java.security.NoSuchAlgorithmException：RSA签名不可用 [英] java.security.NoSuchAlgorithmException: RSA Signature not available

问题描述

这是异常

Exception in thread "main" java.security.NoSuchAlgorithmException: RSA Signature not available
    at java.security.Signature.getInstance(Signature.java:229)
    at MailClient.main(MailClient.java:52)

这是我的代码

import java.io.*;
import java.net.*;
import java.nio.ByteBuffer;
import java.util.*;
import java.security.*;

public class MailClient {

    public String getMessage(Mail m){
        return m.message;
    }

    public static void main(String[] args) throws Exception {

        // Initialisation
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        String host = args[0];
        int port = Integer.parseInt(args[1]);
        String userid = args[2];

        while(true) {
            // connect to server
            Socket s = new Socket(host,port);
            DataInputStream dis = new DataInputStream(s.getInputStream());
            DataOutputStream dos = new DataOutputStream(s.getOutputStream());
            ObjectOutputStream oos = new ObjectOutputStream(s.getOutputStream());
            oos.flush();
            ObjectInputStream ois = new ObjectInputStream(s.getInputStream());

            // TO DO: login

            // these two lines are here just to make the supplied programs run without crashing.
            // You may want to change them, and certainly add things after them
            dos.writeUTF(userid);

            String userPrivateKeyFileName = userid + ".prv";
            // Get the key to create the signature
            ObjectInputStream keyIn = new ObjectInputStream(new FileInputStream(userPrivateKeyFileName));
            PrivateKey privateKey = (PrivateKey)keyIn.readObject();
            keyIn.close();

            // create timeStamp and random number
            long t1 = (new Date()).getTime();
            double q1 = Math.random();
            // ByteBuffer to convert to bytes later
            ByteBuffer bb = ByteBuffer.allocate(16);
            bb.putLong(t1);
            bb.putDouble(q1);

            // create signature, using timeStamp and random number as data
            Signature sig = Signature.getInstance("RSA");
            sig.initSign(privateKey);
            sig.update(bb.array());
            byte[] signature = sig.sign();

            // send data and signature
            DataOutputStream out = new DataOutputStream(s.getOutputStream());
            out.writeUTF(userid);
            out.writeLong(t1);
            out.writeDouble(q1);
            out.writeInt(signature.length);
            out.write(signature);
            out.flush();

            boolean answer = dis.readBoolean();

            //passed the verifyLogin
            if (answer)
                {
                // receive how many messages
                int numMsg = dis.readInt();
                System.out.println("You have " + numMsg + " incoming messages.");

                // TO DO: read messages
                ArrayList<Mail> msg = new ArrayList<>(numMsg);
                for(int i=0;i<numMsg;i++){
                    //@Unchecked
                    msg = (ArrayList<Mail>) ois.readObject();
                }
                while(!msg.isEmpty()){
                    //for each mail, display sender,timestamp,message
                    System.out.println(msg.get(0).sender);
                    System.out.println(msg.get(0).timestamp);
                    System.out.println(msg.get(0).message);
                    MessageDigest md = MessageDigest.getInstance("SHA-1");
                    md.update(msg.get(0).hashcash);

                    byte[] digest = md.digest();
                    boolean normalMail = msg.get(0).checkHashcash(digest);
                    if(normalMail){
                    //check each mail is original that it isn't modified
                    //receive mail
                        System.out.println(msg.get(0).message);
                        }
                    else{System.out.println("it's a spam message.");
                        System.out.println(msg.get(0).message);
                        }
                    msg.remove(0);
                }


                // send messages
                System.out.println("Do you want to send a message [Y/N]?");
                String wantToSend = br.readLine();
                if (!wantToSend.equals("Y")) {
                    dos.writeBoolean(false);
                    return ;
                }
                dos.writeBoolean(true);

                System.out.println("Enter userid of recipient:");
                String recipient = br.readLine();
                System.out.println("Type your message:");
                String message = br.readLine();

                // TO DO: send mail
                Mail m = new Mail(userid, recipient, message);
                MessageDigest md = MessageDigest.getInstance("SHA-1");
                md.update(m.hashcash);

                byte[] digest = md.digest();
                while(m.checkHashcash(digest)){
                    m.setHashcash(digest);

                }

                out.write(digest);
                out.flush();
                // send timeStamp and digest to server
                long mailTimestamp = m.timestamp.getTime();
                out.writeLong(mailTimestamp);




                oos.writeObject(m);

                }
            }


    }

}

推荐答案

如果运行以下代码，您将获得Java安装支持的签名算法列表。

If you run the following code, you will get a list of signature algorithms supported by your Java installation.

TreeSet<String> algorithms = new TreeSet<>();
for (Provider provider : Security.getProviders())
    for (Service service : provider.getServices())
        if (service.getType().equals("Signature"))
            algorithms.add(service.getAlgorithm());
for (String algorithm : algorithms)
    System.out.println(algorithm);

当我运行它时（Windows，Java 1.8.0_65），我得到：

When I run it (Windows, Java 1.8.0_65), I get:

MD2withRSA
MD5andSHA1withRSA
MD5withRSA
NONEwithDSA
NONEwithECDSA
NONEwithRSA
SHA1withDSA
SHA1withECDSA
SHA1withRSA
SHA224withDSA
SHA224withECDSA
SHA224withRSA
SHA256withDSA
SHA256withECDSA
SHA256withRSA
SHA384withECDSA
SHA384withRSA
SHA512withECDSA
SHA512withRSA

正如您所见， RSA 不是有效的签名算法。

可能 NONEwithRSA 就是你所追求的？

As you can see, RSA is not a valid signature algorithm.
Maybe NONEwithRSA is what you're after?

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