IdentityFingerprint feature request

[Daniel Kahn Gillmor]

On Tue 2018-01-09 15:58:00 -0500, Gregory Seidman wrote:
> The IdentityFile config (or -i argument) lets you insist on (or prioritize,
> at least) a particular key file on disk. The key can be retrieved from
> ssh-agent without decrypting the file on disk, but it must be found at the
> specified path. I have a use case in which keys are added to ssh-agent on a
> forwarded connection, but are not present on disk locally. There is
> currently no way to refer to a key in ssh-agent that is not also sitting on
> local disk. I propose either a new config (which I'm calling
> IdentityFingerprint) or extending the existing IdentityFile to accept the
> fingerprint (e.g. output from ssh-add -l: SHA256:...) of a key and use that
> if it's found in ssh-agent.

try storing the output of "ssh-add -L" in a file (instead of "ssh-add
-l"), and pass the name of that file in IdentityFile.  it's a two-stage
process instead of a single stage, but it should work fine.

    --dkg