Everything You Need to Know About Delegated Credentials

TL;DR

This article breaks down delegated credentials, a crucial concept for developers building secure and efficient login systems. Covering delegated credentialing in the context of authentication, authorization, and social login integration, it offers insights into how they improve user security and streamline access management. Benefits, drawbacks, and implementation considerations also included, providing a comprehensive overview.

What are Delegated Credentials?

Delegated credentials, huh? It's like giving someone a limited-time backstage pass to your digital kingdom. But what are they exactly?

Let's break it down. Delegated credentials are a way to grant temporary access to resources without handing over your main login info. Think of it as a digital "power of attorney."

Definition: They're short-lived digital keys that authorize specific actions.
Difference from Traditional Credentials: Unlike passwords, delegated credentials expire quickly, reducing the risk if compromised.
Digital Power of Attorney: Imagine authorizing a server to handle TLS for a limited time, like a temporary permission slip.

So, how does this actually work? It's all about trust between servers. Imagine your main server (let's call it the Resource Owner) needs to allow another server (the Delegated Server) to perform a specific task, like handling TLS connections on its behalf. Instead of giving the Delegated Server permanent access or your main credentials, the Resource Owner issues a delegated credential. This credential is a digital token or key, cryptographically signed by the Resource Owner, that explicitly states what the Delegated Server is allowed to do and for how long.

The trust is established through a secure handshake. The Resource Owner generates the credential, often embedding information about the Delegated Server's identity and the permissions granted. This credential is then presented by the Delegated Server to the service it needs to access. The service verifies the credential's signature against the Resource Owner's public key and checks if the permissions and expiry date are still valid. If everything checks out, access is granted.

Revocation is also built-in. Since these credentials are short-lived, they naturally expire. If a credential needs to be revoked before its expiry, the Resource Owner can publish a revocation list or use other mechanisms to invalidate it, preventing its further use.

Cloudflare uses delegated credentials as a performance optimization for Geo Key Manager and Keyless SSL. This means their servers can handle TLS connections more efficiently without constantly needing to contact the customer's origin server for private keys. It boosts security and is more conservative about where it keeps sensitive keys for customers.

Sounds kinda neat, right? Let's dig into why you'd want to use them in the first place.

Delegated Credentials in Action: Use Cases

Okay, so delegated credentials, huh? Sounds kinda complicated, but trust me, it can be a game-changer. Ever wonder how healthcare providers share sensitive info securely? Or how social logins could be less of a privacy nightmare? Well, delegated credentials might just be the answer.

Let's take a general example first. Imagine you're using a photo editing app on your phone. Instead of giving that app full access to your entire photo library (which would be a bit much, right?), you might grant it temporary permission to access only the specific photos you select for editing. That's a form of delegated credentialing – the app gets a limited, time-bound "key" to a specific resource.

Now, let's get more specific.

Healthcare

Imagine a large hospital system where doctors need to access patient records across different affiliated clinics or even external specialists. Instead of each doctor needing separate, full credentials for every single system, the hospital's central credentialing authority can issue delegated credentials.

Here's how it might work:

Resource Owner (Hospital System): The central authority within the hospital system is the resource owner.
Delegated Entity (Doctor's Workstation/App): The doctor's computer or a specific application they use is the delegated entity.
Resource (Patient Records): The sensitive patient data stored in various databases is the resource.

When a doctor needs to access a patient's record at an affiliated clinic, their workstation requests a delegated credential from the hospital's authority. This credential might specify: "Allow Dr. Smith to access patient record ID 12345 for the next 2 hours." The credential is cryptographically signed by the hospital. The clinic's system then verifies this credential. If valid, it grants Dr. Smith temporary access to that specific record. Once the 2 hours are up, the credential expires, and access is automatically revoked without any manual intervention. This streamlines the process, improves security by limiting access scope and duration, and helps meet compliance requirements for patient data handling.

Social Logins

Social logins, like "Login with Google" or "Login with Facebook," can be a privacy concern. Often, these services ask for broad permissions, like access to your friends list, posts, or even email. Delegated credentials can make this much safer.

Here's the flow:

Resource Owner (You/Your Social Account): Your social media account is the resource owner.
Delegated Entity (Third-Party App): The app you're trying to log into is the delegated entity.
Resource (Your Profile Data): Specific pieces of your profile information (e.g., your name, email, public profile picture) are the resources.

When you click "Login with Google," instead of Google giving the app your main account password, it initiates an OAuth 2.0 flow. Google acts as an authorization server. It presents you with a clear list of what the app is requesting access to (e.g., "This app wants to see your name and email address"). You approve or deny. If you approve, Google issues an access token (a type of delegated credential) to the app. This token is short-lived and specifically grants the app permission to access only your name and email, nothing else. The app uses this token to request that data from Google's servers. Once the token expires, the app can no longer access your data without you going through the approval process again. This token exchange and permission granting process is the core of how delegated credentials enhance social login security.

Next we'll consider social login and authentication - and find out more about how delegated credentials can streamline these processes.

Implementing Delegated Credentials: A Developer's Guide

Delegated credentials, huh? Sounds pretty complex, right? But trust me, understanding the tech side and security stuff doesn't have to be a total headache.

Protocols are key: You'll be working with TLS (Transport Layer Security) to ensure secure communication channels between your servers and clients. For authorization, OAuth 2.0 is your best friend. It's the standard framework for granting delegated access to resources, allowing an application to obtain limited access to an HTTP service, either on behalf of the resource owner or by allowing the application itself to obtain access. Developers interact with OAuth 2.0 by implementing flows like authorization code grant or client credentials grant to obtain access tokens.
x.509 certificate extensions: These are crucial for embedding specific information within digital certificates. In delegated credential scenarios, you might use extensions to define the scope of permissions, the identity of the delegated entity, or the expiry of the credential. Developers might need to understand how to generate certificates with these specific extensions or how to parse them to verify delegated access.
Client-side implementation: You gotta make sure those browsers and mobile apps can handle these credentials too. This often involves JavaScript or native code that can securely store and present the delegated credentials (like access tokens) to your backend services. It's about making sure the user's experience is smooth and secure.
Key management: This is super important. You need robust systems to generate, store, and rotate your cryptographic keys securely. For delegated credentials, this means managing the keys used to sign those credentials. Rotating keys often is a fundamental security practice to limit the impact if a key is ever compromised.
Certificate authority (ca) considerations: If you're using certificates to issue or verify delegated credentials, you'll be interacting with a Certificate Authority. You need to pick a good one, understand their policies for issuing certificates, and ensure they have strong security practices. Developers might need to integrate with CA APIs for certificate issuance or renewal.
Auditing and monitoring: Keep an eye on things, and log everything. You need to track who is requesting what credentials, who is using them, and when they expire. This is vital for security investigations, debugging, and ensuring compliance. Good logging helps you spot suspicious activity quickly.

Okay, so that's the super-brief tour. Wondering how to use delegated credentials IRL?

Challenges and Future Trends

Okay, let's wrap this delegated credentials thing up, shall we? What's on the horizon, and what bumps might we hit along the way?

You know, it's kinda funny—we trust computers with everything, but what happens if their sense of time is off? Inaccurate client clocks can really mess with delegated credentials.

Impact: If a client's clock is way off, it might reject valid credentials or accept expired ones. This can lead to failed operations or security vulnerabilities.
Solutions: Time synchronization protocols like Roughtime could help. Roughtime is a protocol designed to provide a secure and verifiable source of time. It works by having clients query multiple Roughtime servers, which return signed timestamps. The client then uses these signed timestamps to determine a highly accurate and trustworthy time. This helps mitigate issues where a client's local clock might be skewed, ensuring that the expiry times of delegated credentials are correctly interpreted.
Mitigation: We'll need to keep an eye on clock-related issues and have strategies to deal with them, like implementing robust time synchronization on all devices involved.

So, delegated credentials are cool and all, but they're not gonna take over the world on their own. We need standards and widespread adoption.

Standards Bodies: Organizations like the ietf play a crucial role in defining how these things work, creating the specifications that developers and companies can follow.
Industry Adoption: Encouraging companies to actually use delegated credentials is key. The more people use them, the more secure the internet becomes.
Future Enhancements: What new features and improvements can we add down the line? Think about things like more granular control over permissions, automated renewal processes, or even integrating with decentralized identity systems.

Quantum computers are coming, and they could break a lot of our current security. Delegated credentials can actually help us experiment with new cryptographic algorithms.

Experimentation Platform: Delegated credentials let us try out post-quantum crypto without completely overhauling everything. We can start using new algorithms for signing delegated credentials, for example.
Transitioning to Post-Quantum: Makes it easier to switch to new, quantum-resistant algorithms when they become standardized.
Smaller, Faster Signatures: It even lets us use smaller, faster signatures in tls. This can improve performance and reduce overhead, especially on resource-constrained devices.

And honestly? It is going to take a while, but we will get there...