Exercise 1: Why Key-Based Auth Beats Passwords — Possible Solution
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THE TWO ADVANTAGES, PER THIS CHAPTER
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1. "Nothing secret ever crosses the wire to be intercepted or
   brute-forced."
2. "Access is revocable per person - removing one person's public key
   from a system doesn't affect anyone else's access, unlike a shared
   password that has to be rotated for everyone the moment one person
   leaves."

WHY THE FIRST ADVANTAGE MATTERS
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With password authentication, the password itself (or a hash of it)
has to be transmitted or checked as part of the login process, which
means it's a potential target for interception or repeated guessing.
With key-based auth, the private key never leaves the user's own
machine - authentication happens via a cryptographic challenge that
proves possession of the private key without ever transmitting it,
removing that entire category of attack.

WHY THE SECOND ADVANTAGE MATTERS
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A shared password requires rotating the secret for every legitimate
user the moment access needs to be revoked from just one person -
disruptive and easy to skip. Per-key revocation means removing one
specific person's public key from authorized_keys, with zero impact on
anyone else's own access - a much more precise, low-friction way to
manage who currently has access.

WHY THIS WORKS AS AN ANSWER
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It states both advantages accurately from the chapter, and explains
the specific mechanism behind each one (no secret transmitted; precise
per-person revocation) rather than treating "more secure" as a vague,
unexplained claim.