如何使用 boto3 为 AWS Cognito 创建 SECRET_HASH？

我想使用 boto3 和 python 为 AWS Cognito 创建/计算 SECRET_HASH。这将合并到我的 fork 中warrant.

我将我的 Cognito 应用程序客户端配置为使用app client secret。但是，这破坏了以下代码。

def renew_access_token(self):
    """
    Sets a new access token on the User using the refresh token.

    NOTE:
    Does not work if "App client secret" is enabled. 'SECRET_HASH' is needed in AuthParameters.
    'SECRET_HASH' requires HMAC calculations.

    Does not work if "Device Tracking" is turned on.
    https://stackoverflow.com/a/40875783/1783439

    'DEVICE_KEY' is needed in AuthParameters. See AuthParameters section.
    https://docs.aws.amazon.com/cognito-user-identity-pools/latest/APIReference/API_InitiateAuth.html
    """
    refresh_response = self.client.initiate_auth(
        ClientId=self.client_id,
        AuthFlow='REFRESH_TOKEN',
        AuthParameters={
            'REFRESH_TOKEN': self.refresh_token
            # 'SECRET_HASH': How to generate this?
        },
    )

    self._set_attributes(
        refresh_response,
        {
            'access_token': refresh_response['AuthenticationResult']['AccessToken'],
            'id_token': refresh_response['AuthenticationResult']['IdToken'],
            'token_type': refresh_response['AuthenticationResult']['TokenType']
        }
    )

当我运行此程序时，我收到以下异常：

botocore.errorfactory.NotAuthorizedException: 
An error occurred (NotAuthorizedException) when calling the InitiateAuth operation: 
Unable to verify secret hash for client <client id echoed here>.

这个答案通知我使用 cognito 客户端密钥需要 SECRET_HASH。

The AWS API 参考文档AuthParameters 部分说明以下内容：

对于 REFRESH_TOKEN_AUTH/REFRESH_TOKEN：USERNAME（必需）、SECRET_HASH （如果应用程序客户端配置了客户端密钥，则为必需）， REFRESH_TOKEN（必需）、DEVICE_KEY

The boto3 文档声明 SECRET_HASH 是

使用以下方法计算的密钥哈希消息身份验证代码 (HMAC) 用户池客户端的密钥和用户名加上客户端 ID 消息。

该文档解释了需要什么，但没有解释如何实现这一点。

下面get_secret_hash方法是我用 Python 为 Cognito 用户池实现编写的解决方案，示例用法：

import boto3
import botocore
import hmac
import hashlib
import base64


class Cognito:
    client_id = app.config.get('AWS_CLIENT_ID')
    user_pool_id = app.config.get('AWS_USER_POOL_ID')
    identity_pool_id = app.config.get('AWS_IDENTITY_POOL_ID')
    client_secret = app.config.get('AWS_APP_CLIENT_SECRET')
    # Public Keys used to verify tokens returned by Cognito:
    # http://docs.aws.amazon.com/cognito/latest/developerguide/amazon-cognito-user-pools-using-tokens-with-identity-providers.html#amazon-cognito-identity-user-pools-using-id-and-access-tokens-in-web-api
    id_token_public_key = app.config.get('JWT_ID_TOKEN_PUB_KEY')
    access_token_public_key = app.config.get('JWT_ACCESS_TOKEN_PUB_KEY')

    def __get_client(self):
        return boto3.client('cognito-idp')

    def get_secret_hash(self, username):
        # A keyed-hash message authentication code (HMAC) calculated using
        # the secret key of a user pool client and username plus the client
        # ID in the message.
        message = username + self.client_id
        dig = hmac.new(self.client_secret, msg=message.encode('UTF-8'),
                       digestmod=hashlib.sha256).digest()
        return base64.b64encode(dig).decode()

    # REQUIRES that `ADMIN_NO_SRP_AUTH` be enabled on Client App for User Pool
    def login_user(self, username_or_alias, password):
        try:
            return self.__get_client().admin_initiate_auth(
                UserPoolId=self.user_pool_id,
                ClientId=self.client_id,
                AuthFlow='ADMIN_NO_SRP_AUTH',
                AuthParameters={
                    'USERNAME': username_or_alias,
                    'PASSWORD': password,
                    'SECRET_HASH': self.get_secret_hash(username_or_alias)
                }
            )
        except botocore.exceptions.ClientError as e:
            return e.response