Generating a AWS IAM Access Key for Amazon S3

This document describes how to generate an AWS IAM access key for read/write access to S3.

For general information on AWS S3, please see the following document: Amazon S3 Storage.

Amazon Web Services (AWS) provides an Identity and Access Management (IAM) service that allows you to securely control access to AWS resources. One way to provide access to a resource is by generating an IAM access key. The instructions below walk you through this process using the AWS Management Console. 

Using the AWS Management Console

To log in to the AWS Management console,

  1. go to and log in with your Northwestern NetID.
  2. Then, select an appropriate role and click the blue Sign In button.

To access the IAM service:

  1. Click the magnifying glass in the upper left hand corner of the screen.
  2. Type "IAM" into the search box
  3. Select  IAM (Manage access to AWS resources) 

You will see a view of the IAM dashboard that summarizes how many groups, users, roles, policies and identity providers you have access to on the right. On the left, you will see a sidebar with different aspects of IAM. We will be using the Users option in the next section. 

Creating an IAM user

To generate an access key you must first create an IAM user. To create an IAM user: 

Click "Users" in the left navigation and then click the blue"Add users" button on the right.


User Details

You will see the "Add user" screen that asks you to provide user details and select AWS access type.

  • User names must be unique within the account. The names are not case sensitive and must be 64 or fewer characters. They can contain letters, numbers, plus (+), equal (=), comma (,), period (.), at sign (@), underscore (_), and hyphen (-). 
  • Select Access key - Programmatic access as the AWS credential type. This option allows direct access to the resource but not to log in to the AWS management console.

Then click the blue "Next: Permissions" button on the lower right hand side of the screen.


Next, you must specify what types of access the user will have to various resources. Do one of the following options depending on your preference: 

Access to all S3 Buckets

If you want to provide full access to all S3 buckets in your account,

  1. Select the Attach Existing Policies Directly tab.
  2. Then search for `AmazonS3FullAccess` in the filter policies search box. 
  3. Then click the checkbox to the left of the policy name

Access to a specific S3 bucket

To allow access to a specific S3 bucket only, you must create a user policy. To create a user policy: 

  1. Select the Attach Existing Policies Directly tab.
  2. Click the gray Create Policy Button on the left.

Visual Editor

A new window will open containing the "Create Policy" interface. You can create a policy using the Visual Editor. You must specify the following information:

  • Service: S3
  • Actions: Choose these based on what you want the IAM user to be able to do. The options here are incredible granular. Each Checkbox has a sub menu with more options. These options have info buttons that explain exactly what these options do. 
  • Resources: After you select Actions, you can select what resources to apply these actions to. The Visual Editor will prompt you to add resources based on Actions you chose. 

Once you have selected the above information, click the "Next: Tags" button. Tags are optional metadata that describes what this policy does. Each tag has a "Key" (eg: Service) and a "Value" (eg: S3) that you can specify. When you have entered appropriate tags, click "Next: Review".

The review page will ask for the following information about your policy: 

  • Name: Use alphanumeric and '+=,.@-_' characters. Maximum 128 characters.
  • Description: Maximum 1000 characters. Use alphanumeric and '+=,.@-_' characters.

It also displays a summary of the permissions granted and tags applied to the policy. When you are done, Click "Create Policy" in the lower right. 

JSON Template

Some standard processes have JSON templates that give appropriate permissions for a specific task. For example, the following template grants read/write permissions for a specific S3 bucket. 

To use this template, click to the JSON tab of the Create Policy screen and paste it in, then change "YOUR-BUCKET-NAME-HERE" in the Resource lines to match your bucket name:

    "Version": "2012-10-17",
    "Statement": [
            "Sid": "AllBuckets",
            "Effect": "Allow",
            "Action": [
            "Resource": "*"
            "Sid": "Bucket",
            "Effect": "Allow",
            "Action": [
            "Resource": "arn:aws:s3:::YOUR-BUCKET-NAME-HERE"
            "Sid": "Objects",
            "Effect": "Allow",
            "Action": [
            "Resource": "arn:aws:s3:::YOUR-BUCKET-NAME-HERE/*"

Applying the IAM policy to your user

Once your policy is created, return to the "Add User" Screen.

  1. Refresh the policies window so it registers the new policy you created.
  2. Search for the policy name.
  3. Check the box to the left of the policy to apply it to your IAM user.


Then you can enter tags as you did when creating the IAM policy. Then click "Next: Review"

The review page gives you an opportunity to review the permissions you have given to this user. When you are satisfied, click "Create User".

Downloading credentials

You will be prompted to download a CSV file containing the user's credentials (access key ID and secret access key). Either download the file or copy and paste the credentials from this page. The credentials will only be displayed one time so make sure to save them from this page. 

We recommend storing this information in a password manager or AWS Secrets Manager


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Article ID: 2025
Wed 11/16/22 2:37 PM
Wed 5/1/24 9:22 AM

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