如何验证 Microsoft jwt id_token？

Posted 2023-03-08

【中文标题】如何验证 Microsoft jwt id_token？

【英文标题】：How do I validate a Microsoft jwt id_token?

【发布时间】：2020-03-27 19:29:19

【问题描述】：

我正在使用从 Microsoft 到客户端的 jwt 令牌来验证来自它的请求到 Web API（服务器）。我可以控制客户端 (js) 和服务器 (Python) 的代码。

在客户端，我使用以下请求来获取令牌（用户通过租户上的密码/2FA 声明）：

`https://login.microsoftonline.com/$TENANT_ID/oauth2/v2.0/authorize
            ?response_type=id_token+token
            &client_id=$CLIENT_ID
            &redirect_uri=$redirect_uri
            &scope=openid+email+profile
            &state=$guid()
            &nonce=$guid()`

这里guid是唯一值，TENANT_ID是租户，CLIENT_ID是客户端。

得到这个令牌后，我将它作为授权标头发送，如下所示：

init = 
    headers: 
       'Authorization': `Bearer $token`,
    


return fetch(url, init).then(response => 
    return response.json()
)

然后，我在服务器上检索令牌并验证它：

if 'Authorization' in request.headers and request.headers['Authorization'].startswith('Bearer '):
    token = request.headers['Authorization'][len('Bearer '):]
    from authlib.jose import jwt
    claims = jwt.decode(token, jwk)

其中jwk 是https://login.microsoftonline.com/TENANT_ID/discovery/v2.0/keys 的内容。

整个流程一直有效，直到验证失败，并出现以下错误：

authlib.jose.errors.InvalidHeaderParameterName: invalid_header_parameter_name: Invalid Header Parameter Names: nonce

这表示令牌的头部包含一个密钥nonce（我验证过）。

查看 Microsoft 的相关文档 here，标头上没有对 nonce 的引用——只是在有效负载上。

Q1：我在这里做错了什么？

Q2：假设 Microsoft 是将 nonce 放在错误位置的人（标头而不是有效负载），是否可以在将 nonce 传递给 jose 的身份验证库之前从标头（在服务器端）中删除它?这样做安全吗？

【参考方案1】：

见：https://robertoprevato.github.io/Validating-JWT-Bearer-tokens-from-Azure-AD-in-Python/

这是我在 API 中验证 Azure AD Id_tokens 的方法：

import base64
import jwt
from cryptography.hazmat.primitives.asymmetric.rsa import RSAPublicNumbers
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import serialization


def ensure_bytes(key):
    if isinstance(key, str):
        key = key.encode('utf-8')
    return key


def decode_value(val):
    decoded = base64.urlsafe_b64decode(ensure_bytes(val) + b'==')
    return int.from_bytes(decoded, 'big')


def rsa_pem_from_jwk(jwk):
    return RSAPublicNumbers(
        n=decode_value(jwk['n']),
        e=decode_value(jwk['e'])
    ).public_key(default_backend()).public_bytes(
        encoding=serialization.Encoding.PEM,
        format=serialization.PublicFormat.SubjectPublicKeyInfo
    )


# obtain jwks as you wish: configuration file, HTTP GET request to the endpoint returning them;
jwks = 
    "keys": [
        
            "kty": "RSA",
            "use": "sig",
            "kid": "piVlloQDSMKx...",
            "x5t": "piVlloQDSMKx...",
            "n": "0XhhwpmEpN-jDBapnzhF...",
            "e": "AQAB",
            "x5c": [
                "MIIDBTCCAe2gAwIBAgIQMCJcg...."
            ],
            "issuer": "https://login.microsoftonline.com/tenant/v2.0"
        
    ]


# configuration, these can be seen in valid JWTs from Azure B2C:
valid_audiences = ['dd050a67-ebfd-xxx-xxxx-xxxxxxxx'] # id of the application prepared previously

class InvalidAuthorizationToken(Exception):
    def __init__(self, details):
        super().__init__('Invalid authorization token: ' + details)


def get_kid(token):
    headers = jwt.get_unverified_header(token)
    if not headers:
        raise InvalidAuthorizationToken('missing headers')
    try:
        return headers['kid']
    except KeyError:
        raise InvalidAuthorizationToken('missing kid')



def get_jwk(kid):
    for jwk in jwks.get('keys'):
        if jwk.get('kid') == kid:
            return jwk
    raise InvalidAuthorizationToken('kid not recognized')

def get_issuer(kid):
    for jwk in jwks.get('keys'):
        if jwk.get('kid') == kid:
            return jwk.get('issuer')
    raise InvalidAuthorizationToken('kid not recognized')

def get_public_key(token):
    return rsa_pem_from_jwk(get_jwk(get_kid(token)))


def validate_jwt(jwt_to_validate):
    try:
        public_key = get_public_key(jwt_to_validate)
    issuer = get_issuer(kid)


        options = 
            'verify_signature': True,
            'verify_exp': True,  # Skipping expiration date check
            'verify_nbf': False,
            'verify_iat': False,
            'verify_aud': True  # Skipping audience check
        

        decoded = jwt.decode(jwt_to_validate,
                             public_key,
                             options=options,
                             algorithms=['RS256'],
                             audience=valid_audiences,
                             issuer=issuer)

        # do what you wish with decoded token:
        # if we get here, the JWT is validated
        print(decoded)

    except Exception as ex:
        print('The JWT is not valid!')
        return False
    else:
        return decoded
        print('The JWT is valid!')

【讨论】：

@chatzich 见docs.microsoft.com/en-us/azure/active-directory-b2c/… 格式：https://tenant_name.b2clogin.com/tenant_name.onmicrosoft.com/policy_name/discovery/v2.0/keys 例如：https://contoso.b2clogin.com/contoso.onmicrosoft.com/b2c_1_signupsignin1/discovery/v2.0/keys