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Which of the following would best define a digital envelope?

Which of the following would best define a digital envelope?

PrepAway - Latest Free Exam Questions & Answers

A.
A message that is encrypted and signed with a digital certificate.

B.
A message that is signed with a secret key and encrypted with the sender’s private key.

C.
A message encrypted with a secret key attached with the message. The secret key is encrypted with the
public key of the receiver.

D.
A message that is encrypted with the recipient’s public key and signed with the sender’s private key.

Explanation:
Hybrid cryptography is the combined use of symmetric and asymmetric algorithms where the symmetric key
encrypts data and an asymmetric key encrypts the symmetric key.
A digital envelope is another term used to describe hybrid cryptography.
When a message is encrypted with a symmetric key (secret key) and the symmetric key is encrypted with an
asymmetric key, it is collectively known as a digital envelope.
Incorrect Answers:
A: A message that is encrypted and signed with a digital certificate is not the correct definition of a digital
envelope. The message would have to be encrypted with a symmetric key and the symmetric key is encrypted
with an asymmetric key to be a digital envelope. This answer does not specify what type of encryption is used.
B: A message that is signed with a secret key and encrypted with the sender’s private key is not the correct
definition of a digital envelope. A private key is an asymmetric key. In a digital envelope, the message is
encrypted with a symmetric key and the symmetric key is encrypted with an asymmetric key.
D: A message that is encrypted with the recipient’s public key and signed with the sender’s private key is not the
correct definition of a digital envelope. A public key is an asymmetric key. In a digital envelope, the message is
encrypted with a symmetric key and the symmetric key is encrypted with an asymmetric key.

Harris, Shon, All In One CISSP Exam Guide, 6th Edition, McGraw-Hill, 2013, p. 811


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