使用公钥终结点验证 JWT 签名

2022-09-02 21:57:07

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

终结点返回 JSON 公钥的数组。下面是数组中的一个示例。

 {
            "kty": "RSA",
            "use": "sig",
            "kid": "9FXDpbfMFT2SvQuXh846YTwEIBw",
            "x5t": "9FXDpbfMFT2SvQuXh846YTwEIBw",
            "n": "kvt1VmR4nwkNM8jMU0wmj2gSS8NznbOt2pZI6Z7HQT_esF7W19GZR7Y72Xo1i5zXRDM9o3GeTIjBrnr3yy41Q_EaUQ7C-b-Hmg94Vy7EBZyBhi_mznz0dYWs2MIXwR86Nni9TmgTXvjgTPF2YGJoZt4TwcMFefW8rijCVyNrCBA0XspDouNJavvG0BEMXYigoThFjLRXS5U3h4BDfNZFZZS3dyliNOXfgRn2k7oITz8h_ueiPvmDRFh38AeQgx1cELhKWc3P5ugtttraSwgH7nP2NUguO9nCrHuL6TZ-KWpmRWZqwH-jYKFQVt3CDpzwNM6XJL-oHbl1x-gI3YYX5w",
            "e": "AQAB",
            "x5c": [
                "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"
            ],
            "issuer": "https://login.microsoftonline.com/{tenantid}/v2.0"
        }

在JJWT中,我已经实现了SigningKeyResolver接口,并且我需要返回RSAPublicKey的实例来执行验证。我遇到的问题是从 JSON 正确创建该密钥。

我是否从模数和指数开始?

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));

我是否从 x5c 开始,生成一个 X509Certificate 对象并从那里提取公钥?

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

事实证明,这两种方法都是徒劳的。

如果我从模数和指数生成 RSAPublicKey,我是否应该能够打印 Base64 二进制编码密钥以匹配 x5c 属性?也许这不是我应该验证的方式。

我可能误解了如何使用它。

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答案 1

x5c包含认证链。链的第一个证书必须与 JWK 中其他值所表示的密钥值匹配,在这种情况下,和 ,因此从中提取的公钥和构建的公钥必须完全相同。nex5c[0]ne

JWK 值以 base64url 编码,而不是以 base64 编码。改变

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

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

答案 2