使用java进行SSL证书的签名与签验

一、签名与签验的含义

签名：客户端使用私钥对字符串加密，得到一个加密后的字符串

签验（签名验证）：服务端使用公钥对字符串加密，验证加密后的字符串是否和客户端签名后一样

二、创建私钥、证书等文件

在linux中执行一下命令，生成所需的各个文件

1.手动生成私钥pri.key
openssl genrsa -des3 -passout pass:123456 -out pri.key 2048

2.生成pkcs8
openssl pkcs8 -topk8 -in pri.key -out pkcs8.pem -nocrypt -passin pass:123456

3.生成pkcs10申请书P10.key //C国家,ST省,L市,O组织,OU部门,CN域名或ip
openssl req -new -key pri.key -passin pass:123456 -out P10.key -subj "/C=CN/ST=GUANGZHOU/L=GUANGZHOU/O=A/OU=B/CN=xxx"

4.生成公钥pub.key
openssl rsa -in pri.key -passin pass:123456  -pubout -out pub.key

5.生成证书server.crt
openssl x509 -req -days 365 -in P10.key -signkey pri.key -passin pass:123456  -out server.crt

6.生成pk12文件
openssl pkcs12 -export -in server.crt -inkey pri.key -passin pass:123456 -passout pass:123456 -out tomcat.p12

7.生成keystore文件
keytool -importkeystore -v -srckeystore tomcat.p12 -srcstoretype pkcs12 -srcstorepass 123456 -destkeystore tomcat.keystore -deststoretype jks -deststorepass 123456

以上生成的文件，我们需要用到pkcs8和server.crt

生成后的pkcs8内容如下

server.crt内容如下

三、在Java代码中读取这些文件，然后调用对应类进行签名和签验

public class SslUtil {

    
    public static boolean verifySign(X509Certificate certificate, String signStr, String unSignStr)
            throws NoSuchAlgorithmException, InvalidKeyException, SignatureException {
        byte[] data = base64.getDecoder().decode(signStr);
        Signature signature = Signature.getInstance(certificate.getSigAlgName());
        signature.initVerify(certificate.getPublicKey());
        signature.update(unSignStr.getBytes(StandardCharsets.UTF_8));
        return signature.verify(data);
    }

    
    public static String signString(String str, PrivateKey privateKey, X509Certificate certificate)
            throws NoSuchAlgorithmException, InvalidKeyException, SignatureException {
        Signature signature = Signature.getInstance(certificate.getSigAlgName());
        signature.initSign(privateKey);
        signature.update(str.getBytes(StandardCharsets.UTF_8));
        byte[] data = signature.sign();
        return base64.getEncoder().encodeToString(data);
    }

    
    public static X509Certificate getCertificate(String certFile) throws CertificateException, IOException {
        byte[] cert = readCertFile(certFile);
        CertificateFactory factory = CertificateFactory.getInstance("X.509");
        InputStream inputStream = new ByteArrayInputStream(cert);
        X509Certificate certificate = (X509Certificate) factory.generateCertificate(inputStream);
        return certificate;
    }

    
    public static PrivateKey getPrivateKey(String pkcs8File)
            throws NoSuchAlgorithmException, InvalidKeySpecException, IOException {
        byte[] prikey = readPkcs8File(pkcs8File);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(prikey);
        PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
        return privateKey;
    }

    
    private static byte[] readPkcs8File(String pkcs8File) throws IOException {
        StringBuilder stringBuilder = new StringBuilder();
        try(BufferedReader br = new BufferedReader(new FileReader(pkcs8File))){
            String line;
            while((line=br.readLine())!=null){
                if(line.startsWith("-")){
                    continue;
                }
                stringBuilder.append(line);
            }
            return base64.getDecoder().decode(stringBuilder.toString());
        }
    }

    
    private static  byte[] readCertFile(String certFile) throws IOException{
        try(InputStream is = new FileInputStream(certFile)){
            return is.readAllBytes();
        }
    }
}

调用方法验证，最后会返还true

public class Main {
    public static void main(String[] args) {
        String pkcs8File = "pkcs8.pem";
        String certFile = "server.crt";
        String str = "这是原文字符串";
        try{
            PrivateKey privateKey = SslUtil.getPrivateKey(pkcs8File);
            X509Certificate certificate = SslUtil.getCertificate(certFile);
            String signStr = SslUtil.signString(str, privateKey, certificate);
            System.out.println("字符串 ["+str+"] ---签名--->["+signStr+"]");

            boolean result = SslUtil.verifySign(certificate, signStr, str);
            System.out.println("签验结果："+result);
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

四、不使用java来签名，而是使用openssl命令来生成签名，然后使用java来签验

openssl签名的命令

1.创建需要签名的文件
echo "这是原文字符串" > a.txt

2.对文件进行签名
openssl dgst -sha256 -passin pass:123456 -sign pri.key a.txt > b.txt

3.对签名后的文件进行base64编码
base64 b.txt > c.txt

命令生成的c.txt内容如下

BTG52NfjVx6v7yHq4OzCbuzeA4bvlWSPHI4N4yHSDzErmB8nWsQsJ97fKOTbeH7pdLzTuO2RS832
3wbEBo+FFTyOgUENa0J+I22SVVmCAzuPGzATRdvk6rM7kTbeMJZSIiBq/v4hX6btvAOuJ0f0/ZG5
m1bbbr3SZe26DiNl7TKgWpMhFW2OyRmaTq6fPfhOx+1/zWHFiMWrVl5WO3vJpRt2We3/wRwNzgBj
e6M+BlcQvND+gSS//ix/6avvAaNjudXU8r8/T0MKMAsuRk0zPbOjqbNudZrN4aDRf3GUkYiFzp86
5F9kkyqhapISVnpNWDEpSQz14cyoDAFUcd0yDw==

然后Java中直接拿到这个字符串进行签验

public class Main {
    public static void main(String[] args) {
        String pkcs8File = "pkcs8.pem";
        String certFile = "server.crt";
        //注意，文件方式加密的字符串，后面多了一个回车符号
        String str = "这是原文字符串n";
        try{
            X509Certificate certificate = SslUtil.getCertificate(certFile);

            String signStr = "BTG52NfjVx6v7yHq4OzCbuzeA4bvlWSPHI4N4yHSDzErmB8nWsQsJ97fKOTbeH7pdLzTuO2RS8323wbEBo+FFTyOgUENa0J+I22SVVmCAzuPGzATRdvk6rM7kTbeMJZSIiBq/v4hX6btvAOuJ0f0/ZG5m1bbbr3SZe26DiNl7TKgWpMhFW2OyRmaTq6fPfhOx+1/zWHFiMWrVl5WO3vJpRt2We3/wRwNzgBje6M+BlcQvND+gSS//ix/6avvAaNjudXU8r8/T0MKMAsuRk0zPbOjqbNudZrN4aDRf3GUkYiFzp865F9kkyqhapISVnpNWDEpSQz14cyoDAFUcd0yDw==";

            boolean result = SslUtil.verifySign(certificate, signStr, str);
            System.out.println("签验结果："+result);
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

使用java进行SSL证书的签名与签验

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