Cryptographic Algorithm

Public Key Infrastructure

Terence Spies , in Estimator and Data Security Handbook (Third Edition), 2017

Abstruse

Cryptographic algorithms are used for of import tasks such equally information encryption, authentication, and digital signatures, but one problem has to exist solved to enable these algorithms: binding cryptographic keys to machine or user identities. Public key infrastructure (PKI) systems are built to span useful identities (electronic mail addresses, Domain Name System addresses, etc.) and the cryptographic keys used to authenticate or encrypt data passing amongst these identities. This chapter will explain the cryptographic groundwork that forms the foundation of PKI systems, the mechanics of the X.509 PKI organization (as elaborated by a number of standards bodies), practical issues surrounding the implementation of PKI systems, a number of alternative PKI standards, and alternative cryptographic strategies for solving the problem of secure public central distribution. PKI systems are circuitous systems that have proven to be difficult to implement properly. This chapter aims to survey the basic compages of PKI systems and some of the mechanisms used to implement them. Information technology does not aim to be a comprehensive guide to all PKI standards or to contain sufficient technical item to allow implementation of a PKI system. These systems are continually evolving, and the reader interested in building or operating a PKI is advised to consult the current piece of work of standards bodies referenced in this chapter.

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Privacy Preservation in Smart Cities

Youyang Qu , ... Shui Yu , in Smart Cities Cybersecurity and Privacy, 2019

three.one Cryptography

Cryptographic algorithms are the most often used privacy protection method in the IoT domain. Many cryptographic tools have been applied in practice. Unfortunately, traditional encryption mechanisms with overly computational complication cannot meet the new requirements for smart applications, especially for those systems that consist of many resource-constraint devices [ 22]. Consequently, how to develop lightweight still effective encryption algorithms is of significant practical value.

Homomorphic encryption (HE), as a method of performing calculations on encrypted information, has received increasing attention in recent years. The fundamental function of it is to protect sensitive information from being exposed when performing computations on encrypted data. For case, Abdallah et al. [23] adult a lightweight HE-based privacy protection data aggregation method for smart grids that tin avoid involving the smart meter when aggregate readings are performed. Another work by Talpur et al. [24] proposed an IoT network architecture based on HE engineering for healthcare monitoring systems. Despite the cracking potential of HE methods, computational expense may restrict the application of this method.

Zero-knowledge proof is another cryptographic method that allows one party to bear witness something to other parties, without conveying additional data. For application in the Smart City domain, Dousti et al. [25] developed an hallmark protocol for smart cards through zero-knowledge proofs.

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Cryptography

Jason Andress , in The Basics of Information Security (2d Edition), 2014

Symmetric key algorithms

Some of the cryptographic algorithms that are more recognizable to the full general public are symmetric key algorithms. Several of these, such as DES, 3DES, and AES, are or have been in regular use past the US government and others as standard algorithms for protecting highly sensitive data.

DES starting time came into apply in 1976 in the United states of america and has since been used by a diversity of parties globally. DES is a block nada based on symmetric primal cryptography and uses a 56-bit primal. Although DES was considered to exist very secure for some period of time, information technology is no longer considered to be then. In 1999, a distributed computing project was launched to pause a DES central by testing every possible key in the entire keyspace, and the project succeeded in doing so in a piffling more 22   h. This weakness brought near past the brusque key length was compensated for a flow of time through the use of 3DES (pronounced triple DES), which is simply DES used to encrypt each block three times, each time with a different key. DES tin can operate in several different block modes, including Cipher Block Chaining (CBC), Electronic CodeBook (ECB), Cipher Feedback (CFB), Output Feedback (OFB), and Counter Mode (CTR). Each fashion changes the way encryption functions and the way errors are handled.

AES is a prepare of symmetric block ciphers endorsed by the United states government through NIST, and now used by a variety of other organizations, and is the replacement for DES equally the standard encryption algorithm for the US federal authorities. AES uses three dissimilar ciphers: ane with a 128-chip key, one with a 192-chip key, and one with a 256-bit key, all having a cake length of 128 bits. A variety of attacks accept been attempted confronting AES, about of them against encryption using the 128-bit key, and most of them unsuccessful, partially successful, or questionable altogether. At the time of this writing, the The states government still considers AES to exist secure. AES shares the same block modes that DES uses and likewise includes other modes such equally XEX-based Tweaked CodeBook (TCB) mode.

At that place are a large number of other well-known symmetric block ciphers, including Twofish, Serpent, Blowfish, CAST5, RC6, and IDEA, as well equally stream ciphers, such as RC4, ORYX, and SEAL.

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Authentication Systems

Christophe Kiennert , ... Pascal Thoniel , in Digital Identity Management, 2015

3.1.4.iii Hash functions

In addition to cryptographic algorithms that are used to ensure the confidentiality of communications, a specific family unit of algorithms is used to guarantee the integrity of exchanges. These are known as cryptographic hash functions.

For each message, these functions create a hash value (or simply hash) of a stock-still length with a certain number of properties, which volition not be discussed formally here. These are "one-way" functions: it is virtually impossible to recreate the input data from the hash alone. Moreover, if a bulletin is modified even slightly, a skilful hash role will produce a hash very different from that of the original message, and the new hash cannot be predicted based on the modification. Finally, a good hash role should besides exist resistant to collisions, i.eastward. information technology should exist very difficult to find two messages 1000 and M′ with the aforementioned hash.

The hashes produced past widespread hash functions are by and large very small in relation to the size of letters. The hashes produced past the MD5 algorithm [RFC 92a], for case, are of 128 bits; SHA-one [NAT 02] produces 160-bit hashes, and SHA-256 [NAT 02] produces 256-bit hashes. Collisions cannot therefore be avoided completely; the purpose of a hash is therefore not to be "decoded" to obtain the original message, equally this volition not be possible. The role of the hash is but to show whether or not a message has been modified in the form of communication.

In social club to be effective, a hash role should be combined with other cryptographic primitives in a protocol. It would exist easy for an assaulter to recalculate a correct hash for a message which he or she had modified; however, if a bulletin and the associated hash are encrypted by the sender, and then an aggressor would be unable to correctly alter the encrypted value of the message hash.

In the aforementioned way, a digital signature, whereby the sender of a message encrypts the hash using a private key before attaching it to the message, will ensure integrity, authentication of the sender and non-repudiation of a bulletin. The principle of a digital signature is illustrated in Figure 3.four.

Figure three.4. Principle of the digital signature

Finally, note that, while they are still widespread, utilise of the MD5 and SHA-1 hash functions is at present strongly discouraged; the showtime is considered to be broken (it is now easy to create collisions [WAN 05]), and the 2d is considered to be severely weakened.

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Agreement Cybercrime Prevention

Littlejohn Shinder , Michael Cross , in Scene of the Cybercrime (2d Edition), 2008

Securing Information with Cryptographic Algorithms

Literally thousands of different cryptographic algorithms accept been developed over the years. Cryptographic algorithms can exist classified as follows:

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Encryption algorithms that are used to encrypt data and provide confidentiality

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Signature algorithms that are used to digitally "sign" information to provide authentication

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Hashing algorithms that are used to provide information integrity

Algorithms (ciphers) are also categorized by the way they work at the technical level (stream ciphers and cake ciphers). This categorization refers to whether the algorithm is applied to a stream of data, operating on individual bits, or to an unabridged block of information. Stream ciphers are faster because they piece of work on smaller units of data. The key is generated every bit a keystream, and this is combined with the plain text to exist encrypted. RC4 is the most usually used stream cipher. Another is ISAAC.

Cake ciphers take a block of plain text and turn information technology into a cake of cipher text. (Usually the block is 64 or 128 bits in size.) Common block ciphers include DES, Bandage, Blowfish, IDEA, RC5/RC6, and SAFER. About Avant-garde Encryption Standard (AES) candidates are cake ciphers.

Annotation

AES is a standard for cryptography used by the U.Southward. federal authorities to protect sensitive but unclassified information. A number of different algorithms were considered candidates for this standard. The National Institute of Standards and Engineering (NIST) selected the Rijndael algorithm for the AES. You can detect boosted data on AES and its specifications at http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf.

Encryption Algorithms

Some popular encryption algorithms (many of which were AES candidates) are:

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Rijndael (AES standard)

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DES and 3DES

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SAFER

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Idea

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DEAL

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Bandage-256

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MARS

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Blowfish and Twofish

Other encryption algorithms include SERPENT, RC4/RC5/RC6, LOKI-97, FROG, and Hasty Pudding.

Signature Algorithms

Signature algorithms are used to create digital signatures. A digital signature is merely a means of "signing" information (as described before in the section "Disproportionate Encryption") to cosign that the bulletin sender is really the person he or she claims to be. Digital signatures can as well provide for information integrity forth with authentication and nonrepudiation. Digital signatures have become important in a world where many business organization transactions, including contractual agreements, are conducted over the Net. Digital signatures generally utilise both signature algorithms and hash algorithms.

When a message is encrypted with a user'south individual key, the hash value that is created becomes the signature for that message. Signing a different bulletin will produce a different signature. Each signature is unique, and any attempt to move the signature from one message to some other would result in a hash value that would not match the original; thus, the signature would be invalidated.

Hashing Algorithms

Hashing is a technique in which an algorithm (likewise called a hash function) is applied to a portion of data to create a unique digital "fingerprint" that is a fixed-size variable. If anyone changes the data by then much as one binary digit, the hash office will produce a different output (called the hash value) and the recipient volition know that the data has been changed. Hashing can ensure integrity and provide authentication also.

The hash function cannot exist "reverse-engineered"; that is, y'all can't use the hash value to discover the original data that was hashed. Thus, hashing algorithms are referred to as one-way hashes. A adept hash function volition not return the same result from two different inputs (called a collision); each result should exist unique.

In that location are several different types of hashing, including division-rest, digit rearrangement, folding, and radix transformation. These classifications refer to the mathematical procedure used to obtain the hash value. Standard hashing algorithms include:

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MD2, MD4, and MD5 These methods apply a message digest (the hash value) that is 128 bits in length. They were created by Ron Rivest and are popularly used for digital signatures.

▪

Secure Hash Algorithm (SHA) There are several variations on this algorithm, including SHA1, SHA256, SHA384, and SHA512. The differences between them lie in the length of the hash value. SHA was created by a cooperative effort of two U.S. regime agencies, NIST and the National Security Association (NSA).

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Security Protocols and Algorithms

Timothy Stapko , in Applied Embedded Security, 2008

Cryptography and Protocols

Most of the fourth dimension, cryptographic algorithms are non used on their own, but rather as role of a complete security system or protocol. Indeed, as was mentioned earlier, RSA is pretty much always used with some symmetric algorithm as a key exchange machinery. Security protocols are designed to address specific bug in communications. Many protocols are designed to exist used for a item application, such every bit the Secure Trounce (SSH) protocol, which is designed to provide a remote text-based console, like Telnet only secure. * Some protocols are designed to be a full general purpose solution, encrypting everything that is sent between 2 machines on a network. Examples of this type of protocol include SSL and IPSEC.

When choosing a protocol for an application, yous have to wait at not merely the features that the protocol provides, only besides how the protocol has proven itself in the field. SSL version ii (the first publicly available version, implemented as function of the Netscape web browser) seemed to be secure, but was afterwards shown to exist fatally flawed. The replacement, SSL version three, has been in use for nigh a decade now, and seems to work pretty well. You besides need to look at who designed the protocol—was information technology "design by commission" or were there some security experts and cryptographers involved? A recent case of why yous need to inquiry a protocol before using it is the case of the Wired-Equivalent Protocol (WEP), used by the Wi-Fi protocol suite to provide basic security for wireless transmissions. The protocol was designed past a committee that did non include the advisable experts, and once the protocol went public, it did not take very long for some existent experts to bear witness that the protocol was fatally flawed. Having learned their lesson, the committee used some real experts and cryptographers to implement the replacement, called WPA.

Implementing a security protocol tin be a bit tricky, since there are a lot of places where yous can become wrong. Probably the all-time defense against improperly implementing a security protocol is to strictly follow good software engineering practices. You lot should likewise look into hiring a existent security or cryptography proficient as a consultant—an expert volition know exactly where the weak points of an implementation are and assist you lot to set up them. The other trouble is that a security breach is unrelated to the protocol, residing in some other office of the system entirely. This means you can easily fall into the trap of believing that your arrangement is secure since you used a secure protocol, but neglecting the balance of the awarding can make all your efforts with the protocol meaningless. In the next chapter, we are going to look at some means that we can implement a secure embedded application through the use of adept programming practices.

When looking to a protocol for an embedded application, one property to look for is flexibility. An example we volition look at later is SSL, a protocol that you tin get away with only implementing substantially one-half of for a large savings in code. SSL also allows the implementer to cull what cryptographic algorithms to support. You lot tin can cull algorithms that are more suited to an embedded environment and leave out those that may non be equally attractive. We will not get into the details of the flexibility of SSL right at present, as Chapter 4 is dedicated to that particular protocol and how useful it can be.

The reason flexibility is important in a protocol is that security protocols (with good reason) are designed with security in listen first, and resources second. Plainly, a protocol that is extremely secure but takes forever to run volition not always exist used, but near protocol designers today are working with nearly unlimited resources when compared to economic system-priced embedded hardware. Their focus has been on the "large atomic number 26" market—PCs and mainframe communications where plenty of system resources are available. If nosotros were to implement all the features of some protocols, the resulting code could be into the megabyte-plus range. For a target system with around one megabyte total space (code and data combined), this is patently a problem. We need to be able to implement only what we need and null we don't—only nosotros don't want to remove anything of import. In afterwards capacity, we will look at some ways to do exactly that past picking apart protocols and finding what information technology is that we really need.

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Cryptography

In Hack Proofing Your Network (Second Edition), 2002

Learning about Standard Cryptographic Algorithms

The reason why and so many cryptographic algorithms are available for your employ is that each algorithm has its own relative speed, security and ease of use. You need to know enough near the most mutual algorithms to cull one that is appropriate to the situation to which it will be practical.

Data Encryption Standard (DES) is the oldest and almost widely known modern encryption method around. Withal, it is nearing the end of its useful life span, so you should avoid using it in new implementations or for data you desire to go on highly secure.

Advanced Encryption Standard (AES) was designed as a secure replacement for DES, and you tin can use several different keysizes with it.

Be aware that asymmetric cryptography uses entirely unlike principles than symmetric cryptography. Where symmetric cryptography combines a unmarried cardinal with the message for a number of cycles, asymmetric cryptography relies on numbers that are as well large to exist factored.

The two virtually widely used asymmetric algorithms are Diffie-Hellman and RSA.

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Computer Forensics in Today's World

In The Official CHFI Study Guide (Exam 312-49), 2007

Collection: Data Recovery, Evidence Collection

Finding the bear witness, discovering relevant data, preparing an Order of Volatility, eradicating external avenues of alteration, gathering the prove, and preparing a chain of custody are the recommended CHFI processes for collecting data. After you collect data, you should create an MD5 hash of the show. Prior to collection, one should practise preliminary assessment to search for the testify. After the cess is concluded, collect and seize the equipment used in committing the crime, certificate the items collected, such every bit floppy disks, thumb drives, CDs, DVDs, and external back upwardly drives. A photo of the crime scene should be taken earlier removing the prove.

Damage & Defence…

Hashes

Hashes use cryptographic algorithms to create a bulletin digest of the data and represent it as a relatively pocket-size slice of data. The hash can exist used to compare a hash of the original data to the forensic re-create. When the hashes match, it is accustomed as proof that the data is an exact re-create. Although it has not been challenged nevertheless, the traditional hashes of CRC, MD5, and SHA1 have been cracked. Too, there are limitations in the sheer book of 128 flake hashing algorithms such equally MD5. At that place are merely 2 128 possible MD5 hashes. If the large multi-terabyte file server being analyzed stores two128 + i files, there absolutely will be 2 different files with unique information with the aforementioned hash. Now it is understood that 2128 is about 340 billion, and it would be an extremely large storage assortment of tiny files, but this fact opens the door for uncertainty, which could ruin a criminal prosecution. Although 2128 is still a huge number, as storage grows, information technology is not unrealistic to believe that 128 bit hashes volition get an increasing issue. It will probably be an upshot on large storage systems long before it becomes as big an event on single workstations. The future appears to be the use of the SHA-256 algorithm and other 256 bit hashes. For now, the National Software Reference Library Hashes use the SHA-1 and MD5 algorithms.

Afterwards collecting all the data, the investigator tin then listing the steps that can be taken during the investigation and then begin. Caution, it is not necessary to seize the entire organisation. Place the relevant information and copy that, otherwise it can result in over collection.

Head of the Course…

Suggested Tool Kit Contents

Your tool kit should comprise the following components:

Hardware Target difficult drives, write blocker, and cables (network, IDE, and SCSI)

Software Boot disks and drivers for both your forensic organization and any system you may encounter, specially for network cards

Tools Allen keys; big and small screwdrivers (standard, Phillips, and Torx)

Other content Labels, anti-static bags, pens and markers, bare media: (CDs, DVDs), and a camera

Test Day Tip

Sterilize all the media to be used in the examination process, enter the crime scene, take a snap shot of the scene so carefully browse the information sources, Retain and document the state and integrity of items at the offense scene so transport the evidence to the forensic facility

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Securing the Cloud: Information Security

Vic (J.R.) Winkler , in Securing the Deject, 2011

Common Mistakes or Errors with Information Encryption

Cryptography has become pervasive and broadly accessible for even the boilerplate calculator users to secure their digital files on local or remote storage, as well every bit for communication. But as commonly available every bit cryptography is, it is as well often either non used when it should be or it is implemented or used in insecure or ineffective ways. The most obvious case of the ineffective use of cryptography might well exist using cryptography to achieve secure communications and authentication with an Internet service, only to exercise so from a PC that is hopelessly out-of-engagement in security patches or that harbors spyware and is otherwise compromised. In such a case, the dedicated utilise of stiff cryptography from this platform amounts to affixing a banking concern vault door on a cardboard box.

Given the rigor and thought invested by cryptographers when creating and verifying a cryptographic algorithm or implementation, ane marvels at the number of errors and failures that take been reported over the years. What are the causes behind these? The most common mistakes or errors include:

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Failing to use cryptography when cryptographic security is a viable selection. Almost likely, all payloads should be encrypted by default.

•

Failing to use cryptographically secured protocols when you accept a pick. Using FTP, telnet, or HTTP rather than a secured version of these plaintext protocols is simply negligent. Network bundle sniffing is a pastime on many machines that take role in sending packets dorsum and along betwixt your laptop and a cloud-based service. Although these protocols should have been retired long ago, they are notwithstanding common and being available they are used. No deject implementation should allow these, and they should probably all be blocked every bit services.

•

Believing that you are a cryptographer, or inventing your own algorithm (when you shouldn't).

•

Thinking you can implement an existing cryptographic algorithm (when you lot shouldn't). Instead of reinventing the wheel, use a proven implementation.

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Embedding a password or plaintext hugger-mugger key in a binary, configuration, or hugger-mugger file (such as a dotted subconscious file in UNIX). Although this may seem to enable automation of functions or scripting, it often leads to exposure of undercover keys or the disability to modify such keys. In the instance of storing secret keys in binaries, this exposes keys in unanticipated ways including in bandy and crash (core) files. (It's 2 AM, practise y'all know where your keys are?) Withal, bootstrapping encryption betwixt such systems is frequently necessary to deeply identify a system that interoperates in a trust relationship with other systems.

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Storing keys with information. This error is so profoundly egregious, one would wait not to need mentioning information technology except (sadly) at that place are reports that it happens fourth dimension and time again.

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The bus exam. If critical keys for the system are kept by merely ane or a few individuals, how volition your organization recover if these individuals suffer a disaster such as being striking by a bus?

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Sending sensitive data in unencrypted email. Sending passwords, PINs, or other account information in unencrypted email exposes that data in multiple places.

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Side-Aqueduct Attacks

Swarup Bhunia , Mark Tehranipoor , in Hardware Security, 2019

8.3.4 Power Side-Channel Set on Countermeasures

In guild to remove dependency between power consumption and intermediate values of the executed cryptographic algorithm, the cryptographic hardware can be implemented with secure archaic logic cells (such every bit sense-amplified-based logic (SABL) [19], wave dynamic differential logic (WDDL) [20], and t-individual logic excursion [21]) at the design stage. These secure logic styles use unlike methods to make the power consumption of the performed operation independent of the candy information values, thus preventing leakage of hugger-mugger data (i.eastward., key) in power traces. SABL and WDDL consume equal amounts of power in each clock cycle, but t-private logic circuit randomizes amounts of power consumption in each clock wheel past masking each fleck with t random bits. In other words, SABL and WDDL implement the hiding countermeasure, and t-individual logic circuit implements the masking countermeasure.

Whereas all these secure cells have varying level of robustness against SCAs, merely t-individual logic circuit prevents the probing attack, which allows an antagonist to observe simply t-limited number of internal nodes per each clock cycle. In terms of their implementation, t-private logic circuit and WDDL are implemented with the general CMOS digital jail cell library, merely each SABL cell should be full-customized. Of these secure logic blueprint styles, t-private has the largest circuit area, but the power consumption of t-private logic circuit is the smallest. Since SABL and WDDL accept ii-stage (the pre-charge phase and the evaluation phase), during each clock bicycle in which phase signals are switched, the power consumptions of SABL and WDDL are larger than that of t-private logic circuit. Table 8.1 shows the summary of these secure logic styles.

Table 8.1. Secure logic style

SABL WDDL t-individual logic
SCA resistance ✓ ✓ ✓
Probing resistance ✕ ✕ ✓
Method Hiding Hiding Random masking
Blueprint Full custom Semicustom Semicustom
Area Medium Low High
Ability Medium High Depression

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