Data Encryption and Symmetric Block Ciphers

Posted by in Security+ | 0 comments

If you’re planning on taking the Security+ exam, you should have a good understanding of symmetric algorithms that use block ciphers to encrypt data.

For example, can you answer this question?

Q. Which of the following algorithms encrypts data in 64-bit blocks?

A. AES

B. DES

C. Twofish

D. RC4

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.

A block cipher encrypts data in specific-sized blocks, such as 64-bit blocks or 128-bit blocks. The block cipher divides large files or messages into these blocks and then encrypts each individual block separately.

AES

The Advanced Encryption Standard (AES) is a strong symmetric block cipher that encrypts data in 128-bit blocks. The National Institute of Standards and Technology (NIST) adopted AES from the Rijndael encryption algorithm after a lengthy evaluation of several different algorithms. NIST is a U.S. agency that develops and promotes standards. They spent about five years conducting a review of 15 different symmetric algorithms and identified AES as the best of the 15.

AES can use key sizes of 128 bits, 192 bits, or 256 bits, and it’s sometimes referred to as AES-128, AES-192, or AES-256 to identify how many bits are used in the key. When more bits are used, it makes it more difficult to discover the key. AES-128 provides strong protection, but AES-256 provides stronger protection.

CompTIA Security+ Study Guide

The 501 Version of the Study Guide

The CompTIA Security+: Get Certified Get Ahead: SY0-501 Study Guide is an update to the top-selling SY0-201, SY0-301, and SY0-401 study guides, which have helped thousands of readers pass the exam the first time they took it.  It includes the same elements readers raved about in the previous three 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.



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 SY0-501 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.

Because of its strengths, AES has been adopted in a wide assortment of applications. For example, many applications that encrypt data on USB drives use AES. Some of the strengths of AES are:

  • Fast. AES uses elegant mathematical formulas and only requires one pass to encrypt and decrypt data. In contrast, 3DES requires multiple passes to encrypt and decrypt data.
  • Efficient. AES is less resource intensive than other encryption algorithms such as 3DES. AES encrypts and decrypts quickly even when ciphering data on small devices, such as USB flash drives.
  • Strong. AES provides strong encryption of data providing a high level of confidentiality.

Remember this

AES is a strong symmetric block cipher that encrypts data in 128-bit blocks. AES uses 128-bit, 192-bit, or 256-bit keys.

DES

Data Encryption Standard (DES) is a symmetric block cipher that was widely used for many years, dating back to the 1970s. It encrypts data in 64-bit blocks. However, it uses a relatively small key of only 56 bits and can be broken with brute force attacks. In the ’70s, the technology required to break 56-bit encryption wasn’t easily available, but with the advances in computer technology, a 56-bit key is now considered trivial. DES is not recommended for use today.

Block Ciphers

3DES

3DES (pronounced as “Triple DES”) is a symmetric block cipher designed as an improvement over the known weaknesses of DES. In basic terms, it encrypts data using the DES algorithm in three separate passes and uses multiple keys. Just as DES encrypts data in 64-bit blocks, 3DES also encrypts data in 64-bit blocks.

Although 3DES is a strong algorithm, it isn’t used as often as AES today. AES is much less resource intensive. However, if hardware doesn’t support AES, 3DES is a suitable alternative. 3DES uses key sizes of 56 bits, 112 bits, or 168 bits.

Remember this

DES and 3DES are block ciphers that encrypt data in 64-bit blocks. 3DES was originally designed as a replacement for DES, but NIST selected AES as the current standard. However, 3DES is still used in some applications, such as when legacy hardware doesn’t support AES.

Full Security+ Course

SY0-501 Full Security+ Course

Helping you Pass the First Time

Online access includes all of the content from the

CompTIA Security+: Get Certified Get Ahead: SY0-501 Study Guide

  • Introduction
  • About the exam (including information on the number of questions, test duration, passing score, types of questions and more. Also includes a listing of the exam objectives)
  • 75 question pre-assessment exam
  • Mastering Security Basics (full content from Chapter 1 of the study guide including the exam topic review and 15 practice test questions)
  • Understanding Identity and Access Management (full content from Chapter 2 of the study guide including the exam topic review and 15 practice test questions)
  • Exploring Network Technologies and Tools (full content from Chapter 3 of the study guide including the exam topic review and 15 practice test questions)
  • Securing Your Network (full content from Chapter 4 of the study guide including the exam topic review and 15 practice test questions)
  • Securing Hosts and Data (full content from Chapter 5 of the study guide including the exam topic review and 15 practice test questions)
  • Comparing Threats, Vulnerabilities, and Common Attacks (full content from Chapter 6 of the study guide including the exam topic review and 15 practice test questions)
  • Protecting Against Advanced Attacks (full content from Chapter 7 of the study guide including the exam topic review and 15 practice test questions)
  • Using Risk Management Tools (full content from Chapter 8 of the study guide including the exam topic review and 15 practice test questions)
  • Implementing Controls to Protect Assets (full content from Chapter 9 of the study guide including the exam topic review and 15 practice test questions)
  • Understanding Cryptography and PKI (full content from Chapter 10 of the study guide including the exam topic review and 15 practice test questions)
  • Implementing Policies to Mitigate Risks (full content from Chapter 11 of the study guide including the exam topic review and 15 practice test questions)
  • 75 question post-assessment exam
  • Glossary

Get the SY0-501 Full Security+ Course Here


Test your readiness with these quality materials

Random 75-question tests

Random practice tests from the all of the practice test questions in the CompTIA Security+: Get Certified Get Ahead: SY0-501 Study Guide. All questions include explanations so you'll know why the correct answers are correct, and why the incorrect answers are incorrect.

3 sets Performance-based Questions

Three new sets of performance-based questions with a total of 30 questions. These new questions use a new testing engine that includes realistic drag and drop, matching, sorting, and fill in the blank questions.

Flashcard Set

  • 494 Online Security+ Glossary Flashcards
  • 222 Online Security+ Acronyms Flashcards
  • 223 Online Security+ Remember This Slide from the popular CompTIA Security+ Get Certified Get Ahead: SY0-501 Study Guide

Audio - SY0-501 Security+ Remember This Audio Files

Learn by Listening. Over one hour and 20 minutes of audio (MP3 downloads.)

Audio - SY0-501 Security+ Question and Answer Audio Files

Learn by Listening. Over two hours hour and 53 minutes of audio (MP3 downloads.)

Bonus #1

Audio from the end of chapter reviews from each of the chapters in the CompTIA Security+: Get Certified Get Ahead: SY0-501 Study Guide. Over one hour and 40 minutes of additional audio.

Bonus #2

Access to all of the online content that is available for free to anyone that purchases the CompTIA Security+ Get Certified Get Ahead: SY0-501 Study Guide. This includes labs, extra practice test questions, and supplementary materials

Bonus #3 

Access the study materials for a total of 60 days because sometimes life happens.

Get the SY0-501 Full Security+ Course Here


 

Q. Which of the following algorithms encrypts data in 64-bit blocks?

A. AES

B. DES

C. Twofish

D. RC4

Answer is B. Data Encryption Standard (DES) encrypts data in 64-bit blocks similar to how 3DES and Blowfish encrypt data in 64-bit blocks.

Advanced Encryption Standard (AES) and Twofish encrypt data in 128-bit blocks.

Rivest Cipher 4 (RC4) is a stream cipher and it encrypts data one bit at a time.

Security+ Practice Test Questions

SY0-501 Practice Test Questions 

Over 300 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 - 75 random questions. View 75 random questions from the full test bank similar to how the Security+ exam has a potential maximum of 75 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 SY0-501 Practice Test Questions Here

 SY0-501 Practice Test Questions


INCLUDES QUESTIONS TO HELP YOU PREPARE

FOR THE NEW PERFORMANCE BASED QUESTIONS 

Bonus - Performance Based Questions

Three sets of performance-based questions including over 30 questions. These questions show you what you can expect in the live exam. They include drag and drop, matching, sorting, and fill in the blank questions. See a demo here.

Bonus - Extra Practice Test Questions

New multiple-choice questions in the extra test bank. Questions are added occasionally. You can see what has been added recently here.

Get the full bank of Security+ (SYO-501) Practice Test Questions Here

Get the full bank of Security+ Practice Test Questions

Click here if you're looking for SY0-501 Full Study Package

See Chapter 10 of the CompTIA Security+: Get Certified Get Ahead: SY0-401 Study Guide for more information on cryptography.

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.

CompTIA Security+ Get Certified Get Ahead: SY0-501 Study Guide

Subscribe To Our Newsletter

Join our mailing list and get a free excerpt of the CompTIA Security+: Get Certified Get Ahead: SY0-501 Study Guide.  This excerpt includes the introduction and Chapter 1. 

You have Successfully Subscribed!

Get Certified Get Ahead is a participant in the Amazon Services LLC Associates Program,
an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com.

Copyright © 2015 Get Certified Get Ahead. All Rights Reserved.