Which of the following describes the primary difference between PGP and S/MIME? (Select the best answer.)
- PGP can be used to encrypt disk drives, but S/MIME cannot.
- PGP can use SHA1 for data integrity, but S/MIME cannot.
- S/MIME can be used to encrypt email messages, but PGP cannot.
- S/MIME can use RSA for digital signatures, but PGP cannot.
The primary difference between Pretty Good Privacy (PGP) and Secure/Multipurpose Internet Mail Extensions (S/MIME) is that PGP can be used to encrypt not only email messages, but also files and entire disk drives. PGP is software that uses an asymmetric encryption method to encrypt information. To encrypt a file or a message by using PGP, you must use the recipient’s public key. The recipient will then use his or her private key to decrypt the file or message.
Although PGP is an application and S/MIME is a standardsbased protocol, both can be used to provide confidentiality, integrity, and nonrepudiation for email messages. Confidentiality is provided by an encryption method, such as Triple Data Encryption Standard (3DES or TDES). Integrity is provided by a hashing algorithm, such as Secure Hash Algorithm 1 (SHA1). Nonrepudiation is provided by creating digital signatures with an asymmetric encryption method, such as RSA.
Many modern operating systems (OSs) offer their own builtin support for filelevel and disklevel encryption. Therefore, thirdparty software is often no longer necessary for encrypting files.