JWT RSA密钥持久化与重构：避免签名异常的教程

import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureAlgorithm;
import io.jsonwebtoken.io.Encoders;
import io.jsonwebtoken.security.Keys;

import java.security.KeyPair;
import java.security.PrivateKey;
import java.security.PublicKey;

public class KeyGenerationAndEncoding {

    public static void main(String[] args) {
        // 1. 生成RSA密钥对，指定RS256算法
        KeyPair keyPair = Keys.keyPairFor(SignatureAlgorithm.RS256);
        PrivateKey privateKey = keyPair.getPrivate();
        PublicKey publicKey = keyPair.getPublic();

        // 2. 获取私钥和公钥的原始字节数组
        byte[] privateKeyBytes = privateKey.getEncoded();
        byte[] publicKeyBytes = publicKey.getEncoded();

        // 3. 使用Base64URL进行编码，以便于存储和传输
        String encodedPrivateKey = Encoders.BASE64URL.encode(privateKeyBytes);
        String encodedPublicKey = Encoders.BASE64URL.encode(publicKeyBytes);

        System.out.println("Encoded Private Key (Base64URL): " + encodedPrivateKey);
        System.out.println("Encoded Public Key (Base64URL): " + encodedPublicKey);
    }
}

import io.jsonwebtoken.io.Decoders;
import io.jsonwebtoken.security.Keys;
import javax.crypto.SecretKey;

public class IncorrectKeyReconstruction {

    public static void main(String[] args) {
        // 假设这是从配置中读取的Base64URL编码的RSA私钥和公钥字符串
        String encodedPrivateKeyStr = "MIIEvAIBADANBgkqhkiG9w0BAQEFAASCBKYwggSiAgEAAoIBAQDTnkqggdMFu5O58pB8U0f8D4pab_7j5T8jNZfEep23DbvoMCjR6X1cFe4qCsvaY4aDF6d6Vn3TVY2INHMuyOTXqe5vhBWiRgaI3TIPkGjgHZ1f6Up_ZPQFJCGTo2b3OiXBq3LTK7PXvMj2EIQPJrHuX099ACDvO-9F8T_nyLA68JLfS-V6OmH-nvaCjqndbVSUxOE69OncpU3kPUpdzPPdi7jhEphTOcKdSE8YvPyAjj8RREgZsWgYn10qql_GEZ8Lh15KuBRwJAJQYeOYU_thC6pObazr7NWbpk1e0_0tDuMrfunbKCca1Wz_xv9M7bn1BD92122wuPkenQg-s0ohAgMBAAECggEAA3vssJ3SkpqXAQ28UT_xxLWgyoJjiO8CThsYx5RZOmVQfa8lTOdyN-zogeqxloPi-A_Qo1P_OFaFQQPUDaYjFmXm1hEvpf9PJju2EkmHYIE8URLvNg_8cMU6hErBbDqZ2olvF4j1qgyipmJ5OiKh9VG-Zkl1QVsUQmuJaNCGDkJWDgCAAnJz-dwjhTV0J_RCeOcDhc5YTik14lVUxFsWm5F0bFbvh_x-ThhgFYwoUZ-ZWIQjPHD2_VraxX76BqOOa1B56p1xeKsz6sEv_jR7G3fSay8mgMxkAakCYoXANedcdtXpBZx8Ad1QBFUOFBGX67hfD_2PydAu5mA9S18_zQKBgQDixlZw1EbzwAVZ-VxURBZ8-Iw0GGYtOYqCJqB771cLuRrCiYfMrUqWE9A3AqtxhasaBYZ5K8m0abET4oZ7QOOajVhBG1N6v1ilQiUsxcYZVqdEhfH_T1olx_wNWT5GqbUb-sUXr4AmtirWypqdGTIixVLUyQkRhtSbJiDLf6bR0wKBgQDu4-tAOiBotp_tW6ZELrZbAxNTfqUDODd-RBYFT_OHL5PXT2PqgpPC0W8JKEerTIXo_hplr-70YOkJYGZwHk84Ptx_cFDjNq86bR10xaFDkLI-omMT4aPQyx67gaNMx07G6AlV9idC-sYi_Db2dUsiJPJ6A8g-aug7MtFA3y_HuwKBgDf0rqGaj4NXrzpbQD_-qPnfLmEwYA3qs9WXiGPsU7Mt0n-MBfkoDU5oxyi7vOf_DpAWKu89McEVjz8T1xEUmtSo6czu3DNegZYNczTP_CiGbDGJR4Qy5VCLPxNgIPC4sVqdDwLgKCPlMT7csTfwXqGbxOuCS32Kom1CBDeSYOxHAoGAXq2qMRxYd-fZXoMyVFeHIm8Hm9HXqH0BUWO-roBJFuz-VRk76leyJEZJEYILVZLQh9UdtSuTMvutoG-6abk5gHs5fEsbY9HqhOd2Ay_IiDSy0CwfxGNrP3chSQNKK0XarO6NtKoISX2GRZtcVTWLf47RIxaYqFRKkhvD30gVcb0CgYB_Bc5sImIZpyVNJ48b9v6u6s0rPQW0q7pI4GstuhVeTlsukf_p76xf6V50F3mbWE7nb_SbVenJxn0naTWPW9oWmBrJX3eYft_HE4OjURQc6aaOuP-1OSPnioVnfYxQ52e5uHa6cTQvaAOcy3vrFjw7VYTp0W95L5ZYTLaa83nxIw";
        String encodedPublicKeyStr = "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA055KoIHTBbuTufKQfFNH_A-KWm_-4-U_IzWXxHqdtw276DAo0el9XBXuKgrL2mOGgxenelZ901WNiDRzLsjk16nub4QVokYGiN0yD5Bo4B2dX-lKf2T0BSQhk6Nm3zolwaty0yuz17zI9hCEDyax7l9PfQAg7zvvRfE_58iwOvCS30vlejph_p72go6p3W1UlMThOvTp3KVN5D1KXczz3Yu44RKYUznCnUhPGLz8gI4_EURIGbFoGJ9dKqpfxhGfC4deSrgUcCQCUGHjmFP7YQuqTm2s6-zVm6ZNXtP9LQ7jK37p2ygnGtVs_8b_TO259QQ_dtdtsLj5Hp0IPrNKIQIDAQAB";

        // 错误的做法：将RSA密钥字节流用于创建HMAC SecretKey
        SecretKey privateKeyForSigning = Keys.hmacShaKeyFor(Decoders.BASE64URL.decode(encodedPrivateKeyStr));
        SecretKey publicKeyForVerification = Keys.hmacShaKeyFor(Decoders.BASE64URL.decode(encodedPublicKeyStr));

        // 此时，虽然编译通过，但在使用这些SecretKey进行JWT签名和验证时，
        // 将会因为密钥类型不匹配（RSA密钥字节流不适用于HMAC）而导致SignatureException。
        System.out.println("Attempted to reconstruct SecretKeys. This will lead to SignatureException for RSA keys.");
    }
}