使用公钥端点验证JWT签名 [英] Verifying JWT Signature using public key endpoint

问题描述

我想验证微软的一些JWT的签名。我正在使用Spring-Boot，JJWT库和以下端点： https：// login.microsoftonline.com/common/discovery/v2.0/keys

I'm wanting to verify the signature of some JWTs from Microsoft. I'm using Spring-Boot, the JJWT library and following endpoint: https://login.microsoftonline.com/common/discovery/v2.0/keys

端点返回一组JSON公钥。
这是数组中的一个例子。

The endpoint returns an array of JSON public keys. Here is one example from the array.

 {
            "kty": "RSA",
            "use": "sig",
            "kid": "9FXDpbfMFT2SvQuXh846YTwEIBw",
            "x5t": "9FXDpbfMFT2SvQuXh846YTwEIBw",
            "n": "kvt1VmR4nwkNM8jMU0wmj2gSS8NznbOt2pZI6Z7HQT_esF7W19GZR7Y72Xo1i5zXRDM9o3GeTIjBrnr3yy41Q_EaUQ7C-b-Hmg94Vy7EBZyBhi_mznz0dYWs2MIXwR86Nni9TmgTXvjgTPF2YGJoZt4TwcMFefW8rijCVyNrCBA0XspDouNJavvG0BEMXYigoThFjLRXS5U3h4BDfNZFZZS3dyliNOXfgRn2k7oITz8h_ueiPvmDRFh38AeQgx1cELhKWc3P5ugtttraSwgH7nP2NUguO9nCrHuL6TZ-KWpmRWZqwH-jYKFQVt3CDpzwNM6XJL-oHbl1x-gI3YYX5w",
            "e": "AQAB",
            "x5c": [
                "MIIDBTCCAe2gAwIBAgIQZSAeaqWig4BHC1ksmNNcgjANBgkqhkiG9w0BAQsFADAtMSswKQYDVQQDEyJhY2NvdW50cy5hY2Nlc3Njb250cm9sLndpbmRvd3MubmV0MB4XDTE3MDUwNjAwMDAwMFoXDTE5MDUwNzAwMDAwMFowLTErMCkGA1UEAxMiYWNjb3VudHMuYWNjZXNzY29udHJvbC53aW5kb3dzLm5ldDCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAJL7dVZkeJ8JDTPIzFNMJo9oEkvDc52zrdqWSOmex0E/3rBe1tfRmUe2O9l6NYuc10QzPaNxnkyIwa5698suNUPxGlEOwvm/h5oPeFcuxAWcgYYv5s589HWFrNjCF8EfOjZ4vU5oE1744EzxdmBiaGbeE8HDBXn1vK4owlcjawgQNF7KQ6LjSWr7xtARDF2IoKE4RYy0V0uVN4eAQ3zWRWWUt3cpYjTl34EZ9pO6CE8/If7noj75g0RYd/AHkIMdXBC4SlnNz+boLbba2ksIB+5z9jVILjvZwqx7i+k2filqZkVmasB/o2ChUFbdwg6c8DTOlyS/qB25dcfoCN2GF+cCAwEAAaMhMB8wHQYDVR0OBBYEFGKpXQNrF5IoxS6bL4F92+gxOJlIMA0GCSqGSIb3DQEBCwUAA4IBAQA3HgW5SoHlvvQVxqqi+mtscDZLhNfe13iG/nx8Er5il82b79RVydNs+f9sYxc4T4ctnrZu7x5e7jInJedNdAlrPorBdw+SfvKJsmiNndXugMew1FlcQTQVIFDCbziaJav8rKyMxPfeKkc1aixbajWZkKg6OPmmJn2ceTocbn8PMQy20xNvcWUwgF5FZZIuPqu6feOLJcUIYw+0JFZ265xka30QXpmytcIxajIzpD4PRdCIBuVSqgXacAs4t4+w+OhnosD72yvXck8M4GwX1j+vcuyw0yhDGNMmqsHWP7H3jnJiGDrKhhdVyplzDhTfv2Whbv/dIDn+meLE3yyC5yGL"
            ],
            "issuer": "https://login.microsoftonline.com/{tenantid}/v2.0"
        }

在JJWT中，我实现了SigningKeyResolver接口，我需要返回一个RSAPublicKey实例来进行验证。 我遇到的问题是从JSON正确创建密钥。

In JJWT I've implemented the SigningKeyResolver interface and I am required to return an instance of RSAPublicKey to do the verification. The issue I'm having is creating that Key correctly from the JSON.

我是从模数开始的吗？和指数？

Do I start with the Modulus and Exponent?

BigInteger modulus = new BigInteger(1, Base64.decodeBase64(jsonKey.getN()));
BigInteger exponent = new BigInteger(1, Base64.decodeBase64(jsonKey.getE()));
publicKey = KeyFactory.getInstance("RSA").generatePublic(new RSAPublicKeySpec(modulus, exponent));

我是从x5c开始，生成X509Certificate对象并从那里拉出PublicKey吗？

Do I start with the x5c, generate an X509Certificate object and pull the PublicKey from there?

CertificateFactory factory = CertificateFactory.getInstance("X.509");
X509Certificate cert = (X509Certificate) factory.generateCertificate(new ByteArrayInputStream(DatatypeConverter.parseBase64Binary(jsonKey.getX5c())));
publicKey = (RSAPublicKey)cert.getPublicKey();

这两种方法都没有结果。

Both approaches have proved fruitless.

如果我从模数和指数生成RSAPublicKey，我应该能够打印Base64Binary编码的密钥以匹配x5c属性吗？也许这不是我应该如何验证。

If I generated the RSAPublicKey from the modulus and exponent should I be able to print the Base64Binary encoded key to match the x5c property? Maybe that's not how I should be validating.

我可能会误解如何来使用它。

I might be misunderstanding how to use this.

与往常一样，任何文档也都受到赞赏。

As always, any documentation is appreciated as well.

推荐答案

x5c 包含认证链。链的第一个证书必须与JWK中其他值表示的键值匹配，在这种情况下 n 和 e ，因此从 x5c [0] 中提取的公钥以及使用 n 和<$ c构建的公钥$ c> e 必须完全相同

x5c contains the certification chain. The first certificate of the chain must match with the key value represented by the other values in the JWK, in this case n and e, therefore the public key extracted from x5c[0] and the one built with n and e must be exactly the same

JWK值在base64url中编码，而不是在base64中编码。更改

JWK values are encoded in base64url, not in base64. Change

BigInteger modulus = new BigInteger(1, Base64.decodeBase64(jsonKey.getN()));
BigInteger exponent = new BigInteger(1, Base64.decodeBase64(jsonKey.getE()));

with

BigInteger modulus = new BigInteger(1, Base64.getUrlDecoder().decode(jsonKey.getN()));
BigInteger exponent = new BigInteger(1, Base64.getUrlDecoder().decode(jsonKey.getE()));

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