Which of the following two cryptography methods are used by NTFS Encrypting File System (EFS) to encrypt the data stored on a disk on a file-by-file basis?

Question

Options

• ATwofish
• BDigital certificates
• CPublic key
• DRSA

• A
  12% (6)
• B
  83% (43)
• D
  6% (3)

Explanation

EFS encrypts each file with a randomly generated symmetric File Encryption Key (FEK), which is then protected using the user's public key (asymmetric encryption) derived from their digital certificate - making B and C the two correct methods that work in tandem.

Why the distractors are wrong:

• A. Twofish - EFS uses AES (or 3DES in older Windows versions) as its symmetric cipher, not Twofish.
• D. RSA - RSA is a specific public key algorithm, not the method category itself; the question targets the broader cryptographic method ("public key"), and EFS also supports ECC-based certificates, so RSA isn't universally correct.

Memory tip: Think of EFS as a "locked box inside a safe" - the file is locked with a symmetric key (the box), and that key is then secured inside the safe using your public key certificate. No certificate = no access, which is why losing your EFS certificate means permanently losing your data.

No community discussion yet for this question.