java RSA 公钥加密

在Java中使用RSA算法进行公钥加密的步骤如下：

1. 导入所需的类和包：

import java.security.Key;
import java.security.KeyFactory;
import java.security.spec.X509EncodedKeySpec;
import javax.crypto.Cipher;
import java.util.Base64;

2. 定义RSA算法和密钥相关的常量：

private final static String RSA_ALGORITHM = "RSA";
private final static String RSA_PUBLIC_KEY = "RSAPublicKey";

3. 获取公钥字符串，并将其转换为字节数组：

String publicKeyStr = "这里填写你的公钥字符串";
byte[] publicKeyBytes = Base64.getDecoder().decode(publicKeyStr);

4. 根据公钥字节数组生成公钥对象：

X509EncodedKeySpec keySpec = new X509EncodedKeySpec(publicKeyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(RSA_ALGORITHM);
Key publicKey = keyFactory.generatePublic(keySpec);

5. 创建Cipher对象并进行加密操作：

Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
byte[] encryptedBytes = cipher.doFinal(plainText.getBytes());

6. 将加密后的字节数组转换为Base64编码的字符串：

String encryptedStr = Base64.getEncoder().encodeToString(encryptedBytes);

完整的示例代码如下：

import java.security.Key;
import java.security.KeyFactory;
import java.security.spec.X509EncodedKeySpec;
import javax.crypto.Cipher;
import java.util.Base64;

public class RSAEncryptionExample {
    private final static String RSA_ALGORITHM = "RSA";
    private final static String RSA_PUBLIC_KEY = "RSAPublicKey";

    public static void main(String[] args) throws Exception {
        // 获取公钥字符串，并将其转换为字节数组
        String publicKeyStr = "这里填写你的公钥字符串";
        byte[] publicKeyBytes = Base64.getDecoder().decode(publicKeyStr);

        // 根据公钥字节数组生成公钥对象
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(publicKeyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(RSA_ALGORITHM);
        Key publicKey = keyFactory.generatePublic(keySpec);

        // 加密操作
        String plainText = "要加密的数据";
        Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        byte[] encryptedBytes = cipher.doFinal(plainText.getBytes());

        // 将加密后的字节数组转换为Base64编码的字符串
        String encryptedStr = Base64.getEncoder().encodeToString(encryptedBytes);

        System.out.println("加密后的数据：" + encryptedStr);
    }
}