用java的RSA 公钥和私钥到远程文件，然后进行加解密

首先，您需要生成RSA公钥和私钥。可以使用Java中的`KeyPairGenerator`类来生成公钥和私钥。以下是一个示例代码：

import java.security.*;

public class RSAKeyGenerator {

    public static void main(String[] args) throws Exception {
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
        keyPairGenerator.initialize(2048);

        KeyPair keyPair = keyPairGenerator.generateKeyPair();
        PrivateKey privateKey = keyPair.getPrivate();
        PublicKey publicKey = keyPair.getPublic();

        System.out.println("Private Key: " + privateKey);
        System.out.println("Public Key: " + publicKey);
    }
}

生成的公钥和私钥将打印在控制台上。

接下来，您需要将公钥和私钥保存到文件中。可以使用Java中的`KeyStore`类来保存公钥和私钥。以下是一个示例代码：

import java.io.FileOutputStream;
import java.security.KeyStore;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.cert.Certificate;

public class RSAKeyStore {

    public static void main(String[] args) throws Exception {
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
        keyPairGenerator.initialize(2048);

        KeyPair keyPair = keyPairGenerator.generateKeyPair();
        PrivateKey privateKey = keyPair.getPrivate();
        PublicKey publicKey = keyPair.getPublic();

        KeyStore keyStore = KeyStore.getInstance("JKS");
        keyStore.load(null, null);
        keyStore.setKeyEntry("mykey", privateKey, "mypass".toCharArray(), new Certificate[] { });
        keyStore.setCertificateEntry("mycert", new TestCertificate(publicKey));

        FileOutputStream fos = new FileOutputStream("mykeystore.jks");
        keyStore.store(fos, "mystorepass".toCharArray());
        fos.close();
    }
}

class TestCertificate extends Certificate {
    private PublicKey publicKey;

    public TestCertificate(PublicKey publicKey) {
        super("X.509");
        this.publicKey = publicKey;
    }

    @Override
    public PublicKey getPublicKey() {
        return publicKey;
    }

    @Override
    public byte[] getEncoded() {
        return new byte[0];
    }

    @Override
    public void verify(PublicKey key) { }

    @Override
    public void verify(PublicKey key, String sigProvider) { }

    @Override
    public String toString() {
        return "TestCertificate";
    }
}

这个示例代码将生成一个Java密钥库，并将私钥和公钥保存为键值对。然后将密钥库保存到文件中。

现在，您可以使用公钥加密文件，然后使用私钥解密文件。以下是示例代码：

import javax.crypto.Cipher;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.security.*;

public class RSAEncryption {

    public static void main(String[] args) throws Exception {
        // 读取密钥库文件
        String keyStoreFile = "mykeystore.jks";
        String keyStorePass = "mystorepass";
        String keyAlias = "mykey";
        String keyPass = "mypass";

        KeyStore keyStore = KeyStore.getInstance("JKS");
        keyStore.load(new FileInputStream(keyStoreFile), keyStorePass.toCharArray());

        // 获取私钥
        PrivateKey privateKey = (PrivateKey) keyStore.getKey(keyAlias, keyPass.toCharArray());

        // 加密文件
        String inputFile = "plaintext.txt";
        String encryptedFile = "encrypted.txt";

        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
        cipher.init(Cipher.ENCRYPT_MODE, keyStore.getCertificate("mycert").getPublicKey());

        FileInputStream fis = new FileInputStream(inputFile);
        FileOutputStream fos = new FileOutputStream(encryptedFile);

        byte[] buffer = new byte[1024];
        int len;

        while ((len = fis.read(buffer)) != -1) {
            byte[] encrypted = cipher.update(buffer, 0, len);
            if (encrypted != null) {
                fos.write(encrypted);
            }
        }

        byte[] encrypted = cipher.doFinal();
        if (encrypted != null) {
            fos.write(encrypted);
        }

        fis.close();
        fos.flush();
        fos.close();

        // 解密文件
        String decryptedFile = "decrypted.txt";

        cipher.init(Cipher.DECRYPT_MODE, privateKey);

        fis = new FileInputStream(encryptedFile);
        fos = new FileOutputStream(decryptedFile);

        buffer = new byte[1024];

        while ((len = fis.read(buffer)) != -1) {
            byte[] decrypted = cipher.update(buffer, 0, len);
            if (decrypted != null) {
                fos.write(decrypted);
            }
        }

        byte[] decrypted = cipher.doFinal();
        if (decrypted != null) {
            fos.write(decrypted);
        }

        fis.close();
        fos.flush();
        fos.close();
    }
}

这个示例代码将使用公钥加密`plaintext.txt`文件，并将加密后的文件保存为`encrypted.txt`。然后，使用私钥解密`encrypted.txt`文件，并将解密后的文件保存为`decrypted.txt`。