A Public Key Infrastructure (PKI) is a group of technologies used to request, create, manage, store, distribute, and revoke digital certificates. A PKI allows two entities to privately share symmetric keys without any prior communication. If you’re planning to take the Security+ exam, you should have a basic understanding of cryptographic keys that establish secure access to data.
For example, can you answer this question?
Q. A user’s laptop developed a problem and can no longer boot. Help desk personnel tried to recover the data on the disk, but the disk is encrypted. Which of the following can be used to retrieve data from the hard drive?
A. A trust relationship
B. Public key
C. Recovery agent
D. CRL
More, do you know why the correct answer is correct and the incorrect answers are incorrect? The answer and explanation is available at the end of this post.
Wildcard Certificates
In some situations, organizations choose to use wildcard certificates to reduce the management burden associated with certificates. As an example, imagine a web site with the domain name of GetCertifiedGetAhead.com. If a typical certificate is associated with this web site, it will only be valid for web pages in that domain. However, an organization can get a wildcard certificate for *. GetCertifiedGetAhead.com. This wildcard certificate is valid for the following domain names, too:
- train.GetCertifiedGetAhead.com
- blogs.getcertifiedgetahead.com
The * in the wildcard certificate will work for any single name added onto the domain name. In other words, administrators only need to purchase and install a single certificate for all three domain names. However, it only works for one level of domain names. It wouldn’t be valid for something like this: north.train.GetCertifiedGetAhead.com.
Remember this
A PKI requires a trust model between CAs. Most trust models are hierarchical and centralized with a central root CA. Wildcard certificates reduce the management burden associated with certificates.
Outdated Certificates
In some situations, users can find that they can no longer access data because they don’t have access to a previously used certificate. The classic example occurs when users are issued new smart cards. As an example, many contractors have contracts of a specific length, such as one year. When the year expires, the contract is typically renewed, but they need to get a new smart card. They’ll have problems digitally signing email and opening encrypted email.
The problem is that their previous certificate is published in the organization, typically in a global address list accessible to everyone else in the organization. What these users need to do is publish the new certificate embedded in their new smart card and this will resolve the problem.
Remember this
When an organization issues a user a new certificate, such as with a new smart card, the user needs to publish it within the organization, such as via a global address list. Otherwise, other people in the organization use the original certificate.
The 601 Version of the Study Guide
The CompTIA Security+: Get Certified Get Ahead: SY0-601 Study GuideEach of the eleven chapters presents topics in an easy to understand manner and includes real-world examples of security principles in action.
You’ll understand the important and relevant security topics for the Security+ exam, without being overloaded with unnecessary details. Additionally, each chapter includes a comprehensive review section to help you focus on what’s important.
Over 300 realistic practice test questions with in-depth explanations will help you test your comprehension and readiness for the exam. The book includes:
- A 75 question pre-test
- A 75 question post-test
- Practice test questions at the end of every chapter.
Each practice test question includes a detailed explanation to help you understand the content and the reasoning behind the question. You’ll be ready to take and pass the exam the first time you take it.
If you plan to pursue any of the advanced security certifications, this guide will also help you lay a solid foundation of security knowledge. Learn this material, and you’ll be a step ahead for other exams. This SY0-601 study guide is for any IT or security professional interested in advancing in their field, and a must-read for anyone striving to master the basics of IT security.
Key Escrow
Key escrow is the process of placing a copy of a private key in a safe environment. This is useful for recovery. If the original is lost, the organization retrieves the copy of the key to access the data. Key escrow isn’t required, but if an organization determines that data loss is unacceptable, it will implement a key escrow process.
In some cases, an organization provides a copy of the key to a third party. Another method is to designate employees within the organization who will be responsible for key escrow. These employees maintain and protect copies of the key, and if the original key is lost, they check out a copy of the key to an administrator or user.
Recovery Agent
A key recovery agent is a designated individual who can recover or restore cryptographic keys. In the context of a PKI, a recovery agent can recover private keys to access encrypted data. The recovery agent may be a security professional, administrator, or anyone designated by the company.
In some cases, the recovery agent can recover encrypted data using a different key. For example, Microsoft’s BitLocker supports encryption of entire drives. It’s possible to add a data recovery agent field when creating a BitLocker encrypted drive. In this case, BitLocker uses two keys. The user has one key and uses it to unlock the drive during day-to-day use. The second key is only accessible by the recovery agent and used for recovery purposes if the original key is lost or becomes inaccessible.
Remember this
Recovery agents can recover user messages and data when users lose access to their private keys. In some cases, recovery agents can recover the private key from a key escrow.
Q. A user’s laptop developed a problem and can no longer boot. Help desk personnel tried to recover the data on the disk, but the disk is encrypted. Which of the following can be used to retrieve data from the hard drive?
A. A trust relationship
B. Public key
C. Recovery agent
D. CRL
Answer is C. Recovery agents can decrypt data and messages if the user’s private key is no longer available.
Although certificate authorities use trust models, a trust relationship doesn’t directly apply here.
A user’s public key is already publicly available, so it isn’t useful here.
A certificate revocation list (CRL) is a list of revoked certificates and doesn’t apply in this scenario.
