sign in with apple后端校验（java）

　　最近新开发的ios平台的app在提审的时候，被拒了，原因是app上如果有接第三方登陆（比如，微信，微博，facebook等），那就必须要接apple id登陆，坑爹~苹果霸权啊！然而没办法，靠他吃饭，他是爸爸，唯有顺从。下面我来说一下对接苹果登陆的后端验证模块，目前这一块网上资料比较少，而且说得不够完整。至于app端的对接，网上一搜，一大堆，很完善。

　　这里先说一下apple id登陆的主要流程和涉及到的一些知识点。首先apple登陆的时序图如下：

　　先是app和苹果服务器通信获得identitytoken，然后把identitytoken交给业务后台验证，验证通过就可以了。其中appServer涉及到的验证，就是identitytoken，其实identitytoken就是一个jws（关于jws的只是可以参考https://www.jianshu.com/p/50ade6f2e4fd），至于校验jws，其实是有现成的jar包可以实现，验证jws的签名，保证数据没有被篡改之后，还要校验从identitytokendecode出来的nonce,iss,aud,exp，主要是iss和exp这两个。下面我直接上代码：

1.通过maven引入一下两个包，主要是用于验证jws，如下：

        <dependency>
            <groupId>com.auth0</groupId>
            <artifactId>jwks-rsa</artifactId>
            <version>0.9.0</version>
        </dependency>
        <dependency>
            <groupId>org.bitbucket.b_c</groupId>
            <artifactId>jose4j</artifactId>
            <version>0.6.4</version>
        </dependency>
        <dependency>
            <groupId>io.jsonwebtoken</groupId>
            <artifactId>jjwt</artifactId>
            <version>0.9.1</version>
        </dependency>

　　

2.验证是identitytoken是否有效，其中有两个主要的地方，第一个就是把从appleServer获取到的publicKey字符串转换为PublicKey对象；第二个就是使用函数"jsonWebSignature.verifySignature()"验证jws的signature，代码如下：

public class AppleIdAccountValidationService {
    private final static Logger logger = LoggerFactory.getLogger(AppleIdAccountValidationService.class);
    private final static int APPLE_ID_PUBLIC_KEY_EXPIRE = 24; //24h

    @Autowired
    private StringRedisUtils stringRedisUtils;

    public boolean isValid(String accessToken) {
        //校验基本信息:nonce,iss,aud,exp
        CusJws cusJws = this.getJws(accessToken);
        if (cusJws == null) {
            return false;
        }
        //iss
        long curTime = System.currentTimeMillis();
        if (cusJws.getJwsPayload().getExp() * 1000 < curTime) {
            return false;
        }
        if (!JwsPayload.ISS.equals(cusJws.getJwsPayload().getIss())) {
            return false;
        }
        //校验签名
        if (!this.verifySignature(accessToken)) {
            return false;
        }
        return true;
    }

    /**
     * verify signature
     * @param accessToken
     * @return
     */
    private boolean verifySignature(String accessToken) {
        PublicKey publicKey = this.getAppleIdPublicKey();
        JsonWebSignature jsonWebSignature = new JsonWebSignature();
        jsonWebSignature.setKey(publicKey);
        try {
            jsonWebSignature.setCompactSerialization(accessToken);
            return jsonWebSignature.verifySignature();
        } catch (JoseException e) {
            return false;
        }
    }

    /**
     * publicKey会本地缓存1天
     * @return
     */
    private PublicKey getAppleIdPublicKey() {
        String publicKeyStr = stringRedisUtils.getString(Constants.REDIS_KEY_APPLE_ID_PUBLIC_KEY);
        if (publicKeyStr == null) {
            publicKeyStr = this.getAppleIdPublicKeyFromRemote();
            if (publicKeyStr == null) {
                return null;
            }
            try {
                PublicKey publicKey = this.publicKeyAdapter(publicKeyStr);
                stringRedisUtils.setString(Constants.REDIS_KEY_APPLE_ID_PUBLIC_KEY, publicKeyStr, APPLE_ID_PUBLIC_KEY_EXPIRE, TimeUnit.HOURS);
                return publicKey;
            } catch (Exception ex) {
                ex.printStackTrace();
                return null;
            }
        }
        return this.publicKeyAdapter(publicKeyStr);
    }

    /**
     * 将appleServer返回的publicKey转换成PublicKey对象
     * @param publicKeyStr
     * @return
     */
    private PublicKey publicKeyAdapter(String publicKeyStr) {
        if (!StringUtils.hasText(publicKeyStr)) {
            return null;
        }
        Map maps = (Map)JSON.parse(publicKeyStr);
        List keys = (List<Map>)maps.get("keys");
        Map o = (Map) keys.get(0);
        Jwk jwa = Jwk.fromValues(o);
        try {
            PublicKey publicKey = jwa.getPublicKey();
            return publicKey;
        } catch (InvalidPublicKeyException e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 从appleServer获取publicKey
     * @return
     */
    private String getAppleIdPublicKeyFromRemote() {
        ResponseEntity<String> responseEntity = new RestTemplate().getForEntity("https://appleid.apple.com/auth/keys", String.class);
        if (responseEntity == null || responseEntity.getStatusCode() != HttpStatus.OK) {
            logger.error(String.format("getAppleIdPublicKeyFromRemote [%s] exception, detail:", appleIdPublicKeyUrl));
            return null;
        }
        return responseEntity.getBody();
    }

    private CusJws getJws(String identityToken) {
        String[] arrToken = identityToken.split("\.");
        if (arrToken == null || arrToken.length != 3) {
            return null;
        }
        Base64.Decoder decoder = Base64.getDecoder();
        JwsHeader jwsHeader = JSON.parseObject(new String(decoder.decode(arrToken[0])), JwsHeader.class);
        JwsPayload jwsPayload = JSON.parseObject(new String(decoder.decode(arrToken[1])), JwsPayload.class);
        return new CusJws(jwsHeader, jwsPayload, arrToken[2]);
    }

    class CusJws {
        private JwsHeader jwsHeader;
        private JwsPayload jwsPayload;
        private String signature;

        public CusJws(JwsHeader jwsHeader, JwsPayload jwsPayload, String signature) {
            this.jwsHeader = jwsHeader;
            this.jwsPayload = jwsPayload;
            this.signature = signature;
        }

        public JwsHeader getJwsHeader() {
            return jwsHeader;
        }

        public void setJwsHeader(JwsHeader jwsHeader) {
            this.jwsHeader = jwsHeader;
        }

        public JwsPayload getJwsPayload() {
            return jwsPayload;
        }

        public void setJwsPayload(JwsPayload jwsPayload) {
            this.jwsPayload = jwsPayload;
        }

        public String getSignature() {
            return signature;
        }

        public void setSignature(String signature) {
            this.signature = signature;
        }
    }

    static class JwsHeader {
        private String kid;
        private String alg;

        public String getKid() {
            return kid;
        }

        public void setKid(String kid) {
            this.kid = kid;
        }

        public String getAlg() {
            return alg;
        }

        public void setAlg(String alg) {
            this.alg = alg;
        }
    }

    static class JwsPayload {
        private String iss;
        private String sub;
        private String aud;
        private long exp;
        private long iat;
        private String nonce;
        private String email;
        private boolean email_verified;

        public final static String ISS = "https://appleid.apple.com";

        public String getIss() {
            return iss;
        }

        public void setIss(String iss) {
            this.iss = iss;
        }

        public String getSub() {
            return sub;
        }

        public void setSub(String sub) {
            this.sub = sub;
        }

        public String getAud() {
            return aud;
        }

        public void setAud(String aud) {
            this.aud = aud;
        }

        public long getExp() {
            return exp;
        }

        public void setExp(long exp) {
            this.exp = exp;
        }

        public long getIat() {
            return iat;
        }

        public void setIat(long iat) {
            this.iat = iat;
        }

        public String getNonce() {
            return nonce;
        }

        public void setNonce(String nonce) {
            this.nonce = nonce;
        }

        public String getEmail() {
            return email;
        }

        public void setEmail(String email) {
            this.email = email;
        }

        public boolean isEmail_verified() {
            return email_verified;
        }

        public void setEmail_verified(boolean email_verified) {
            this.email_verified = email_verified;
        }
    }
}

　　

warn：以上是后台的验证方式一，后来发现有问题，更新后的方案以及后端验证的第二种方式，统一在微信公众号“ismallboy”更新。

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