I have Java code sitting on a server for decrypting data that I am trying to run locally for some testing. The code runs fine on the server but throws an error in my local build.
ECB mode cannot use IV
public static String triple_des_decrypt(String key, String data)
{
try
{
//needs to have an even number of digits
if (key.length() % 2 == 1)
{
key = "0" + key;
}
byte[] desKey = Hex.decodeHex(key.toCharArray());
// pad out key for cipher routine
int deskeyLength = desKey.length;
byte[] desKey24 = new byte[24];
int copySize = 16;
if (copySize > deskeyLength)
{
copySize = deskeyLength;
}
System.arraycopy(desKey, 0, desKey24, 0, copySize);
copySize = 8;
if (copySize > deskeyLength)
{
copySize = deskeyLength;
}
System.arraycopy(desKey, 0, desKey24, 16, 8);
DESedeKeySpec keySpec = new DESedeKeySpec(desKey24);
Cipher cipher = Cipher.getInstance("DESede/ECB/NoPadding");
String algo = "DESede";
SecretKey secretKey = SecretKeyFactory.getInstance(algo).generateSecret(keySpec);
IvParameterSpec iv = new IvParameterSpec(new byte[8]);
cipher.init(Cipher.DECRYPT_MODE, secretKey, iv); //Error thrown here
byte[] byteData = Hex.decodeHex(data.toCharArray());
byte[] decryptedData = cipher.doFinal(byteData);
char tempString[] = Hex.encodeHex(decryptedData);
String decryptedString = new String(tempString).toUpperCase();
return decryptedString;
}
catch (Exception e)
{
throw new RuntimeException(e);
}
}
I'm not familiar with encryption and I'm at a loss as to why this error is thrown.
Edit Removing the IV parameter from cipher.init fixes the issue, but I'm still curious as to why no error is thrown in a different environment.
ECB doesn't perform chaining between blocks so there is no way to use initialization vector (wiki). Therefore, you get the error message that ECB mode cannot use IV
Related
I have a c# code which does the encryption and a java code which decrypt, but in Java I get
"Given final block not properly padded. Such issues can arise if a bad key is used during decryption".
But if I encrypt in JAVA and decrypt in JAVA , it works fine. Please help I am stuck since a week.
I read PKCS5Padding and PKCS7Padding both are same in JAVA, is it true?
to try with PKCS7Padding in Java, I used bouncy Castle but that gave below error
" BadPaddingException: pad block corrupted"
C# Encryption Logic:
string Encrypt(string textToEncrypt, string key)
{
RijndaelManaged rijndaelCipher = new RijndaelManaged();
rijndaelCipher.Mode = CipherMode.CBC;
rijndaelCipher.Padding = PaddingMode.PKCS7;
rijndaelCipher.KeySize = 0x80;
rijndaelCipher.BlockSize = 0x80;
byte[] pwdBytes = Encoding.UTF8.GetBytes(key);
byte[] keyBytes = new byte[0x10];
int len = pwdBytes.Length;
if (len > keyBytes.Length)
{
len = keyBytes.Length;
}
Array.Copy(pwdBytes, keyBytes, len);
rijndaelCipher.Key = keyBytes;
rijndaelCipher.IV = keyBytes;
ICryptoTransform transform = rijndaelCipher.CreateEncryptor();
byte[] plainText = Encoding.UTF8.GetBytes(textToEncrypt);
return Convert.ToBase64String(transform.TransformFinalBlock(plainText, 0, plainText.Length));
}
Java Decryption Logic
public String decryptInputData(String encryptedRequest, String key1) {
byte[] cipherData = Base64.getDecoder().decode(encryptedRequest);
byte[] keyByte = key1.getBytes(StandardCharsets.UTF_8);
byte[] IV=new byte[16];
SecretKeySpec key = new SecretKeySpec(keyByte, "AES");
IvParameterSpec iv = new IvParameterSpec(IV);
Cipher aesCBC;
try {
aesCBC = Cipher.getInstance("AES/CBC/PKCS5Padding");
aesCBC.init(Cipher.DECRYPT_MODE, key, iv);
byte[] decryptedData = aesCBC.doFinal(cipherData);
return new String(decryptedData, StandardCharsets.UTF_8);
} catch (NoSuchAlgorithmException | NoSuchPaddingException |InvalidKeyException | InvalidAlgorithmParameterException |IllegalBlockSizeException | BadPaddingException e) {
e.printStackTrace();
return null;
}
}
Test Data:
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
Key:TL3U2HAQJZ79F8O5X4CNW6S10IEKGPYB
PlainText:
Salutation=MRS|Customer_Name=ITMSYAR EBMEEN|Address=ABCD EFG~WERT|City=GHTTG|Pin_Code=310012|State=WERY|DOB=1900-02-19|Gender=F|Mobile_Number=010007000007|Nationality=IN|Email_Address=ABCDEFG#GMAIL.COM|Marital_Status=Y|Occupation_Type=Housewife|PAN_Number=AOIPM1619P|Nominee_Name=|Nominee_DOB=|Relationship_of_Nominee=|Timestamp=7/26/2022 11:06:16 AM|Website_Ref_No=1zEeSs97MAao5UIi|CRM_Lead_Id=9121421421|Source_Id=MB_LoggedIn|Referral_Code=123456|utm_source=|utm_medium=|utm_campaign=|Product_Name=Group Active Health Plan|Partner_Name=ABCD|SP_Code=|LG_SOL_ID=002|Producer_Code=202324134|EBCC_Flag=N|Scheme_Code=FSGSW|CKYC_NO=|Acc_No=1234567889|Acc_Type=Main|
I trying to implement this same code to encrypt on c# but always i get some different encrypted code :
This is my Java class :
public class AES256 {
private static final String SECRET_KEY = "my_super_secret_key_ho_ho_ho";
private static final String SALT = "ssshhhhhhhhhhh!!!!";
public static String encrypt(String strToEncrypt) {
try {
byte[] iv = "1234567891234567".getBytes("UTF-8");
IvParameterSpec ivspec = new IvParameterSpec(iv);
SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
KeySpec spec = new PBEKeySpec(SECRET_KEY.toCharArray(), SALT.getBytes(), 65536, 256);
SecretKey tmp = factory.generateSecret(spec);
SecretKeySpec secretKey = new SecretKeySpec(tmp.getEncoded(), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, secretKey, ivspec);
return Base64.getEncoder()
.encodeToString(cipher.doFinal(strToEncrypt.getBytes(StandardCharsets.UTF_8)));
} catch (Exception e) {
System.out.println("Error while encrypting: " + e.toString());
}
return null;
}
}
How can i implement the same on c#? i usig this as a model -> c# AES Encrypt but the result is diffetent even using the same secret , salt ,interaction hash count
This what i have on c# :
var passPhrase = "my_super_secret_key_ho_ho_ho";
// Initialization Vector (16 bit length)
var iv = "1234567891234567";
// Encrypt & Decrypt (with advanced settings)
var opts = new AESCryptOptions()
{
PasswordHash = AESPasswordHash.SHA1,
PasswordHashIterations = 65536,
PasswordHashSalt = "ssshhhhhhhhhhh!!!!",
PaddingMode = PaddingMode.PKCS7,
MinSaltLength = 4,
MaxSaltLength = 16,
FixedKeySize=256
};
var encryptedText = new AESCrypt(passPhrase, iv, opts).Encrypt(text);
And the encrypt Method, i changed the hash to sha256, the only change made from the implement from gitHub:
PasswordDeriveBytes password = new PasswordDeriveBytes(
passPhrase,
saltValueBytes,
("SHA256"),
Options.PasswordHashIterations);
// Convert key to a byte array adjusting the size from bits to bytes.
keyBytes = password.GetBytes(keySize / 8);
I have the following code for encrypt
public static String encrypt(String value, char[] secret) {
try {
final byte[] bytes = value != null ? value.getBytes(StandardCharsets.UTF_8) : new byte[0];
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBEWithMD5AndDES");
SecretKey key = keyFactory.generateSecret(new PBEKeySpec(secret));
Cipher pbeCipher = Cipher.getInstance("PBEWithMD5AndDES");
pbeCipher.init(Cipher.ENCRYPT_MODE, key, new PBEParameterSpec(IsoGame.$().crossPlatformManager.getCrossPlatformUtilsInstance().getDeviceUniqueIdentifier().getBytes(StandardCharsets.UTF_8), 20));
return new String(Base64.encodeBase64(pbeCipher.doFinal(bytes)), StandardCharsets.UTF_8);
} catch (Exception e) {
e.printStackTrace();
}
return value;
}
and the following code for decrypt.
public static String decrypt(String value, char[] secret) {
try {
final byte[] bytes = value != null ? Base64.decodeBase64(value.getBytes(StandardCharsets.UTF_8)) : new byte[0];
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBEWithMD5AndDES");
SecretKey key = keyFactory.generateSecret(new PBEKeySpec(secret));
Cipher pbeCipher = Cipher.getInstance("PBEWithMD5AndDES");
pbeCipher.init(Cipher.DECRYPT_MODE, key, new PBEParameterSpec(IsoGame.$().crossPlatformManager.getCrossPlatformUtilsInstance().getDeviceUniqueIdentifier().getBytes(StandardCharsets.UTF_8), 20));
return new String(pbeCipher.doFinal(bytes), StandardCharsets.UTF_8);
} catch (Exception e) {
e.printStackTrace();
}
return value;
}
However, sometimes the exception is being thrown at
pbeCipher.doFinal(bytes)
in decrypt method.
The exception is javax.crypto.BadPaddingException: pad block corrupted
It's strange, as I'm getting this exception sometimes with the same values .
Any ideas?
Thanks.
The most likely reason would simply be the wrong password to be supplied. If the wrong password is supplied then the wrong key is derived. Then the ciphertext will be decrypted to garbage plaintext. This will only be noticed if the padding exception gets thrown: unpadding random bytes is likely to fail.
You could e.g. first validate that the derived key is correct by performing a HMAC over known data using the derived key. In addition, it would be a good idea to use some kind of authenticated encryption, so that if the key or data is wrong or corrupted that decryption does indeed fail. If you're unlucky then - at this time - the data will decrypt, unpadding will succeed and you end up with garbage plaintext.
Of course, you'd better upgrade to PBKDF2 for key derivation, and upgrade AES to e.g. AES-GCM instead of DES. Currently your encryption is entirely insecure, even if you use a strong password.
Your problem is
IsoGame.$().crossPlatformManager.getCrossPlatformUtilsInstance().getDeviceUniqueIdentifier().getBytes(StandardCharsets.UTF_8)
I have ran the following code multiple times and no exception occurred and the decrypted data was equal to "Hello there!":
public static void main(String[] args)
{
new CryptographyError();
}
private CryptographyError()
{
char[] secret = "MySecret".toCharArray();
String mesasge = "Hello there!";
EncryptedData encryptedData = encrypt(mesasge, secret);
System.out.println("ENCRYPTED " + encryptedData.encryptedString);
String decrypted = decrypt(encryptedData, secret);
System.out.println("DECRYPTED " + decrypted);
}
private static final SecureRandom RANDOM = new SecureRandom();
public static EncryptedData encrypt(String value, char[] secret) {
try {
final byte[] bytes = value != null ? value.getBytes(StandardCharsets.UTF_8) : new byte[0];
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBEWithMD5AndDES");
SecretKey key = keyFactory.generateSecret(new PBEKeySpec(secret));
Cipher pbeCipher = Cipher.getInstance("PBEWithMD5AndDES");
byte[] salt = new byte[8];
RANDOM.nextBytes(salt);
pbeCipher.init(Cipher.ENCRYPT_MODE, key, new PBEParameterSpec(salt, 20));
return new EncryptedData(salt, new String(Base64.getEncoder().encode(pbeCipher.doFinal(bytes)), StandardCharsets.UTF_8));
} catch (Exception e) {
e.printStackTrace();
System.out.println(value);
}
return null;
}
public static String decrypt(EncryptedData encryptedData, char[] secret) {
try {
String value = encryptedData.encryptedString;
byte[] salt = encryptedData.salt;
final byte[] bytes = value != null ? Base64.getDecoder().decode(value.getBytes(StandardCharsets.UTF_8)) : new byte[0];
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBEWithMD5AndDES");
SecretKey key = keyFactory.generateSecret(new PBEKeySpec(secret));
Cipher pbeCipher = Cipher.getInstance("PBEWithMD5AndDES");
pbeCipher.init(Cipher.DECRYPT_MODE, key, new PBEParameterSpec(salt, 20));
return new String(pbeCipher.doFinal(bytes), StandardCharsets.UTF_8);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
private static class EncryptedData
{
private final byte[] salt;
private final String encryptedString;
private EncryptedData(byte[] salt, String encryptedString)
{
this.salt = salt;
this.encryptedString = encryptedString;
}
}
The only main difference between my code and your code is
IsoGame.$().crossPlatformManager.getCrossPlatformUtilsInstance().getDeviceUniqueIdentifier().getBytes(StandardCharsets.UTF_8)
which means that must not return the same value on encryption and decryption.
Also if you want to test this you can just change the salt between them and notice the exception is thrown again.
Also Maarten Bodewes gave you some good notes about how to improve your code.
I'm currently running into an issue where our decryption portion of our C# site is having trouble with the padding with the encrypted string from java. The .Net code throws this error "Padding is invalid and cannot be removed". The _signKey and _encKey are both 64 bytes.
public String encryptString(String plainText) {
byte[] ciphertext;
byte[] iv = new byte[16];
byte[] plainBytes = plainText.getBytes(StandardCharsets.UTF_8);
String _signKey = "****************************************************************";
String _encKey = "****************************************************************";
try {
Mac sha256 = Mac.getInstance("HmacSHA256");
SecretKeySpec shaKS = new SecretKeySpec(_signKey.getBytes(StandardCharsets.UTF_8), "HmacSHA256");
sha256.init(shaKS);
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
SecureRandom randomSecureRandom = SecureRandom.getInstance("SHA1PRNG");
iv = new byte[cipher.getBlockSize()];
randomSecureRandom.nextBytes(iv);
IvParameterSpec ivParams = new IvParameterSpec(iv);
byte[] sessionKey = sha256.doFinal((_encKey + iv).getBytes(StandardCharsets.UTF_8));
// Perform Encryption
SecretKeySpec eks = new SecretKeySpec(sessionKey, "AES");
cipher.init(Cipher.ENCRYPT_MODE, eks, ivParams);
ciphertext = cipher.doFinal(plainBytes);
System.out.println("ciphertext= " + new String(ciphertext));
// Perform HMAC using SHA-256 on ciphertext
SecretKeySpec hks = new SecretKeySpec(_signKey.getBytes(StandardCharsets.UTF_8), "HmacSHA256");
Mac mac = Mac.getInstance("HmacSHA256");
mac.init(hks);
ByteArrayOutputStream outputStream2 = new ByteArrayOutputStream();
outputStream2.write(iv);
outputStream2.write(ciphertext);
outputStream2.flush();
outputStream2.write(mac.doFinal(outputStream2.toByteArray()));
return Base64.encodeBase64String(outputStream2.toByteArray());
} catch (Exception e) {
e.printStackTrace();
}
return plainText;
}
Does does encrypt the string properly as far as I can tell. We cannot change any code on the .Net side to decrypt this because this is being used today.
public static string DecryptString(string ciphertext)
{
using (HMACSHA256 sha256 = new HMACSHA256(Encoding.UTF8.GetBytes(_signKey)))
{
// Convert message to bytes
byte[] encBytes = Convert.FromBase64String(ciphertext);
// Get arrays for comparing HMAC tags
byte[] sentTag = new byte[sha256.HashSize / 8];
byte[] calcTag = sha256.ComputeHash(encBytes, 0, (encBytes.Length - sentTag.Length));
// If message length is too small return null
if (encBytes.Length < sentTag.Length + _ivLength) { return null; }
// Copy tag from end of encrypted message
Array.Copy(encBytes, (encBytes.Length - sentTag.Length), sentTag, 0, sentTag.Length);
// Compare tags with constant time comparison, return null if no match
int compare = 0;
for (int i = 0; i < sentTag.Length; i++) { compare |= sentTag[i] ^ calcTag[i]; }
if (compare != 0) { return null; }
using (AesCryptoServiceProvider csp = new AesCryptoServiceProvider())
{
// Set parameters
csp.BlockSize = _blockBits;
csp.KeySize = _keyBits;
csp.Mode = CipherMode.CBC;
csp.Padding = PaddingMode.PKCS7;
// Copy init vector from message
var iv = new byte[_ivLength];
Array.Copy(encBytes, 0, iv, 0, iv.Length);
// Derive session key
byte[] sessionKey = sha256.ComputeHash(Encoding.UTF8.GetBytes(_encKey + iv));
// Decrypt message
using (ICryptoTransform decrypt = csp.CreateDecryptor(sessionKey, iv))
{
return Encoding.UTF8.GetString(decrypt.TransformFinalBlock(encBytes, iv.Length, encBytes.Length - iv.Length - sentTag.Length));
}
}
}
}
If there is anything that sticks out it would be appreciated for the reply.
I didn't read all your code, but this line in Java:
byte[] sessionKey = sha256.doFinal((_encKey + iv).getBytes(StandardCharsets.UTF_8));
does nothing useful or sensible. The "+" operator does string concatenation, but iv is a byte[], not a String. So java uses iv.toString(), which simply returns a String containing something like [B#1188e820 which is meaningless in this context.
Refer four java code and DotNet code:
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding"); //Java
csp.Padding = PaddingMode.PKCS7; //.Net
You are essentially using different padding, that is the probable source of error; however, there is an alternate view, Refer this great post and this for general fundamentals on padding
The cipher suites supported by deafult Oracle JVM implementation are here
If you notice it does not have 'AES/CBC/PKCS7Padding', a PKCS#7 padding implementation is available in sun.security package, refer this, otherwise you could use Bouncy Castle packages. It would be recommendable to use Bouncy Castle as com.sun package are generally considered unsupported.
I want to convert String to secretKey
public void generateCode(String keyStr){
KeyGenerator kgen = KeyGenerator.getInstance("AES");
kgen.init(128); // 192 and 256 bits may not be available
// Generate the secret key specs.
secretKey skey=keyStr; //How can I make the casting here
//SecretKey skey = kgen.generateKey();
byte[] raw = skey.getEncoded();
}
I try to use BASE64Decoder instead of secretKey, but I face a problem which is I cannot specify key length.
EDIT:
I want to call this function from another place
static public String encrypt(String message , String key , int keyLength) throws Exception {
// Get the KeyGenerator
KeyGenerator kgen = KeyGenerator.getInstance("AES");
kgen.init(keyLength); // 192 and 256 bits may not be available
// Generate the secret key specs.
SecretKey skey = key; //here is the error
byte[] raw = skey.getEncoded();
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
// Instantiate the cipher
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
System.out.println("msg is" + message + "\n raw is" + raw);
byte[] encrypted = cipher.doFinal(message.getBytes());
String cryptedValue = new String(encrypted);
System.out.println("encrypted string: " + cryptedValue);
return cryptedValue;
}
If anybody could help, I'd be very thankful.
No integrity checks, for these particular reasons
The need is not apparent from the use case.
"AES/GCM/NoPadding" mode is only available from Java 7 onward
It depends on the user if they want to deploy e.g. HMAC and/or AESCMAC (recommended).
It would require an additional key at the minimum, and two full passes.
If you got an implementation of GCM mode at both sides - e.g. using Bouncy Castle on Java 6 - please go for it, as it is much more secure (as long as the "IV" is really unique). It should be really easy to change the implementation.
Implementation notes regarding encryption
This implementation is not safe when used in an unrestricted client / server role because of padding oracle attacks (they require 128 tries per byte or lower, on average, independent of algorithm or key size). You will need to use a MAC, HMAC or Signature over the encrypted data, and verify it before decrypting to deploy it in client/server mode.
Decrypt will return null if decryption fails. This can only indicate a padding exception, which should be adequately handled (did I warn about padding oracle attacks?)
Invalid keys will be returned as InvalidArgumentException.
All other security related exceptions are "swept under the table" as it means that the Java runtime environment is invalid. For example, supporting "UTF-8" and "AES/CBC/PKCS5Padding" is required for every Java SE implementation.
Some other notes
Please don't try the opposite and insert bytes directly into the input string of the encrypt method (using new String(byte[]) for instance). The method may fail silently!
Optimized for readability. Go for Base64 stream and CipherStream implementations if you rather prefer speed and better memory footprint.
You need at least Java 6 SE or compatible to run this code.
Encryption/decryption may fail for AES key sizes over 128 bit as you may need policy files for unrestricted encryption (available from Oracle)
Beware of governmental regulations when exporting encryption.
This implementation uses hex keys instead of base64 keys as they are small enough, and hex is just easier to edit/verify manually.
Used hex and base64 encoding/decoding retrieved from the JDK, no external libraries needed whatsoever.
Uber simple to use, but of course not very object oriented, no caching of object instances used in encrypt/decrypt. Refactor at will.
OK, here comes some code...
public static String encrypt(final String plainMessage,
final String symKeyHex) {
final byte[] symKeyData = DatatypeConverter.parseHexBinary(symKeyHex);
final byte[] encodedMessage = plainMessage.getBytes(Charset
.forName("UTF-8"));
try {
final Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
final int blockSize = cipher.getBlockSize();
// create the key
final SecretKeySpec symKey = new SecretKeySpec(symKeyData, "AES");
// generate random IV using block size (possibly create a method for
// this)
final byte[] ivData = new byte[blockSize];
final SecureRandom rnd = SecureRandom.getInstance("SHA1PRNG");
rnd.nextBytes(ivData);
final IvParameterSpec iv = new IvParameterSpec(ivData);
cipher.init(Cipher.ENCRYPT_MODE, symKey, iv);
final byte[] encryptedMessage = cipher.doFinal(encodedMessage);
// concatenate IV and encrypted message
final byte[] ivAndEncryptedMessage = new byte[ivData.length
+ encryptedMessage.length];
System.arraycopy(ivData, 0, ivAndEncryptedMessage, 0, blockSize);
System.arraycopy(encryptedMessage, 0, ivAndEncryptedMessage,
blockSize, encryptedMessage.length);
final String ivAndEncryptedMessageBase64 = DatatypeConverter
.printBase64Binary(ivAndEncryptedMessage);
return ivAndEncryptedMessageBase64;
} catch (InvalidKeyException e) {
throw new IllegalArgumentException(
"key argument does not contain a valid AES key");
} catch (GeneralSecurityException e) {
throw new IllegalStateException(
"Unexpected exception during encryption", e);
}
}
public static String decrypt(final String ivAndEncryptedMessageBase64,
final String symKeyHex) {
final byte[] symKeyData = DatatypeConverter.parseHexBinary(symKeyHex);
final byte[] ivAndEncryptedMessage = DatatypeConverter
.parseBase64Binary(ivAndEncryptedMessageBase64);
try {
final Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
final int blockSize = cipher.getBlockSize();
// create the key
final SecretKeySpec symKey = new SecretKeySpec(symKeyData, "AES");
// retrieve random IV from start of the received message
final byte[] ivData = new byte[blockSize];
System.arraycopy(ivAndEncryptedMessage, 0, ivData, 0, blockSize);
final IvParameterSpec iv = new IvParameterSpec(ivData);
// retrieve the encrypted message itself
final byte[] encryptedMessage = new byte[ivAndEncryptedMessage.length
- blockSize];
System.arraycopy(ivAndEncryptedMessage, blockSize,
encryptedMessage, 0, encryptedMessage.length);
cipher.init(Cipher.DECRYPT_MODE, symKey, iv);
final byte[] encodedMessage = cipher.doFinal(encryptedMessage);
// concatenate IV and encrypted message
final String message = new String(encodedMessage,
Charset.forName("UTF-8"));
return message;
} catch (InvalidKeyException e) {
throw new IllegalArgumentException(
"key argument does not contain a valid AES key");
} catch (BadPaddingException e) {
// you'd better know about padding oracle attacks
return null;
} catch (GeneralSecurityException e) {
throw new IllegalStateException(
"Unexpected exception during decryption", e);
}
}
Usage:
String plain = "Zaphod's just zis guy, ya knöw?";
String encrypted = encrypt(plain, "000102030405060708090A0B0C0D0E0F");
System.out.println(encrypted);
String decrypted = decrypt(encrypted, "000102030405060708090A0B0C0D0E0F");
if (decrypted != null && decrypted.equals(plain)) {
System.out.println("Hey! " + decrypted);
} else {
System.out.println("Bummer!");
}
Here's the version using Base64 Util class instead of DatatypeConverter
public static String encrypt(final String plainMessage,
final String symKeyHex) {
final byte[] symKeyData = Base64.decode(symKeyHex,Base64.DEFAULT);
final byte[] encodedMessage = plainMessage.getBytes(Charset
.forName("UTF-8"));
try {
final Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
final int blockSize = cipher.getBlockSize();
// create the key
final SecretKeySpec symKey = new SecretKeySpec(symKeyData, "AES");
// generate random IV using block size (possibly create a method for
// this)
final byte[] ivData = new byte[blockSize];
final SecureRandom rnd = SecureRandom.getInstance("SHA1PRNG");
rnd.nextBytes(ivData);
final IvParameterSpec iv = new IvParameterSpec(ivData);
cipher.init(Cipher.ENCRYPT_MODE, symKey, iv);
final byte[] encryptedMessage = cipher.doFinal(encodedMessage);
// concatenate IV and encrypted message
final byte[] ivAndEncryptedMessage = new byte[ivData.length
+ encryptedMessage.length];
System.arraycopy(ivData, 0, ivAndEncryptedMessage, 0, blockSize);
System.arraycopy(encryptedMessage, 0, ivAndEncryptedMessage,
blockSize, encryptedMessage.length);
final String ivAndEncryptedMessageBase64 = Base64.encodeToString(ivAndEncryptedMessage,Base64.DEFAULT);
return ivAndEncryptedMessageBase64;
} catch (InvalidKeyException e) {
throw new IllegalArgumentException(
"key argument does not contain a valid AES key");
} catch (GeneralSecurityException e) {
throw new IllegalStateException(
"Unexpected exception during encryption", e);
}
}
public static String decrypt(final String ivAndEncryptedMessageBase64,
final String symKeyHex) {
final byte[] symKeyData = Base64.decode((symKeyHex),Base64.DEFAULT);
final byte[] ivAndEncryptedMessage = Base64.decode(ivAndEncryptedMessageBase64,Base64.DEFAULT);
try {
final Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
final int blockSize = cipher.getBlockSize();
// create the key
final SecretKeySpec symKey = new SecretKeySpec(symKeyData, "AES");
// retrieve random IV from start of the received message
final byte[] ivData = new byte[blockSize];
System.arraycopy(ivAndEncryptedMessage, 0, ivData, 0, blockSize);
final IvParameterSpec iv = new IvParameterSpec(ivData);
// retrieve the encrypted message itself
final byte[] encryptedMessage = new byte[ivAndEncryptedMessage.length
- blockSize];
System.arraycopy(ivAndEncryptedMessage, blockSize,
encryptedMessage, 0, encryptedMessage.length);
cipher.init(Cipher.DECRYPT_MODE, symKey, iv);
final byte[] encodedMessage = cipher.doFinal(encryptedMessage);
// concatenate IV and encrypted message
final String message = new String(encodedMessage,
Charset.forName("UTF-8"));
return message;
} catch (InvalidKeyException e) {
throw new IllegalArgumentException(
"key argument does not contain a valid AES key");
} catch (BadPaddingException e) {
// you'd better know about padding oracle attacks
return null;
} catch (GeneralSecurityException e) {
throw new IllegalStateException(
"Unexpected exception during decryption", e);
}
}
Just a reminder for those who get a Padding exception. Make sure you are using the correct Key length. Hint: look at Maarten's post: his hex is exactly 32 ;) That's no coincidence :)