What determines the strength of a secret key within a symmetric key cryptosystem?

A. A combination of key length, degree of permutation, and the complexity of the data- encryption algorithm that uses the key

B. A combination of key length, initial input vectors, and the complexity of the data- encryption algorithm that uses the key

C. A combination of key length and the complexity of the data-encryption algorithm that uses the key

D. Initial input vectors and the complexity of the data-encryption algorithm that uses the key

Explanation:

The strength of a secret key within a symmetric key cryptosystem is determined by a combination of key length, initial input vectors, and the complexity of the data-encryption algorithm that uses the key.