I tried ssh-ing to a server that uses RSA verification. I was already able to ssh to this server months back but I find out that I can't do so today.

I investigated the keys in my computer. I emailed my public key to the server's owner months back and I see that my attachment and my id_rsa.pub still matches. Next, I tried generating the public key for the private key currently in my computer.

.ssh$ ssh-keygen -y -f id_rsa > ~/Documents/public_key.txt
Enter passphrase:

Then, I diff it to the one I sent over email months back.

Documents$ diff public_key.txt attach_public_key.txt 

Upon visual inspection, it seems that the only difference is that attach_public_key.txt has my email address appended at the end. I then validate my hunch...

Documents$ cp rsa_public_key.txt noemail_public_key.txt
Documents$ vi noemail_public_key.txt # remove email add here
Documents$ diff public_key.txt noemail_public_key.txt


So, how come my private key no longer requires my email address on the matching public key? What should I do to be able to ssh to the server again? Should I tell the admin that my key was modified (isn't this alarming?) ? Or is there a way for me to tweak my local keys?

1 Answer 1


Your email address on your .pub is only a comment, and could be anything.
It's point is to help you tell multiple key's apart in you ~/.authorized_keys file, and not strictly necessary for a key to work.

I would also suggest ssh-copy-id in the future, instead of email.

  • Thanks. I guess this just calls for a follow-up question.
    – skytreader
    Jun 1, 2013 at 17:46

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