Skip to main content

Cryptography


Cryptographic systems are characterized in three independent dimensions:
  1. The type of operations used for transforming plaintext to ciphertext. All encryption algorithms are based on two general principles: substitution, in which each element in the plaintext (bit, letter, group of bits or letters) is mapped into another element, and transposition, in which elements in the plaintext are realign. The fundamental requirement is that no information be lost (i.e., that all operations are reversible). Maximum systems, referred to as product systems, involve multiple stages of substitutions and transpositions.
  2. The number of keys used. If sender and receiver use the same key, the system is referred to as symmetric, single-key, secret-key, or conventional encryption. If the sender and receiver use different keys, the system is referred to as asymmetric, two-key, or public-key encryption.
  3. The way in which the plaintext is processed. A block cipher processes the input one block of elements at a time, producing an output block for each input block. A stream cipher processes the input elements continuously, producing output one element at a time, as it goes along.
Labels:

Comments

Post a Comment

Popular Post

Procurement Management Using Buyer's Internal Market Place

Improvements to procurement have been attempted for decades, usually by using information technologies. The real opportunity for improvement lies in the use of e-procurement, the electronic acquisition of goods and services for organisations. The general e-procurement process (with the exception of tendering) is shown in figure 2.8 .  One effective solution to the procurement problem in large organisations is to aggregate the catalogues of all approved suppliers, combining them into a single internal electronic catalogue. Prices can be negotiated in advance or determined by a tendering, so that the buyers do not have to negotiate each time they place an order. By aggregating the suppliers' catalogues on the buyer's server, it is also easier to centralise and control all procurement. Such an aggregation of catalogues is called an internal procurement marketplace .  Benefits of Internal Marketplaces   1) Corporate buyers can use search engines to look through internal aggre...
Post a Comment
Read more

Infrastructure for EC

Introduction The e-commerce infrastructure is defined here as the supporting capabilities for online trading between multiple companies which include hardware, software, networks, online payment technologies, security and encryption technologies, online trading business models, legal and regulatory framework, and managerial and organisation capabilities.  Infrastructure is the shared human, informational , and technical resources on which the work system relies in order to operate, even though these resources exist and are managed outside of the work system.  To evaluate the interdisciplinary aspects of construction e-commerce infrastructure, one proposes using a four pillar approach. Figure 5.1 illustrates the skeleton for the proposed integrated construction e-commerce infrastructure. The proposed integrated e-business infrastructure can be broken down into the following four groups of components:  1) Technological Infrastructure : Technology infrastructure is a work...
1 comment
Read more

What is COVID-19 ?

COVID-19 is a disease caused due to the infection of novel coronavirus. The first case of COVID-19 disease was founded at Wuhan, China in December 2019. It also named as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). COVID-19 is the most widely spread disease ever in the world. In most cases it infects the respiratory system that causes fever, dry cough, and shortness of breath. Previous : What is the difference between coronavirus and COVID-19 ?
Post a Comment
Read more