如何从 base64 编码字符串创建 Java 密钥对象，以便使用 JWT 进行 PS256 解析

Question

我正在使用 JJWT 尝试创建并稍后验证 JWT 密钥。当我尝试将键转换为字符串时它不起作用，反之亦然 - 以便存储以备后用。

这个例子工作正常：

    KeyPair keyPair = Keys.keyPairFor(SignatureAlgorithm.PS256);
    Key publicKey = keyPair.getPublic();
    Key privateKey = keyPair.getPrivate();

    Claims claims = Jwts.claims();
    claims.setIssuedAt(new Date());

    String jws = Jwts.builder().setSubject("Joe").claim("Hello", "World").signWith(privateKey).compact();

    boolean result = Jwts.parserBuilder().setSigningKey(publicKey).build().parseClaimsJws(jws).getBody().getSubject().equals("Joe");

    System.out.println("Verified:" + result);
    return "";

但是，当我将密钥转换为 Base64Encoded 字符串时：

    String base64Public = Encoders.BASE64.encode(publicKey.getEncoded());
    String base64Private = Encoders.BASE64.encode(privateKey.getEncoded());

如何将 public 密钥（从字符串）加载回算法并使用 public 密钥验证 JWS？

String base64Public = Encoders.BASE64.encode(publicKey.getEncoded());
boolean result2 = Jwts.parserBuilder().setSigningKey(base64Public).build().parseClaimsJws(jws).getBody().getSubject().equals("Joe");

失败：

Key bytes can only be specified for HMAC signatures. Please specify a PublicKey or PrivateKey instance.

Answer 1

导出的 public 密钥具有 X.509/SPKI 格式，必须相应地导入：

import java.security.KeyFactory;
import java.security.spec.X509EncodedKeySpec;
import java.security.PublicKey;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.io.Encoders;
import io.jsonwebtoken.io.Decoders;

...

// Export
String base64Public = Encoders.BASE64.encode(publicKey.getEncoded());
        
// Import
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(Decoders.BASE64.decode(base64Public));
PublicKey publicKeyReloaded = (PublicKey)keyFactory.generatePublic(x509EncodedKeySpec);

// Verification 
boolean result = Jwts.parserBuilder().setSigningKey(publicKeyReloaded).build().parseClaimsJws(jws).getBody().getSubject().equals("Joe");
System.out.println("Verified:" + result); // Verified:true

编辑：

私钥为PKCS#8格式，导入方式如下：

import java.security.KeyFactory;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.PrivateKey;

...

// Export
String base64Private = Encoders.BASE64.encode(privateKey.getEncoded());

// Import
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(Base64.getDecoder().decode(base64Private));
PrivateKey privateKeyReloaded = (PrivateKey)keyFactory.generatePrivate(pkcs8EncodedKeySpec);

// Sign
String jws = Jwts.builder().setSubject("Joe").claim("Hello", "World").signWith(privateKeyReloaded).compact();
System.out.println("JWS:" + jws); // e.g. JWS:eyJhbGciOiJSUzI1NiJ9.eyJzdWIiOiJKb2UiLCJIZWxsbyI6IldvcmxkIn0.bk9EtxqRU3cfn7nMyn7MsDSKTlFUUwxjkWXVXqbpjVacEd6lEVG2jmkLSQ2oAoiA8fmKTlSXnULUKhv4XvDbvG2_BIx22JpceuYVdFhbvzkxv3EffPYrsYXftqws0vo-Wg05ubXk7qfeyIs9S-oq_Jf-5w_2oe6GLlcBqnNu-wLy8gAMiKNQPtuE7PmCT9ZEE7ALg_aGMBl2ttOEYN6bQcgxkbJLiS9pWm_RQbPsRCF34Q7alrETQPFltVJOPXd34aMPTaWSkYlyccj-0gVv8p5-BRpsGc3M9XaZWnwLm5CYzZ7tpfcd0BhKtkEO5mSFU7jo4P_T8BWCbEn2jYyzPA

如何从 base64 编码字符串创建 Java 密钥对象，以便使用 JWT 进行 PS256 解析

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