Key Stretching

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Key stretching is one of the new topics in the SY0-401 Security+ exam so if you plan on taking it, you should have a basic understanding of key stretching. It’s also a topic in the CompTIA Advanced Security Practitioner Certification Exam Objectives (CAS-002) exam.

Key Stretching Sample Question

As an example, you should be able to answer this sample question from the CompTIA Security+: Get Certified Get Ahead: SY0-401 Study Guide.

Q. An application requires users to log on with passwords. The application developers want to store the passwords in such a way that it will thwart rainbow table attacks. Which of the following is the BEST solution?

A. SHA

B. Blowfish

C. ECC

D. Bcrypt

Do you know the answer? Ideally you should know why the correct answer is correct, and why the incorrect answers are incorrect. The answer is at the end of this post.

CompTIA Security+ Study Guide

The 401 Version of the Study Guide

SY0-401 Study GuideThe CompTIA Security+: Get Certified Get Ahead: SY0-401 Study Guide is an update to the top-selling SY0-201 and SY0-301 study guides, which have helped thousands of readers pass the exam the first time they took it.

CompTIA Authorized Quality Content (CAQC)After a comprehensive review by ProCert Labs, the SY0-401 version has been certified as CompTIA Approved Quality Content (CAQC) and covers every aspect of the SY0-401 exam.

It includes the same elements readers raved about in the previous two versions.

Each 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.


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Over 400 realistic practice test questions with in-depth explanations will help you test your comprehension and readiness for the exam. The book includes:

  • A 100 question pre-test
  • A 100 question post-test
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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 SY0-401 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.

Kindle edition also available.

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Key Stretching Purpose

Key stretching is a technique used to increase the strength of stored passwords and prevent the success of some password attacks such as brute force attacks and rainbow table attacks.

Using complex passwords goes a long way toward preventing brute force attacks and rainbow table attacks but doesn’t prevent them all. A better method is to salt the passwords with additional random bits to make them even more complex. Key stretching techniques use salts.

Two common key stretching techniques are bcrypt and Password-Based Key Derivation Function 2 (PBKDF2):

  • Bcrypt. Based on the Blowfish block cipher, bcrypt is used on many Unix and Linux distributions to protect the passwords stored in the shadow password file. Bcrypt salts the password by adding additional bits before encrypting it with Blowfish.
  • PBKDF2. Many algorithms such as Wi-Fi Protected Access II (WPA2), Apple’s iOS mobile operating system, and Cisco operating systems use PBKDF2 to increase the security of passwords. PBKDF2 adds a salt of at least 64 bits.

Password attacks attempt to discover or bypass passwords used for authentication on systems and networks, and for different types of files. Although there are many attack methods, they fall into two generic categories: online password attacks and offline password attacks.

An online password attack attempts to discover a password from an online system. For example, an attacker trying to log on to an account by trying to guess a user’s password is an online attack.

Offline password attacks attempt to discover passwords from a captured database or captured packet scan. For example, when attackers hack into a web site causing a data breach, they can download entire databases. They then perform offline attacks to discover the passwords contained within the databases.

Key stretching techniques provide significant protection against offline password attacks.

Security+ Practice Test Questions

SYO-501 Practice Test Questions Now Available

SYO-401 Practice Test Questions

Over 440 realistic Security+ practice test questions

All questions include explanations so you'll know why the correct answers are correct,

and why the incorrect answers are incorrect.

Pass the Security+ Exam

the First Time You Take It

Multiple quiz formats to let you use these questions based on the way you learn.
  • Learn mode - randomized. View each of the questions in random order. Learn mode allows you to keep selecting answers until you select the correct answer. Once you select the correct answer, you'll see the explanation. Click here to see how learn mode works.
  • Learn mode - not randomized. View each of the questions in the same order. Use this if you want to make sure that you see all of the questions. Learn mode allows you to keep selecting answers until you select the correct answer. Once you select the correct answer, you'll see the explanation. Click here to see how learn mode works.
  • Test mode - randomized. View each of the questions in random order. In test mode, you can only see the correct answers and explanations after you complete the test. Click here to see how test mode works.
  • Test mode - not randomized. View each of the questions in the same order. In test mode, you can only see the correct answers and explanations after you complete the test. Click here to see how test mode works.
  • Test mode - 100 random questions. View 100 random questions from the full test bank similar to how the Security+ exam has a potential maximum of 100 multiple choice questions. In test mode, you can only see the correct answers and explanations after you complete the test. Click here to see how test mode works.

Get the full bank of Security+ (SYO-401) Practice Test Questions Here

 SYO-401 Practice Test Questions


INCLUDES QUESTIONS TO HELP YOU PREPARE

FOR THE NEW PERFORMANCE BASED QUESTIONS 

Bonus - Performance Based Questions

Additional Security+ questions to help you prepare for the new performance based questions. These are included with the full bank of Security+ practice test questions and are divided into different sections. For example, you'll have access to the following links:

- Performance Based Question - Set 1

You'll see a graphic explaining what you might be required to do on the actual exam to match different types of security to mobile devices and servers in a data center. You'll then have two questions that test your knowledge and ability to correctly answer the questions. This question also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 2

You'll see a graphic explaining what you might be required to do on the actual exam to match different types of attacks with the name of the attack type. You'll then have five questions that test your knowledge and ability to correctly answer the questions. This question also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 3

You'll see a graphic showing a network with computers and servers separated by a firewall. The firewall is used to control traffic between the computers and users using rules within an access control list (ACL).  You'll have three questions that test your knowledge and ability to correctly identify the relevant components of the rule. The incorrect answers and explanation provide you with insight into how to correctly answer this type of question on the actual exam.

- Performance Based Question - Set 4

You'll see a graphic explaining what you might be required to do on the actual exam related to what a forensic analyst would do during an investigation. You'll then have two questions that test your knowledge and ability to correctly answer the questions. This question also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 5

You'll see a graphic explaining what you might be required to do on the actual exam to match protocols and ports. You'll then have seven questions that test your knowledge and ability to correctly answer the questions. This question also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 6

You'll see a list of security controls along with a graphic showing devices and locations within an organization, along with instructions on what you might be required to do on the actual exam to match the controls with the devices and locations. You'll then have four questions that test your knowledge and ability to correctly answer the questions. This question also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 7

You'll see a list of authentication methods and authentication factors along with instructions on what you might be required to do on the actual exam to match the authentication methods with the authentication factors. You'll then have six questions that test your knowledge and ability to correctly answer the questions. This set also includes a link to a graphic showing the end solution for the overall performance based question simulation.

- Performance Based Question - Set 8

You'll see a graphic explaining what you might be required to do on the actual exam to match different types of attacks with the name of the attack type. You'll then have five questions that test your knowledge and ability to correctly answer the questions. This is similar to Set 2 but expands on the possibilities. The set also includes a link to a page showing the end solution for the overall performance based question simulation.

New - Performance Based Question - Set 9

New questions recently added using a different testing engine. See a demo here. This set includes drag and drop and matching questions on ports.

New - Performance Based Question - Set 10

A random set of 20 performance-based questions using drag and drop, matching, sorting, and fill in-the blank. This set includes performance-based questions on RAID.

Get the full bank of Security+ (SYO-401) Practice Test Questions Here

Get the full bank of Security+ Practice Test Questions

Click here if you're looking for SYO-501 Practice Test Questions

Remember this

Bcrypt and PBKDF2 are key stretching techniques that help prevent brute force and rainbow table attacks. Both salt the password with additional bits.

Key Stretching Sample Question Answer

Q. An application requires users to log on with passwords. The application developers want to store the passwords in such a way that it will thwart rainbow table attacks. Which of the following is the BEST solution?

A. SHA

B. Blowfish

C. ECC

D. Bcrypt

D is correct. Bcrypt is a key stretching technique designed to protect against brute force attempts and is the best choice of the given answers. Another alternative is Password-Based Key Derivation Function 2 (PBKDF2). Both salt the password with additional bits.

Passwords stored using Secure Hash Algorithm (SHA) only are easier to crack because they don’t use salts.

PBKDF2 is based on Blowfish, but Blowfish itself isn’t commonly used to encrypt passwords.

Elliptic curve cryptography (ECC) is efficient and sometimes used with mobile devices, but not to encrypt passwords.


Pass the Security+ exam the first time!

CompTIA Security+: Get Certified Get Ahead: SY0-401 Study Guide

Get Certified Get Ahead Security+ SY0-401

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  1. Rainbow Table Attacks - Get Certified Get Ahead | Get Certified Get Ahead - […] Check out this blog post, which covers bcrypt and Password-Based Key Derivation Function 2 (PBKDF2…. Both use salting techniques to increase…
  2. Password Attacks - Get Certified Get Ahead | Get Certified Get Ahead - […] key stretching techniques such as bcrypt and Password-Based Key Derivation Function 2 (PBKDF2) add a salt to the password […]

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