I am using AESCrypt (gradle :compile 'com.scottyab:aescrypt:0.0.1')
to encrypt and decrypt the data.
TextView tv=(TextView)findViewById(R.id.demotext);
String encrypted="",decrypted="";
try {
encrypted = AESCrypt.encrypt("password","This is the best thing to go by");
decrypted = AESCrypt.decrypt("password",encrypted);
} catch (GeneralSecurityException e) {
e.printStackTrace();
}
System.out.println("EncryptedData:"+encrypted);
System.out.println("DecryptedData:"+decrypted);
tv.setText("Encrypted:"+encrypted +"\n"+"Decrypted:"+decrypted);
The code works perfectly fine in this case, I get the same input as decrypted text.
But, when I try to use already encrypted string using the same method (AES) from the site http://aesencryption.net/ as shown in the screenshot:
And copy paste that encrypted text like:
decrypted = AESCrypt.decrypt("password","sttA+FbNm3RkTovjHI8CcAdStXiMl45s29Jqle+y+pA=");
And then run the code then I get error saying :
javax.crypto.BadPaddingException: error:1e06b065:Cipher functions:EVP_DecryptFinal_ex:BAD_DECRYPT
But when I use the decrypted text into the same site it works fine as shown in the screenshot below.
private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
byte[] decrypted = cipher.doFinal(encrypted);
return decrypted;
}
Probably due to the algorithm to convert the passphrase 'password' to SecretKeySpec
This is the algorithm in AESCrypt
private static SecretKeySpec GenerateKey (final String password) throws NoSuchAlgorithmException, UnsupportedEncodingException {
final MessageDigest digest = MessageDigest.getInstance (HASH_ALGORITHM);
byte [] bytes = password.getBytes ("UTF-8");
digest.update (bytes, 0, bytes.length);
byte [] key = digest.digest ();
log ("SHA-256 key" key);
SecretKeySpec secretKeySpec = new SecretKeySpec (key, "AES");
secretKeySpec return;
}
And this is the (Java) example aesencryption.net
sha = MessageDigest.getInstance ("SHA-1");
key = sha.digest (key);
key = Arrays.copyOf (key, 16); // Use only first 128 bit
SecretKey = new SecretKeySpec (key, "AES");
The first one applies SHA256 hashing, and the second SHA-1 after completing up to 16 bytes, so the key is different.
I think you are encrypting and decrypting AES in the right way. You do not need to change anything.
But if you want to be compatible with aesencryption.net, you need to implement the same key generation algorithm. The code is not too good. I try to summarize
//Code from aesencryption.net
// Generate key
MessageDigest sha = null;
key = myKey.getBytes ("UTF-8");
sha = MessageDigest.getInstance ("SHA-1");
key = sha.digest (key);
key = Arrays.copyOf (key, 16); // Use only first 128 bit
SecretKey = new SecretKeySpec (key, "AES");
public static String encrypt (String strToEncrypt) {
Cipher cipher = Cipher.getInstance ("AES / ECB / PKCS5Padding");
cipher.init (Cipher.ENCRYPT_MODE, SecretKey);
Base64.encodeBase64String return (cipher.doFinal (strToEncrypt.getBytes ("UTF-8"))));
}
public static String decrypt (String strToDecrypt) {
Cipher cipher = Cipher.getInstance ("AES / ECB / PKCS5PADDING");
cipher.init (Cipher.DECRYPT_MODE, SecretKey);
return new String (cipher.doFinal (Base64.decodeBase64 (strToDecrypt))));
}
I can also provide my own code extracted from an Android app witch requires to store private user data. Data is ciphered with an AES key protected with an user passphrase
public static String SIMMETRICAL_ALGORITHM = "AES";
//Generate cipher key with user provided password
private static String getPassphraseSize16(String key) {
if (TextUtils.isEmpty(key)) {
return null;
}
char controlChar = '\u0014';
String key16 = key + controlChar;
if (key16.length() < 16) {
while (key16.length() < 16) {
key16 += key + controlChar;
}
}
if (key16.length() > 16) {
key16 = key16.substring(key16.length() - 16, key16.length());
}
return key16;
}
//AES cipher with passphrase
public static byte[] encrypt(byte[] message, String passphrase)
throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
String passphrase16 = getPassphraseSize16(passphrase);
SecretKeySpec secretKey = new SecretKeySpec(passphrase16.getBytes(), SIMMETRICAL_ALGORITHM);
Cipher cipher = Cipher.getInstance(SIMMETRICAL_ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE, secretKey);
byte[] encoded = cipher.doFinal(message);
return encoded;
}
//AES decipher with passphrase
public static byte[] decrypt(byte[] encodedMessage, String key) throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
String passphrase16 = getPassphraseSize16(key);
SecretKeySpec secretKey = new SecretKeySpec(passphrase16.getBytes(), SIMMETRICAL_ALGORITHM);
Cipher cipher = Cipher.getInstance(SIMMETRICAL_ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE, secretKey);
byte decoded[] = cipher.doFinal(encodedMessage);
return decoded;
}
Related
I have been trying to send data effectively between two applications. One is implemented in C# (Sender) the other in Java (Receiver). The sender has to encrypt data using the transformation "AES/GCM/NOPadding" with a 32-byte key while the receiver has to decrypt using the same parameters. Here is the sender encryption function in C# (using bouncy castle)
public static string Encrypt(string plainText, string msgId)
{
const byte GcmTagSize = 16;
byte[] hashKey;
byte[] secretKey = Encoding.UTF8.GetBytes(msgId);
Console.WriteLine(secretKey.Length);
using (var hasher = SHA512.Create())
{
byte[] digestSeed = hasher.ComputeHash(secretKey);
hashKey = new byte[16];
Array.Copy(digestSeed, hashKey, hashKey.Length);
}
var keyParameter = new KeyParameter(hashKey);
var keyParameters = new AeadParameters(keyParameter, GcmTagSize * 8, secretKey);
var cipher = CipherUtilities.GetCipher("AES/GCM/NoPadding");
cipher.Init(true, keyParameters);
var plainTextData = Encoding.ASCII.GetBytes(plainText);
var cipherText = cipher.DoFinal(plainTextData); //bouncy castle
return Convert.ToBase64String(cipherText);
}
Here is the receiver decryption function in java
private static byte[] decrypt(byte[] message, SecretKey key) throws NoSuchPaddingException, NoSuchAlgorithmException,
IllegalBlockSizeException, BadPaddingException, InvalidAlgorithmParameterException, InvalidKeyException {
Cipher cipher = Cipher.getInstance("AES/GCM/NOPadding"); //NoPadding
byte[] nonce = Arrays.copyOfRange(message, message.length - cipher.getBlockSize(), message.length);
byte[] encryptedKycData = Arrays.copyOf(message, message.length - cipher.getBlockSize());
System.out.println(doEncode(nonce));
System.out.println(doEncode(nonce));
GCMParameterSpec gcmParameterSpec = new GCMParameterSpec(128, nonce);
cipher.init(Cipher.DECRYPT_MODE, key, gcmParameterSpec);
byte[] decryptedValue=cipher.doFinal(encryptedKycData);
return decryptedValue;
}
When I try to decrypt with the java decryption function I get the error
javax.crypto.AEADBadTagException: Tag mismatch
Struggling with this issue and any help would be appreciated.
I'm trying to encrypt and decrypt some texts using Cipher with the "AES/CBC/PKCS5Padding" algorithm but if I restart the application the text that was encrypt can't be decrypted.
I'm encrypting the text, transforming the encrypted bytes in base64 text, storing it and retrieving it when necessary, so transforming the base64 text in bytes and trying to decrypt to take the original text.
The code I'm using is:
private static SecretKey getKeyFromPassword(String password, String salt)
throws NoSuchAlgorithmException, InvalidKeySpecException {
SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
KeySpec spec = new PBEKeySpec(password.toCharArray(), salt.getBytes(UTF_8),
65536, 256);
SecretKey secret = new SecretKeySpec(factory.generateSecret(spec)
.getEncoded(), "AES");
return secret;
}
private static IvParameterSpec generateIv() {
byte[] iv = new byte[16];
new SecureRandom().nextBytes(iv);
return new IvParameterSpec(iv);
}
public static void main(String[] args) throws NoSuchAlgorithmException, InvalidKeySpecException, InvalidAlgorithmParameterException, InvalidKeyException, NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException {
// string for test
String teste = "teste teste teste teste";
//getting start with Cipher
SecretKey secretKey = getKeyFromPassword("pass", "salt");
IvParameterSpec ivParameterSpec = generateIv();
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
//encrypting
cipher.init(Cipher.ENCRYPT_MODE, secretKey, ivParameterSpec);
byte[] cipherText = new byte[0];
cipherText = cipher.doFinal(teste.getBytes(UTF_8));
// encrypt to base64 text
String criptado = Base64.getEncoder().encodeToString(cipherText);
//decripting
byte[] plainText = new byte[0];
byte[] rawText = Base64.getDecoder().decode(criptado);
cipher.init(Cipher.DECRYPT_MODE, secretKey, ivParameterSpec);
plainText = cipher.doFinal(rawText);
String decriptado = new String(plainText);
The problem is something with the size of the bit key? Like in this topic: java AES/CBC/PKCS5PADDING in php (AES-256-CBC) resulting different result
I took this guide to the code: baeldung.com/java-aes-encryption-decryption
First, please excuse my bad english, this is not my native language.
i am trying to encode and then decode some text of different lengths.
I tried to encode some text with RSA algorithm in java. In the progress, I found out that RSA-encoding is limited to a specific size of bytes, so this approach doesn't fit my specs as my text could be large.
As I want to stay with a public and a private key only, I came up with the idea to use a 'hard-coded' AES key which will be encoded with RSA public key and than use this to encode the data. (see code)
//harcoded secretkey base64 encoded
private static final String secretkey_base64 = "xtnN6Pove5AovbLXtGRJKw==";
//this is how RSA key are generated
public static KeyPair genKeys() throws Exception {
KeyPairGenerator kpg = KeyPairGenerator.getInstance( "RSA" );
kpg.initialize(2048);
KeyPair kp = kpg.generateKeyPair();
return kp;
}
//here text should be encoded
public static String encodeText(String plainText, PublicKey publicKey) throws Exception
{
Cipher encryptCipher = Cipher.getInstance("RSA");
encryptCipher.init(Cipher.ENCRYPT_MODE, publicKey);
byte[] cipherText = encryptCipher.doFinal(CryptoUtil.secretkey_base64.getBytes(UTF_8));
String encodedSecKey = Base64.getEncoder().encodeToString(cipherText);
SecretKeySpec k = new SecretKeySpec(Base64.getDecoder().decode(encodedSecKey), "AES");
Cipher aesCipher = Cipher.getInstance("AES");
aesCipher.init(Cipher.ENCRYPT_MODE, k);
byte[] byteCipherText = aesCipher.doFinal(plainText.getBytes());
return Base64.getEncoder().encodeToString(byteCipherText);
}
Obviously this doesn't work because the RSA encoded AES key is too long for AES encryption. Throws "Invalid AES key length: 256 bytes"
Does anyone have an idea how I could get the encryption running with this particular approach ?
Is this even possible, or do I have to use a different approach?
Thanks in advance.
//edit - Solved thanks to #ewramner
// here is the working solution:
public static String encodeText(String plainText, PublicKey publicKey) throws Exception
{
KeyGenerator generator = KeyGenerator.getInstance("AES");
generator.init(128); // The AES key size in number of bits
SecretKey secKey = generator.generateKey();
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.PUBLIC_KEY, publicKey);
byte[] encSecKey = cipher.doFinal(secKey.getEncoded());
Cipher aesCipher = Cipher.getInstance("AES");
aesCipher.init(Cipher.ENCRYPT_MODE, secKey);
byte[] byteCipherText = aesCipher.doFinal(plainText.getBytes());
return Base64.getEncoder().encodeToString(encSecKey) + "#" + Base64.getEncoder().encodeToString(byteCipherText);
}
public static String decodeText(String cipherText, PrivateKey privateKey) throws Exception
{
String[] split = cipherText.split("#");
String encSecKey = split[0];
String encText = split[1];
byte[] bytesSecKey = Base64.getDecoder().decode(encSecKey);
byte[] bytesText = Base64.getDecoder().decode(encText);
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.PRIVATE_KEY, privateKey);
byte[] decSecKey = cipher.doFinal(bytesSecKey);
SecretKey secKey = new SecretKeySpec(decSecKey , 0, decSecKey .length, "AES");
Cipher aesCipher = Cipher.getInstance("AES");
aesCipher.init(Cipher.DECRYPT_MODE, secKey);
return new String(aesCipher.doFinal(bytesText));
}
I wrote a simple Encryption and Decryption helper class for my android app to encrypt and store Strings securely.
It consists of a single static public method to encrypt, then it calls a private static method to decrypt the encrypted message and returns it. I wrote the method this way to check if the message is intact after encryption/decryption.
I wrote a simple JUnit test with a String and called AssertEquals on the String before and after sending it to the Crypto encryption method.
I get this following errors from running the test:
javax.crypto.AEADBadTagException: Tag mismatch!
The error stack:
at com.sun.crypto.provider.GaloisCounterMode.decryptFinal(GaloisCounterMode.java:571)
at com.sun.crypto.provider.CipherCore.finalNoPadding(CipherCore.java:1046)
at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:983)
at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:845)
at com.sun.crypto.provider.AESCipher.engineDoFinal(AESCipher.java:446)
at javax.crypto.Cipher.doFinal(Cipher.java:2165)
at util.Crypto.decrypt(Crypto.java:94)
at util.Crypto.encrypt(Crypto.java:64)
at com.example.ali.meappley.CryptoTest.encryptAndDecryptTest(CryptoTest.java:29)
I'm new to cryptography, but I read different stackoverflow replies and couldn't find anything of help. Some users suggested calling cipher.update(someByteArray) before calling cipher.doFinal(someByteArray) but I couldnt manage to get it working. Any suggestions?
This is my helper class
public class Crypto {
//public methods
//public static encrypt method
public static String encrypt(String messageToEncrypt, #Nullable byte[] associatedData) throws NoSuchPaddingException,
NoSuchAlgorithmException,
InvalidAlgorithmParameterException,
InvalidKeyException,
BadPaddingException,
IllegalBlockSizeException {
byte[] plainBytes = messageToEncrypt.getBytes();
/////////////////////////////////////////////////////////////////
SecureRandom secureRandom = new SecureRandom();
byte[] key = new byte[16];
secureRandom.nextBytes(key);
SecretKey secretKey = new SecretKeySpec(key, "AES");
byte[] iv = new byte[12]; //NEVER REUSE THIS IV WITH SAME KEY
secureRandom.nextBytes(iv);
final Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
GCMParameterSpec parameterSpec = new GCMParameterSpec(128, iv); //128 bit auth tag length
cipher.init(Cipher.ENCRYPT_MODE, secretKey, parameterSpec);
if (associatedData != null) {
cipher.updateAAD(associatedData);
}
byte[] cipherText = cipher.doFinal(plainBytes);
ByteBuffer byteBuffer = ByteBuffer.allocate(4 + iv.length + cipherText.length);
byteBuffer.putInt(iv.length);
byteBuffer.put(iv);
byteBuffer.put(cipherText);
byte[] cipherMessage = byteBuffer.array();
Arrays.fill(key,(byte) 0); //overwrite the content of key with zeros
///////////////////////////////////////////////////////////////////
byte[] decrypted = decrypt(cipherMessage, null, key);
return decrypted.toString();
}
//public static decrypt method
private static byte[] decrypt(byte[] cipherMessage, #Nullable byte[] associatedData, byte[] key) throws NoSuchPaddingException,
NoSuchAlgorithmException,
InvalidAlgorithmParameterException,
InvalidKeyException,
BadPaddingException,
IllegalBlockSizeException {
ByteBuffer byteBuffer = ByteBuffer.wrap(cipherMessage);
int ivLength = byteBuffer.getInt();
if(ivLength < 12 || ivLength >= 16) { // check input parameter
throw new IllegalArgumentException("invalid iv length");
}
byte[] iv = new byte[ivLength];
byteBuffer.get(iv);
byte[] cipherText = new byte[byteBuffer.remaining()];
byteBuffer.get(cipherText);
final Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(key, "AES"), new GCMParameterSpec(128, iv));
if (associatedData != null) {
cipher.updateAAD(associatedData);
}
cipher.update(cipherText);
byte[] plainText= cipher.doFinal(cipherText);
return plainText;
}
There are a few issues with your code:
1) In your encrypt-method remove the following line (or shift it behind the decrypt-call).
Arrays.fill(key, (byte) 0); // overwrite the content of key with zeros
Otherwise the key for encryption and decryption differ.
2) In your encrypt-method also pass the associatedData in your decrypt-call i.e. replace
byte[] decrypted = decrypt(cipherMessage, null, key);
with
byte[] decrypted = decrypt(cipherMessage, associatedData, key);
The associatedData passed for encryption and decryption have to match for validity. For the purpose of the associatedData see e.g. https://crypto.stackexchange.com/questions/6711/how-to-use-gcm-mode-and-associated-data-properly
3) In your decrypt-method remove the line
cipher.update(cipherText);
For the purpose of the update-method see e.g. What does cipher.update do in java?
All three issues give rise to an AEADBadTagException.
4) I suspect for testing purposes your encrypt-method returns decrypted.toString() which however only gives you the object's class and hashcode. It would make more sense to return e.g. new String(decrypted).
I need to encrypt string on Java, and then decrypt it on Kotlin.
I do following things:
encrypt string like that
private static String encrypt(String value, String password) throws NoSuchPaddingException, ... {
final SecretKeySpec secretKeySpec = new SecretKeySpec(password.getBytes(Charset.forName("UTF-8")), "AES");
final Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec);
final byte[] encryptedValue = cipher.doFinal(value.getBytes(Charset.forName("UTF-8")));
return DatatypeConverter.printBase64Binary(encryptedValue);
}
For decrypt in Kotlin I use this method:
fun String.decrypt(password: String): String {
val secretKeySpec = SecretKeySpec(password.toByteArray(), "AES")
val iv = ByteArray(16)
val charArray = password.toCharArray()
for (i in 0 until charArray.size){
iv[i] = charArray[i].toByte()
}
val ivParameterSpec = IvParameterSpec(iv)
val cipher = Cipher.getInstance("AES/GCM/NoPadding")
cipher.init(Cipher.DECRYPT_MODE, secretKeySpec, ivParameterSpec)
(1) val decryptedByteValue = cipher.doFinal(Base64.decode(this, Base64.DEFAULT))
return String(decryptedByteValue)
}
In that case on line (1) I receive AEADBadTagException: mac check in GCM failed
So, I changed it a little bit
fun String.decrypt(password: String): String {
val secretKeySpec = SecretKeySpec(password.toByteArray(), "AES")
val cipher = Cipher.getInstance("AES/GCM/NoPadding")
(2) cipher.init(Cipher.DECRYPT_MODE, secretKeySpec)
val decryptedByteValue = cipher.doFinal(Base64.decode(this, Base64.DEFAULT))
return String(decryptedByteValue)
}
In that case in line (2) I receive RuntimeException: java.security.InvalidAlgorithmParameterException: IV must be specified in GCM mode
So, after that, I changed encryption method
private static String encrypt(String value, String password) throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidKeyException, BadPaddingException, IllegalBlockSizeException, InvalidAlgorithmParameterException {
final SecretKeySpec secretKeySpec = new SecretKeySpec(password.getBytes(Charset.forName("UTF-8")), "AES");
final Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
final byte[] iv = new byte[16];
for (int i = 0; i < password.length(); i++) {
iv[i] = (byte) password.toCharArray()[0];
}
final IvParameterSpec ivSpec = new IvParameterSpec(iv);
(3) cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, ivSpec);
final byte[] encryptedValue = cipher.doFinal(value.getBytes(Charset.forName("UTF-8")));
return DatatypeConverter.printBase64Binary(encryptedValue);
}
But here in line (3) I receive java.security.InvalidAlgorithmParameterException: Unsupported parameter: javax.crypto.spec.IvParameterSpec#6d311334
Please help me to solve this puzzle
Executing SecretKeySpec(password.toByteArray(), "AES") is clearly a functionality and a security problem. AES requires a key of 16/24/32 bytes, but your password is of variable length. Never use a password as a key. Use a key derivation algorithm like PBKDF2 instead.
Regarding your error:
You are using an IvParameterSpec, however GCM does not use an IV, but a Nonce and it requires to specify the authentication tag length. Therefore you have to provide an GCMParameterSpec.