This demo uses the SigV4 Library for authenticating the S3 object download requests sent to the
AWS S3 HTTP Server. The AWS S3 HTTP server's TLS connection uses server authentication only. Follow
the steps below to configure your connection to AWS.
Accounts and permissions are set using AWS Identity and Access Management (IAM). IAM allows
you to manage permissions for each user in your account. By default, a user doesn't have
permissions until granted by the root owner.
Keep track of the name you gave your thing for use in a later step.
Register a certificate:
If your AWS IoT Thing already has a certificate attached to it, then
that certificate's ARN can be used in the step "Attach a policy" below. Otherwise, you
can create a certificate and attach it to the thing using AWS IoT Core Console.
It is also possible to sign the thing's certificate using your own Certificate
Authority (CA) certificate. You must register both certificates with AWS IoT before your device
can authenticate to AWS IoT. If you do not already have a CA certificate, you can use OpenSSL
to create a CA certificate, as described in
Use Your Own Certificate. To register your CA
certificate with AWS IoT, follow the steps in
Registering Your CA Certificate. You must then
create a device certificate signed by the CA certificate and register it with AWS IoT. You can
do this by following the steps in
Creating a Device Certificate Using Your CA Certificate.
Save the certificate and the corresponding key pair; you will use them when you request a
security token later. Also, remember the password you provide when you create the certificate.
Run the following command in the AWS CLI to attach the device certificate to your thing so that
you can use thing attributes in policy variables.
Configure an IAM role in your AWS account that will be assumed by the credentials provider
on behalf of your device. You are required to associate two policies with the role: a trust policy
that controls who can assume the role, and an access policy that controls which actions can be
performed on which resources by assuming the role. The following trust policy grants the credentials
provider permission to assume the role. Put it in a text document and save the document with the
Run the following command in the AWS CLI to create the access policy.
aws iam create-policy --policy-name accesspolicyfors3 --policy-document file://accesspolicyfors3.json
Run the following command in the AWS CLI to attach the access policy to your role, substituting
aws iam attach-role-policy --role-name s3-access-role --policy-arn arn:aws:iam::<your_aws_account_id>:policy/accesspolicyfors3
Configure the PassRole permissions:
The IAM role that you have created must be passed to AWS IoT to create a role alias, as
described in the previous step. The IAM user who performs the operation requires
iam:PassRole permission to authorize this action. You also should add
permission for the iam:GetRole action to allow the IAM user to retrieve
information about the specified role. Create the following policy to grant
iam:PassRole and iam:GetRole permissions, substituting
<your_aws_account_id>. Name this policy passrolepermission.json.
CredentialDurationSeconds: This is an optional attribute specifying the validity (in
seconds) of the security token. The minimum value is 900 seconds (15 minutes), and the
maximum value is 3,600 seconds (60 minutes). If not specified, the default value is
Run the following command in the AWS CLI to create a role alias. Use the credentials
of the user to whom you have given the iam:PassRole permission.
Earlier, you created and registered a certificate with AWS IoT for successful authentication of your
device. Now, you need to create and attach a policy to the certificate to authorize the request for
the security token.
Copy the following JSON into a text file named thingpolicy.json, substituting
your <aws_region_name> and <your_aws_account_id>:
To make an HTTPS request to the credentials provider to fetch a security token, you have to
supply the following information:
Certificate and key pair: Because this is an HTTP request over TLS mutual authentication,
you have to provide the certificate and the corresponding key pair to your client while
making the request. Use the same certificate and key pair that you used during certificate
registration with AWS IoT.
RoleAlias: Provide the role alias (in this example, Thermostat-dynamodb-access-role-alias)
to be assumed in the request.
ThingName: Provide the thing name that you created earlier in the AWS IoT thing registry
database. This is passed as a header with the name x-amzn-iot-thingname. Note
that the thing name is mandatory only if you have thing attributes as policy variables in
AWS IoT or IAM policies.
AWS account-specific endpoint
Run the following command in the AWS CLI to obtain your AWS account-specific endpoint for the
credentials provider. (See the DescribeEndpoint API documentation for further details.)
Copy and paste your AWS account-specific endpoint to the file demo_config.h as the value of
the macro democonfigIOT_CREDENTIAL_PROVIDER_ENDPOINT.
#define democonfigIOT_CREDENTIAL_PROVIDER_ENDPOINT "<your_aws_account_specific_prefix>.credentials.iot.us-east-1.amazonaws.com"
#define CLIENT_CERT_PATH "path of the client certificate downloaded when setting up the device certificate in AWS IoT Account Setup"
#define CLIENT_PRIVATE_KEY_PATH "path of the private key downloaded when setting up the device certificate in AWS IoT Account Setup"
Configure the following macros in demo_config.h
#define democonfigIOT_THING_NAME "Name of IOT Thing that you provided in STEP 1"
#define democonfigIOT_CREDENTIAL_PROVIDER_ROLE "Name of ROLE ALIAS that you provided in STEP 4"
#define democonfigS3_BUCKET_NAME "Name of Bucket that contains the object that needs to be downloaded"
#define democonfigS3_BUCKET_REGION "Region where Bucket is located"
#define democonfigS3_OBJECT_NAME "Name of object that needs to be downloaded from AWS S3"
The name of the AWS IoT thing for your device registered with AWS IoT core.
The name for the role alias for S3.
The name of the policy attached to the device certificate in the step "Attach a policy".
The name of the S3 bucket from which the demo will download.
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