Phase 10 of docs/PLAN.md; closes AUDIT §3.6, the README's oldest lie
("Support for key rotation", with no occurrence of "rotat" in src/).
Rotation only ever adds. `rotateKey` generates a replacement under the next
name in the series — prod → prod-2 → prod-3 — and encrypts it *alongside*
the key it replaces, so both are in the vault at once. `retireKey` is a
separate operation, and the only one in keyman that destroys an encrypted
key. The gap between the two is where the new public key gets deployed and
tested: a rotation that replaces the key in one step locks you out of the
host you were rotating for, because the replacement is not on it yet and
the only copy of the one that is has gone.
The name has to change — the vault layout derives the directory from it, so
a replacement also called `prod` *is* the `prod` entry. `nextRotationName`
skips any version already taken in the vault, in tmp or in .ssh, so it
never asks ssh-keygen to overwrite a private key in use. Retirement warns
when nothing in the vault supersedes the key and then makes the user type
its name, since that deletion is unrecoverable.
Three things extracted rather than copied: `listVaultKeys` (vault.ts) now
backs decrypt, rotate and retire; `createKeyPair` and `promptKeyOptions`
(generate.ts) are shared with rotation, which also carries the old key's
comment over as the default. Verified against the real binaries that a
hyphen-suffixed name survives ssh-keygen and age, that the vault entry
round-trips byte-identically, and that ssh-keygen writes the replacement
0600 without help.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Generate prompted for the passphrase itself and passed it as `-N <value>`,
so it sat in this process's argv — readable by any user on the box through
`ps` for the length of the spawn — and in keyman's memory before that.
Verified that omitting `-N` makes ssh-keygen prompt *and* confirm, so the
prompt and the flag are both gone and the spawn inherits stdio. keyman no
longer learns the passphrase, which is strictly better than handling it more
carefully, and it deletes code.
The other half is the missing `.pub`. The selection list is built from
private keys, so an orphan is offered like any other, and copyFileSync
discovered the absent sibling only *after* age had written the encrypted
key: a vault entry with no public key, and an exception that took the rest
of the batch with it. It is now derived with `ssh-keygen -y -f`, before the
vault directory is created. Verified against real binaries that the derived
key matches the original byte for byte, that an encrypted key prompts (on
stderr — hence stdout piped, stdin and stderr inherited), and that a refused
derivation degrades to storing the private key alone rather than failing.
encrypt's loop now isolates per key and reports which ones did not make it,
except for ToolNotFoundError: age missing is not a per-key problem and nine
more identical errors help nobody.
storeInVault is the shared write path both callers had a copy of. It also
undoes its own mess: age has to write into a directory that already exists,
so a failure could leave an empty directory or a truncated .age — which list
counts as a vault entry and decrypt offers. The .age is removed because we
named it, the directory only while empty, since one holding an earlier key
is not ours to delete.
Benjamin Diedrichsen