Exam 20: Symmetric Encryption and Message Confidentiality

A ________ cipher processes the input elements continuously, producing output one element at a time as it goes along.

If both sender and receiver use the same key the system is referred to asasymmetric.

It is possible to convert any block cipher into a stream cipher by usingthe cipher feedback (CFB) mode.

A ________ cipher processes the input one block of elements at a time, producing an output block for each input block.

The ciphertext-only attack is the easiest to defend against.

Public-key encryption was developed in the late ________.

For stream-oriented transmission over noisy channel you would typically use _______ mode.

A brute-force approach involves trying every possible key until anintelligible translation of the ciphertext into plaintext is obtained.

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.

"The input to the encryption algorithm is the XOR of the next 64 bits of plaintext and the preceding 64 bits of ciphertext" is a description of the ________ mode of operation.

One desirable property of a stream cipher is that the ciphertext be ofthe same length as the plaintext.

In using encryption, we need to decide what to encrypt and where theencryption gear should be located.

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

The _______ module performs end-to-end encryption and obtains session keys on behalf of users.

For general-purpose block-oriented transmission you would typically use _______ mode.

If the analyst is able to get the source system to insert into the system a message chosen by the analyst, then a ________ attack is possible.

With ______ encryption each vulnerable communications link is equipped on both ends with an encryption device.

For symmetric encryption to work the two parties to an exchange must share the same _____, which must be protected from access by others.

Symmetric encryption is also referred to as secret-key or single-keyencryption.

The most widely used encryption scheme is based on the _________ adopted in 1977 by the National Bureau of Standards.