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The Java Developers Almanac 1.4Order this book from Amazon. |
e464. Encrypting with DES Using a Pass PhraseThis example demonstrates how to use a pass phrase (a string password of multiple words) for encryption.public class DesEncrypter { Cipher ecipher; Cipher dcipher; // 8-byte Salt byte[] salt = { (byte)0xA9, (byte)0x9B, (byte)0xC8, (byte)0x32, (byte)0x56, (byte)0x35, (byte)0xE3, (byte)0x03 }; // Iteration count int iterationCount = 19; DesEncrypter(String passPhrase) { try { // Create the key KeySpec keySpec = new PBEKeySpec(passPhrase.toCharArray(), salt, iterationCount); SecretKey key = SecretKeyFactory.getInstance( "PBEWithMD5AndDES").generateSecret(keySpec); ecipher = Cipher.getInstance(key.getAlgorithm()); dcipher = Cipher.getInstance(key.getAlgorithm()); // Prepare the parameter to the ciphers AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt, iterationCount); // Create the ciphers ecipher.init(Cipher.ENCRYPT_MODE, key, paramSpec); dcipher.init(Cipher.DECRYPT_MODE, key, paramSpec); } catch (java.security.InvalidAlgorithmParameterException e) { } catch (java.security.spec.InvalidKeySpecException e) { } catch (javax.crypto.NoSuchPaddingException e) { } catch (java.security.NoSuchAlgorithmException e) { } catch (java.security.InvalidKeyException e) { } } public String encrypt(String str) { try { // Encode the string into bytes using utf-8 byte[] utf8 = str.getBytes("UTF8"); // Encrypt byte[] enc = ecipher.doFinal(utf8); // Encode bytes to base64 to get a string return new sun.misc.BASE64Encoder().encode(enc); } catch (javax.crypto.BadPaddingException e) { } catch (IllegalBlockSizeException e) { } catch (UnsupportedEncodingException e) { } catch (java.io.IOException e) { } return null; } public String decrypt(String str) { try { // Decode base64 to get bytes byte[] dec = new sun.misc.BASE64Decoder().decodeBuffer(str); // Decrypt byte[] utf8 = dcipher.doFinal(dec); // Decode using utf-8 return new String(utf8, "UTF8"); } catch (javax.crypto.BadPaddingException e) { } catch (IllegalBlockSizeException e) { } catch (UnsupportedEncodingException e) { } catch (java.io.IOException e) { } return null; } } // Here is an example that uses the class try { // Create encrypter/decrypter class DesEncrypter encrypter = new DesEncrypter("My Pass Phrase!"); // Encrypt String encrypted = encrypter.encrypt("Don't tell anybody!"); // Decrypt String decrypted = encrypter.decrypt(encrypted); } catch (Exception e) { }
e462. Encrypting a String with DES e463. Encrypting a File or Stream with DES e465. Converting a 56-bit Value to a DES Key e466. Encrypting an Object with DES
© 2002 Addison-Wesley. |