import android.text.TextUtils; import org.apache.commons.lang3.StringUtils; import java.security.SecureRandom; import javax.crypto.Cipher; import javax.crypto.KeyGenerator; import javax.crypto.SecretKey; import javax.crypto.spec.SecretKeySpec; public class AesUtils { private final static String HEX = "0123456789ABCDEF"; //private static final String CBC_PKCS5_PADDING = "AES/CBC/PKCS5Padding";//AES是加密方式 CBC是工作模式 PKCS5Padding是填充模式 private static final String CBC_PKCS7_PADDING = "AES/ECB/PKCS7Padding"; private static final String AES = "AES";//AES 加密 private static final String SHA1PRNG = "SHA1PRNG";//// SHA1PRNG 强随机种子算法, 要区别4.2以上版本的调用方法 private final static int JELLY_BEAN_4_2 = 17; /* * 生成随机数,可以当做动态的密钥 加密和解密的密钥必须一致,不然将不能解密 */ public static String generateKey() { try { SecureRandom localSecureRandom = SecureRandom.getInstance(SHA1PRNG); byte[] bytes_key = new byte[20]; localSecureRandom.nextBytes(bytes_key); String str_key = toHex(bytes_key); return str_key; } catch (Exception e) { e.printStackTrace(); } return null; } // 对密钥进行处理 private static byte[] getRawKey(byte[] seed) throws Exception { KeyGenerator kgen = KeyGenerator.getInstance(AES); //for android SecureRandom sr = null; // 在4.2以上版本中,SecureRandom获取方式发生了改变 if (android.os.Build.VERSION.SDK_INT >= JELLY_BEAN_4_2) { sr = SecureRandom.getInstance(SHA1PRNG, "Crypto"); } else { sr = SecureRandom.getInstance(SHA1PRNG); } sr.setSeed(seed); kgen.init(128, sr); //256 bits or 128 bits,192bits //AES中128位密钥版本有10个加密循环,192比特密钥版本有12个加密循环,256比特密钥版本则有14个加密循环。 SecretKey skey = kgen.generateKey(); byte[] raw = skey.getEncoded(); return raw; } /* * 加密 */ public static String encrypt(String key, String cleartext) { if (StringUtils.isEmpty(cleartext)) { return cleartext; } try { byte[] result = encrypt(key, cleartext.getBytes()); return toHex(result);//Base64Encoder.encode(result); } catch (Exception e) { e.printStackTrace(); } return null; } /* * 真正的加密
* @param key
* 密钥
* @param clear
* 将要加密的内容
* @return 已经加密的内容
*/ private static byte[] encrypt(String key, byte[] clear) throws Exception { byte[] raw = getRawKey(key.getBytes()); SecretKeySpec skeySpec = new SecretKeySpec(raw, AES); Cipher cipher = Cipher.getInstance(CBC_PKCS7_PADDING); //cipher.init(Cipher.ENCRYPT_MODE, skeySpec, new IvParameterSpec(new byte[cipher.getBlockSize()])); cipher.init(Cipher.ENCRYPT_MODE, skeySpec); byte[] encrypted = cipher.doFinal(clear); return encrypted; } /* * 解密 */ public static String decrypt(String key, String encrypted) { if (TextUtils.isEmpty(encrypted)) { return encrypted; } try { //byte[] enc = Base64Decoder.decodeToBytes(encrypted); byte[] enc = toByte(encrypted); byte[] result = decrypt(key, enc); return new String(result); } catch (Exception e) { e.printStackTrace(); } return null; } /* * 解密 */ private static byte[] decrypt(String key, byte[] encrypted) throws Exception { byte[] raw = getRawKey(key.getBytes()); SecretKeySpec skeySpec = new SecretKeySpec(raw, AES); Cipher cipher = Cipher.getInstance(CBC_PKCS7_PADDING); //ECB mode does not use an IV //cipher.init(Cipher.DECRYPT_MODE, skeySpec, new IvParameterSpec(new byte[cipher.getBlockSize()])); cipher.init(Cipher.DECRYPT_MODE, skeySpec); byte[] decrypted = cipher.doFinal(encrypted); return decrypted; } //二进制转字符 public static String toHex(byte[] buf) { if (buf == null) { return ""; } StringBuffer result = new StringBuffer(2 * buf.length); for (int i = 0; i < buf.length; i++) { appendHex(result, buf[i]); } return result.toString(); } private static void appendHex(StringBuffer sb, byte b) { sb.append(HEX.charAt((b >> 4) & 0x0f)).append(HEX.charAt(b & 0x0f)); } public static byte[] toByte(String hexString) { int len = hexString.length() / 2; byte[] result = new byte[len]; for (int i = 0; i < len; i++) { result[i] = Integer.valueOf(hexString.substring(2 * i, 2 * i + 2), 16).byteValue(); } return result; } }