I have the following test code to encrypt and decrypt a string. It works fine if I leave out the wrapping and unwrapping code for my key in test(), but when I try to wrap my key, and then unwrap it again and use it for the decryption, it fails and I don't get "Test" back as the resulting decrypted string but "�J��" instead.
Does anybody see the error I'm doing with the wrapping and unwrapping? Thanks.
private static void test() throws Exception {
// create wrap key
KeyGenerator keyGenerator = KeyGenerator.getInstance("AESWrap");
keyGenerator.init(256);
Key wrapKey = keyGenerator.generateKey();
SecretKey key = generateKey(PASSPHRASE);
Cipher cipher;
// wrap key
cipher = Cipher.getInstance("AESWrap");
cipher.init(Cipher.WRAP_MODE, wrapKey);
byte[] wrappedKeyBytes = cipher.wrap(key);
// unwrap key again
cipher.init(Cipher.UNWRAP_MODE, wrapKey);
key = (SecretKey)cipher.unwrap( wrappedKeyBytes, "AES/CTR/NOPADDING", Cipher.SECRET_KEY);
// encrypt
cipher = Cipher.getInstance("AES/CTR/NOPADDING");
cipher.init(Cipher.ENCRYPT_MODE, key, generateIV(cipher), random);
byte[] b = cipher.doFinal("Test".toString().getBytes());
// decrypt
cipher = Cipher.getInstance("AES/CTR/NOPADDING");
cipher.init(Cipher.DECRYPT_MODE, key, generateIV(cipher), random);
b = cipher.doFinal(b);
System.out.println(new String(b));
// should output "Test", but outputs �J�� if wrapping/unwrapping
}
And the two helper methods that are called in the code above:
private static IvParameterSpec generateIV(Cipher cipher) throws Exception {
byte [] ivBytes = new byte[cipher.getBlockSize()];
random.nextBytes(ivBytes); // random = new SecureRandom();
return new IvParameterSpec(ivBytes);
}
private static SecretKey generateKey(String passphrase) throws Exception {
PBEKeySpec keySpec = new PBEKeySpec(passphrase.toCharArray(), salt.getBytes(), iterations, keyLength);
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(PBE_ALGORITHM); //"PBEWITHSHA256AND256BITAES-CBC-BC"
return keyFactory.generateSecret(keySpec);
}
It looks like you're giving a different IV to cipher.init(Cipher.ENCRYPT_MODE, ...) and cipher.init(Cipher.DECRYPT_MODE, ...) by calling generateIV() twice.
Related
I am tying to implement Intilization vector 4 the issue I am facing is I am able to encrypt my text using intilization vector4 algorithm but when it comes to decryption I always get this error can anyone tell me what is wrong with my code
public static final int GCM_TAG_LENGTH = 16;
public static final int AES_KEY_SIZE = 256;
public static final int GCM_IV_LENGTH = 12;
SecretKey key;
public void init() throws NoSuchAlgorithmException {
KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
keyGenerator.init(AES_KEY_SIZE);
// Generate Key
key = keyGenerator.generateKey();
}
#PostMapping("/encrypt/{name}")
public void getValues(#PathVariable("name") String name) throws Exception {
init();
byte[] IV = new byte[GCM_IV_LENGTH];
SecureRandom random = new SecureRandom();
random.nextBytes(IV);
System.out.println("Original Text : " + name);
byte[] cipherText = encrypt(subId.getBytes(), key, IV);
System.out.println("Encrypted Text : " + Base64.getEncoder().encodeToString(cipherText));
}
#PostMapping("/decrypt/{name}")
public void getDecryptValues(#PathVariable("name") String name) throws Exception {
byte [] cipherText=name.getBytes();
byte[] IV = new byte[GCM_IV_LENGTH];
String decryptedText = decrypt(cipherText, key, IV);
System.out.println("DeCrypted Text : " + decryptedText);
}
public static byte[] encrypt(byte[] plaintext, SecretKey key, byte[] IV) throws Exception
{
// Get Cipher Instance for selected algorithm
Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
// Create SecretKeySpec for key
SecretKeySpec keySpec = new SecretKeySpec(key.getEncoded(), "AES");
// Create GCMParameterSpec for key
GCMParameterSpec gcmParameterSpec = new GCMParameterSpec(GCM_TAG_LENGTH * 8, IV);
// Initialize Cipher for ENCRYPT_MODE for encrypt plaintext
cipher.init(Cipher.ENCRYPT_MODE, keySpec, gcmParameterSpec);
// Perform Encryption
byte[] cipherText = cipher.doFinal(plaintext);
return cipherText;
}
public static String decrypt(byte[] cipherText, SecretKey key, byte[] IV) throws Exception
{
// Get Cipher Instance based on selective AES algorithm
Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
// Create SecretKeySpec for key
SecretKeySpec keySpec = new SecretKeySpec(key.getEncoded(), "AES");
GCMParameterSpec gcmParameterSpec = new GCMParameterSpec(GCM_TAG_LENGTH * 8, IV);
// Initialize Cipher for DECRYPT_MODE to in plain text
cipher.init(Cipher.DECRYPT_MODE, keySpec, gcmParameterSpec);
// Perform Decryption on encrypted text
byte[] decryptedText = cipher.doFinal(cipherText);
return new String(decryptedText);
}
My encryption code works fine but there is issue with decryption I always get this error "javax.crypto.AEADBadTagException: Tag mismatch!" How can I resolve this error
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 receive an error while decrypting: (javax.crypto.BadPaddingException: error:06065064:digital envelope routines:EVP_DecryptFinal_ex:bad decrypt)
My code encryption / decryption:
private static byte[] password = null; // this.password = editText.getBytes();
static final byte[] ivBytes = {'6','g','6','o','d','a','0','u','4','n','w','i','6','9','i','j'};
public static byte[] encrypt(String text) throws Exception {
byte[] clear = text.getBytes("UTF-8");
IvParameterSpec ivSpec = new IvParameterSpec(ivBytes);
KeyGenerator kgen = KeyGenerator.getInstance("AES");
SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
sr.setSeed(password);
kgen.init(256, sr); // 192 and 256 bits may not be available
SecretKey skey = kgen.generateKey();
byte[] key = skey.getEncoded();
SecretKeySpec skeySpec = new SecretKeySpec(key, "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec, ivSpec);
byte[] encrypted = cipher.doFinal(clear);
return encrypted;
}
public static String decrypt(byte[] encrypted) throws Exception {
IvParameterSpec ivSpec = new IvParameterSpec(ivBytes);
KeyGenerator kgen = KeyGenerator.getInstance("AES");
SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
sr.setSeed(password);
kgen.init(256, sr); // 192 and 256 bits may not be available
SecretKey skey = kgen.generateKey();
byte[] key = skey.getEncoded();
SecretKeySpec skeySpec = new SecretKeySpec(key, "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE, skeySpec, ivSpec);
String decrypted = new String(cipher.doFinal(encrypted));
return decrypted;
}
I suspect that the bug generateKey.
You're doing two things wrong:
Generating a key from a password by using the key to seed a PRNG is a bad idea. Use password-based-encryption instead. Java has an implementation of PKCS#5 that will generate a key from a password.
You need to use a new strong-random IV for each encryption:
When you encrypt, don't specify an IV in cipher.init(). A new one will be generated for you.
encrypt() needs to serialise both the IV (cipher.getIV()) and the ciphertext into a byte array.
decrypt(): separate the IV from the ciphertext, build an IvParameterSpec from it and feed into cipher.init() as you currently do.
Your issues is that when you decrypt, you generate a new secret key instead of deriving it from password. Check out this blog post to see how password-based encryption has to be implemented. There are examples of encryption and decryption functions.
Replace the below line:
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
with below line:
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding","BC");
I am doing a simple implementation for AES Algorithm.
// Get the Key Generator
KeyGenerator kgen = KeyGenerator.getInstance("AES");
kgen.init(128); // 192 and 256 bits may not be available
// Generate the secret key specs.
SecretKey secret = kgen.generateKey();
byte[] raw = secret.getEncoded();
String key = new String(Base64.encodeBase64(raw));
I am saving "key" in database.
Now again in another operation i am fetching a "key" from database n trying to decrypt data. i call decryption function as
String dencryptReq = Utils.decrypt2(new String(Base64.decodeBase64(secretKeyInformation.getSecretKey().getBytes())),Base64.decodeBase64(encryptReq.getBytes()) );
public static String decrypt2(String key, byte[] encrypted)
throws GeneralSecurityException {
byte[] raw = Base64.decodeBase64(key.getBytes());
if (raw.length != 16) {
throw new IllegalArgumentException("Invalid key size.");
}
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE, skeySpec,
new IvParameterSpec(new byte[16]));
byte[] original = cipher.doFinal(encrypted);
return new String(original, Charset.forName("US-ASCII"));
}
But it is throwing me invalid key size exception.
If i do in one time this without saving in databse and fetching from database it is working fine.
I have tried your code with some modifications I have used apache commons codec library for Base64 conversion,
/* Derive the key, given password and salt. */
SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
KeySpec spec = new PBEKeySpec("password".toCharArray(), "salt".getBytes(), 65536, 128);
SecretKey tmp = factory.generateSecret(spec);
SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");
/* Encrypt the message. */
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, secret);
AlgorithmParameters params = cipher.getParameters();
byte[] iv = params.getParameterSpec(IvParameterSpec.class).getIV();
byte[] ciphertext = cipher.doFinal("Hello, World! My data is here.. !".getBytes("UTF-8"));
System.out.println("cipher :"+new String(ciphertext));
/*String-key convertion */
String stringKey=Base64.encodeBase64String(secret.getEncoded());//To String key
byte[] encodedKey = Base64.decodeBase64(stringKey.getBytes());
SecretKey originalKey = new SecretKeySpec(encodedKey, 0, encodedKey.length, "AES");// Convert from string
/* Decrypt the message, given derived key and initialization vector. */
Cipher cipher1 = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher1.init(Cipher.DECRYPT_MODE, originalKey, new IvParameterSpec(iv));
String plaintext = new String(cipher1.doFinal(ciphertext), "UTF-8");
System.out.println(plaintext);
This code worked perfectly in my system.
I have generated on my android application a pair of RSA Keys.
I receive from a web service
- an AES Key, encrypted with my RSA public key
- a String encoded with the AES key.
So I must do the following:
- decrypt the AES Key
- decrypt the string with the obtained AES Key.
To generate the RSA Keys I did:
keyGen = KeyPairGenerator.getInstance("RSA");
keyGen.initialize(size);
keypair = keyGen.genKeyPair();
privateKey = keypair.getPrivate();
publicKey = keypair.getPublic();
On RSA decrypt I use :
public static byte[] decryptRSA( PrivateKey key, byte[] text) throws Exception
{
byte[] dectyptedText = null;
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.DECRYPT_MODE, key);
dectyptedText = cipher.doFinal(text);
return dectyptedText;
}
On AES decrypt I use:
public static byte[] decryptAES(byte[] key, byte[] text) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(key, "AES");
Cipher cipher = Cipher.getInstance("AES/ECB/PKCS1Padding");
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
byte[] decrypted = cipher.doFinal(text);
return decrypted;
}
So, in my code, to obtain the decrypted AES Key I do
byte[] decryptedAESKey = sm.decryptRSA(key, Base64.decode(ReceivedBase64EncryptedAESKey));
byte[] decryptedString = sm.decryptAES(decryptedAESKey, Base64.decode(ReceivedEncryptedAESString));
On the end I get a null for decryptedString.
What am I doing wrong ?
Well, the thing is that the key decrypted was 8 byte long and I had to make it 16 byte to be AES 128 bits compatible
So, I made a method to convert it back
private static byte[] GetKey(byte[] suggestedKey)
{
byte[] kRaw = suggestedKey;
ArrayList<Byte> kList = new ArrayList<Byte>();
for (int i = 0; i < 128; i += 8)
{
kList.add(kRaw[(i / 8) % kRaw.length]);
}
byte[] byteArray = new byte[kList.size()];
for(int i = 0; i<kList.size(); i++){
byteArray[i] = kList.get(i);
}
return byteArray;
}
And the rewritten decrypt method:
public static byte[] decryptAES(byte[] key, byte[] text) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(GetKey(key), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding","BC");
byte [] iv = new byte[cipher.getBlockSize()];
for(int i=0;i<iv.length;i++)iv[i] = 0;
IvParameterSpec ivSpec = new IvParameterSpec(iv);
cipher.init(Cipher.DECRYPT_MODE, skeySpec, ivSpec);
byte[] decrypted = cipher.doFinal(text);
return decrypted;
}
I'm not sure what language or libraries you are using (looks like Java?), but some really general things to try:
Did you get the encrypted string, ok? Check the length of ReceivedEncryptedAESString and the output of the Base64.decode to check they look alright.
AES decryption can't fail so it must be a problem in the library initialisation. Check the value/state of cipher after the construction step and the init step.
Try a simpler testcase: ignore the RSA encryption and just try to decrypt something using your Cipher object.