毕业课题中需要使用加解密算法，要求加解密前后的数据长度不会变化，查了一些资料，发现可以采用AES加密的CFB跟OFB模式是无填充的模式，可以保持加解密前后数据的长度相等。下面上代码：
import java.io.UnsupportedEncodingException;import java.security.InvalidAlgorithmParameterException;import java.security.InvalidKeyException;import java.security.NoSuchAlgorithmException;import javax.crypto.BadPaddingException;import javax.crypto.Cipher;import javax.crypto.IllegalBlockSizeException;import javax.crypto.NoSuchPaddingException;import javax.crypto.spec.IvParameterSpec;import javax.crypto.spec.SecretKeySpec;public class Encrypt_Decrypt_AES {/*** AES加密算法，调用Java自有类库，采用CFB模式密文反馈无填充模式，可以保证数据长度在加密前后是相同的* @param content 待加密内容* @param key 密钥* @return byte[] 加密结果用byte数组表示* */public static byte[] encrypt_AES(String content, String key) {try {Cipher aesECB = Cipher.getInstance("AES/CFB/NoPadding");SecretKeySpec keySpec = new SecretKeySpec(key.getBytes(), "AES");IvParameterSpec ivSpec = new IvParameterSpec(key.getBytes());aesECB.init(Cipher.ENCRYPT_MODE, keySpec, ivSpec);byte[] result = aesECB.doFinal(content.getBytes());return result;} catch (NoSuchAlgorithmException e) {e.printStackTrace();} catch (NoSuchPaddingException e) {e.printStackTrace();} catch (InvalidKeyException e) {e.printStackTrace();} catch (IllegalBlockSizeException e) {e.printStackTrace();} catch (BadPaddingException e) {e.printStackTrace();} catch (InvalidAlgorithmParameterException e) {// TODO 自动生成的 catch 块 e.printStackTrace();}return null;}/*** * @param content 待解密内容，字符串形式* @param key 解密用的密钥* @return 使用字符串形式返回解密内容* @throws UnsupportedEncodingException*/public static String decrypt_AES(byte[] content, String key) throws UnsupportedEncodingException {try {Cipher aesECB = Cipher.getInstance("AES/CFB/NoPadding");SecretKeySpec keySpec = new SecretKeySpec(key.getBytes(), "AES");IvParameterSpec ivSpec = new IvParameterSpec(key.getBytes());aesECB.init(Cipher.DECRYPT_MODE, keySpec, ivSpec);byte[] result = aesECB.doFinal(content);String AES_decode=new String(result,"utf-8");/************************************/// System.out.println("解密结果："+AES_decode);return AES_decode;} catch (NoSuchAlgorithmException e) {e.printStackTrace();} catch (NoSuchPaddingException e) {e.printStackTrace();} catch (InvalidKeyException e) {e.printStackTrace();} catch (IllegalBlockSizeException e) {e.printStackTrace();} catch (BadPaddingException e) {e.printStackTrace();} catch (InvalidAlgorithmParameterException e) {// TODO 自动生成的 catch 块 e.printStackTrace();}return null;}public static void main(String[] str) throws InvalidKeyException,InvalidAlgorithmParameterException, IllegalBlockSizeException,BadPaddingException, UnsupportedEncodingException {String s = "fire fox 22";byte[] r = encrypt_AES(s, "@93456781234567A");for (byte i : r){String l = Integer.toBinaryString((i & 0xFF) + 0x100).substring(1); System.out.print(l+" ");}System.out.println();decrypt_AES(r, "@93456781234567A");}}
