Which of the following is a US Federal government algorithm created to generate a secure message
digest?
A.
DSA
B.
RSA
C.
Triple DES
D.
SHA
Explanation:
SHA is a Federal government algorithm created to generate a secure message digest. The Secure
Hash Algorithm (SHA) is a cryptographic hash algorithm. It generates a fixed-length digital
representation (message digest) of an input data sequence of any length. The SHA algorithm is very
secure, as it is computationally very difficult to find a message that corresponds to a given message
digest. In this algorithm, any change to a message will result in a completely different message
digest. There are five SHA algorithms: SHA-1, SHA-224, SHA-256, SHA-384, and SHA-512.Answer A is incorrect. Digital Signature Algorithm (DSA) is a United States Federal Government
standard or FIPS for digital signatures. DSA is a public key algorithm; the secret key operates on the
message hash generated by SHA-1; to verify a signature, one recomputes the hash of the message,
uses the public key to decrypt the signature and then compares the results. The key size is variable
from 512 to 1024 bits, which is adequate for the current computing capabilities as long as a user
uses more than 768 bits.Answer B is incorrect. RSA stands for Rivest, Shamir, and Adleman. It is an algorithm for public-key
cryptography. It is the first algorithm known to be suitable for signing as well as encryption, and one
of the first great advances in public key cryptography. RSA is widely used in electronic commerce
protocols, and is believed to be secure given sufficiently long keys and the use of up-to-date
implementations.Answer C is incorrect. Triple DES is the common name for the Triple Data Encryption Algorithm
(TDEA). It is so named because it applies the Data Encryption Standard (DES) cipher algorithm three
times to each data block. The Data Encryption Standard (DES) is a block cipher (a form of shared
secret encryption), which is based on a symmetric-key algorithm that uses a 56-bit key. The
algorithm was initially controversial with classified design elements, a relatively short key length, and
suspicions about a National Security Agency (NSA) backdoor. Triple DES provides a relatively simple
method of increasing the key size of DES to protect against brute force attacks, without requiring a
completely new block cipher algorithm.