javaDSA實現加密和解密（簽名和驗證）

創建主函數測試

　　public static void main(String[] args) throws Exception {
        
        String data = "跳梁小豆tlxd666";
        
        //創建秘鑰生成器
        KeyPairGenerator kpg = KeyPairGenerator.getInstance("DSA");
        kpg.initialize(512);
        KeyPair keypair = kpg.generateKeyPair();//生成秘鑰對
        DSAPublicKey publickey = (DSAPublicKey)keypair.getPublic();
        DSAPrivateKey privatekey = (DSAPrivateKey)keypair.getPrivate();
        
        //簽名和驗證
        //簽名
        Signature sign = Signature.getInstance("SHA1withDSA");
        sign.initSign(privatekey);//初始化私鑰，簽名只能是私鑰
        sign.update(data.getBytes());//更新簽名數據
        byte[] b = sign.sign();//簽名，返回簽名后的字節數組
        
        
        //驗證
        sign.initVerify(publickey);//初始化公鑰，驗證只能是公鑰
        sign.update(data.getBytes());//更新驗證的數據
        boolean result = sign.verify(b);//簽名和驗證一致返回true  不一致返回false
        System.out.println(result);
        
        
    }