of user credentials and send it to a SOAP web service. The following code snippet (I think it's C#) is provided in the documentation, and my Java code is based on it.
private string Encrypt256(string text, AesCryptoServiceProvider aes)
{
// Convert string to byte array
byte[] src = Encoding.Unicode.GetBytes(text);
// encryption
using (ICryptoTransform encrypt = aes.CreateEncryptor())
{
byte[] dest = encrypt.TransformFinalBlock(src, 0, src.Length);
// Convert byte array to Base64 strings
return Convert.ToBase64String(dest);
}
}
...
Credentials credential = new Credentials();
credential.UserName = "username";
credential.Password = "password";
credential.ClientUtcTime = DateTime.UtcNow.ToString("yyyy-MM-ddTHH:mm:ssZ", System.Globalization.CultureInfo.InvariantCulture);
//--Serialize credential
XmlSerializer serializer = new XmlSerializer(credential.GetType());
string xmlCredential = string.Empty;
using (var stringwriter = new System.IO.StringWriter())
{
serializer.Serialize(stringwriter, credential);
xmlCredential = stringwriter.ToString();
}
//--Encrypt credential with AES256 symmetric
String encryptedCredential = Encrypt256(xmlCredential, aesServiceProvider);
...
The following is my Java code.
KeyGenerator kg = KeyGenerator.getInstance("AES");
kg.init(256);
SecretKey sk = kg.generateKey();
Cipher aesCipher = Cipher.getInstance("AES");
aesCipher.init(Cipher.ENCRYPT_MODE, sk);
Credentials cred = new UsernamePasswordCredentials("username", "password");//no need for time field?
String eCred = Base64.encodeBase64String(aesCipher.doFinal(objectToByteArray(cred)));
...
private byte[] objectToByteArray(Object obj) {
byte[] bytes = null;
try (
ByteArrayOutputStream bos = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(bos);
) {
oos.writeObject(obj);
oos.flush();
bytes = bos.toByteArray();
}
catch (IOException e) {
e.printStackTrace();
}
return bytes;
}
Then I came across SealedObject and CipherOutputStream. I tried writing code snippets for those.
Using SealedObject
// slight change here; cred must implement Serializable
UsernamePasswordCredentials cred = new UsernamePasswordCredentials("username", "password");
// same as above except for the following two lines
SealedObject so = new SealedObject(cred, aesCipher);
String eCred = Base64.encodeBase64String(objectToByteArray(so));
Using CipherOutputStream
Credentials cred = new UsernamePasswordCredentials("username", "password");
ByteArrayOutputStream bos = new ByteArrayOutputStream();
CipherOutputStream cos = new CipherOutputStream(bos, aesCipher);
cos.write(objectToByteArray(cred));
cos.close();
String eCred = Base64.encodeBase64String(bos.toByteArray());
For all three code snippets, is the code correct? Considering that this code will be called frequently, which approach is the most efficient?
In my project a textfile is chosen and become encrypted. The encrypted text is saved seperatly as well as the key. Now I try to create a program which is decrypting the file when the right keyfile is available. I think the decrypting program needs to look pretty like the encrypting program just in DECRYPT_MODE. When I read in the key I don't know how to do the next step at it to decrypt the textfile. Maybe anyone can help me how I use the key from .txt file and use it to decrypt the encoded file.
The encrypting program:
public class encrypt {
public static void main(String[] args) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IOException {
//Key is created and saved in File
KeyGenerator keygenerator = KeyGenerator.getInstance("AES");
SecretKey myDesKey = keygenerator.generateKey();
String encodedKey = Base64.getEncoder().encodeToString(myDesKey.getEncoded());
Path keypath = Paths.get("C:/xxx/key.txt");
Path keyfile = Files.createFile(keypath);
Files.write(keyfile, encodedKey.getBytes(), StandardOpenOption.WRITE);
Cipher desalgCipher;
desalgCipher = Cipher.getInstance("AES");
desalgCipher.init(Cipher.ENCRYPT_MODE, myDesKey);
Path target = Paths.get("C:/xxx/encrypted.txt");
Path file = Files.createFile(target);
Path path = Paths.get("test.txt");
try(InputStream is = Files.newInputStream(path);
CipherInputStream cipherIS = new CipherInputStream(is, desalgCipher);
BufferedReader reader = new BufferedReader(new InputStreamReader(cipherIS));){
String line;
while((line = reader.readLine()) != null){
System.out.println(line);
Files.write(file, line.getBytes(), StandardOpenOption.WRITE);
}
}
}
}
Decrypt: read in the key and decrypt it
public class decrypt {
public static void main(String[] args) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IOException {
try {
File fileDir = new File("C:/Users/JT/Desktop/key.txt");
BufferedReader in = new BufferedReader(
new InputStreamReader(new FileInputStream(fileDir), "UTF-8"));
String str;
while ((str = in.readLine()) != null) {
System.out.println(str);
}
in.close();
}
catch (UnsupportedEncodingException e)
{
System.out.println(e.getMessage());
}
catch (IOException e)
{
System.out.println(e.getMessage());
}
catch (Exception e)
{
System.out.println(e.getMessage());
}
byte[] decodedKey = Base64.getDecoder().decode(sb.toString());
SecretKey originalKey = new SecretKeySpec(decodedKey, 0, decodedKey.length, "AES");
SecretKeySpec key = new SecretKeySpec(sb.toString().getBytes(), "Base64");
Cipher desalgCipher;
desalgCipher = Cipher.getInstance("AES");
desalgCipher.init(Cipher.DECRYPT_MODE, key);
Path path = Paths.get("encrypted.txt"); // path to your file
try(InputStream is = Files.newInputStream(path); // get an IS on your file
CipherInputStream cipherIS = new CipherInputStream(is, desalgCipher); // wraps stream using cipher
BufferedReader reader = new BufferedReader(new InputStreamReader(cipherIS));){ // init reader.
String line;
while((line = reader.readLine()) != null){
System.out.println(line);
}
}
}
}
Your application is not being programmed the right way. Currently you try to encrypt by wrapping the input stream with a CipherInputStream instance. Then this instance again is wrapped with a BufferedReader instance.
So what you are doing is to first convert the bytes of the input file - probably text - into ciphertext. This ciphertext can contain any byte value. Then you try to read those bytes in line-by-line using the default character set and line endings. Obviously after encryption even the notion of lines doesn't exist anymore, so you'll loose data in that final step.
Then you convert back to bytes, which you then (somehow) try to decrypt. This will obviously fail as you lost data during the readLine statement.
What you should do is to read in the file using bytes. You can then write to a CipherOutputStream. If the file with the ciphertext needs to be actual text you can use a Base64 stream which the new java.util.Base64 nicely provides.
Only once you programmed the encryption correctly you can try and reverse the process. As long as data is lost obviously the decryption will fail (with an error or garbage output, depending on the mode and your luck).
If you're unlucky you will end up with code that works 99% of the time. So good luck and heed the comments: don't try and perform encryption without understanding what you're doing. It will end with tears - or a smashed keyboard.
I am working on android application in which i want to encrypt my text which is stored using ormlite, so if any one from outside get the DB file, he will not be able to read it with out decrypting it. My major concern is to encrypt the data using base64 and when i want to read the data it should decrypt it. I have read some sample code from a link for base64 please suggest me the way for encrypting my text before saving it to the DB and on retrieving time it should decrypt it.
// Sending side
byte[] data = text.getBytes("UTF-8");
String base64 = Base64.encodeToString(data, Base64.DEFAULT);
// Receiving side
byte[] data = Base64.decode(base64, Base64.DEFAULT);
String text = new String(data, "UTF-8");
You can use this code for encryption and decryption.
I am using 3DES encryption scheme here. I hope it will help you.
public PasswordEncryption_TrippleDES() throws Exception {
myEncryptionKey = //your encryption key
myEncryptionScheme = DESEDE_ENCRYPTION_SCHEME;
arrayBytes = myEncryptionKey.getBytes(UNICODE_FORMAT);
ks = new DESedeKeySpec(arrayBytes);
skf = SecretKeyFactory.getInstance(myEncryptionScheme);
cipher = Cipher.getInstance(myEncryptionScheme);
key = skf.generateSecret(ks);
}
public String encrypt(String unencryptedString) {
String encryptedString = null;
try {
cipher.init(Cipher.ENCRYPT_MODE, key);
byte[] plainText = unencryptedString.getBytes(UNICODE_FORMAT);
byte[] encryptedText = cipher.doFinal(plainText);
encryptedString = new String(Base64.encodeBase64(encryptedText));
} catch (Exception e) {
e.printStackTrace();
}
return encryptedString;
}
public String decrypt(String encryptedString) {
String decryptedText=null;
try {
cipher.init(Cipher.DECRYPT_MODE, key);
byte[] encryptedText = Base64.decodeBase64(encryptedString);
byte[] plainText = cipher.doFinal(encryptedText);
decryptedText= new String(plainText);
} catch (Exception e) {
e.printStackTrace();
}
return decryptedText;
}
I decrypt a file on the internal memory, as follows:
CipherInputStream cip = new CipherInputStream(context.openFileInput("filename"), cipher);
How can I get the decoded result and convert it, for example, to the string?
UPDATE:
File, which is stored in the phone's internal memory is encrypted json-file. The method should read this file, decrypt and return the result as a string:
public String getJSON() {
String jsonString = "";
try {
String algorithm = "DESede";
jsonString = "";
SecretKeyFactory skf = SecretKeyFactory.getInstance(algorithm);
DESedeKeySpec kspec = new DESedeKeySpec(readKey().getBytes());
SecretKey key = skf.generateSecret(kspec);
Cipher cipher = Cipher.getInstance(algorithm);
cipher.init(Cipher.DECRYPT_MODE, key);
CipherInputStream cip = new CipherInputStream(context.openFileInput("filename"), cipher);
// here I have to get the result of decoding and write it to the jsonString
cip.close();
} catch (Exception e) {
e.printStackTrace();
}
return jsonString;
}
So I have been working with the Bouncycastle libraries in an attempt to connect with a remote server. This process has been problematic from the get go and now I'm close to getting everything working but some odd things are happening.
When I first started building out the encryption process I was told to use AES 256 with PKCS7Padding. After some nagging I was provided with a c++ example of the server code. It turned out that the IV is 256 bit so I had to use the RijndaelEngine instead. Also in order for this to work correctly I have to use ZeroBytePadding.
Here is my code:
socket = new Socket(remoteIP, port);
outputStream = new PrintWriter(socket.getOutputStream());
inputStream = new BufferedReader(new InputStreamReader(socket.getInputStream()));
byte[] base_64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".getBytes("UTF-8");
Security.addProvider(new BouncyCastleProvider());
public String AESEncrypt(String out) throws IOException, DataLengthException, IllegalStateException, InvalidCipherTextException {
byte[] EncKey = key;
byte randKey;
Random randNumber = new Random();
randKey = base_64[randNumber.nextInt(base_64.length)];
EncKey[randKey&0x1f] = randKey;
RijndaelEngine rijndaelEngine = new RijndaelEngine(256);
PaddedBufferedBlockCipher cipher = new PaddedBufferedBlockCipher(new CBCBlockCipher(rijndaelEngine), new ZeroBytePadding());
ParametersWithIV keyParameter = new ParametersWithIV(new KeyParameter(EncKey), iv);
cipher.init(true, keyParameter);
byte[] txt = out.getBytes();
byte[] encoded = new byte[cipher.getOutputSize(txt.length)];
int len = cipher.processBytes(txt, 0, txt.length, encoded, 0);
cipher.doFinal(encoded, len);
char keyChar = (char) randKey;
String encString = new String(Base64.encode(encoded));
encString = encString.substring(0, encString.length()-1) + randKey;
return encString;
}
public void AESDecrypt(String in) throws DataLengthException, IllegalStateException, IOException, InvalidCipherTextException {
byte[] decKey = key;
byte[] msg = in.getBytes();
byte randKey = msg[msg.length-1];
decKey[randKey&0x1f] = randKey;
byte[] trimMsg = new byte[msg.length-1];
System.arraycopy(msg, 0, trimMsg, 0, trimMsg.length);
in = new String(trimMsg);
RijndaelEngine rijndaelEngine = new RijndaelEngine(256);
PaddedBufferedBlockCipher cipher = new PaddedBufferedBlockCipher(new CBCBlockCipher(rijndaelEngine), new ZeroBytePadding());
ParametersWithIV keyParameter = new ParametersWithIV(new KeyParameter(decKey), iv);
cipher.init(false, keyParameter);
byte[] encoded = Base64.decode(in.trim());
byte[] decoded = new byte[cipher.getOutputSize(encoded.length)];
int len = cipher.processBytes(encoded, 0, encoded.length, decoded, 0);
cipher.doFinal(decoded, len);
String decString = new String(decoded);
}
Here is a test function I am using to send and receive messages:
public void serverTest() throws DataLengthException, IllegalStateException, InvalidCipherTextException, IOException {
//out = AESEncrypt(out);
outputStream.write(out + "\n");
outputStream.flush();
String msg = "";
while ((msg = inputStream.readLine()) != null) {
AESDecrypt(msg);
}
}
The key and iv don't change with the exception of the last byte in the key. If I am encrypting I get a random base64 char and change the last byte to that. If its decryption I get the last byte from the message and set the last value of the key to it for decryption.
In the c++ example there was an unencrypted message and two encrypted messages. I could deal with those fine.
Here is the problem, when I send my message to the remote server "encrypted" the app waits for a response until the connection times out but never gets one. If I send the message unencrypted I get either 7 responses which I can successfully decrypt and finally
org.bouncycastle.util.encoders.DecoderException: unable to decode base64 string:
String index out of range: -4 at org.bouncycastle.util.encoders.Base64.decode(Unknown Source)
or my last line before the error will look like this:
?"??n?i???el????s???!_S=??ah????CR??l6??]?{?l??Y?????Gn???+?????9!'??gU&4>??{X????G?.$c=??0?5??GP???_Q5????8??Z\?~???<Kr?????[2\ ???a$?C??z%?W???{?.?????eR?j????~?B"$??"z??W;???<?Yu??Y*???Z?K?e!?????f?;O(?Zw0B??g<???????????,)?L>???A"?????<?????W??#\???f%??j ?EhY/?? ?5R?34r???#?1??I??????M
If I set the encryption/decryption to use PKCS7Padding I get no response when my message is encrypted still but with decryption from the server I get between 2 to 6 responses and then
org.bouncycastle.crypto.InvalidCipherTextException: pad block corrupted
I am at a loss with this. I don't know what I might be doing wrong so I have come here. I'm hoping the so community can point out my errors and guide me in the right direction.
I have a bit of an update I found my error in the encryption. I wasn't placing the random base64 value at the end of the encrypted string correctly so now I am doing like this.
encString += (char)randKey;
I can get response from the server now. Now the problem is I will some times get one or two readable lines but the rest are all garbage. I asked the individuals who run the server about it and they said in some c# code that they reference the have
return UTF8Encoding.UTF8.GetString(resultArray);
and thats all I have to go off of. I have tried UTF-8 encoding any place where I do getBytes or new String, and I have tried making the BurrferReader stream UTF-8 but it's still garbage.
Have you seedn the BCgit? this has bouncycastle code and examples. I am using the Csharp version in this repository. https://github.com/bcgit/bc-java
All crypto primitive examples are stored here: https://github.com/bcgit/bc-java/tree/master/core/src/test/java/org/bouncycastle/crypto/test
Try this code for testing Aes-CBC
private void testNullCBC()
throws InvalidCipherTextException
{
BufferedBlockCipher b = new BufferedBlockCipher(new CBCBlockCipher(new AESEngine()));
KeyParameter kp = new KeyParameter(Hex.decode("5F060D3716B345C253F6749ABAC10917"));
b.init(true, new ParametersWithIV(kp, new byte[16]));
byte[] out = new byte[b.getOutputSize(tData.length)];
int len = b.processBytes(tData, 0, tData.length, out, 0);
len += b.doFinal(out, len);
if (!areEqual(outCBC1, out))
{
fail("no match on first nullCBC check");
}
b.init(true, new ParametersWithIV(null, Hex.decode("000102030405060708090a0b0c0d0e0f")));
len = b.processBytes(tData, 0, tData.length, out, 0);
len += b.doFinal(out, len);
if (!areEqual(outCBC2, out))
{
fail("no match on second nullCBC check");
}
}