Exam 3: Public-Key Cryptography and Message Authentication

A __________ is when the sender "signs" a message with its private key, which is achieved by a cryptographic algorithm applied to the message or to a small block of data that is a function of the message.

The private key is known only to its owner.

In the ECB mode of encryption if an attacker reorders the blocks of ciphertext then each block will still decrypt successfully, however, the reordering may alter the meaning of the overall data sequence.

Public key algorithms are based on mathematical functions rather than on simple operations on bit patterns.

Private key encryption is used to produce digital signatures which provide an enhanced form of message authentication.

As with symmetric encryption, there are two approaches to attacking a secure hash function: brute-force attack and ___________ .

Bob uses his own private key to encrypt the message.When Alice receives the ciphertext she finds that she can decrypt it with Bob's public key, thus proving that the message must have been encrypted by Bob.No one else has Bob's private key and therefore no one else could have created a ciphertext that could be decrypted with Bob's public key.Therefore the entire encrypted message serves as a _________ .

Public key algorithms are useful in the exchange of conventional encryption keys.

Protection against active attacks (falsification of data and transactions) is known as ___________ .