e462. encrypting a string with des.txt

来自「这里面包含了一百多个JAVA源文件」· 文本 代码 · 共 73 行

This 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) {
    }