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I'm completely new with encryption stuff and i have some questions about encryption in java
I use to do this for RSA encryption in java
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPTION_MODE,publicKey);
byte result = cipher.doFinal(data);
and same way to use AES and I use this code to generate a AES key
SecureRandom random = new SecureRandom();
byte [] key = new byte [16];
random.nextByte(key);
SecretKeySpec secretKey = new SecretKeySpec(key,"AES");
but as i saw in other programs code this is not how they use encryption i always see they use something as IV param in AES and they never use "AES" or "RSA" to get a cipher instance.
Is the way i using to encrypt data safe?
I'm sure that i missing something
UPDATE:
I also have a question about changing data size in AES encryption in the way that i use to encrypt data with AES it changes the data size from 1024 to 1040
byte key [] = new byte[16];
SecureRandom random = new SecureRandom();
random.nextBytes(key);
SecretKeySpec keySpec = new SecretKeySpec(key,"AES");
Cipher c = Cipher.getInstance("AES");
c.init(Cipher.ENCRYPT_MODE,keySpec);
FileInputStream in = new FileInputStream("test.txt");
byte [] buffer = new byte[1024];
byte [] encrypted;
while (in.read()>0){
encrypted = c.doFinal(buffer);
System.out.println(encrypted.length);
}
the out put is:
1040
1040
.
.
1040
Simply encrypted data size is always 16 bytes more than original data
Do i have to deal with this or it's because i using Cipher.getInstance("AES");
This is not the recommended way and you will need to change it. You may want to have a better look on StackOverflow. Your question is (in)directly answered in this post How to encrypt String in Java.
Make sure you look further down to all the answers. For example this one will probably help you to understand more.
The most simple is to use the below class
package com.toptal.gif_downloader.tools;
import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import java.util.Base64;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
public class CipherDecrypt {
private static SecretKeySpec secretKey;
private static byte[] key;
public static void setKey(final String myKey) {
MessageDigest sha = null;
try {
key = myKey.getBytes("UTF-8");
sha = MessageDigest.getInstance("SHA-1");
key = sha.digest(key);
key = Arrays.copyOf(key, 16);
secretKey = new SecretKeySpec(key, "AES");
} catch (NoSuchAlgorithmException | UnsupportedEncodingException e) {
e.printStackTrace();
}
}
public static String Encrypt(final String strToEncrypt, final String secret) {
try {
setKey(secret);
Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, secretKey);
return Base64.getEncoder()
.encodeToString(cipher.doFinal(strToEncrypt.getBytes("UTF-8")));
} catch (Exception e) {
System.out.println("Error while encrypting: " + e.toString());
}
return null;
}
public static String Decrypt(final String strToDecrypt, final String secret) {
try {
setKey(secret);
Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5PADDING");
cipher.init(Cipher.DECRYPT_MODE, secretKey);
return new String(cipher.doFinal(Base64.getDecoder()
.decode(strToDecrypt)));
} catch (Exception e) {
System.out.println("Error while decrypting: " + e.toString());
}
return null;
}
}
What's wrong with the following example?
The problem is that the first part of the decrypted string is nonsense. However, the rest is fine, I get...
Result: `£eB6O�geS��i are you? Have a nice day.
#Test
public void testEncrypt() {
try {
String s = "Hello there. How are you? Have a nice day.";
// Generate key
KeyGenerator kgen = KeyGenerator.getInstance("AES");
kgen.init(128);
SecretKey aesKey = kgen.generateKey();
// Encrypt cipher
Cipher encryptCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
encryptCipher.init(Cipher.ENCRYPT_MODE, aesKey);
// Encrypt
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
CipherOutputStream cipherOutputStream = new CipherOutputStream(outputStream, encryptCipher);
cipherOutputStream.write(s.getBytes());
cipherOutputStream.flush();
cipherOutputStream.close();
byte[] encryptedBytes = outputStream.toByteArray();
// Decrypt cipher
Cipher decryptCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
IvParameterSpec ivParameterSpec = new IvParameterSpec(aesKey.getEncoded());
decryptCipher.init(Cipher.DECRYPT_MODE, aesKey, ivParameterSpec);
// Decrypt
outputStream = new ByteArrayOutputStream();
ByteArrayInputStream inStream = new ByteArrayInputStream(encryptedBytes);
CipherInputStream cipherInputStream = new CipherInputStream(inStream, decryptCipher);
byte[] buf = new byte[1024];
int bytesRead;
while ((bytesRead = cipherInputStream.read(buf)) >= 0) {
outputStream.write(buf, 0, bytesRead);
}
System.out.println("Result: " + new String(outputStream.toByteArray()));
}
catch (Exception ex) {
ex.printStackTrace();
}
}
Lot of people including myself face lot of issues in making this work due to missing some information like, forgetting to convert to Base64, initialization vectors, character set, etc. So I thought of making a fully functional code.
Hope this will be useful to you all:
To compile you need additional Apache Commons Codec jar, which is available here:
http://commons.apache.org/proper/commons-codec/download_codec.cgi
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import org.apache.commons.codec.binary.Base64;
public class Encryptor {
public static String encrypt(String key, String initVector, String value) {
try {
IvParameterSpec iv = new IvParameterSpec(initVector.getBytes("UTF-8"));
SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes("UTF-8"), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec, iv);
byte[] encrypted = cipher.doFinal(value.getBytes());
System.out.println("encrypted string: "
+ Base64.encodeBase64String(encrypted));
return Base64.encodeBase64String(encrypted);
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
public static String decrypt(String key, String initVector, String encrypted) {
try {
IvParameterSpec iv = new IvParameterSpec(initVector.getBytes("UTF-8"));
SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes("UTF-8"), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
cipher.init(Cipher.DECRYPT_MODE, skeySpec, iv);
byte[] original = cipher.doFinal(Base64.decodeBase64(encrypted));
return new String(original);
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
public static void main(String[] args) {
String key = "Bar12345Bar12345"; // 128 bit key
String initVector = "RandomInitVector"; // 16 bytes IV
System.out.println(decrypt(key, initVector,
encrypt(key, initVector, "Hello World")));
}
}
In this answer I choose to approach the "Simple Java AES encrypt/decrypt example" main theme and not the specific debugging question because I think this will profit most readers.
This is a simple summary of my blog post about AES encryption in Java so I recommend reading through it before implementing anything. I will however still provide a simple example to use and give some pointers what to watch out for.
In this example I will choose to use authenticated encryption with Galois/Counter Mode or GCM mode. The reason is that in most case you want integrity and authenticity in combination with confidentiality (read more in the blog).
AES-GCM Encryption/Decryption Tutorial
Here are the steps required to encrypt/decrypt with AES-GCM with the Java Cryptography Architecture (JCA). Do not mix with other examples, as subtle differences may make your code utterly insecure.
1. Create Key
As it depends on your use-case, I will assume the simplest case: a random secret key.
SecureRandom secureRandom = new SecureRandom();
byte[] key = new byte[16];
secureRandom.nextBytes(key);
SecretKey secretKey = SecretKeySpec(key, "AES");
Important:
always use a strong pseudorandom number generator like SecureRandom
use 16 byte / 128 bit long key (or more - but more is seldom needed)
if you want a key derived from a user password, look into a password hash function (or KDF) with stretching property like PBKDF2 or bcrypt
if you want a key derived from other sources, use a proper key derivation function (KDF) like HKDF (Java implementation here). Do not use simple cryptographic hashes for that (like SHA-256).
2. Create the Initialization Vector
An initialization vector (IV) is used so that the same secret key will create different cipher texts.
byte[] iv = new byte[12]; //NEVER REUSE THIS IV WITH SAME KEY
secureRandom.nextBytes(iv);
Important:
never reuse the same IV with the same key (very important in GCM/CTR mode)
the IV must be unique (ie. use random IV or a counter)
the IV is not required to be secret
always use a strong pseudorandom number generator like SecureRandom
12 byte IV is the correct choice for AES-GCM mode
3. Encrypt with IV and Key
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);
byte[] cipherText = cipher.doFinal(plainText);
Important:
use 16 byte / 128 bit authentication tag (used to verify integrity/authenticity)
the authentication tag will be automatically appended to the cipher text (in the JCA implementation)
since GCM behaves like a stream cipher, no padding is required
use CipherInputStream when encrypting large chunks of data
want additional (non-secret) data checked if it was changed? You may want to use associated data with cipher.updateAAD(associatedData); More here.
3. Serialize to Single Message
Just append IV and ciphertext. As stated above, the IV doesn't need to be secret.
ByteBuffer byteBuffer = ByteBuffer.allocate(iv.length + cipherText.length);
byteBuffer.put(iv);
byteBuffer.put(cipherText);
byte[] cipherMessage = byteBuffer.array();
Optionally encode with Base64 if you need a string representation. Either use Android's or Java 8's built-in implementation (do not use Apache Commons Codec - it's an awful implementation). Encoding is used to "convert" byte arrays to string representation to make it ASCII safe e.g.:
String base64CipherMessage = Base64.getEncoder().encodeToString(cipherMessage);
4. Prepare Decryption: Deserialize
If you have encoded the message, first decode it to byte array:
byte[] cipherMessage = Base64.getDecoder().decode(base64CipherMessage)
Important:
be careful to validate input parameters, so to avoid denial of service attacks by allocating too much memory.
5. Decrypt
Initialize the cipher and set the same parameters as with the encryption:
final Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
//use first 12 bytes for iv
AlgorithmParameterSpec gcmIv = new GCMParameterSpec(128, cipherMessage, 0, 12);
cipher.init(Cipher.DECRYPT_MODE, secretKey, gcmIv);
//use everything from 12 bytes on as ciphertext
byte[] plainText = cipher.doFinal(cipherMessage, 12, cipherMessage.length - 12);
Important:
don't forget to add associated data with cipher.updateAAD(associatedData); if you added it during encryption.
A working code snippet can be found in this gist.
Note that most recent Android (SDK 21+) and Java (7+) implementations should have AES-GCM. Older versions may lack it. I still choose this mode, since it is easier to implement in addition to being more efficient compared to similar mode of Encrypt-then-Mac (with e.g. AES-CBC + HMAC). See this article on how to implement AES-CBC with HMAC.
Here a solution without Apache Commons Codec's Base64:
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
public class AdvancedEncryptionStandard
{
private byte[] key;
private static final String ALGORITHM = "AES";
public AdvancedEncryptionStandard(byte[] key)
{
this.key = key;
}
/**
* Encrypts the given plain text
*
* #param plainText The plain text to encrypt
*/
public byte[] encrypt(byte[] plainText) throws Exception
{
SecretKeySpec secretKey = new SecretKeySpec(key, ALGORITHM);
Cipher cipher = Cipher.getInstance(ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE, secretKey);
return cipher.doFinal(plainText);
}
/**
* Decrypts the given byte array
*
* #param cipherText The data to decrypt
*/
public byte[] decrypt(byte[] cipherText) throws Exception
{
SecretKeySpec secretKey = new SecretKeySpec(key, ALGORITHM);
Cipher cipher = Cipher.getInstance(ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE, secretKey);
return cipher.doFinal(cipherText);
}
}
Usage example:
byte[] encryptionKey = "MZygpewJsCpRrfOr".getBytes(StandardCharsets.UTF_8);
byte[] plainText = "Hello world!".getBytes(StandardCharsets.UTF_8);
AdvancedEncryptionStandard advancedEncryptionStandard = new AdvancedEncryptionStandard(
encryptionKey);
byte[] cipherText = advancedEncryptionStandard.encrypt(plainText);
byte[] decryptedCipherText = advancedEncryptionStandard.decrypt(cipherText);
System.out.println(new String(plainText));
System.out.println(new String(cipherText));
System.out.println(new String(decryptedCipherText));
Prints:
Hello world!
դ;��LA+�ߙb*
Hello world!
Looks to me like you are not dealing properly with your Initialization Vector (IV).
It's been a long time since I last read about AES, IVs and block chaining, but your line
IvParameterSpec ivParameterSpec = new IvParameterSpec(aesKey.getEncoded());
does not seem to be OK. In the case of AES, you can think of the initialization vector as the "initial state" of a cipher instance, and this state is a bit of information that you can not get from your key but from the actual computation of the encrypting cipher. (One could argue that if the IV could be extracted from the key, then it would be of no use, as the key is already given to the cipher instance during its init phase).
Therefore, you should get the IV as a byte[] from the cipher instance at the end of your encryption
cipherOutputStream.close();
byte[] iv = encryptCipher.getIV();
and you should initialize your Cipher in DECRYPT_MODE with this byte[] :
IvParameterSpec ivParameterSpec = new IvParameterSpec(iv);
Then, your decryption should be OK.
Hope this helps.
The IV that your using for decryption is incorrect. Replace this code
//Decrypt cipher
Cipher decryptCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
IvParameterSpec ivParameterSpec = new IvParameterSpec(aesKey.getEncoded());
decryptCipher.init(Cipher.DECRYPT_MODE, aesKey, ivParameterSpec);
With this code
//Decrypt cipher
Cipher decryptCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
IvParameterSpec ivParameterSpec = new IvParameterSpec(encryptCipher.getIV());
decryptCipher.init(Cipher.DECRYPT_MODE, aesKey, ivParameterSpec);
And that should solve your problem.
Below includes an example of a simple AES class in Java. I do not recommend using this class in production environments, as it may not account for all of the specific needs of your application.
import java.nio.charset.StandardCharsets;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.util.Base64;
public class AES
{
public static byte[] encrypt(final byte[] keyBytes, final byte[] ivBytes, final byte[] messageBytes) throws InvalidKeyException, InvalidAlgorithmParameterException
{
return AES.transform(Cipher.ENCRYPT_MODE, keyBytes, ivBytes, messageBytes);
}
public static byte[] decrypt(final byte[] keyBytes, final byte[] ivBytes, final byte[] messageBytes) throws InvalidKeyException, InvalidAlgorithmParameterException
{
return AES.transform(Cipher.DECRYPT_MODE, keyBytes, ivBytes, messageBytes);
}
private static byte[] transform(final int mode, final byte[] keyBytes, final byte[] ivBytes, final byte[] messageBytes) throws InvalidKeyException, InvalidAlgorithmParameterException
{
final SecretKeySpec keySpec = new SecretKeySpec(keyBytes, "AES");
final IvParameterSpec ivSpec = new IvParameterSpec(ivBytes);
byte[] transformedBytes = null;
try
{
final Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding");
cipher.init(mode, keySpec, ivSpec);
transformedBytes = cipher.doFinal(messageBytes);
}
catch (NoSuchAlgorithmException | NoSuchPaddingException | IllegalBlockSizeException | BadPaddingException e)
{
e.printStackTrace();
}
return transformedBytes;
}
public static void main(final String[] args) throws InvalidKeyException, InvalidAlgorithmParameterException
{
//Retrieved from a protected local file.
//Do not hard-code and do not version control.
final String base64Key = "ABEiM0RVZneImaq7zN3u/w==";
//Retrieved from a protected database.
//Do not hard-code and do not version control.
final String shadowEntry = "AAECAwQFBgcICQoLDA0ODw==:ZtrkahwcMzTu7e/WuJ3AZmF09DE=";
//Extract the iv and the ciphertext from the shadow entry.
final String[] shadowData = shadowEntry.split(":");
final String base64Iv = shadowData[0];
final String base64Ciphertext = shadowData[1];
//Convert to raw bytes.
final byte[] keyBytes = Base64.getDecoder().decode(base64Key);
final byte[] ivBytes = Base64.getDecoder().decode(base64Iv);
final byte[] encryptedBytes = Base64.getDecoder().decode(base64Ciphertext);
//Decrypt data and do something with it.
final byte[] decryptedBytes = AES.decrypt(keyBytes, ivBytes, encryptedBytes);
//Use non-blocking SecureRandom implementation for the new IV.
final SecureRandom secureRandom = new SecureRandom();
//Generate a new IV.
secureRandom.nextBytes(ivBytes);
//At this point instead of printing to the screen,
//one should replace the old shadow entry with the new one.
System.out.println("Old Shadow Entry = " + shadowEntry);
System.out.println("Decrytped Shadow Data = " + new String(decryptedBytes, StandardCharsets.UTF_8));
System.out.println("New Shadow Entry = " + Base64.getEncoder().encodeToString(ivBytes) + ":" + Base64.getEncoder().encodeToString(AES.encrypt(keyBytes, ivBytes, decryptedBytes)));
}
}
Note that AES has nothing to do with encoding, which is why I chose to handle it separately and without the need of any third party libraries.
Online Editor Runnable version:-
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
//import org.apache.commons.codec.binary.Base64;
import java.util.Base64;
public class Encryptor {
public static String encrypt(String key, String initVector, String value) {
try {
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
IvParameterSpec iv = new IvParameterSpec(initVector.getBytes("UTF-8"));
SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes("UTF-8"), "AES");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec, iv);
byte[] encrypted = cipher.doFinal(value.getBytes());
//System.out.println("encrypted string: "
// + Base64.encodeBase64String(encrypted));
//return Base64.encodeBase64String(encrypted);
String s = new String(Base64.getEncoder().encode(encrypted));
return s;
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
public static String decrypt(String key, String initVector, String encrypted) {
try {
IvParameterSpec iv = new IvParameterSpec(initVector.getBytes("UTF-8"));
SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes("UTF-8"), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
cipher.init(Cipher.DECRYPT_MODE, skeySpec, iv);
byte[] original = cipher.doFinal(Base64.getDecoder().decode(encrypted));
return new String(original);
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
public static void main(String[] args) {
String key = "Bar12345Bar12345"; // 128 bit key
String initVector = "RandomInitVector"; // 16 bytes IV
System.out.println(encrypt(key, initVector, "Hello World"));
System.out.println(decrypt(key, initVector, encrypt(key, initVector, "Hello World")));
}
}
This is an improvement over the accepted answer.
Changes:
(1) Using random IV and prepend it to the encrypted text
(2) Using SHA-256 to generate a key from a passphrase
(3) No dependency on Apache Commons
public static void main(String[] args) throws GeneralSecurityException {
String plaintext = "Hello world";
String passphrase = "My passphrase";
String encrypted = encrypt(passphrase, plaintext);
String decrypted = decrypt(passphrase, encrypted);
System.out.println(encrypted);
System.out.println(decrypted);
}
private static SecretKeySpec getKeySpec(String passphrase) throws NoSuchAlgorithmException {
MessageDigest digest = MessageDigest.getInstance("SHA-256");
return new SecretKeySpec(digest.digest(passphrase.getBytes(UTF_8)), "AES");
}
private static Cipher getCipher() throws NoSuchPaddingException, NoSuchAlgorithmException {
return Cipher.getInstance("AES/CBC/PKCS5PADDING");
}
public static String encrypt(String passphrase, String value) throws GeneralSecurityException {
byte[] initVector = new byte[16];
SecureRandom.getInstanceStrong().nextBytes(initVector);
Cipher cipher = getCipher();
cipher.init(Cipher.ENCRYPT_MODE, getKeySpec(passphrase), new IvParameterSpec(initVector));
byte[] encrypted = cipher.doFinal(value.getBytes());
return DatatypeConverter.printBase64Binary(initVector) +
DatatypeConverter.printBase64Binary(encrypted);
}
public static String decrypt(String passphrase, String encrypted) throws GeneralSecurityException {
byte[] initVector = DatatypeConverter.parseBase64Binary(encrypted.substring(0, 24));
Cipher cipher = getCipher();
cipher.init(Cipher.DECRYPT_MODE, getKeySpec(passphrase), new IvParameterSpec(initVector));
byte[] original = cipher.doFinal(DatatypeConverter.parseBase64Binary(encrypted.substring(24)));
return new String(original);
}
It's often the good idea to rely on standard library provided solution:
private static void stackOverflow15554296()
throws
NoSuchAlgorithmException, NoSuchPaddingException,
InvalidKeyException, IllegalBlockSizeException,
BadPaddingException
{
// prepare key
KeyGenerator keygen = KeyGenerator.getInstance("AES");
SecretKey aesKey = keygen.generateKey();
String aesKeyForFutureUse = Base64.getEncoder().encodeToString(
aesKey.getEncoded()
);
// cipher engine
Cipher aesCipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
// cipher input
aesCipher.init(Cipher.ENCRYPT_MODE, aesKey);
byte[] clearTextBuff = "Text to encode".getBytes();
byte[] cipherTextBuff = aesCipher.doFinal(clearTextBuff);
// recreate key
byte[] aesKeyBuff = Base64.getDecoder().decode(aesKeyForFutureUse);
SecretKey aesDecryptKey = new SecretKeySpec(aesKeyBuff, "AES");
// decipher input
aesCipher.init(Cipher.DECRYPT_MODE, aesDecryptKey);
byte[] decipheredBuff = aesCipher.doFinal(cipherTextBuff);
System.out.println(new String(decipheredBuff));
}
This prints "Text to encode".
Solution is based on Java Cryptography Architecture Reference Guide and https://stackoverflow.com/a/20591539/146745 answer.
Another solution using java.util.Base64 with Spring Boot
Encryptor Class
package com.jmendoza.springboot.crypto.cipher;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.util.Base64;
#Component
public class Encryptor {
#Value("${security.encryptor.key}")
private byte[] key;
#Value("${security.encryptor.algorithm}")
private String algorithm;
public String encrypt(String plainText) throws Exception {
SecretKeySpec secretKey = new SecretKeySpec(key, algorithm);
Cipher cipher = Cipher.getInstance(algorithm);
cipher.init(Cipher.ENCRYPT_MODE, secretKey);
return new String(Base64.getEncoder().encode(cipher.doFinal(plainText.getBytes(StandardCharsets.UTF_8))));
}
public String decrypt(String cipherText) throws Exception {
SecretKeySpec secretKey = new SecretKeySpec(key, algorithm);
Cipher cipher = Cipher.getInstance(algorithm);
cipher.init(Cipher.DECRYPT_MODE, secretKey);
return new String(cipher.doFinal(Base64.getDecoder().decode(cipherText)));
}
}
EncryptorController Class
package com.jmendoza.springboot.crypto.controller;
import com.jmendoza.springboot.crypto.cipher.Encryptor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
#RestController
#RequestMapping("/cipher")
public class EncryptorController {
#Autowired
Encryptor encryptor;
#GetMapping(value = "encrypt/{value}")
public String encrypt(#PathVariable("value") final String value) throws Exception {
return encryptor.encrypt(value);
}
#GetMapping(value = "decrypt/{value}")
public String decrypt(#PathVariable("value") final String value) throws Exception {
return encryptor.decrypt(value);
}
}
application.properties
server.port=8082
security.encryptor.algorithm=AES
security.encryptor.key=M8jFt46dfJMaiJA0
Example
http://localhost:8082/cipher/encrypt/jmendoza
2h41HH8Shzc4BRU3hVDOXA==
http://localhost:8082/cipher/decrypt/2h41HH8Shzc4BRU3hVDOXA==
jmendoza
Optimized version of the accepted answer.
no 3rd party libs
includes IV into the encrypted message (can be public)
password can be of any length
Code:
import java.io.UnsupportedEncodingException;
import java.security.SecureRandom;
import java.util.Base64;
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
public class Encryptor {
public static byte[] getRandomInitialVector() {
try {
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
SecureRandom randomSecureRandom = SecureRandom.getInstance("SHA1PRNG");
byte[] initVector = new byte[cipher.getBlockSize()];
randomSecureRandom.nextBytes(initVector);
return initVector;
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
public static byte[] passwordTo16BitKey(String password) {
try {
byte[] srcBytes = password.getBytes("UTF-8");
byte[] dstBytes = new byte[16];
if (srcBytes.length == 16) {
return srcBytes;
}
if (srcBytes.length < 16) {
for (int i = 0; i < dstBytes.length; i++) {
dstBytes[i] = (byte) ((srcBytes[i % srcBytes.length]) * (srcBytes[(i + 1) % srcBytes.length]));
}
} else if (srcBytes.length > 16) {
for (int i = 0; i < srcBytes.length; i++) {
dstBytes[i % dstBytes.length] += srcBytes[i];
}
}
return dstBytes;
} catch (UnsupportedEncodingException ex) {
ex.printStackTrace();
}
return null;
}
public static String encrypt(String key, String value) {
return encrypt(passwordTo16BitKey(key), value);
}
public static String encrypt(byte[] key, String value) {
try {
byte[] initVector = Encryptor.getRandomInitialVector();
IvParameterSpec iv = new IvParameterSpec(initVector);
SecretKeySpec skeySpec = new SecretKeySpec(key, "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec, iv);
byte[] encrypted = cipher.doFinal(value.getBytes());
return Base64.getEncoder().encodeToString(encrypted) + " " + Base64.getEncoder().encodeToString(initVector);
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
public static String decrypt(String key, String encrypted) {
return decrypt(passwordTo16BitKey(key), encrypted);
}
public static String decrypt(byte[] key, String encrypted) {
try {
String[] encryptedParts = encrypted.split(" ");
byte[] initVector = Base64.getDecoder().decode(encryptedParts[1]);
if (initVector.length != 16) {
return null;
}
IvParameterSpec iv = new IvParameterSpec(initVector);
SecretKeySpec skeySpec = new SecretKeySpec(key, "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
cipher.init(Cipher.DECRYPT_MODE, skeySpec, iv);
byte[] original = cipher.doFinal(Base64.getDecoder().decode(encryptedParts[0]));
return new String(original);
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
}
Usage:
String key = "Password of any length.";
String encrypted = Encryptor.encrypt(key, "Hello World");
String decrypted = Encryptor.decrypt(key, encrypted);
System.out.println(encrypted);
System.out.println(decrypted);
Example output:
QngBg+Qc5+F8HQsksgfyXg== yDfYiIHTqOOjc0HRNdr1Ng==
Hello World
What's wrong with the following example?
The problem is that the first part of the decrypted string is nonsense. However, the rest is fine, I get...
Result: `£eB6O�geS��i are you? Have a nice day.
#Test
public void testEncrypt() {
try {
String s = "Hello there. How are you? Have a nice day.";
// Generate key
KeyGenerator kgen = KeyGenerator.getInstance("AES");
kgen.init(128);
SecretKey aesKey = kgen.generateKey();
// Encrypt cipher
Cipher encryptCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
encryptCipher.init(Cipher.ENCRYPT_MODE, aesKey);
// Encrypt
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
CipherOutputStream cipherOutputStream = new CipherOutputStream(outputStream, encryptCipher);
cipherOutputStream.write(s.getBytes());
cipherOutputStream.flush();
cipherOutputStream.close();
byte[] encryptedBytes = outputStream.toByteArray();
// Decrypt cipher
Cipher decryptCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
IvParameterSpec ivParameterSpec = new IvParameterSpec(aesKey.getEncoded());
decryptCipher.init(Cipher.DECRYPT_MODE, aesKey, ivParameterSpec);
// Decrypt
outputStream = new ByteArrayOutputStream();
ByteArrayInputStream inStream = new ByteArrayInputStream(encryptedBytes);
CipherInputStream cipherInputStream = new CipherInputStream(inStream, decryptCipher);
byte[] buf = new byte[1024];
int bytesRead;
while ((bytesRead = cipherInputStream.read(buf)) >= 0) {
outputStream.write(buf, 0, bytesRead);
}
System.out.println("Result: " + new String(outputStream.toByteArray()));
}
catch (Exception ex) {
ex.printStackTrace();
}
}
Lot of people including myself face lot of issues in making this work due to missing some information like, forgetting to convert to Base64, initialization vectors, character set, etc. So I thought of making a fully functional code.
Hope this will be useful to you all:
To compile you need additional Apache Commons Codec jar, which is available here:
http://commons.apache.org/proper/commons-codec/download_codec.cgi
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import org.apache.commons.codec.binary.Base64;
public class Encryptor {
public static String encrypt(String key, String initVector, String value) {
try {
IvParameterSpec iv = new IvParameterSpec(initVector.getBytes("UTF-8"));
SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes("UTF-8"), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec, iv);
byte[] encrypted = cipher.doFinal(value.getBytes());
System.out.println("encrypted string: "
+ Base64.encodeBase64String(encrypted));
return Base64.encodeBase64String(encrypted);
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
public static String decrypt(String key, String initVector, String encrypted) {
try {
IvParameterSpec iv = new IvParameterSpec(initVector.getBytes("UTF-8"));
SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes("UTF-8"), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
cipher.init(Cipher.DECRYPT_MODE, skeySpec, iv);
byte[] original = cipher.doFinal(Base64.decodeBase64(encrypted));
return new String(original);
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
public static void main(String[] args) {
String key = "Bar12345Bar12345"; // 128 bit key
String initVector = "RandomInitVector"; // 16 bytes IV
System.out.println(decrypt(key, initVector,
encrypt(key, initVector, "Hello World")));
}
}
In this answer I choose to approach the "Simple Java AES encrypt/decrypt example" main theme and not the specific debugging question because I think this will profit most readers.
This is a simple summary of my blog post about AES encryption in Java so I recommend reading through it before implementing anything. I will however still provide a simple example to use and give some pointers what to watch out for.
In this example I will choose to use authenticated encryption with Galois/Counter Mode or GCM mode. The reason is that in most case you want integrity and authenticity in combination with confidentiality (read more in the blog).
AES-GCM Encryption/Decryption Tutorial
Here are the steps required to encrypt/decrypt with AES-GCM with the Java Cryptography Architecture (JCA). Do not mix with other examples, as subtle differences may make your code utterly insecure.
1. Create Key
As it depends on your use-case, I will assume the simplest case: a random secret key.
SecureRandom secureRandom = new SecureRandom();
byte[] key = new byte[16];
secureRandom.nextBytes(key);
SecretKey secretKey = SecretKeySpec(key, "AES");
Important:
always use a strong pseudorandom number generator like SecureRandom
use 16 byte / 128 bit long key (or more - but more is seldom needed)
if you want a key derived from a user password, look into a password hash function (or KDF) with stretching property like PBKDF2 or bcrypt
if you want a key derived from other sources, use a proper key derivation function (KDF) like HKDF (Java implementation here). Do not use simple cryptographic hashes for that (like SHA-256).
2. Create the Initialization Vector
An initialization vector (IV) is used so that the same secret key will create different cipher texts.
byte[] iv = new byte[12]; //NEVER REUSE THIS IV WITH SAME KEY
secureRandom.nextBytes(iv);
Important:
never reuse the same IV with the same key (very important in GCM/CTR mode)
the IV must be unique (ie. use random IV or a counter)
the IV is not required to be secret
always use a strong pseudorandom number generator like SecureRandom
12 byte IV is the correct choice for AES-GCM mode
3. Encrypt with IV and Key
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);
byte[] cipherText = cipher.doFinal(plainText);
Important:
use 16 byte / 128 bit authentication tag (used to verify integrity/authenticity)
the authentication tag will be automatically appended to the cipher text (in the JCA implementation)
since GCM behaves like a stream cipher, no padding is required
use CipherInputStream when encrypting large chunks of data
want additional (non-secret) data checked if it was changed? You may want to use associated data with cipher.updateAAD(associatedData); More here.
3. Serialize to Single Message
Just append IV and ciphertext. As stated above, the IV doesn't need to be secret.
ByteBuffer byteBuffer = ByteBuffer.allocate(iv.length + cipherText.length);
byteBuffer.put(iv);
byteBuffer.put(cipherText);
byte[] cipherMessage = byteBuffer.array();
Optionally encode with Base64 if you need a string representation. Either use Android's or Java 8's built-in implementation (do not use Apache Commons Codec - it's an awful implementation). Encoding is used to "convert" byte arrays to string representation to make it ASCII safe e.g.:
String base64CipherMessage = Base64.getEncoder().encodeToString(cipherMessage);
4. Prepare Decryption: Deserialize
If you have encoded the message, first decode it to byte array:
byte[] cipherMessage = Base64.getDecoder().decode(base64CipherMessage)
Important:
be careful to validate input parameters, so to avoid denial of service attacks by allocating too much memory.
5. Decrypt
Initialize the cipher and set the same parameters as with the encryption:
final Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
//use first 12 bytes for iv
AlgorithmParameterSpec gcmIv = new GCMParameterSpec(128, cipherMessage, 0, 12);
cipher.init(Cipher.DECRYPT_MODE, secretKey, gcmIv);
//use everything from 12 bytes on as ciphertext
byte[] plainText = cipher.doFinal(cipherMessage, 12, cipherMessage.length - 12);
Important:
don't forget to add associated data with cipher.updateAAD(associatedData); if you added it during encryption.
A working code snippet can be found in this gist.
Note that most recent Android (SDK 21+) and Java (7+) implementations should have AES-GCM. Older versions may lack it. I still choose this mode, since it is easier to implement in addition to being more efficient compared to similar mode of Encrypt-then-Mac (with e.g. AES-CBC + HMAC). See this article on how to implement AES-CBC with HMAC.
Here a solution without Apache Commons Codec's Base64:
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
public class AdvancedEncryptionStandard
{
private byte[] key;
private static final String ALGORITHM = "AES";
public AdvancedEncryptionStandard(byte[] key)
{
this.key = key;
}
/**
* Encrypts the given plain text
*
* #param plainText The plain text to encrypt
*/
public byte[] encrypt(byte[] plainText) throws Exception
{
SecretKeySpec secretKey = new SecretKeySpec(key, ALGORITHM);
Cipher cipher = Cipher.getInstance(ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE, secretKey);
return cipher.doFinal(plainText);
}
/**
* Decrypts the given byte array
*
* #param cipherText The data to decrypt
*/
public byte[] decrypt(byte[] cipherText) throws Exception
{
SecretKeySpec secretKey = new SecretKeySpec(key, ALGORITHM);
Cipher cipher = Cipher.getInstance(ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE, secretKey);
return cipher.doFinal(cipherText);
}
}
Usage example:
byte[] encryptionKey = "MZygpewJsCpRrfOr".getBytes(StandardCharsets.UTF_8);
byte[] plainText = "Hello world!".getBytes(StandardCharsets.UTF_8);
AdvancedEncryptionStandard advancedEncryptionStandard = new AdvancedEncryptionStandard(
encryptionKey);
byte[] cipherText = advancedEncryptionStandard.encrypt(plainText);
byte[] decryptedCipherText = advancedEncryptionStandard.decrypt(cipherText);
System.out.println(new String(plainText));
System.out.println(new String(cipherText));
System.out.println(new String(decryptedCipherText));
Prints:
Hello world!
դ;��LA+�ߙb*
Hello world!
Looks to me like you are not dealing properly with your Initialization Vector (IV).
It's been a long time since I last read about AES, IVs and block chaining, but your line
IvParameterSpec ivParameterSpec = new IvParameterSpec(aesKey.getEncoded());
does not seem to be OK. In the case of AES, you can think of the initialization vector as the "initial state" of a cipher instance, and this state is a bit of information that you can not get from your key but from the actual computation of the encrypting cipher. (One could argue that if the IV could be extracted from the key, then it would be of no use, as the key is already given to the cipher instance during its init phase).
Therefore, you should get the IV as a byte[] from the cipher instance at the end of your encryption
cipherOutputStream.close();
byte[] iv = encryptCipher.getIV();
and you should initialize your Cipher in DECRYPT_MODE with this byte[] :
IvParameterSpec ivParameterSpec = new IvParameterSpec(iv);
Then, your decryption should be OK.
Hope this helps.
The IV that your using for decryption is incorrect. Replace this code
//Decrypt cipher
Cipher decryptCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
IvParameterSpec ivParameterSpec = new IvParameterSpec(aesKey.getEncoded());
decryptCipher.init(Cipher.DECRYPT_MODE, aesKey, ivParameterSpec);
With this code
//Decrypt cipher
Cipher decryptCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
IvParameterSpec ivParameterSpec = new IvParameterSpec(encryptCipher.getIV());
decryptCipher.init(Cipher.DECRYPT_MODE, aesKey, ivParameterSpec);
And that should solve your problem.
Below includes an example of a simple AES class in Java. I do not recommend using this class in production environments, as it may not account for all of the specific needs of your application.
import java.nio.charset.StandardCharsets;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.util.Base64;
public class AES
{
public static byte[] encrypt(final byte[] keyBytes, final byte[] ivBytes, final byte[] messageBytes) throws InvalidKeyException, InvalidAlgorithmParameterException
{
return AES.transform(Cipher.ENCRYPT_MODE, keyBytes, ivBytes, messageBytes);
}
public static byte[] decrypt(final byte[] keyBytes, final byte[] ivBytes, final byte[] messageBytes) throws InvalidKeyException, InvalidAlgorithmParameterException
{
return AES.transform(Cipher.DECRYPT_MODE, keyBytes, ivBytes, messageBytes);
}
private static byte[] transform(final int mode, final byte[] keyBytes, final byte[] ivBytes, final byte[] messageBytes) throws InvalidKeyException, InvalidAlgorithmParameterException
{
final SecretKeySpec keySpec = new SecretKeySpec(keyBytes, "AES");
final IvParameterSpec ivSpec = new IvParameterSpec(ivBytes);
byte[] transformedBytes = null;
try
{
final Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding");
cipher.init(mode, keySpec, ivSpec);
transformedBytes = cipher.doFinal(messageBytes);
}
catch (NoSuchAlgorithmException | NoSuchPaddingException | IllegalBlockSizeException | BadPaddingException e)
{
e.printStackTrace();
}
return transformedBytes;
}
public static void main(final String[] args) throws InvalidKeyException, InvalidAlgorithmParameterException
{
//Retrieved from a protected local file.
//Do not hard-code and do not version control.
final String base64Key = "ABEiM0RVZneImaq7zN3u/w==";
//Retrieved from a protected database.
//Do not hard-code and do not version control.
final String shadowEntry = "AAECAwQFBgcICQoLDA0ODw==:ZtrkahwcMzTu7e/WuJ3AZmF09DE=";
//Extract the iv and the ciphertext from the shadow entry.
final String[] shadowData = shadowEntry.split(":");
final String base64Iv = shadowData[0];
final String base64Ciphertext = shadowData[1];
//Convert to raw bytes.
final byte[] keyBytes = Base64.getDecoder().decode(base64Key);
final byte[] ivBytes = Base64.getDecoder().decode(base64Iv);
final byte[] encryptedBytes = Base64.getDecoder().decode(base64Ciphertext);
//Decrypt data and do something with it.
final byte[] decryptedBytes = AES.decrypt(keyBytes, ivBytes, encryptedBytes);
//Use non-blocking SecureRandom implementation for the new IV.
final SecureRandom secureRandom = new SecureRandom();
//Generate a new IV.
secureRandom.nextBytes(ivBytes);
//At this point instead of printing to the screen,
//one should replace the old shadow entry with the new one.
System.out.println("Old Shadow Entry = " + shadowEntry);
System.out.println("Decrytped Shadow Data = " + new String(decryptedBytes, StandardCharsets.UTF_8));
System.out.println("New Shadow Entry = " + Base64.getEncoder().encodeToString(ivBytes) + ":" + Base64.getEncoder().encodeToString(AES.encrypt(keyBytes, ivBytes, decryptedBytes)));
}
}
Note that AES has nothing to do with encoding, which is why I chose to handle it separately and without the need of any third party libraries.
Online Editor Runnable version:-
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
//import org.apache.commons.codec.binary.Base64;
import java.util.Base64;
public class Encryptor {
public static String encrypt(String key, String initVector, String value) {
try {
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
IvParameterSpec iv = new IvParameterSpec(initVector.getBytes("UTF-8"));
SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes("UTF-8"), "AES");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec, iv);
byte[] encrypted = cipher.doFinal(value.getBytes());
//System.out.println("encrypted string: "
// + Base64.encodeBase64String(encrypted));
//return Base64.encodeBase64String(encrypted);
String s = new String(Base64.getEncoder().encode(encrypted));
return s;
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
public static String decrypt(String key, String initVector, String encrypted) {
try {
IvParameterSpec iv = new IvParameterSpec(initVector.getBytes("UTF-8"));
SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes("UTF-8"), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
cipher.init(Cipher.DECRYPT_MODE, skeySpec, iv);
byte[] original = cipher.doFinal(Base64.getDecoder().decode(encrypted));
return new String(original);
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
public static void main(String[] args) {
String key = "Bar12345Bar12345"; // 128 bit key
String initVector = "RandomInitVector"; // 16 bytes IV
System.out.println(encrypt(key, initVector, "Hello World"));
System.out.println(decrypt(key, initVector, encrypt(key, initVector, "Hello World")));
}
}
This is an improvement over the accepted answer.
Changes:
(1) Using random IV and prepend it to the encrypted text
(2) Using SHA-256 to generate a key from a passphrase
(3) No dependency on Apache Commons
public static void main(String[] args) throws GeneralSecurityException {
String plaintext = "Hello world";
String passphrase = "My passphrase";
String encrypted = encrypt(passphrase, plaintext);
String decrypted = decrypt(passphrase, encrypted);
System.out.println(encrypted);
System.out.println(decrypted);
}
private static SecretKeySpec getKeySpec(String passphrase) throws NoSuchAlgorithmException {
MessageDigest digest = MessageDigest.getInstance("SHA-256");
return new SecretKeySpec(digest.digest(passphrase.getBytes(UTF_8)), "AES");
}
private static Cipher getCipher() throws NoSuchPaddingException, NoSuchAlgorithmException {
return Cipher.getInstance("AES/CBC/PKCS5PADDING");
}
public static String encrypt(String passphrase, String value) throws GeneralSecurityException {
byte[] initVector = new byte[16];
SecureRandom.getInstanceStrong().nextBytes(initVector);
Cipher cipher = getCipher();
cipher.init(Cipher.ENCRYPT_MODE, getKeySpec(passphrase), new IvParameterSpec(initVector));
byte[] encrypted = cipher.doFinal(value.getBytes());
return DatatypeConverter.printBase64Binary(initVector) +
DatatypeConverter.printBase64Binary(encrypted);
}
public static String decrypt(String passphrase, String encrypted) throws GeneralSecurityException {
byte[] initVector = DatatypeConverter.parseBase64Binary(encrypted.substring(0, 24));
Cipher cipher = getCipher();
cipher.init(Cipher.DECRYPT_MODE, getKeySpec(passphrase), new IvParameterSpec(initVector));
byte[] original = cipher.doFinal(DatatypeConverter.parseBase64Binary(encrypted.substring(24)));
return new String(original);
}
It's often the good idea to rely on standard library provided solution:
private static void stackOverflow15554296()
throws
NoSuchAlgorithmException, NoSuchPaddingException,
InvalidKeyException, IllegalBlockSizeException,
BadPaddingException
{
// prepare key
KeyGenerator keygen = KeyGenerator.getInstance("AES");
SecretKey aesKey = keygen.generateKey();
String aesKeyForFutureUse = Base64.getEncoder().encodeToString(
aesKey.getEncoded()
);
// cipher engine
Cipher aesCipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
// cipher input
aesCipher.init(Cipher.ENCRYPT_MODE, aesKey);
byte[] clearTextBuff = "Text to encode".getBytes();
byte[] cipherTextBuff = aesCipher.doFinal(clearTextBuff);
// recreate key
byte[] aesKeyBuff = Base64.getDecoder().decode(aesKeyForFutureUse);
SecretKey aesDecryptKey = new SecretKeySpec(aesKeyBuff, "AES");
// decipher input
aesCipher.init(Cipher.DECRYPT_MODE, aesDecryptKey);
byte[] decipheredBuff = aesCipher.doFinal(cipherTextBuff);
System.out.println(new String(decipheredBuff));
}
This prints "Text to encode".
Solution is based on Java Cryptography Architecture Reference Guide and https://stackoverflow.com/a/20591539/146745 answer.
Another solution using java.util.Base64 with Spring Boot
Encryptor Class
package com.jmendoza.springboot.crypto.cipher;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.util.Base64;
#Component
public class Encryptor {
#Value("${security.encryptor.key}")
private byte[] key;
#Value("${security.encryptor.algorithm}")
private String algorithm;
public String encrypt(String plainText) throws Exception {
SecretKeySpec secretKey = new SecretKeySpec(key, algorithm);
Cipher cipher = Cipher.getInstance(algorithm);
cipher.init(Cipher.ENCRYPT_MODE, secretKey);
return new String(Base64.getEncoder().encode(cipher.doFinal(plainText.getBytes(StandardCharsets.UTF_8))));
}
public String decrypt(String cipherText) throws Exception {
SecretKeySpec secretKey = new SecretKeySpec(key, algorithm);
Cipher cipher = Cipher.getInstance(algorithm);
cipher.init(Cipher.DECRYPT_MODE, secretKey);
return new String(cipher.doFinal(Base64.getDecoder().decode(cipherText)));
}
}
EncryptorController Class
package com.jmendoza.springboot.crypto.controller;
import com.jmendoza.springboot.crypto.cipher.Encryptor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
#RestController
#RequestMapping("/cipher")
public class EncryptorController {
#Autowired
Encryptor encryptor;
#GetMapping(value = "encrypt/{value}")
public String encrypt(#PathVariable("value") final String value) throws Exception {
return encryptor.encrypt(value);
}
#GetMapping(value = "decrypt/{value}")
public String decrypt(#PathVariable("value") final String value) throws Exception {
return encryptor.decrypt(value);
}
}
application.properties
server.port=8082
security.encryptor.algorithm=AES
security.encryptor.key=M8jFt46dfJMaiJA0
Example
http://localhost:8082/cipher/encrypt/jmendoza
2h41HH8Shzc4BRU3hVDOXA==
http://localhost:8082/cipher/decrypt/2h41HH8Shzc4BRU3hVDOXA==
jmendoza
Optimized version of the accepted answer.
no 3rd party libs
includes IV into the encrypted message (can be public)
password can be of any length
Code:
import java.io.UnsupportedEncodingException;
import java.security.SecureRandom;
import java.util.Base64;
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
public class Encryptor {
public static byte[] getRandomInitialVector() {
try {
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
SecureRandom randomSecureRandom = SecureRandom.getInstance("SHA1PRNG");
byte[] initVector = new byte[cipher.getBlockSize()];
randomSecureRandom.nextBytes(initVector);
return initVector;
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
public static byte[] passwordTo16BitKey(String password) {
try {
byte[] srcBytes = password.getBytes("UTF-8");
byte[] dstBytes = new byte[16];
if (srcBytes.length == 16) {
return srcBytes;
}
if (srcBytes.length < 16) {
for (int i = 0; i < dstBytes.length; i++) {
dstBytes[i] = (byte) ((srcBytes[i % srcBytes.length]) * (srcBytes[(i + 1) % srcBytes.length]));
}
} else if (srcBytes.length > 16) {
for (int i = 0; i < srcBytes.length; i++) {
dstBytes[i % dstBytes.length] += srcBytes[i];
}
}
return dstBytes;
} catch (UnsupportedEncodingException ex) {
ex.printStackTrace();
}
return null;
}
public static String encrypt(String key, String value) {
return encrypt(passwordTo16BitKey(key), value);
}
public static String encrypt(byte[] key, String value) {
try {
byte[] initVector = Encryptor.getRandomInitialVector();
IvParameterSpec iv = new IvParameterSpec(initVector);
SecretKeySpec skeySpec = new SecretKeySpec(key, "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec, iv);
byte[] encrypted = cipher.doFinal(value.getBytes());
return Base64.getEncoder().encodeToString(encrypted) + " " + Base64.getEncoder().encodeToString(initVector);
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
public static String decrypt(String key, String encrypted) {
return decrypt(passwordTo16BitKey(key), encrypted);
}
public static String decrypt(byte[] key, String encrypted) {
try {
String[] encryptedParts = encrypted.split(" ");
byte[] initVector = Base64.getDecoder().decode(encryptedParts[1]);
if (initVector.length != 16) {
return null;
}
IvParameterSpec iv = new IvParameterSpec(initVector);
SecretKeySpec skeySpec = new SecretKeySpec(key, "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
cipher.init(Cipher.DECRYPT_MODE, skeySpec, iv);
byte[] original = cipher.doFinal(Base64.getDecoder().decode(encryptedParts[0]));
return new String(original);
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
}
Usage:
String key = "Password of any length.";
String encrypted = Encryptor.encrypt(key, "Hello World");
String decrypted = Encryptor.decrypt(key, encrypted);
System.out.println(encrypted);
System.out.println(decrypted);
Example output:
QngBg+Qc5+F8HQsksgfyXg== yDfYiIHTqOOjc0HRNdr1Ng==
Hello World
PHP Encrypt Function
$privateKey = "1234567812345678";
$iv = "1234567812345678";
$data = "Test string";
$encrypted = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $privateKey, $data, MCRYPT_MODE_CBC, $iv);
echo(base64_encode($encrypted));
Result: iz1qFlQJfs6Ycp+gcc2z4w==
When I try to decrypt this result in Java using the function below, all I get back is ì�š#ÔBKxnfÈ~¯Ô'M while I am expecting "Test string". Any ideas where I am wrong? Thanks
public static String decrypt() throws Exception{
try{
String Base64EncodedText = "iz1qFlQJfs6Ycp+gcc2z4w==";
String decodedText = com.sun.xml.internal.messaging.saaj.util.Base64.base64Decode(Base64EncodedText);
String key = "1234567812345678";
String iv = "1234567812345678";
javax.crypto.spec.SecretKeySpec keyspec = new javax.crypto.spec.SecretKeySpec(key.getBytes(), "AES");
javax.crypto.spec.IvParameterSpec ivspec = new javax.crypto.spec.IvParameterSpec(iv.getBytes());
javax.crypto.Cipher cipher = javax.crypto.Cipher.getInstance("AES/CBC/NoPadding");
cipher.init(javax.crypto.Cipher.DECRYPT_MODE, keyspec, ivspec);
byte[] decrypted = cipher.doFinal(decodedText.getBytes());
String str = new String(decrypted);
return str;
}catch(Exception e){
return null;
}
}
EDIT: As of Java 8 Java now includes an acceptable Base64 class, java.util.Base64.
This line
String decodedText = com.sun.xml.internal.messaging.saaj.util.Base64.base64Decode(Base64EncodedText);
looks wrong. Instead, use the apache commons codec classes or the Harder base64 class. Also the default padding used by mcrypt, zero padding, is arguably wrong and makes it difficult to use the results in other languages. The users comments section for the mcrypt_encrypt web pages has examples of how to do this.
Here is small example that uses the apache commons classes to decrypt your string.
import java.nio.charset.Charset;
import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import org.apache.commons.codec.binary.Base64;
import org.apache.commons.codec.binary.Hex;
public class AESToy3 {
private static final Charset ASCII = Charset.forName("US-ASCII");
public static void main(String[] args) throws Exception {
String base64Cipher = "iz1qFlQJfs6Ycp+gcc2z4w==";
byte [] cipherBytes = Base64.decodeBase64(base64Cipher);
byte [] iv = "1234567812345678".getBytes(ASCII);
byte [] keyBytes = "1234567812345678".getBytes(ASCII);
SecretKey aesKey = new SecretKeySpec(keyBytes, "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/NOPADDING");
cipher.init(Cipher.DECRYPT_MODE, aesKey, new IvParameterSpec(iv));
byte[] result = cipher.doFinal(cipherBytes);
System.out.println(Hex.encodeHexString(result));
}
}
this produces the following output:
5465737420737472696e670000000000
which when decoded as ASCII and removing the trailing zeros gives you Test string
Why does not this AES encryption work? I've written it in Java to test, but I am not able to decrypt. I get garbage upon decryption. Why? Its so simple - In the main method, print plain text, encrypt, print cipher text, decrypt, print plain text again. Am I doing something wrong? Please help me figure out the problem.
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
public class AESTest {
public static void main(String [] args) {
try {
String plainText = "Hello World!!!!!";
String encryptionKey = "E072EDF9534053A0B6C581C58FBF25CC";
System.out.println("Before encryption - " + plainText);
String cipherText = encrypt(plainText, encryptionKey);
System.out.println("After encryption - " + cipherText);
String decrypted = decrypt(cipherText, encryptionKey);
System.out.println("After decryption - " + decrypted);
} catch (Exception e) {
e.printStackTrace();
}
}
public static String encrypt(String plainText, String passkey) throws Exception {
Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding", "SunJCE");
SecretKeySpec key = new SecretKeySpec(hexStringToByteArray(passkey), "AES");
cipher.init(Cipher.ENCRYPT_MODE, key, new IvParameterSpec(new byte[cipher.getBlockSize()]));
String cipherText = new String(cipher.doFinal(plainText.getBytes()));
return cipherText;
}
public static String decrypt(String cipherText, String passkey) throws Exception{
Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding", "SunJCE");
SecretKeySpec key = new SecretKeySpec(hexStringToByteArray(passkey), "AES");
cipher.init(Cipher.DECRYPT_MODE, key, new IvParameterSpec(new byte[cipher.getBlockSize()]));
String plainText = new String(cipher.doFinal(cipherText.getBytes()));
return plainText;
}
public static byte[] hexStringToByteArray(String s) {
int len = s.length();
byte[] data = new byte[len / 2];
for (int i = 0; i < len; i += 2) {
data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4)
+ Character.digit(s.charAt(i+1), 16));
}
return data;
}
}
The output of the cipher is a sequence of random-looking bytes. You have no guarantee that these bytes will be a valid encoding for a character string in whatever is your system's default encoding. So this line:
String cipherText = new String(cipher.doFinal(.....));
is likely to lose information that you'll need for decryption.
Therefore you will not get the right bytes reconstructed in your decrypt operation. For example, if your default encoding is UTF-8, it is overwhelmingly unlikely that the correct ciphertext is something that String.getBytes() is even able to produce.
Two things:
No padding can only work if you use input that is an exact mulitple of your key size, which is 128 bit or 16 bytes. So in your particular case "Hello World!!!!!".getBytes() is actually a multiple of 16, but this is of course not true for arbitrary Strings.
Use "AES/CBC/PKCS5Padding" instead to solve this issue.
Do not turn your encrypted data into a String - this will and change the encrypted output. There's no guarantee that new String(byte[]).getBytes() returns the exact same byte array!
So you should leave the encrypted data as what it is - a stream of bytes. Thus encrypt should return byte[] instead and decrypt should take byte[] as input - this is a working example:
public class NewClass {
public static void main(String [] args) {
try {
String plainText = "Hello World!!!!";
String encryptionKey = "E072EDF9534053A0B6C581C58FBF25CC";
System.out.println("Before encryption - " + plainText);
byte[] cipherText = encrypt(plainText, encryptionKey);
System.out.println("After encryption - " + cipherText);
String decrypted = decrypt(cipherText, encryptionKey);
// -> Hello World!!!!
System.out.println("After decryption - " + decrypted);
} catch (Exception e) {
e.printStackTrace();
}
}
public static byte[] encrypt(String plainText, String passkey) throws Exception {
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding", "SunJCE");
SecretKeySpec key = new SecretKeySpec(hexStringToByteArray(passkey), "AES");
cipher.init(Cipher.ENCRYPT_MODE, key, new IvParameterSpec(new byte[cipher.getBlockSize()]));
return cipher.doFinal(plainText.getBytes());
}
public static String decrypt(byte[] cipherText, String passkey) throws Exception{
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding", "SunJCE");
SecretKeySpec key = new SecretKeySpec(hexStringToByteArray(passkey), "AES");
cipher.init(Cipher.DECRYPT_MODE, key, new IvParameterSpec(new byte[cipher.getBlockSize()]));
return new String(cipher.doFinal(cipherText));
}
You need to create the SecretKeySpec object once and use it for both encrypt and decrypt. Currently the code is creating two different keys for each operation and this will definitely lead to incorrect results.