Exam 2: Symmetric Encryption and Message Confidentiality

Three broad categories of cryptographic algorithms are commonly used to create PRNGs: Asymmetric ciphers, Hash functions and message authentication codes, and ___________ .

A _________ cipher processes the plaintext input in fixed sized blocks and produces a block of ciphertext of equal size for each plaintext block.

The process of attempting to discover the plaintext or key is known as _________ .

The Feistel structure is a particular example of the more general structure used by all symmetric block ciphers.

The ciphertext-only attack is the easiest to defend against because the opponent has the least amount of information to work with.

Ciphertext is the scrambled message produced as output.

The essence of a symmetric block cipher is that a single round offers inadequate security but that multiple rounds offer increasing security.

With the use of symmetric encryption, the principal security problem is maintaining the secrecy of the _________ .

AES uses a Feistel structure.

Smaller block sizes mean greater security but reduced encryption/decryption speed.

Also referred to as conventional encryption, secret-key, or single-key encryption, _________ encryption was the only type of encryption in use prior to the development of public-key encryption in the late 1970's.

The most commonly used symmetric encryption algorithms are stream ciphers.

An encryption scheme is __________ if the cost of breaking the cipher exceeds the value of the encrypted information and/or the time required to break the cipher exceeds the useful lifetime of the information.

All encryption algorithms are based on two general principles: _________, in which each element in the plaintext is mapped into another element, and transposition, in which elements in the plaintext are rearranged.

Two requirements for secure use of symmetric encryption are: sender and receiver must have obtained copies of the secret key in a secure fashion and a strong __________ is needed.

In the _________ mode the input to the encryption algorithm is the XOR of the current plaintext block and the preceeding ciphertext block; the same key is used for each block.

The advantage of a block cipher is that you can reuse keys.

__________ is a stream cipher used in the Secure Sockets Layer/Transport Layer Security standards that have been defined for communication between Web browsers and servers and is also used in WEP and WPA protocols.

Public-key encryption is also referred to as conventional encryption, secret-key, or single-key encryption.

Triple DES was first standardized for use in financial applications in ANSI standard X9.17 in 1985.