Using the Java Cryptographic Extensions - Revision history

CEastus: /* AES Encryption and Decryption */

2019-07-10T16:38:38Z

‎AES Encryption and Decryption

CEastus: /* AES Encryption and Decryption */

2019-07-10T16:25:40Z

‎AES Encryption and Decryption

CEastus: /* AES Encryption and Decryption */

2019-07-10T15:51:50Z

‎AES Encryption and Decryption

CEastus: Reworked from Joe Prasanna Kumar's sample with suggestions and notes made by Kevin W. Wall.

2019-07-10T15:30:35Z

Reworked from Joe Prasanna Kumar's sample with suggestions and notes made by Kevin W. Wall.

Show changes

Imifos: Moved page into the right category. See Java space page for me details. Content has not been reviewed in this edit.

2017-11-10T21:51:02Z

Moved page into the right category. See Java space page for me details. Content has not been reviewed in this edit.

Kevin W. Wall: Updated FIXME comment.

2017-03-18T01:13:23Z

Updated FIXME comment.

Jmanico at 04:02, 9 March 2017

2017-03-09T04:02:55Z

Imifos: Update obsolete contact information

2015-11-26T10:40:42Z

Update obsolete contact information

Jaxley: fixing imports

2014-05-27T21:34:09Z

fixing imports

Jaxley at 21:29, 27 May 2014

2014-05-27T21:29:35Z

@@ Line 130: / Line 130: @@
   * and PKCS7 padding act identically for block sizes <= 255 bits.
   * Be sure to specify the mode explicitly as most JCE providers default to ECB mode, which is not secure!
-  * For this example, we are use "CCM" mode with no padding in order to avoid padding oracle attacks.
+  * For this example, we are use CFB mode with no padding in order to avoid padding attacks.
+  *
   * Notes on initialization vectors (IVs):

@@ Line 143: / Line 143: @@
    public static final int keyLength = 128;
    public static final String charEnc = "UTF-8";
-   public static final String transformationString = "AES/CFB/PKCS5Padding";
+   public static final String transformationString = "AES/CFB/NoPadding";
    public static void main(String[] args) {

@@ Line 130: / Line 130: @@
   * and PKCS7 padding act identically for block sizes <= 255 bits.
   * Be sure to specify the mode explicitly as most JCE providers default to ECB mode, which is not secure!
-  * For this example, we are use "CCM" mode with no padding in order to avoid Oracle Padding attacks.
+  * For this example, we are use "CCM" mode with no padding in order to avoid padding oracle attacks.
+  *
   * Notes on initialization vectors (IVs):

@@ Line 370: / Line 370: @@
+}
 </pre>
-[[Category:OWASP Java Project]]
+[[Category:Java]]

@@ Line 1: / Line 1: @@
 {{taggedDocument
 | type=old
-| comment=The page should be updated.
+| comment=The page should be updated; see Discussion tab for some details.
 }}

← Older revision		Revision as of 04:02, 9 March 2017
Line 1:		Line 1:
		+	{{taggedDocument
		+	\| type=old
		+	\| comment=The page should be updated.
		+	}}
		+
	==Meta==		==Meta==
−
−	~~Last Update: 27 May 2014‎~~

	The code included in this article has not been reviewed and should not be used without proper analysis. If you have reviewed the included code or portions of it, please post your findings back to the Java Project mailing list or contact the [[OWASP_Java_Project\|OWASP Java and JVM Project]] team.		The code included in this article has not been reviewed and should not be used without proper analysis. If you have reviewed the included code or portions of it, please post your findings back to the Java Project mailing list or contact the [[OWASP_Java_Project\|OWASP Java and JVM Project]] team.

@@ Line 1: / Line 1: @@
-==Note:==
+==Meta==
-''The code included in this article has not been reviewed and should not be used without proper analysis.  If you have reviewed the included code (or portions of it), please post your findings back to this page or to: stephen [at] corsaire.com.''
 == Overview ==

@@ Line 100: / Line 100: @@
 package org.owasp.java.crypto;
-import javax.crypto.KeyGenerator;
+import java.security.InvalidAlgorithmParameterException;
-import javax.crypto.SecretKey;
+import java.security.InvalidKeyException;
-import javax.crypto.Cipher;
+import java.security.NoSuchAlgorithmException;
 import javax.crypto.BadPaddingException;
 import javax.crypto.IllegalBlockSizeException;
 import sun.misc.BASE64Encoder;
@@ Line 120: / Line 122: @@
+  *
   * High Level Algorithm :
-  * 1. Generate a DES key (specify the Key size during this phase)
+  * 1. Generate a AES key (specify the Key size during this phase)
   * 2. Create the Cipher
   * 3. To Encrypt : Initialize the Cipher for Encryption

@@ Line 134: / Line 134: @@
 		String strCipherText = new String();
 		String strDecryptedText = new String();
-−
-		try{
+		try {
-		/**
+			/**
-		 *  Step 1. Generate an AES key using KeyGenerator
+			 * Step 1. Generate an AES key using KeyGenerator Initialize the
-		 *  		Initialize the keysize to 128
+			 * keysize to 128 bits (16 bytes)
-−
+			 *
-		 */
+			 */
-		KeyGenerator keyGen = KeyGenerator.getInstance("AES");
+			KeyGenerator keyGen = KeyGenerator.getInstance("AES");
-		keyGen.init(128);
+			keyGen.init(128);
-		SecretKey secretKey = keyGen.generateKey();
+			SecretKey secretKey = keyGen.generateKey();
-−
-		/**
+			/**
-		 *  Step2. Create a Cipher by specifying the following parameters
+			 * Step 2. Generate an Initialization Vector (IV)
-		 * 			a. Algorithm name - here it is AES
+			 * 		a. Use SecureRandom to generate random bits
-		 */
+			 * 		   The size of the IV matches the blocksize of the cipher (128 bits for AES)
+			 * 		b. Construct the appropriate IvParameterSpec object for the data to pass to Cipher's init() method
-		Cipher aesCipher = Cipher.getInstance("AES/CBC"); /* Must specify the mode explicitly as most JCE providers default to ECB mode!! */
+			 */
-−
-		/**
+			final int AES_KEYLENGTH = 128;	// change this as desired for the security level you want
-		 *  Step 3. Initialize the Cipher for Encryption
+			byte[] iv = new byte[AES_KEYLENGTH / 8];	// Save the IV bytes or send it in plaintext with the encrypted data so you can decrypt the data later
-		 */
+			SecureRandom prng = new SecureRandom();
+			prng.nextBytes(iv);
-		aesCipher.init(Cipher.ENCRYPT_MODE,secretKey);
+			/**
-		/**
+			 * Step 3. Create a Cipher by specifying the following parameters
-		 *  Step 4. Encrypt the Data
+			 * 		a. Algorithm name - here it is AES
-		 *  		1. Declare / Initialize the Data. Here the data is of type String
+			 * 		b. Mode - here it is CBC mode
-		 *  		2. Convert the Input Text to Bytes
+			 * 		c. Padding - e.g. PKCS7 or PKCS5
-		 *  		3. Encrypt the bytes using doFinal method
+			 */
-		 */
-		strDataToEncrypt = "Hello World of Encryption using AES ";
+			Cipher aesCipherForEncryption = Cipher.getInstance("AES/CBC/PKCS7PADDING"); // Must specify the mode explicitly as most JCE providers default to ECB mode!!
-		byte[] byteDataToEncrypt = strDataToEncrypt.getBytes();
-		byte[] byteCipherText = aesCipher.doFinal(byteDataToEncrypt);
+			/**
-		strCipherText = new BASE64Encoder().encode(byteCipherText);
+			 * Step 4. Initialize the Cipher for Encryption
-		System.out.println("Cipher Text generated using AES is " +strCipherText);
+			 */
-−
-		/**
+			aesCipherForEncryption.init(Cipher.ENCRYPT_MODE, secretKey,
-		 *  Step 5. Decrypt the Data
+					new IvParameterSpec(iv));
-		 *  		1. Initialize the Cipher for Decryption
-		 *  		2. Decrypt the cipher bytes using doFinal method
+			/**
-		 */
+			 * Step 5. Encrypt the Data
-		aesCipher.init(Cipher.DECRYPT_MODE,secretKey,aesCipher.getParameters());
+			 * 		a. Declare / Initialize the Data. Here the data is of type String
-		byte[] byteDecryptedText = aesCipher.doFinal(byteCipherText);
+			 * 		b. Convert the Input Text to Bytes
-		strDecryptedText = new String(byteDecryptedText);
+			 * 		c. Encrypt the bytes using doFinal method
-		System.out.println(" Decrypted Text message is " +strDecryptedText);
+			 */
+		}
-−
-		catch (NoSuchAlgorithmException noSuchAlgo)
+		catch (NoSuchAlgorithmException noSuchAlgo) {
 			System.out.println(" No Such Algorithm exists " + noSuchAlgo);
+		}
-−
-			catch (NoSuchPaddingException noSuchPad)
+		catch (NoSuchPaddingException noSuchPad) {
 			System.out.println(" No Such Padding exists " + noSuchPad);
-				System.out.println(" No Such Padding exists " + noSuchPad);
-−
 		catch (InvalidKeyException invalidKey) {
-				catch (InvalidKeyException invalidKey)
+			System.out.println(" Invalid Key " + invalidKey);
-−
+		}
-					System.out.println(" Invalid Key " + invalidKey);
+		catch (BadPaddingException badPadding) {
+			System.out.println(" Bad Padding " + badPadding);
-				catch (BadPaddingException badPadding)
-−
-					System.out.println(" Bad Padding " + badPadding);
+		catch (IllegalBlockSizeException illegalBlockSize) {
+			System.out.println(" Illegal Block Size " + illegalBlockSize);
-−
+		}
-				catch (IllegalBlockSizeException illegalBlockSize)
+		catch (InvalidAlgorithmParameterException invalidParam) {
-					System.out.println(" Illegal Block Size " + illegalBlockSize);
+			System.out.println(" Invalid Parameter " + invalidParam);
-−
+		}
+	}
+}
 </pre>