Question

Which of the following are used to generate a message digest by the network security protocols?

(P) RSA (Q) SHA-1 (R) DES (S) MD5

1. P and R only
2. Q and R only
3. Q and S only
4. R and S only

Answer 1

Correct Answer - Option 3 : Q and S only

SHA 1 and MD5 both generate the message digest.

1. SHA 1 –SHA 1 is a cryptographic hash function that produces a 160 bit (20 byte) hash value (message digest).
2. MD5 –MD5 is a widely used cryptographic hash function that produces a 128 bit hash value (message digest).

Therefore option 3 is correct.

Important Point:

RSA and DES both are encryption algorithms.

• RSA is also used to decrypt the encrypted message by same RSA algorithm.
• Data encryption standard (DES) is a block cipher that encrypts data in blocks of size 64 bits each. That is 64 bits of plain text goes input to the DES which produces 64 bit of cipher text. Key length is 56 bits.
• RSA and SHA- 1 do not allow generating message digests.