如何使用BouncyCastle从java/kotlin文件/字符串中读取RSA公钥_如何在java中读取rsa公钥文件？_如何使用C＃中的Bouncycastle将Pem公钥转换为rsa公钥？ - 腾讯云开发者社区

如何使用BouncyCastle从java/kotlin文件/字符串中读取RSA公钥

基础概念

BouncyCastle是一个广泛使用的Java库，提供了大量的加密算法实现，包括RSA公钥和私钥的生成、解析和使用。RSA是一种非对称加密算法，广泛应用于数据加密和数字签名。

类型

RSA公钥：用于加密数据和验证数字签名。
RSA私钥：用于解密数据和生成数字签名。

应用场景

数据加密：使用公钥加密数据，私钥解密。
数字签名：使用私钥生成数字签名，公钥验证签名。

读取RSA公钥的方法

从文件中读取RSA公钥

import org.bouncycastle.asn1.x509.SubjectPublicKeyInfo;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import java.io.FileInputStream;
import java.security.KeyFactory;
import java.security.PublicKey;
import java.security.Security;
import java.security.spec.X509EncodedKeySpec;

public class RSAKeyReader {
    public static void main(String[] args) throws Exception {
        Security.addProvider(new BouncyCastleProvider());

        FileInputStream fis = new FileInputStream("path/to/publicKey.pem");
        byte[] keyBytes = new byte[fis.available()];
        fis.read(keyBytes);
        fis.close();

        SubjectPublicKeyInfo publicKeyInfo = SubjectPublicKeyInfo.getInstance(keyBytes);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(publicKeyInfo.getEncoded());
        KeyFactory keyFactory = KeyFactory.getInstance("RSA", "BC");
        PublicKey publicKey = keyFactory.generatePublic(x509KeySpec);

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

从字符串中读取RSA公钥

import org.bouncycastle.asn1.x509.SubjectPublicKeyInfo;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import java.security.KeyFactory;
import java.security.PublicKey;
import java.security.Security;
import java.security.spec.X509EncodedKeySpec;

public class RSAKeyReader {
    public static void main(String[] args) throws Exception {
        Security.addProvider(new BouncyCastleProvider());

        String publicKeyString = "-----BEGIN PUBLIC KEY-----\n" +
                "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA...\n" +
                "-----END PUBLIC KEY-----";

        byte[] keyBytes = publicKeyString.replace("-----BEGIN PUBLIC KEY-----", "")
                .replace("-----END PUBLIC KEY-----", "")
                .replaceAll("\\s", "")
                .getBytes();

        SubjectPublicKeyInfo publicKeyInfo = SubjectPublicKeyInfo.getInstance(keyBytes);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(publicKeyInfo.getEncoded());
        KeyFactory keyFactory = KeyFactory.getInstance("RSA", "BC");
        PublicKey publicKey = keyFactory.generatePublic(x509KeySpec);

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