Rsa is a public-key cryptosystem developed by mit professors ronald l. rivest, adi shamir, and leonard m. adleman in 1977 in an effort to ensure internet security. rsa uses modular arithmetic and elementary number theory to do computations using two very large prime numbers. identify the statement which is true for rc6 algorithm:
a. is a variable key-size stream cipher with byte-oriented operations and is based on the use of a random permutation
b. includes integer multiplication and the use of four 4-bit working registers
c. is a parameterized algorithm with a variable block size, key size, and a variable number of rounds
d. is a 64 bit block cipher that uses a key length that can vary between 32 and 448 bits