The best replacement for ssh key is pgp key.

The best alternatives to ssh key are rated as following:
★★★★★  pgp key
★★★★  ssl certificate
★★★  gpg key

Your alternative for ssh key is not listed? Suggest!
Speaking about ssh key, one probably shouldn't forget about putty.

Other search terms related to ssh key and their ratings are:
★★★★★ putty
★★★ github
★ sftp
You have in mind a companion for ssh key and it is not yet here? Propose!



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Scale is based on the average worldwide traffic of ssh key in all years. Click on graph for more.
ssh key
pgp key
ssl certificate