Concepts
Bearer tokens play a crucial role in modern web services and cloud environments, such as Amazon Web Services (AWS), by providing a mechanism to establish a user or service’s identity and permissions. Common token-based authentication methods include JSON Web Tokens (JWTs), OAuth, and AWS Security Token Service (STS).
JSON Web Tokens (JWTs):
A JWT is a compact, URL-safe means of representing claims to be transferred between two parties. It can be used for authentication and information exchange, and is composed of three parts: the header, the payload, and the signature.
Example JWT:
Header.Payload.Signature
The header typically consists of two parts: the token type (typ) and the hashing algorithm (alg) being used, such as HS256 or RS256.
{
“alg”: “HS256”,
“typ”: “JWT”
}
The payload contains the claims, which are statements about an entity (typically the user) and additional metadata.
{
“sub”: “1234567890”,
“name”: “John Doe”,
“admin”: true
}
The signature ensures that the token has not been altered after it was issued.
OAuth:
OAuth, on the other hand, is an open standard for access delegation, commonly used to grant websites or applications access to information on other websites without giving them the passwords. For example, a website might use OAuth to request access to your email contacts or cloud storage.
OAuth Flow:
- The application requests authorization to access service resources from the user.
- If the user authorizes the request, the application receives an authorization grant.
- The application requests an access token from the authorization server (API) by presenting authentication of its own identity and the authorization grant.
- If valid, the authorization server issues an access token to the application.
AWS Security Token Service (AWS STS):
AWS STS is a web service that enables you to request temporary, limited-privilege credentials for AWS Identity and Access Management (IAM) users or for users you authenticate (federated users).
AWS STS Token Example:
Assume that you have an IAM role with the necessary permissions for your application. You can request temporary security credentials using the AssumeRole API.
import boto3
# create a STS client
sts_client = boto3.client(‘sts’)
# Assume an IAM role
response = sts_client.assume_role(
RoleArn=”arn:aws:iam::ACCOUNT_ID:role/ROLE_NAME”,
RoleSessionName=”AppSession”
)
# Temporary security credentials that are retrieved
temp_credentials = response[‘Credentials’]
Comparison:
| Aspect | JWT | OAuth | AWS STS |
|---|---|---|---|
| Primary Use | Token creation & validation | Access delegation | Temporary AWS credentials |
| Security | Based on token integrity | Based on authorization grants | Based on IAM and federation |
| Lifespan | Configurable | Configurable | Configurable, up to a maximum limit |
| Revokability | Difficult to revoke | Tokens can be revoked | Credentials expire automatically; can be revoked |
| Integration | Application level | Service-to-service | AWS-specific services |
Conclusion:
Bearer tokens are an integral part of service security in cloud computing, whether it’s for authentication purposes with JWTs, access delegation with OAuth, or temporary credential issuance like AWS STS. Each system has its merits and is selected based on the use case.
When preparing for the AWS Certified Developer – Associate (DVA-C02) exam, understanding the practical application and differences between these tokens is fundamental. You will need to know how to implement token-based authentication securely in your applications, how to delegate access with OAuth, and how to efficiently use AWS STS for temporary, limited-privilege credentials in an AWS environment.
Answer the Questions in Comment Section
True/False: Bearer tokens ensure the integrity and confidentiality of the data they contain without any additional security measures like HTTPS.
- True
- False
False
Bearer tokens, such as JWTs, ensure data integrity using signature algorithms but do not ensure confidentiality unless paired with a secure transport mechanism like HTTPS.
Multiple Select: Which of the following are characteristics of a JSON Web Token (JWT)?
- Encrypted
- Self-contained
- Stateless
- Requires a database for validation
Self-contained, Stateless
JWTs are self-contained, carrying all necessary information within themselves. They are stateless as they do not require server-side state for validation.
True/False: AWS Security Token Service (AWS STS) allows you to request temporary security credentials for AWS resources, which last indefinitely.
- True
- False
False
AWS STS allows you to request temporary, limited-privilege credentials for AWS resources. These credentials are short-term and not indefinite.
Single Select: What HTTP method is typically used to send a Bearer token to an API for authentication or authorization?
- GET
- POST
- PUT
- DELETE
POST
A POST method is typically used to send credentials including Bearer tokens to an API to establish a session or get a resource.
True/False: OAuth is an open standard for access delegation commonly used for token-based authentication.
- True
- False
True
OAuth is indeed an open standard for access delegation, which is widely used for token-based authentication and authorization.
Multiple Select: In the context of AWS, which services can integrate with AWS Security Token Service (AWS STS)?
- Amazon S3
- AWS Identity and Access Management (IAM)
- Amazon EC2
- Amazon RDS
Amazon S3, AWS Identity and Access Management (IAM), Amazon EC2, Amazon RDS
AWS STS can be used to provide temporary credentials that can be used to access a wide array of AWS services including S3, IAM, EC2, and RDS.
Single Select: Which of the following is NOT a component of a JWT token?
- Header
- Payload
- Signature
- Encryption Key
Encryption Key
A JWT is composed of three parts: the Header, the Payload, and the Signature. An encryption key is not a part of the JWT structure itself; it may be used outside the token to secure the token in transit or at rest.
True/False: AWS STS tokens can be used to make API requests on behalf of the user who has delegated their permissions.
- True
- False
True
AWS STS tokens are meant to allow temporary access and can be used to make API requests according to the permissions delegated to the temporary credentials.
True/False: JWT tokens cannot be transmitted through URL parameters due to security concerns.
- True
- False
False
While not recommended due to potential exposure in web server logs, JWT tokens can technically be transmitted through URL parameters.
Single Select: What is the primary function of the AWS Security Token Service (AWS STS)?
- Managing permanent AWS access keys.
- Logging and monitoring AWS resource usage.
- Granting temporary tokens with limited permissions.
- Encrypting data stored in Amazon S
Granting temporary tokens with limited permissions.
The primary function of AWS STS is to grant temporary security credentials (tokens) that allow access to AWS resources with limited permissions and a defined expiration time.
True/False: The use of bearer tokens over unencrypted channels is recommended for secure deployments.
- True
- False
False
The use of bearer tokens over unencrypted channels is not recommended as the tokens can be intercepted by malicious parties. Secure deployments always use encrypted channels, typically HTTPS.
Multiple Select: What considerations should be taken into account when using bearer tokens for authentication?
- Token expiration periods
- Secure token storage
- Transmission over encrypted channels
- Requirement for user interaction in token renewal
Token expiration periods, Secure token storage, Transmission over encrypted channels
Token expiration periods must be managed to ensure timely invalidation, secure token storage is important to prevent unauthorized access, and transmission over encrypted channels like HTTPS ensures the token is not intercepted in transit. Token renewal may or may not require user interaction depending on the implementation.
Great post! I found the section on JWT particularly insightful.
How do JWTs compare to OAuth in terms of security?
Thanks for this detailed guide! It helped me understand AWS STS better.
Which one is more widely used in microservices, JWT or OAuth?
This is an excellent resource for preparing for the AWS Certified Developer exam!
Could someone explain the main differences between AWS STS and other token services?
Wonderful article. Cleared many doubts about OAuth.
I’m struggling to integrate AWS STS with my existing security system. Any advice?