如何在Java中使用令牌和公钥验证JWT签名

Question

我有一个字符串形式的令牌，我下载了公共证书，并创建了一个公钥，如下所示。

但我不确定如何进行验证与这么多的信息。

我找到了C#和的解决方案。NET而不是Java。请注意，我没有jks文件或私钥。

    FileInputStream fin = new FileInputStream("d://public.crt");
    CertificateFactory f = CertificateFactory.getInstance("X.509");
    X509Certificate certificate = (X509Certificate)f.generateCertificate(fin);
    PublicKey pk = certificate.getPublicKey();

Answer 1

如果您询问JSON WebToken，您可以按照以下代码示例：

import javax.xml.bind.DatatypeConverter;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.Claims;

//Sample method to validate and read the JWT
private void parseJWT(String jwt) {

    //This line will throw an exception if it is not a signed JWS (as expected)
    Claims claims = Jwts.parser()         
       .setSigningKey(DatatypeConverter.parseBase64Binary(apiKey.getSecret()))
       .parseClaimsJws(jwt).getBody();
    System.out.println("ID: " + claims.getId());
    System.out.println("Subject: " + claims.getSubject());
    System.out.println("Issuer: " + claims.getIssuer());
    System.out.println("Expiration: " + claims.getExpiration());
}

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Answer 2

我这样做是为了验证JWT

try {
        DecodedJWT decodedJWT = JWT.decode(jwt); // your string
        JwkProvider provider =  new JwkProviderBuilder(new URL("JWKS URL")).build();
        Jwk jwk = provider.get(decodedJWT.getKeyId());
        Algorithm algorithm = Algorithm.RSA256((RSAPublicKey) jwk.getPublicKey(), null);

        Verification verifier = JWT.require(algorithm);
        verifier.build().verify(decodedJWT);
    } catch (JWTVerificationException | JwkException | MalformedURLException e) {
        // throw your exception
    }

JwkProviderBuilder可能很昂贵，因此如果使用Spring，可以将其提取为另一种方法，并使用@PostConstruct对其进行注释以优化。

Answer 3

要使用Auth0库（com.Auth0:JavaJWT）在Java中验证JWT，请执行以下操作：

>

检索密钥已签名的算法，例如：

// Load your public key from a file
final PublicKey ecdsa256PublicKey = getPublicKey(...);
final Algorithm algorithm = Algorithm.ECDSA256((ECPublicKey) ecdsa256PublicKey, null);

使用相应的算法验证其签名：

final DecodedJWT decodedJWT = JWT.decode("J.W.T[...]");
// Will throw a SignatureVerificationException if the token's signature is invalid
algorithm.verify(decodedJWT);