Files used by the ssh-keygen utility

The ssh-keygen utility uses various files for storing public and private keys. The files used by ssh-keygen utility are as follows:

• $HOME/.ssh/identity: The $HOME/.ssh/identity file contains the RSA private key when using the SSH protocol version 1.
• $HOME/.ssh/identity.pub: The $HOME/.ssh/identity.pub file contains the RSA public key for authentication when you are using the SSH protocol version 1. A user should copy its contents in the $HOME/.ssh/authorized_keys file of the remote system where a user wants to log in using RSA authentication.
• $HOME/.ssh/id_dsa: The $HOME/.ssh/id_dsa file contains the protocol version 2 DSA authentication identity of the user.
• $HOME/.ssh/id_dsa.pub: The $HOME/.ssh/id_dsa.pub file contains the DSA public key for authentication when you are using the SSH protocol version 2. A user should copy its contents in the $HOME/.ssh/authorized_keys file of the remote system where a user wants to log in using DSA authentication.
• $HOME/.ssh/id_rsa: The $HOME/.ssh/id_rsa file contains the protocol version 2 RSA authentication identity of the user. This file should not be readable by anyone but the user.
• $HOME/.ssh/id_rsa.pub: The $HOME/.ssh/id_rsa.pub file contains the protocol version 2 RSA public key for authentication. The contents of this file should be added to $HOME/.ssh/authorized_keys on all computers where a user wishes to log in using public key authentication

https://en.wikipedia.org/wiki/Ssh-keygen