You have been assigned the task of selecting a hash algorithm. The algorithm will be specifically
used to ensure the integrity of certain sensitive files. It must use a 128 bit hash value. Which of the
following should you use?

A.
AES

B.
SHA

C.
MD5

D.
DES

Explanation:
Message Digest 5 (MD5) uses a 128 bit hash value and is specifically used to ensure file
integrity.
Message Digest 5 (MD5) is a cryptographic hash function designed by Ron Rivest. It has a 128-bit
hash value. As an Internet standard (RFC
1321), MD5 has been employed in a wide variety of security applications, and is also commonly used
to check the integrity of files. However,
now that it is easy to generate MD5 collisions, it is possible for the person who created the file to
create a second file with the same
checksum, so this technique cannot protect against some forms of malicious tampering. In this case
MD5 can only provide error-checking
functionality. It will recognize a corrupt or incomplete download, which becomes more likely when
downloading larger files. An MD5 hash is
typically expressed as a 32 digit hexadecimal number.
Answer option B is incorrect. SHA (Secure Hash Standard) does not necessarily use a 128 bit hash
value and it is not designed specifically to
ensure file integrity (though it could be used in that fashion).