You are asked to create a new Ed25519 SSH identity for your own account, in the default file names, specifying nothing but the key type. Type the complete command.
LPIC-1 Exam 102-500, objective 110. Security easy
Machine-checked — no person has signed for it. This question was read against the source cited below by an automated pass, which found no contradiction. That is a weaker claim than it sounds: the same kind of process wrote the question, so it can confirm its own mistake.
Treat it as a good draft rather than as settled fact, and read the source below before you rely on it. It is not used in mock exams here — only questions a person has signed for are.
How these questions are written — where each question comes from, what the verification ledger records, and what happens when one is found wrong.
Answer
Type the answer.
Accepted answers
ssh-keygen -t ed25519ssh-keygen --type ed25519ssh-keygen -t Ed25519ssh-keygen -t ED25519
Case sensitive — Linux is, and grading LS as ls would teach a falsehood.
Why
ssh-keygen -t chooses the algorithm, and without -f the pair goes to the default names for that type, here ~/.ssh/id_ed25519 for the private key and ~/.ssh/id_ed25519.pub for the public one. The other types -t accepts are rsa, ecdsa and the obsolete dsa, plus the hardware-backed ed25519-sk and ecdsa-sk. -b sets the key length for rsa and selects the curve (256, 384 or 521) for ecdsa, but it is ignored for ed25519, whose size is fixed. The passphrase prompt encrypts the private key file on disk and is what ssh-agent later caches.
Where this comes from
- Cited
- manual page ssh-keygen(1)
Practise this
Reading one question is not practice. The trainer will draw a short set from objective 110 and space the ones you get wrong.
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