Exam 7: Block Cipher Operation

"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 __________ mode.

S-AES is the most widely used multiple encryption scheme.

Cipher Feedback (CFB) is used for the secure transmission of single values.

the__________ is a technique in which an encryption algorithm is used multiple times.

the _________ must be a data block that is unique to each execution of the encryption operation and may be a counter, a timestamp, or a message number.

the XtS-AES mode is based on the concept of a tweakable block cipher.

Format-preserving encryption refers to any encryption technique that takes a plaintext in a given format and produces a ciphertext in the same format.

the sender is the only one who needs to know an initialization vector.

__________ refers to any encryption technique that takes a plaintext in a given format and produces a ciphertext in the same format.

One of the most widely used multiple-encryption schemes is __________ .

the XtS-AES standard describes a method of decryption for data stored in sector-based devices where the threat model includes possible access to stored data by the adversary.

A __________ cipher can operate in real time and eliminates the need to pad a message to be an integral number of blocks.

In the first instance of multiple encryption plaintext is converted to __________ using the encryption algorithm.

the __________ method is ideal for a short amount of data and is the appropriate mode to use if you want to transmit a DES or AES key securely.

Both __________ produce output that is independent of both the plaintext and the ciphertext.this makes them natural candidates for stream ciphers that encrypt plaintext by XOR one full block at a time.

the output of the encryption function is fed back to the shift register in Output Feedback mode, whereas in ___________ the ciphertext unit is fed back to the shift register.

Five modes of operation have been standardized by NISt for use with symmetric block ciphers such as DES and AES: electronic codebook mode, cipher block chaining mode, cipher feedback mode, __________, and counter mode.

_________ mode is similar to Cipher Feedback, except that the input to the encryption algorithm is the preceding DES output.

__________ modes of operation have been standardized by NISt for use with symmetric block ciphers such as DES and AES.

the _________ and _________ block cipher modes of operation are used for authentication.