Jane, a VPN administrator, was asked to implement an encryption cipher with a MINIMUM effective
security of 128-bits. Which of the following should Jane select for the tunnel encryption?

A.
Blowfish

B.
DES

C.
SHA256

D.
HMAC

Explanation:
Blowfish is an encryption system that performs a 64-bit block cipher at very fast speeds. It is a symmetric
block cipher that can use variable-length keys (from 32 bits to 448 bits). Among the alternatives listed
above, it is the only cipher that can use a 128-bit key and which does provide additional security through
a symmetric key.
Incorrect Answers:
B: DES does not provide 128 bit security. DES uses a 56-bit key.
C: The hash size for the SHA256 algorithm is 256 bits.
D: HMAC (Hash-Based Message Authentication Code) uses a hashing algorithm along with a symmetric
key. HMAC with 128 bit would provide more additional security compared to Blowfish 128 bit as HMAC
uses a symmetric key as well.

Dulaney, Emmett and Chuck Eastton, CompTIA Security+ Study Guide, 6th Edition, Sybex, Indianapolis,
2014, pp. 139, 250, 251, 255-256, 260