使用 java-jwt 验证访问令牌签名答案

【问题标题】：Verify Access token signature using java-jwt使用 java-jwt 验证访问令牌签名
【发布时间】：2021-11-16 02:35:43
【问题描述】：

我正在尝试验证由 KeyCloak 授权服务器生成的 JWT 访问令牌。

我已经从 http://ip-address:port/auth/realms/

为了验证访问令牌，我使用https://mvnrepository.com/artifact/com.auth0/java-jwt

并参考https://www.baeldung.com/java-jwt-token-decode 验证签名。

我正在尝试的代码：

 String publicKey =<public_key from http://<ip>:<port>/auth/realms/<app> >
 
 String accessToken =<valid access token from keycloak>
  
 String[] chunks = accessToken.split("\\.");
 
 Base64.Decoder decoder = Base64.getDecoder();
 String header = new String(decoder.decode(chunks[0]));  // {"alg":"RS256","typ" : "JWT","kid" : "dsssdssdf"}
 String payload = new String(decoder.decode(chunks[1])); //{"exp":1632237161,"iat":1632236861,"auth_time":1632236854,"jt..."}
 String signature = chunks[2]; // <signature from access token>
 
 SignatureAlgorithm sa = SignatureAlgorithm.RS256;
 String tokenWithoutSignature = chunks[0] + "." + chunks[1];
 SecretKeySpec secretKeySpec = new SecretKeySpec(publicKey.getBytes(), sa.getJcaName());
 
 DefaultJwtSignatureValidator validator = new DefaultJwtSignatureValidator(sa, secretKeySpec);
 
 if (!validator.isValid(tokenWithoutSignature, signature)) {
      System.out.println("=============== Invalid access token");
    } else {
      System.out.println("============= valid access token");
    }

运行上述代码后观察到以下错误：

java.lang.IllegalArgumentException: RSA Signature validation requires either a RSAPublicKey or RSAPrivateKey instance.
    at io.jsonwebtoken.lang.Assert.isTrue(Assert.java:38)
    at io.jsonwebtoken.impl.crypto.RsaSignatureValidator.<init>(RsaSignatureValidator.java:36)
    at io.jsonwebtoken.impl.crypto.DefaultSignatureValidatorFactory.createSignatureValidator(DefaultSignatureValidatorFactory.java:43)
    at io.jsonwebtoken.impl.crypto.DefaultJwtSignatureValidator.<init>(DefaultJwtSignatureValidator.java:37)
    at io.jsonwebtoken.impl.crypto.DefaultJwtSignatureValidator.<init>(DefaultJwtSignatureValidator.java:32)

有人可以帮忙吗？

【问题讨论】：

标签： java oauth jjwt

【解决方案1】：

我尝试类似：

String publicKey =<public_key from http://<ip>:<port>/auth/realms/<app> >
byte[] decoded = Base64.getDecoder().decode(publicKey);

String algorithm = "RSA";
KeyFactory kf = KeyFactory.getInstance(algorithm);
PublicKey generatedPublic = kf.generatePublic(new X509EncodedKeySpec(decoded));

String accessToken =<valid access token from keycloak> 
String[] chunks = accessToken.split("\\.");

Base64.Decoder decoder = Base64.getDecoder();

String header = new String(decoder.decode(chunks[0]));  // {"alg":"RS256","typ" : "JWT","kid" : "dsssdssdf"}
String payload = new String(decoder.decode(chunks[1])); //{"exp":1632237161,"iat":1632236861,"auth_time":1632236854,"jt..."}
String signature = chunks[2]; // <signature from access token>

SignatureAlgorithm sa = SignatureAlgorithm.RS256;
String tokenWithoutSignature = chunks[0] + "." + chunks[1];

DefaultJwtSignatureValidator validator = new DefaultJwtSignatureValidator(sa, generatedPublic);

if (!validator.isValid(tokenWithoutSignature, signature)) {
           System.out.println("=============== Invalid access token");
} else {
          System.out.println("============= valid access token");
}

而且成功了！！

【讨论】：