Classified along three independent dimensions:
The type of operations used for transforming plaintext to ciphertext
The number of keys used
symmetric (single key)
asymmetric (two-keys, or public-key encryption)
The way in which the plaintext is processed
Ebook "Network security technologies" presents key security technologies from diverse fields, using a hierarchical framework that enables understanding of security components, how they relate to one another, and how they interwork. This text is unique in that it classifies technologies as basic, enhanced, integrated, and architectural as a means of associating their functional complexities, providing added insight into their interrelationships. It introduces and details security components and their relationships to each other.
Các kiểu thao tác đầu tiên được đề nghị (ECB, CBC, OFB, CFB) đảm bảo tính bí mật (confidentiality), không giúp đảm bảo tính toàn vẹn thông tin (message integrity). Các kiểu thao tác được thiết kế cho phép (CCM, EAX và OCB) vừa đảm bảo tính bí mật, vừa đảm bảo xác định tính toàn vẹn thông tin.
Up to this point we have seen:
These systems have focused on issues of confidentiality: Ensuring that an adversary cannot infer the original plaintext message, or cannot learn any information about the original plaintext from the ciphertext.
In today’s lecture we will put a more formal framework around the notion of what information is, and use this to provide a definition of security from an information-theoretic point of view.
MM, Inc. strongly discourages the storage of large numbers of e-mail messages for a number of
reasons. First, because e-mail messages frequently contain company confidential information, it is
good to limit the number of such messages to protect the company’s information. Second, retention of
messages fills up large amounts of storage space on the e-mail server and personal hard disks, and can
slow down the performance of both the network and individual personal computers.