IST 451 Test 1 Review
False
All symmetric encryption schemes are block cryptography; i.e., process the plaintext one block of elements at a time.
False
If a hash function H has "one way" property; i.e., given code h it is computationally infeasible to find x such that H(x) = h; then the hash function can be used for message authentication.
Alice's private key
In a public-key cryptosystem, suppose Alice wants to create her digital signature on a message sending to Bob, which of the following key should be used by Alice?
True
The various cipher block modes of operation (e.g. ECB, CBC, CFB, etc.) are intended for being used with any symmetric block cipher, including triple DES and AES
False
A Hash function has to generate the message digest based on a secret key in order to achieve message authentication.
false
AES always uses a block length of 128 bits and a key length of 256 bits.
False
Both message authentication and message encryption functions could be implemented based on a symmetric encryption algorithm.
All of them (confidentiality, integrity, & availability)
For a database that stores student grade records, which of the following is significant security objective?
Confidentiality
For a search engine website such as Google, which one of the following is not significant as a security objective?
Integrity
For a web page that provides faculty bio information, which one of the following is the most significant security objective?
The receiver is assured that the message contents have not been released to anybody else
If the MAC generated from a received message matches the MAC received together with the message, then which one of the following is NOT true?
True
In a public-key cryptosystem, suppose Alice encrypts a message with Bob's public key, then Alice herself cannot decrypt the message anymore.
Bob's public key
In a public-key cryptosystem, suppose Alice wants to send a private message to Bob, which of the following key will Alice use to encrypt the message?
True
In a symmetric encryption scheme, the sender and receiver must obtain copies of the secret key in a secure fashion and must keep the key secure.
False
In both secret key and public key encryption structures, the decryption process follows the same algorithm but in a reverse direction.
True
In the OSI security architecture, a security service can be offered by implementing one or multiple security mechanisms.
True
It is difficult to prevent active attacks absolutely but it is possible to detect them and recover from any disruption caused by them.
True
Passive security attacks are difficult to detect but it is feasible to prevent the success of these attacks, usually by means of encryption.
True
Public-key cryptographic algorithms allow either one of the two related keys (the public-private key pair) used for encryption with the other key for decryption
False
SHA-512 is the only secure hash function suggested by the standard RFC 2104 for implementing HMAC
False
Since public-key encryption is more secure than conventional symmetric encryption, it will gradually replace the latter.
Alice's private key
Suppose Alice received a message from Bob that was encrypted using asymmetric encryption, what key should Alice use to decrypt the message?
Bob's public key
Suppose Alice received a message from Bob with his digital signature, what key should Alice use to verify the signature?
False
Symmetric encryption alone is sufficient for message authentication.
56
The DES algorithm defined in FIP 46 standard uses a key of ____ bits
56
The DES scheme defined by the FIPS 46 standard uses ____ bits key.
Can be used only for digital signature
The DSS standard from NIST uses an algorithm that ____.
Key exchange to generate a shared secret key
The Diffie-Hellmen algorithm can be used for ____ .
For both encryption/decryption and digital signature
The RSA algorithm can be used _____ .
512
The SHA-512 secure hash algorithm takes as input a message with a maximum length of up to 2^128 bits and produces a _____ -bit message digest as output.
False
The encryption/decryption algorithm of a symmetric encryption scheme must be kept secret
True
The main requirement to a pseudo random number generator used in cryptography applications is unpredictable; i.e. the successive number of the sequence cannot be determined by the current number.
False
The message digest generated from a hash function must be encrypted in order to achieve message authentication.
False
The standard HMAC function, as defined in RFC 2104, encrypts the message digest produced by a secure hash function to generate the message authentication code.
It extends the total key length by using three keys
Triple-DES makes brute-force attacks more difficult than the single-DES because ____
Diffie-Hellman algorithm
Which one of the following can NOT be used for digital signature?
Nonrepudiation
Which one of the following can only be achieved by asymmetric encryption?
CFB (Cipher Feedback) mode
Which one of the following cipher block modes can convert block cipher into a stream cipher?
RSA and Diffie-Hellmen
Which one of the following gives two most widely used public key algorithms?
Support a variable key length from 1 to 256 bytes
Which one of the following is NOT a main design objective for AES?
Protecting the confidentiality of a message
Which one of the following is NOT achieved by message authentication?
Public Key
Which one of the following is NOT an ingredient of a symmetric encryption scheme?
RC4
Which one of the following is a stream cipher algorithm?
RC4 typically can run much faster than DES and AES
Which one of the following is an advantage of RC4 algorithm over block cipher such as DES and AES?
Site-to-site VPN communication channel
Which one of the following situations would be the best environment for use of a symmetric instead of asymmetric cryptosystem?
Key distribution for public-key encryption is no simpler or more efficient than that of secret-key encryption.
Which one of the following statements about public-key and secret-key encryption is correct?