How can you compare centralized and distributed authentication models?

1 Centralized authentication

Centralized authentication is a model where a single server or authority is responsible for validating the credentials of all users and devices that request access to the network. The server maintains a database of usernames, passwords, certificates, or other authentication factors, and grants or denies access based on predefined rules and policies. Centralized authentication simplifies the management and administration of user accounts and access rights, as well as the enforcement of security standards and compliance. However, it also introduces a single point of failure and a potential target for attacks. If the server is compromised, unavailable, or overloaded, the entire network access can be affected.

2 Distributed authentication

Distributed authentication is a model where multiple servers or authorities share the responsibility of validating the credentials of users and devices that request access to the network. The servers communicate with each other using protocols such as Kerberos, LDAP, or RADIUS, and exchange information about the authentication factors and policies. Distributed authentication increases the reliability and scalability of the network access, as well as the flexibility and diversity of the authentication methods. However, it also increases the complexity and cost of the network infrastructure and administration, as well as the risk of inconsistency and conflict among the servers.

3 Hybrid authentication

Hybrid authentication is a model that combines elements of both centralized and distributed authentication. It allows for different levels of authentication depending on the context and needs of the network access. For example, a network can use a centralized server for verifying the identity of users and devices, but delegate the authorization of access rights and privileges to distributed servers. Hybrid authentication can offer the best of both worlds, balancing the benefits and drawbacks of centralized and distributed authentication. However, it also requires careful design and coordination of the authentication processes and policies.

4 Authentication factors

Authentication factors are the pieces of information or evidence that are used to prove the identity of a user or device. They can be classified into three categories: something you know, something you have, and something you are. Something you know is a secret or personal information that only you know, such as a password, a PIN, or a security question. Something you have is a physical or digital object that only you possess, such as a smart card, a token, or a smartphone. Something you are is a biometric feature that is unique to you, such as a fingerprint, a face, or a voice. The more factors are used, the more secure the authentication is.

5 Authentication protocols

Authentication protocols are the rules and mechanisms that govern how the authentication factors are exchanged and verified between the users or devices and the servers or authorities. They can be classified into two types: symmetric and asymmetric. Symmetric protocols use the same key or secret for both encryption and decryption of the authentication factors, such as password-based protocols. Asymmetric protocols use different keys or secrets for encryption and decryption of the authentication factors, such as certificate-based protocols. Symmetric protocols are faster and simpler, but less secure and scalable than asymmetric protocols.

6 Authentication examples

Authentication examples are the specific implementations or applications of the authentication models, factors, and protocols in real-world scenarios. For example, a common centralized authentication example is the use of Active Directory, a Microsoft service that manages the user accounts and access rights for a Windows network. A common distributed authentication example is the use of Kerberos, a protocol that uses tickets and keys to authenticate users and devices across different servers and domains. A common hybrid authentication example is the use of OAuth, a standard that allows users to authorize third-party applications to access their online accounts without sharing their passwords.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?