Cryptography and Network Security PDF - Eighth Edition

Cryptograph y and Network Security Eighth Edition by Wil...

Cryptograph y and Network Security Eighth Edition by William Stallings © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Chapter 1 Information and Network Security Concepts © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Cybersecurity Cybersecurity is the collection of tools, policies, security concepts, security safeguards, guidelines, risk management approaches, actions, training, best practices, assurance, and technologies that can be used to protect the cyberspace environment and organization and users’ assets. Organization and users’ assets include connected computing devices, personnel, infrastructure, applications, services, telecommunications systems, and the totality of transmitted and/or stored information in the cyberspace environment. Cybersecurity strives to ensure the attainment and maintenance of the security properties of the organization and users’ assets against relevant security risks in the cyberspace environment. The general security objectives comprise the following: availability; integrity, which may include data authenticity and nonrepudiation; and confidentiality © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Cybersecurity Information Security Network Security This term refers to This term refers to preservation of protection of networks confidentiality, integrity, and their service from and availability of unauthorized information. In addition, modification, destruction, other properties, such as or disclosure, and authenticity, provision of assurance accountability, that the network performs nonrepudiation, and its critical functions reliability can also be correctly and there are no involved harmful side effects © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Security Objectives The cybersecurity definition introduces three key objectives that are at the heart of information and network security: Confidentiality: This term covers two related concepts: Data confidentiality: Assures that private or confidential information is not made available or disclosed to unauthorized individuals Privacy: Assures that individuals control or influence what information related to them may be collected and stored and by whom and to whom that information may be disclosed © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Security Objectives Integrity: This term covers two related concepts: Data integrity: Assures that data and programs are changed only in a specified and authorized manner. This concept also encompasses data authenticity, which means that a digital object is indeed what it claims to be or what it is claimed to be, and nonrepudiation, which is assurance that the sender of information is provided with proof of delivery and the recipient is provided with proof of the sender’s identity, so neither can later deny having processed the information System integrity: Assures that a system performs its intended function in an unimpaired manner, free from deliberate or inadvertent unauthorized manipulation of the system Availability: Assures that systems work promptly © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Computer Security Challenges Security is not simple Security mechanisms typically involve more than Potential attacks on the a particular algorithm or security features need to protocol be considered Procedures used to Security is essentially a provide particular battle of wits between a services are often perpetrator and the counter-intuitive designer It is necessary to decide Little benefit from security where to use the various investment is perceived security mechanisms until a security failure occurs Requires constant monitoring Strong security is often viewed as an impediment Is too often an to efficient and user- afterthought friendly operation © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  OSI Security Architecture Security Security Security attack mechanism service A processing or A process (or a Intended to communication device counter security Any action that service that incorporating attacks, and they compromises the enhances the such a process) make use of one security of security of the that is designed or more security information data processing to detect, mechanisms to owned by an systems and the prevent, or provide the organization information recover from a service transfers of an security attack organization © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Threats and Attacks © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Security Attacks A means of classifying security attacks, used both in X.800 and RFC 4949, is in terms of passive attacks and active attacks A passive attack attempts to learn or make use of information from the system but does not affect system resources An active attack attempts to alter system resources or affect their operation © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Passive Attacks Are in the nature of eavesdropping on, or monitoring of, transmissions Two types of passive Goal of the opponent is to obtain information attacks are: that is being The release of transmitted message contents Traffic analysis © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Active Attacks Involve some modification Takes place when one entity of the data stream or the Masquerad pretends to be a different entity creation of a false stream e Usually includes one of the other forms of active attack Difficult to prevent because of the wide variety of Involves the passive capture of potential physical, a data unit and its subsequent Replay retransmission to produce an software, and network unauthorized effect vulnerabilities Some portion of a legitimate Goal is to detect attacks Data message is altered, or and to recover from any Modificatio messages are delayed or disruption or delays caused reordered to produce an n unauthorized effect by them Prevents or inhibits the normal Denial of use or management of service communications facilities © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Authentication Concerned with assuring that a communication is authentic In the case of a single message, assures the recipient that the message is from the source that it claims to be from In the case of ongoing interaction, assures the two entities are authentic and that the connection is not interfered with in such a way that a third party can masquerade as one of the two legitimate parties Two specific authentication services are defined in X.800: Peer entity authentication Data origin authentication © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Authentication Peer entity authentication Provides for the corroboration of the identity of a peer entity in an association. Two entities are considered peers if they implement the same protocol in different systems. Peer entity authentication is provided for use at the establishment of, or at times during the data transfer phase of, a connection. It attempts to provide confidence that an entity is not performing either a masquerade or an unauthorized replay of a previous connection Data origin authentication Provides for the corroboration of the source of a data unit. It does not provide protection against the duplication or modification of data units. This type of service supports applications like electronic mail, where there are no ongoing interactions between the communicating entities © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Access Control The ability to limit and control the access to host systems and applications via communications links To achieve this, each entity trying to gain access must first be indentified, or authenticated, so that access rights can be tailored to the individual © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Data Confidentiality The protection of transmitted data from passive attacks Broadest service protects all user data transmitted between two users over a period of time Narrower forms of service includes the protection of a single message or even specific fields within a message The protection of traffic flow from analysis This requires that an attacker not be able to observe the source and destination, frequency, length, or other characteristics of the traffic on a communications facility © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Data Integrity Can apply to a stream of messages, a single message, or selected fields within a message Connection-oriented integrity service, one that deals with a stream of messages, assures that messages are received as sent with no duplication, insertion, modification, reordering, or replays A connectionless integrity service, one that deals with individual messages without regard to any larger context, generally provides protection against message modification only © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Nonrepudiation Prevents either sender or receiver from denying a transmitted message When a message is sent, the receiver can prove that the alleged sender in fact sent the message When a message is received, the sender can prove that the alleged receiver in fact received the message © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Availability Service Protects a system to ensure its availability This service addresses the security concerns raised by denial-of-service attacks It depends on proper management and control of system resources and thus depends on access control service and other security services © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Security Mechanisms Cryptographic algorithms: We can distinguish between reversible cryptographic mechanisms and irreversible cryptographic mechanisms. A reversible cryptographic mechanism is simply an encryption algorithm that allows data to be encrypted and subsequently decrypted. Irreversible cryptographic mechanisms include hash algorithms and message authentication codes, which are used in digital signature and message authentication applications. Data integrity: This category covers a variety of mechanisms used to assure the integrity of a data unit or stream of data units. Digital signature: Data appended to, or a cryptographic transformation of, a data unit that allows a recipient of the data unit to prove the source and integrity of the data unit and protect against forgery. Authentication exchange: A mechanism intended to ensure the identity of an entity by means of information exchange. Traffic padding: The insertion of bits into gaps in a data stream to frustrate traffic analysis attempts. Routing control: Enables selection of particular physically or logically secure routes for certain data and allows routing changes, especially when a breach of security is suspected. Notarization: The use of a trusted third party to assure certain properties of a data exchange Access control: A variety of mechanisms that enforce access rights to resources. © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Keyless Algorithms Deterministic functions that have certain properties useful for cryptography One type of keyless algorithm is the cryptographic hash function A hash function turns a variable amount of text into a small, fixed-length value called a hash value, hash code, or digest A cryptographic hash function is one that has additional properties that make it useful as part of another cryptographic algorithm, such as a message authentication code or a digital signature A pseudorandom number generator produces a deterministic sequence of numbers or bits that has the appearance of being a truly random sequence © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Single-Key Algorithms Encryption algorithms that Symmetric Single-key encryption takes cryptographic use a single key are referred to as the following algorithms forms: depend on the symmetric use of a secret encryption key algorithms Block cipher A block cipher operates With symmetric encryption, on data as a sequence of an encryption algorithm blocks takes as input some data to In most versions of the be protected and a secret block cipher, known as key and produces an modes of operation, the unintelligible transformation transformation depends on that data not only on the current data block and the secret key but also on the A corresponding content of preceding decryption algorithm blocks takes the transformed data and the same secret Stream cipher key and recovers the A stream cipher operates on original data data as a sequence of bits As with the block cipher, the transformation depends on a secret key © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Single-Key Algorithms Another form of single-key cryptographic algorithm is the message authentication code (MAC) A MAC is a data element associated with a data block or message The MAC is generated by a cryptographic transformation involving a secret key and, typically, a cryptographic hash function of the message The MAC is designed so that someone in possession of the secret key can verify the integrity of the message The recipient of the message plus the MAC can perform the same calculation on the message; if the calculated MAC matches the MAC accompanying the message, this provides assurance that the message has not been altered © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Asymmetric Algorithms Encryption algorithms that use a single key are referred to as asymmetric encryption algorithms Digital signature algorithm A digital signature is a value computed with a cryptographic algorithm and associated with a data object in such a way that any recipient of the data can use the signature to verify the data’s origin and integrity Key exchange The process of securely distributing a symmetric key to two or more parties User authentication The process of authenticating that a user attempting to access an application or service is genuine and, similarly, that the application or service is genuine © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Communications Security Deals with the protection of communications through the network, including measures to protect against both passive and active attacks Communications security is primarily implemented using network protocols A network protocol consists of the format and procedures that governs the transmitting and receiving of data between points in a network A protocol defines the structure of the individual data units and the control commands that manage the data transfer With respect to network security, a security protocol may be an enhancement that is part of an existing protocol or a standalone protocol © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Device Security The other aspect of network security is the protection of network devices, such as routers and switches, and end systems connected to the network, such as client systems and servers The primary security concerns are intruders that gain access to the system to perform unauthorized actions, insert malicious software (malware), or overwhelm system resources to diminish availability Three types of device security are: Firewall A hardware and/or software capability that limits access between a network and device attached to the network, in accordance with a specific security policy. The firewall acts as a filter that permits or denies data traffic, both incoming and outgoing, based on a set of rules based on traffic content and/or traffic pattern Intrusion detection Hardware or software products that gather and analyze information from various areas within a computer or a network for the purpose of finding, and providing real-time or near- real-time warning of, attempts to access system resources in an unauthorized manner Intrusion prevention Hardware or software products designed to detect intrusive activity and attempt to stop the activity, ideally before it reaches its target © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Trust Model One of the most widely accepted and most cited definitions of trust is: “the willingness of a party to be vulnerable to the actions of another party based on the expectation that the other will perform a particular action important to the trustor, irrespective of the ability to monitor or control that other party” Three related concepts are relevant to a trust model: Trustworthiness: A characteristic of an entity that reflects the degree to which that entity is deserving of trust Propensity to trust: A tendency to be willing to trust others across a broad spectrum of situations and trust targets. This suggests that every individual has some baseline level of trust that will influence the person’s willingness to rely on the words and actions of others Risk: A measure of the extent to which an entity is threatened by a potential circumstance or event, and typically a function of 1) the adverse impacts that would arise if the circumstance or event occurs; and 2) the likelihood of occurrence © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  The Trust Model and Information Security Trust is confidence Trust is always that an entity will restricted to specific perform in a way that functions or ways of will not prejudice the behavior and is security of the user meaningful only in of the system of the context of a which that entity is a security policy part In this context, the Generally, an entity term entity may refer is said to trust a to a single hardware second entity when component or the first entity software module, a assumes that the piece of equipment second entity will identified by make behave exactly as and model, a site or the first entity location, or an expects organization © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Trustworthiness of an Individual Organizations need to be concerned about both internal users (employees, on-site contractors) and external users (customers, suppliers) of their information systems With respect to internal users, an organization develops a level of trust in individuals by policies in the following two areas: Human resource security Sound security practice dictates that information security requirements be embedded into each stage of the employment life cycle, specifying security-related actions required during the induction of each individual, their ongoing management, and termination of their employment. Human resource security also includes assigning ownership of information (including responsibility for its protection) to capable individuals and obtaining confirmation of their understanding and acceptance Security awareness and training This area refers to disseminating security information to all employees, including IT staff, IT security staff, and management, as well as IT users and other employees. A workforce that has a high level of security awareness and appropriate security training for each individual’s role is as important, if not more important, than any other security countermeasure or control © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Trustworthiness of an Organization Most organizations rely on information system service and information provided by external organizations, as well as partnerships to accomplish missions and business functions (examples are cloud service providers and companies that form part of the supply chain for the organization) To manage risk to the organization, it must establish trust relationships with these external organizations NIST SP 800-39 (Managing Information Security Risk, March 2011) indicates that such trust relationships can be: Formally established, for example, by documenting the trust-related information in contracts, service-level agreements, statements of work, memoranda of agreement/understanding, or interconnection security agreements Scalable and inter-organizational or intra-organizational in nature Represented by simple (bilateral) relationships between two partners or more complex many-to-many relationships among many diverse partners © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Trustworthiness of Information Systems SP 800-39 defines trustworthiness for information systems as “the degree to which information systems (including the information technology products from which the systems are built) can be expected to preserve the confidentiality, integrity, and availability of the information being processed, stored, or transmitted by the systems across the full range of threats” Two factors affecting the trustworthiness of information systems are: Security functionality: The security features/functions employed within the system. These include cryptographic and network security technologies Security assurance: The grounds for confidence that the security functionality is effective in its application. This area is addressed by security management techniques, such as auditing and incorporating security considerations into the system development life cycle © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Establishing Trust Relationships Direct Validated Mediated Mandated historical trust: trust: trust: trust: Trust is This type of Mediated An based on trust is trust organization evidence based on the involves the establishes a obtained by security- use of a third level of trust the trusting related track party that is with another organization record mutually organization about the exhibited by trusted by based on a trusted an two parties, specific organization organization with the mandate or entity. The in the past, third party issued by a information particularly providing third party in may include in assurance or a position of information interactions guarantee of authority security with the a given level policy, organization of trust security seeking to between the measures, establish first two and level of trust parties oversight © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Standards National Institute of Standards and Technology: NIST is a U.S. federal agency that deals with measurement science, standards, and technology related to U.S. government use and to the promotion of U.S. private-sector innovation. Despite its national scope, NIST Federal Information Processing Standards (FIPS) and Special Publications (SP) have a worldwide impact Internet Society: ISOC is a professional membership society with worldwide organizational and individual membership. It provides leadership in addressing issues that confront the future of the Internet and is the organization home for the groups responsible for Internet infrastructure standards, including the Internet Engineering Task Force (IETF) and the Internet Architecture Board (IAB). These organizations develop Internet standards and related specifications, all of which are published as Requests for Comments (RFCs). ITU-T: The International Telecommunication Union (ITU) is an international organization within the United Nations System in which governments and the private sector coordinate global telecom networks and services. The ITU Telecommunication Standardization Sector (ITU-T) is one of the three sectors of the ITU. ITU-T’s mission is the development of technical standards covering all fields of telecommunications. ITU-T standards are referred to as Recommendations ISO: The International Organization for Standardization (ISO) is a worldwide federation of national standards bodies from more than 140 countries, one from each country. ISO is a nongovernmental organization that promotes the development of standardization and related activities with a view to facilitating the international exchange of goods and services and to developing cooperation in the spheres of intellectual, scientific, technological, and economic activity. ISO’s work results in international agreements that are published as International Standards © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved  Summary Describe the key Provide an overview security requirements of the main areas of of confidentiality, network security integrity, and availability Describe a trust List and briefly model for information describe key security organizations involved in cryptography Discuss the types of standards security threats and attacks that must be Provide an overview of dealt with and give keyless, single-key and examples of the types two-key of threats and attacks cryptographic that apply to different algorithms categories of © 2020 Pearson Education, Inc., Hoboken, NJ. All rights reserved computer and