Keys need to be only readable by you:
chmod 400 ~/.ssh/id_rsaIf Keys need to be read-writable by you:
chmod 600 ~/.ssh/id_rsa600 appears to be fine as well (in fact better in most cases, because you don't need to change file permissions later to edit it).
man ssh:
~/.ssh/id_rsa
Contains the private key for authentication. These files contain sensitive
data and should be readable by the user but not
accessible by others (read/write/execute). ssh will simply ignore a private
key file if it is
accessible by others. It is possible to specify a
passphrase when generating the key which will be used to encrypt the sensitive
part of this file using 3DES.
~/.ssh/id_rsa.pub
Contains the public key for authentication. These files are not sensitive and
can (but need not) be readable by anyone.
