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Cipher Feedback (CFB)

A mode in which the DES algorithm is used to encrypt the preceding block of cipher text. This block is then XORed with the next block of plain text to produce the next block of cipher text.

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Maturity Level Details:Maturity levels consist of a predefined set of process areas. The maturity levels are measured by the achievement of the specific and generic goals that apply to each predefined set of process areas. The following sections describe the characteristics of each maturity level in detail.Maturity Level 1 - Initial At maturity level 1, processes are usually ad hoc and chaotic. The organization usually does not provide a stable environment. Success in these organizations depends on the competence and heroics of the people in the organization and not on the use of proven processes.Maturity level 1 organizations often produce products and services that work; however, they frequently exceed the budget and schedule of their projects.Maturity level 1 organizations are characterized by a tendency to over commit, abandon processes in the time of crisis, and not be able to repeat their past successes.Maturity Level 2 - Managed At maturity level 2, an organization has achieved all the specific and generic goals of the maturity level 2 process areas. In other words, the projects of the organization have ensured that requirements are managed and that processes are planned, performed, measured, and controlled.The process discipline reflected by maturity level 2 helps to ensure that existing practices are retained during times of stress. When these practices are in place, projects are performed and managed according to their documented plans.At maturity level 2, requirements, processes, work products, and services are managed. The status of the work products and the delivery of services are visible to management at defined points.Commitments are established among relevant stakeholders and are revised as needed. Work products are reviewed with stakeholders and are controlled.The work products and services satisfy their specified requirements, standards, and objectives.Maturity Level 3 - Defined At maturity level 3, an organization has achieved all the specific and generic goals of the process areas assigned to maturity levels 2 and 3.At maturity level 3, processes are well characterized and understood, and are described in standards, procedures, tools, and methods.A critical distinction between maturity level 2 and maturity level 3 is the scope of standards, process descriptions, and procedures. At maturity level 2, the standards, process descriptions, and procedures may be quite different in each specific instance of the process (for example, on a particular project). At maturity level 3, the standards, process descriptions, and procedures for a project are tailored from the organization's set of standard processes to suit a particular project or organizational unit. The organization's set of standard processes includes the processes addressed at maturity level 2 and maturity level 3. As a result, the processes that are performed across the organization are consistent except for the differences allowed by the tailoring guidelines.Another critical distinction is that at maturity level 3, processes are typically described in more detail and more rigorously than at maturity level 2. At maturity level 3, processes are managed more proactively using an understanding of the interrelationships of the process activities and detailed measures of the process, its work products, and its services.Maturity Level 4 - Quantitatively Managed At maturity level 4, an organization has achieved all the specific goals of the process areas assigned to maturity levels 2, 3, and 4 and the generic goals assigned to maturity levels 2 and 3.At maturity level 4 Subprocesses are selected that significantly contribute to overall process performance. These selected subprocesses are controlled using statistical and other quantitative techniques.Quantitative objectives for quality and process performance are established and used as criteria in managing processes. Quantitative objectives are based on the needs of the customer, end users, organization, and process implementers. Quality and process performance are understood in statistical terms and are managed throughout the life of the processes.For these processes, detailed measures of process performance are collected and statistically analyzed. Special causes of process variation are identified and, where appropriate, the sources of special causes are corrected to prevent future occurrences.Quality and process performance measures are incorporated into the organization.s measurement repository to support fact-based decision making in the future.A critical distinction between maturity level 3 and maturity level 4 is the predictability of process performance. At maturity level 4, the performance of processes is controlled using statistical and other quantitative techniques, and is quantitatively predictable. At maturity level 3, processes are only qualitatively predictable.Maturity Level 5 - Optimizing At maturity level 5, an organization has achieved all the specific goals of the process areas assigned to maturity levels 2, 3, 4, and 5 and the generic goals assigned to maturity levels 2 and 3.Processes are continually improved based on a quantitative understanding of the common causes of variation inherent in processes.Maturity level 5 focuses on continually improving process performance through both incremental and innovative technological improvements.Quantitative process-improvement objectives for the organization are established, continually revised to reflect changing business objectives, and used as criteria in managing process improvement.The effects of deployed process improvements are measured and evaluated against the quantitative process-improvement objectives. Both the defined processes and the organization's set of standard processes are targets of measurable improvement activities.Optimizing processes that are agile and innovative depends on the participation of an empowered workforce aligned with the business values and objectives of the organization. The organization's ability to rapidly respond to changes and opportunities is enhanced by finding ways to accelerate and share learning. Improvement of the processes is inherently part of everybody's role, resulting in a cycle of continual improvement.A critical distinction between maturity level 4 and maturity level 5 is the type of process variation addressed. At maturity level 4, processes are concerned with addressing special causes of process variation and providing statistical predictability of the results. Though processes may produce predictable results, the results may be insufficient to achieve the established objectives. At maturity level 5, processes are concerned with addressing common causes of process variation and changing the process (that is, shifting the mean of the process performance) to improve process performance (while maintaining statistical predictability) to achieve the established quantitative process-improvement objectives.
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A process in which each block of unencrypted text is XORed with the block of cipher text immediately preceding it before it is encrypted using the DES algorithm.
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A mode in which the Data Encryption Standard XORs plain text with a seed value. For the first encrypted block, an initialization vector is used to create the seed value. Future seed values are derived by running the DES algorithm on the preceding seed value. The major advantage of OFB mode is that transmission errors do not propagate to affect the decryption of future blocks.
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A private key cryptosystem published by the National Institutes of Standards and Technology (NIST). DES is a symmetric block cipher with a block length of 64 bits and an effective key length of 56 bits. DES has been used commonly for data encryption in the forms of software and hardware implementation. A standard cryptosystem proposed in 1977 for all government communications. DES and 3DES were superseded by Advanced Encryption Standard (AES) in December 2001. Cryptographic algorithm, designed for the protection of unclassified data and published by the National Institute of Standards and Technology (NIST) in Federal Information Processing Standard (FIPS) Publication 46. (FIPS 463 withdrawn 19 May 2005) (. See Triple DES) and CNSS Advisory IA/0204 Revised March 2005)
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An attack in which the attacker has the ability to encrypt plain- text messages of their choosing and then analyze the cipher-text output of the encryption algorithm.
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