Computer Science
Encryption
Encryption is the process of converting data into a code to prevent unauthorized access. It is commonly used to secure sensitive information during transmission or storage. Encryption algorithms use mathematical functions to scramble the data, and only those with the correct decryption key can access the original information.
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12 Key excerpts on "Encryption"
eBook - PDF- Ido Dubrawsky(Author)
- 2011(Publication Date)
- Syngress(Publisher)
What Is Encryption? Encryption is a form of cryptography that “scrambles” plaintext into unintelligible ciphertext. Encryption is the foundation of such security measures as digital signatures, digital certificates, and the Public Key Infrastructure (PKI) that uses these technologies to make computer transactions more secure. Computer-based Encryption techniques use keys to encrypt and decrypt data. A key is a vari-able (sometimes represented as a password) that is a large binary number—the larger, the better. Key length is measured in bits, and the more bits in a key, the more difficult the key will be to “crack.” For example, a 40-bit key is considered insecure by today’s standards, but it can have a value between 1 and 2^140 (1,099,511,627,776, over a trillion). The key is only one component in the Encryption process. It must be used in conjunction with an Encryption algorithm (a process or calculation) to produce the ciphertext. Encryption methods are usually categorized as either symmetric or asymmetric , depending on the number of keys that are used . These two basic types of Encryption technology are discussed in the following sections. Symmetric Encryption Algorithms The most widely used type of Encryption is symmetric Encryption , which is aptly named because it uses one key for both the Encryption and decryption processes. Symmetric Encryption is also commonly referred to as secret-key Encryption and shared-secret Encryption , but all terms refer to the same class of algorithms. The reason why symmetric Encryption systems are abundant is speed and simplicity.The strength of symmetric algorithms lies primarily in the size of the keys used in the algorithm, as well as the number of cycles each algorithm employs.The cardinal rule is “fewer is faster.” By definition, all symmetric algorithms are theoretically vulnerable to brute-force attacks (covered in Chapter 2), which are exhaustive searches of all possible keys.
No longer available |Learn more- Michael Whitman, Herbert Mattord, David Mackey, Andrew Green(Authors)
- 2012(Publication Date)
- Cengage Learning EMEA(Publisher)
(Note: the algorithms used in most current Encryption are freely available and published to allow aca-demic and professional review.) Encryption is the process of converting an original message into a form that is unreadable to unauthorized individuals — that is, to anyone without the tools to convert the encrypted message back to its original format. Decryption is the process of converting the ciphertext message back into plaintext so that it can be readily understood. These are key terms that will be used throughout the book. The field of cryptology is so complex it can fill volumes; this textbook seeks to provide only a general overview of cryptology and some specific information about cryptographic tools. The early sections of this chapter provide background on cryptology and general definitions of key concepts in cryptography. In later sections, you will learn about common cryptographic proto-cols and some of the attack methods used against cryptosystems.
eBook - PDF- James Stanger(Author)
- 2011(Publication Date)
- Syngress(Publisher)
Basics of Cryptography and Encryption 9 Chapter 8 stand up to current and future attacks, speed refers to the processing power and time required to encrypt and decrypt a message, and ease of implementation refers to an algorithm's predispo- sition (if any) to hardware or software usage. Each algorithm has different strengths and drawbacks, and none of them are ideal in every way. This section discusses the key algo- rithms, which fall into three main categories: 9 Symmetric cryptography 9 Asymmetric cryptography 9 Hashing algorithms What Is Encryption? Encryption is a form of cryptography that scrambles plaintext into unintelligible ciphertext. Encryption is the foundation of such security measures as digital signatures, digital certifi- cates, and the Public Key Infrastructure (PKI) that uses these technologies to make computer transactions more secure. Computer-based Encryption techniques use keys to encrypt and decrypt data. A key is a variable (sometimes represented as a password) that is a large binary number~the larger, the better. Key length is measured in bits, and the more bits in a key, the more difficult the key will be to crack. For example, a 40-bit key is considered inse- cure by today's standards, but it can have a value between 1 and 2^140 (1,099,511,627,776, over a trillion). The key is only one component in the Encryption process. It must be used in conjunc- tion with an Encryption algorithm (a process or calculation) to produce the ciphertext. Encryption methods are usually categorized as either symmetric or asymmetric, depending on the number of keys that are used. These two basic types of Encryption technology are discussed in the following sections. Symmetric Encryption Algorithms The most widely used type of Encryption is symmetric Encryption, which is aptly named because it uses one key for both the Encryption and decryption processes.
eBook - PDF- Peter Gregory(Author)
- 2014(Publication Date)
- Cengage Learning EMEA(Publisher)
Trusting Cryptography The information security profession, and cryptography in particular, has passed into a new era where credible evidence has surfaced that reveals that several world governments have played a role in the deliberate weakening of cryptosystems to facilitate domestic and interna-tional espionage. Prior to these revelations, information security professionals could place their trust in national standards bodies, major Encryption product vendors, and government organizations. This trust has been broken and will not be easily mended. A significant challenge in both public and private sectors will be the establishment of new ways to measure the validity and integrity of cryptosystems. Or perhaps a new approach will involve novel uses of cryptography in order to make the compromise of a cryptosystem more difficult than before. The collective discussion on this topic will run its course over several years, resulting in the development of new validation platforms as well as improved application of cryptosystems. Chapter Summary Cryptography is the science of hiding information in plain sight, usually through the use of algorithms-based upon mathematical operations. Encryption is the process of transforming original plaintext into unreadable ciphertext. Encryption typically involves the use of an Encryption key, which is a block of text that is kept secret. The methods of Encryption are substitution, transposition, monoalphabetic, polyalphabetic, running key, and one-time pads. The types of Encryption are block ciphers and stream ciphers. Block ciphers are used to encrypt messages and files. Stream ciphers are used to encrypt continuous streams of data, such as video or audio. Figure 5-10 Example of watermarking Photo by Rebecca Steele 202 Chapter 5 Copyright 2015 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part.
eBook - PDFCryptography
Algorithms, Protocols, and Standards for Computer Security
- Zoubir Z. Mammeri(Author)
- 2024(Publication Date)
- Wiley(Publisher)
Note. [5] is an excellent book for readers who are interested in the history of cryptography. 2.1.3 Basic Terms Related to Encryption Systems Confidentiality is supported by Encryption and decryption algorithms, which process three basic elements, namely plain- text, ciphertext, and key, as illustrated by Figure 2.4. Channel is any unsecure means to access the encrypted data. It may be a communication network (e.g. Internet, a private network, or a cellular network) or storage device (e.g. a USB key). The attacker can listen to the channel or read the storage device. Definition 2.2 Plaintext (or cleartext): it is a data either on a storage device or in transit over a communication network. Definition 2.3 Ciphertext: it is data after Encryption; it is not readable for human beings or usable by any application, without possession of the decryption key. A ciphertext is either transmitted over an unsecure channel or stored in an unsecure area. It can be intercepted or com- promised by anyone who has access to the communication channel or the storage area. Definition 2.4 Cryptographic key (also called secret key or simply key): it is a parameter used by Encryption and decryp- tion algorithms. It is the most critical material. Static keys are intended to be used for a long period of time (e.g. the PIN code to access a bank account), while ephemeral keys are used for a very limited time (e.g. to encrypt one message). Definition 2.5 Encryption algorithm (also called enciphering): it is the process of creating a ciphertext. It makes use of a key to scramble the input (i.e. the plaintext), so that the result (i.e. the ciphertext) looks like a noise for any observer who does not know the decryption key. Definition 2.6 Decryption algorithm: it is the process of transforming a ciphertext into a plaintext; i.e. it is the reverse pro- cess of Encryption. Figure 2.4 Main components of Encryption/decryption chain.
- Syngress(Author)
- 2002(Publication Date)
- Syngress(Publisher)
Of course, computers also make it much easier to decrypt encrypted data. Ciphers www.syngress.com 376 Chapter 7 • Understanding Cybercrime Prevention that would take hundreds or thousands of years to break with a team of top cryptanalysts working on them manually can be cracked in hours, days, or weeks using high-powered computers. One of the first well-known computer ciphering systems was LUCIFER, an IBM project that formed the foundation of the popular Data Encryption Standard (DES) cipher that is still widely used (along with its more secure ver-sion, 3DES). LUCIFER was a block cipher, as is DES. It used a 128-bit key to encrypt blocks of binary data that were 128 bits in length.The cipher was applied to each block several times. Even though LUCIFER uses a larger block and key than DES, it is less secure.That’s because its key schedule is regular and thus more predictable. In the “Encryption Algorithms” section later in this chapter, we dis-cuss DES and other modern ciphers used by computerized Encryption schemes. N OTE For much more detailed information about how different types of ciphers and cipher devices work, see http://pardus-larus.student .utwente.nl/librarilo/texts/computers/crypto. What Is Encryption? Encryption is a form of cryptography that “scrambles” plain text into unintelligible cipher text. Encryption is the foundation of such security measures as digital sig-natures, digital certificates, and the public key infrastructure that uses these tech-nologies to make computer transactions more secure. Computer-based Encryption techniques use keys to encrypt and decrypt data. A key is a variable (sometimes represented as a password) that is a large binary number—the larger, the better. Key length is measured in bits, and the more bits in a key, the more difficult the key will be to “crack.” The key is only one component in the Encryption process.
eBook - PDF- Michael Whitman, Herbert Mattord(Authors)
- 2021(Publication Date)
- Cengage Learning EMEA(Publisher)
Table 10-1 History of Cryptology Copyright 2022 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Principles of Information Security 386 • Cipher—When used as a verb, the transformation of the individual components (characters, bytes, or bits) of an unencrypted message into encrypted components or vice versa (see Decryption and Encryption); when used as a noun, the process of Encryption or the algorithm used in Encryption, and a term synonymous with cryptosystem. • Ciphertext or cryptogram—The unintelligible encrypted or encoded message resulting from an Encryption. • Code—The process of converting components (words or phrases) of an unencrypted message into encrypted components. • Decipher—See Decryption. • Decryption—The process of converting an encoded or enciphered message (ciphertext) back to its original readable form (plaintext); also referred to as deciphering. • Encipher—See Encryption. • Encryption—The process of converting an original message (plaintext) into a form that cannot be used by unauthorized individuals (ciphertext); also referred to as enciphering. • Key or cryptovariable—The information used in conjunction with the algorithm to create the ciphertext from the plaintext; it can be a series of bits used in an algorithm or the knowledge of how to manipulate the plaintext. Sometimes called a cryptovariable. • Keyspace—The entire range of values that can be used to construct an individual key.
- David Riley, Kenny A. Hunt(Authors)
- 2014(Publication Date)
- Chapman and Hall/CRC(Publisher)
In this section we look at six other specific approaches commonly used to mitigate information security. Each subsection begins with the vulnerability, then explores an associated mitigation strategy to illustrate how computational thinking was applied. 12.7.1 Encryption The first vulnerability is plaintext itself. The problem is that anyone can determine what characters or numbers are stored in a particu-lar piece of computer data, because most data encoding formats are highly standardized and widely known common. Recall that the ways in which computer data encodes information was the main topic of Chapter 2. Unfortunately, these encoding standards make it relatively easy for an attacker to discover the text of any data that has been intercepted. If an attacker can gain access to your files, e-mail, or other data, then the information contained by those data are easily discovered, violating any intended confidentiality. In addition attackers can create or corrupt data because they know how to formulate bit strings in the way that you inter-pret them. A general mitigation scheme to overcome the encoding standard vulner-ability is to obfuscate information by way of Encryption . The idea of encryp-tion is to scramble data (rearrange bit patterns) in a way that makes the data 360 ◾ Computational Thinking for the Modern Problem Solver essentially unintelligible to those who are unauthorized. The usual trick is to do this in a way that still allows access to those who are authorized. Encryption requires the use of encrypting software, which is now a part of all computers. Encrypting a message can be described as transform-ing the plaintext version of the data into a scrambled (encrypted) form. The left portion of Figure 12.4 shows how two-way encrypting works. The original data in this figure is labeled plaintext and the name ciphertext refers to the encrypted form of the data. Using two-way Encryption is particularly effective for preserving con-fidentiality.
eBook - PDF- John Rittinghouse PhD CISM, William M. Hancock PhD CISSP CISM, John Rittinghouse, PhD, CISM, William M. Hancock, PhD, CISSP, CISM(Authors)
- 2003(Publication Date)
- Digital Press(Publisher)
7 Securing Communications 7.1 Cryptography is the art of devising codes and ciphers. Cryptanalysis is the art of breaking those very codes and ciphers. Cryptology is a combination of the two arts. Information to be encrypted is known as plain text; the result of that process yields cipher text. The various parameters of the Encryption process that transforms plain text to cipher text are generally referred to as keys. Cryptography Cryptography, more formally defined, is the science of using mathematical algorithms to encrypt and decrypt data. Sometimes more art than science, cryptography enables organizations or individuals to store sensitive infor- mation or transmit it across insecure networks, such as the Internet so that it cannot be read by anyone except the intended recipient. Cryptanalysis, as opposed to cryptography, is the science of analyzing and breaking secure communications. A classical cryptanalysis process involves a combination of analytical reasoning, application of mathematical tools, pattern matching and discovery, patience, determination, and sheer luck. 7.1.1 Why cryptography is needed Cryptography without strength is no cryptography. Essentially, the level of cryptography needed is proportionate to the sensitivity of the data you need to protect. For organizations such as governments and large enterprises the cost of losing sensitive data may be catastrophic. Loss of such data could harm one, many, hundreds, or even thousands of individuals. Factoring in the severity of such a loss generally determines the extent of effort needed to protect that data through use of cryptographic means. In the following sec- tions, we will explain various facets of the cryptographic science. 7.1.2 Strength of cryptographic algorithms A cryptographic system is only as strong as its weakest link. Good crypto- graphic systems should always be designed so that they are as difficult to 231
eBook - PDF- Michael Simpson, Nicholas Antill(Authors)
- 2016(Publication Date)
- Cengage Learning EMEA(Publisher)
chapter 12 Cryptography After reading this chapter and completing the exercises, you will be able to: ● Summarize the history and principles of cryptography ● Describe symmetric and asymmetric Encryption algorithms ● Explain public key infrastructure (PKI) ● Describe possible attacks on cryptosystems ● Compare hashing algorithms and how they ensure data integrity 329 Copyright 2017 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300 Protecting data as it traverses the Internet or while it ’ s stored on a computer is one of a network security professional ’ s most important jobs. Companies as well as users don ’ t want others to be able to view confidential documents and files. In this chapter, you examine the cryptography technologies that security professionals use to protect a company ’ s data. You see how information can be converted into an unreadable for-mat and how only those with the correct key or “ decoder ” can read the message. You also look at cryptography attacks and some of the tools used to conduct these attacks. Understanding Cryptography Basics Cryptography is the process of converting plaintext , which is readable text, into ciphertext , which is unreadable or encrypted text. Cryptography can be used on data that people or organi-zations want to keep private or data that should be accessible to only certain users. In other words, cryptography is used to hide information from unauthorized users. Decryption is the pro-cess of converting ciphertext back to plaintext (also called cleartext). As a kid, you might have had a decoder ring from a box of cereal that you could use to write a letter to a friend in secret code. If your friend had the same decoder ring, he or she could decode your letter and read it. History of Cryptography Cryptography has been around for thousands of years. For example, some Egyptian hiero-glyphics on ancient monuments were encrypted.
eBook - ePubOpen-Source Robotics and Process Control Cookbook
Designing and Building Robust, Dependable Real-time Systems
- Lewin Edwards(Author)
- 2011(Publication Date)
- Newnes(Publisher)
CHAPTER 5Encryption and Data Security Primer
5.1 Introduction
It is impossible to build a trustworthy control network unless the topic of security is addressed and designed into the product from the beginning. Whether you are designing a system for your own use, or for installation into some industrial or commercial application, you will need to consider how to protect it against some level of attack from the outside world, and how to protect recorded data from theft or forgery.Although data security involves physical, procedural and other holistic aspects, most security techniques in consumer and commercial applications are centered around adding Encryption to existing protocols and data formats. This is primarily because Encryption is cheap, being provided by “free” software, and it is also much easier to force users to run a “secure” version of a program (with Encryption features forced to be on) than it is to get them to change their data security habits. Note that Encryption technology really embraces two related topics: protecting valuable data from being intercepted and read by people who aren’t entitled to read it, and authenticating transmissions so that commands from untrusted sources can be identified and ignored. The latter task involves encoding or wrapping data from a trusted source with a layer that cannot be forged by a third party. It doesn’t necessarily involve encrypting the actual data being transmitted. Be sure not to confuse these two points.When considering measures to protect your data, you must take account of the following factors:What part of the data needs to be protected. In many applications, a considerable proportion of the data throughput doesn’t need to be protected; only a small core of data needs protection. In other cases, it may be necessary to use different levels of protection for different classes of data.35What types of attack you need to protect against.
- William J. Buchanan(Author)
- 2011(Publication Date)
- Auerbach Publications(Publisher)
85 3 Encryption . . http://asecuritybook .com/unit03.html, . Select. . Principles of Encryption . 3.1 Objectives The.key.objectives.of.this.unit.are.to •. Define. the. methods. used. in. Encryption,. especially. for. public-. and. private-key. Encryption •. Understand. methods. that. can. be. used. to. crack.encrypted.content •. Outline. a. range. of. standard. Encryption. methods 3.2 Introduction The.future.of.the.Internet,.especially.in.expanding. the.range.of.applications,.involves.a.much.deeper. degree. of. privacy. and. authentication . . Without. these. the. Internet. cannot. be. properly. used. to. replace. existing. applications. such. as. in. voting,. finance,.and.so.on . .The.future.is.thus.toward.data. Encryption,.which.is.the.science.of.cryptographics * . and.provides.a.mechanism.for.two.entities.to.com-municate. without. any. other. entity. being. able. to. read.their.messages . .In.a.secret.communications. system,.Bob.and.Alice.should.be.able.to.commu-nicate.securely,.without.Eve.finding.out.the.con-tents.of.their.messages.or.in.keeping.other.details. *. The.word. cryptography .is.derived.from.the.Greek.word.that.means. hidden.or.secret.writing . 86 Introduction to Security and Network Forensics secure,. such. as. their. location,. or. the. date. that. their. messages. are. sent. (Figure 3.1). The.two.main.methods.used.are.to.either.use.a.unique.algorithm.that.both. Bob.and.Alice.know.and.not.tell.Eve.or.use.a.well-known.algorithm.that.Eve. also.knows,.and.use.some.special.electronic.key.to.uniquely.define.how.the.mes-sage.is.converted.into.cipertext,.and.back.again . .A.particular.problem.in.any. type.of.Encryption.is.the.passing.of.the.secret.algorithm.or.the.key.in.a.secure. way,.as.Bob.or.Alice.does.not.know.if.Eve.is.listening.to.their.communications . . If.Eve.finds.out.the.algorithm.or.the.key,.neither.Bob.nor.Alice.is.able.to.detect. this. .This.chapter.looks.at.some.of.the.basic.principles.of.Encryption,.including.
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