Signature类用于提供数字签名，用于保证数据的完整性，用非对称密钥中的私钥签名，公钥验签。

Java的实现

签名

/**
 * 签名算法
 */
public static final String SIGN_ALGORITHMS = "SHA1WithRSA";

/**
 * RSA签名
 *
 * @param content    待签名数据
 * @param privateKey 私钥
 * @param encode     字符集编码
 * @return 签名值
 */
public static String sign(String content, PrivateKey privateKey, String encode) {
    try {

        Signature signature = Signature.getInstance(SIGN_ALGORITHMS);
        signature.initSign(privateKey);
        signature.update(content.getBytes(encode));
        byte[] signed = signature.sign();
        return byte2Base64(signed);
    } catch (Exception e) {
        e.printStackTrace();
    }

    return null;
}

检签

/**
 * 验签
 *
 * @param content 待签名数据
 * @param sign    签名值
 * @param pubKey  公钥
 * @return 失败时，返回false。
 */
public static boolean verifySignature(String content, String sign, PublicKey pubKey) {
    if (null == content || null == sign || "".equals(content) || "".equals(sign)) {
        return false;
    }
    try {
        byte[] signed = base642Byte(sign);
        Signature signatureChecker = Signature.getInstance(SIGN_ALGORITHMS);
        signatureChecker.initVerify(pubKey);
        signatureChecker.update(content.getBytes());
        // 验证签名是否正常
        return signatureChecker.verify(signed);
    } catch (Exception e) {
        return false;
    }
}

public static String byte2Base64(byte[] bytes) {
    BASE64Encoder encoder = new BASE64Encoder();
    return encoder.encode(bytes);
}

public static byte[] base642Byte(String base64Key) throws IOException {
    BASE64Decoder decoder = new BASE64Decoder();
    return decoder.decodeBuffer(base64Key);
}

测试

@Test
public void testSignature() throws Exception {
     // 随机生成一对非对称加密的秘钥对
     KeyPair keyPair = RSAUtil.getKeyPair();
                
     String content = "helloWord123" + (new SecureRandom().nextLong() + "_测试内容");
     System.out.println("验签内容：" + content);

     String sign = SignatureUtil.sign(content, keyPair.getPrivate(), "utf-8");
     System.out.println("签名结果=" + sign);

         boolean verify = SignatureUtil.verifySignature(content, sign, keyPair.getPublic());
     System.out.println("验签结果="+verify);

}

验签内容：helloWord123-1206901626301061997_测试内容
签名结果=HKY4rVCJ2tC0WJKe+J9siB0PWOz3uqzwg60gyfwT1tbmd9S00mOXeaIg/V6D/uLEkfC20d0fs9Sf
tP/zWNNklnVJLWfbGkLs8MlU0Mi1GGV6A8HozfWEnukzidTf4kx2iEU9LzETbcqbWflxlKKqShi6
lgdqKPC5wtC2byZjCIpAkutVE0u/GbtZQixyYJQbo/MODr8AC710gWJ8YS9WxIPntoeqoqkKC7Eg
47nAZsBgMAbtPZTFLhOJy1skTDhFwMx8cWKr6jrOBRZSfWNCmERU7Le3fkVjeg1UCKTDAQ3EMb0F
WeLWKvGnoUBi/iXABgR/PC8PM3m8ZPV/HmYH8A==
验签结果=true

Java-加密篇
Java加解-RSA加解密
Java加密-Signature数据签名
Java加密-AES加解密
Java加密-密钥的保存与获取