首先要注意一點,默認的JDK是不支持256位加密的,需要到Oracle官網下載加密增強文件(Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files 8),否則編譯會報錯:
java.security.InvalidKeyException: Illegal key size
解壓后替換jre/lib/security/目錄下的同名文件即可。
最簡單的應用實例:
public class IotServer { private static final byte[] key = {..};//key.length須滿足16的整數倍 private static final byte[] iv = {..};//iv.length須滿足16的整數倍 private static final String transform = "AES/CBC/PKCS5Padding"; private static final String algorithm = "AES"; private static final SecretKeySpec keySpec = new SecretKeySpec(key, algorithm); public static void main(String[] args) { Cipher cipher = Cipher.getInstance(transform); cipher.init(Cipher.ENCRYPT_MODE, keySpec, new IvParameterSpec(iv)); byte[] cipherData = cipher.doFinal("待加密的明文".getBytes("UTF-8")); System.out.println(Arrays.toString(cipherData)); } }
key和iv都可以通過更復雜的方式生成,方法很多這里不再列出,更多的使用技巧會在實際應用中發現。