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The Java Developers Almanac 1.4Order this book from Amazon. |
e462. Encrypting a String with DESThis example implements a class for encrypting and decrypting strings using DES. The class is created with a key and can be used repeatedly to encrypt and decrypt strings using that key.public class DesEncrypter { Cipher ecipher; Cipher dcipher; DesEncrypter(SecretKey key) { try { ecipher = Cipher.getInstance("DES"); dcipher = Cipher.getInstance("DES"); ecipher.init(Cipher.ENCRYPT_MODE, key); dcipher.init(Cipher.DECRYPT_MODE, key); } 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's an example that uses the class: try { // Generate a temporary key. In practice, you would save this key. // See also e464 Encrypting with DES Using a Pass Phrase. SecretKey key = KeyGenerator.getInstance("DES").generateKey(); // Create encrypter/decrypter class DesEncrypter encrypter = new DesEncrypter(key); // Encrypt String encrypted = encrypter.encrypt("Don't tell anybody!"); // Decrypt String decrypted = encrypter.decrypt(encrypted); } catch (Exception e) { }
e463. Encrypting a File or Stream with DES e464. Encrypting with DES Using a Pass Phrase e465. Converting a 56-bit Value to a DES Key e466. Encrypting an Object with DES
© 2002 Addison-Wesley. |