code: public static String decryptData(String dataString, String encoding,
  			PrivateKey key) {
  		byte[] data = null;
  		try {
  			data = SecureUtil.base64Decode(dataString.getBytes(encoding));
  			data = decryptData(key, data);
  			return new String(data, encoding);
  		} catch (Exception e) {
  			LogUtil.writeErrorLog(e.getMessage(), e);
  			return "";
  		}
  	}
docs: 通过私钥解密
  
  @param dataString
  base64过的数据
  @param encoding
  编码
  @param key
  私钥
  @return 解密后的数据