I want to use RSA/AES file encryption on my project. I make a pair of keys private/public with rsa, and one AES key, after that, i'll cipher AES key with public key. Finally i decrypt AES encrypted key with private RSA key.
This is the code: RSA key:
public class EncriptionRSAKey {
public static final int RSA_Key_Size = 512; // dimensione chiave RSA
private PrivateKey privKey;// chiave privata
private PublicKey pubKey;// chiave pubblica
/**
* Costruttore che genera una chiave privata e una pubblica in RSA
* @throws NoSuchAlgorithmException
*/
public EncriptionRSAKey() throws NoSuchAlgorithmException{
KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
keyGen.initialize(RSA_Key_Size);
privKey = keyGen.genKeyPair().getPrivate();
pubKey = keyGen.genKeyPair().getPublic();
}
/**
* Decripta una chiave RSA cifrata con una chiave pubblica
* @param data chiave AES
* @return
* @throws NoSuchAlgorithmException
* @throws NoSuchPaddingException
* @throws InvalidKeyException
* @throws IllegalBlockSizeException
* @throws BadPaddingException
*/
public SecretKey decryptAESKey(byte[] data ) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException
{
SecretKey key = null;
Cipher cipher = Cipher.getInstance("RSA");;
cipher.init(Cipher.DECRYPT_MODE, privKey ); // inizializza il cipher
key = new SecretKeySpec ( cipher.doFinal(data), "AES" ); // genera la chiave AES
return key;
}
/**
* Restituisce la chiave pubblica
* @return pubKey chiave pubblica
*/
public PublicKey getPubKey() {
return pubKey;
}
For AES key:
public class EncriptionAESKey {
public static final int AES_Key_Size = 256; // dimensione chiave AES
/**
* Genera una chiave AES
* @return aesKey Chiave AES
* @throws NoSuchAlgorithmException
*/
public static SecretKey makeAESKey() throws NoSuchAlgorithmException {
KeyGenerator keyGen = KeyGenerator.getInstance("AES");
keyGen.init(AES_Key_Size);
return keyGen.generateKey();
}
/**
* Cifra una chiave AES data una chiave pubblica RSA
* @param skey Chiave AES da cifrare
* @param publicKey Chiave RSA pubblica
* @return key AES cifrato con RSA
* @throws InvalidKeyException
* @throws NoSuchAlgorithmException
* @throws NoSuchPaddingException
* @throws IllegalBlockSizeException
* @throws BadPaddingException
*/
public static byte[] EncryptSecretKey (SecretKey skey, PublicKey publicKey) throws InvalidKeyException, NoSuchAlgorithmException, NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException
{
Cipher cipher = null;
byte[] key = null;
// initialize the cipher with the user's public key
cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, publicKey );
key = cipher.doFinal(skey.getEncoded());
return key;
}
Test Class
public class EncriptionTest {
@Test
public void testAESEncription() {
try {
EncriptionRSAKey rsa = new EncriptionRSAKey();
SecretKey aes = EncriptionAESKey.makeAESKey();
byte[] aesEnc = EncriptionAESKey.EncryptSecretKey(aes, rsa.getPubKey());
assertEquals(rsa.decryptAESKey(aesEnc),aes);
} catch (NoSuchAlgorithmException | InvalidKeyException | NoSuchPaddingException | IllegalBlockSizeException | BadPaddingException e) {
e.printStackTrace();
fail();
}
}
on this line:byte[] aesEnc = EncriptionAESKey.EncryptSecretKey(aes, rsa.getPubKey());
Gives me this Exception:`javax.crypto.BadPaddingException: Decryption error
at sun.security.rsa.RSAPadding.unpadV15(Unknown Source)
at sun.security.rsa.RSAPadding.unpad(Unknown Source)
at com.sun.crypto.provider.RSACipher.doFinal(RSACipher.java:363)
at com.sun.crypto.provider.RSACipher.engineDoFinal(RSACipher.java:389)
at javax.crypto.Cipher.doFinal(Cipher.java:2165)
at model.EncriptionRSAKey.decryptAESKey(EncriptionRSAKey.java:54)
at test.EncriptionTest.testAESEncription(EncriptionTest.java:26)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)`
Thanks for your help
