How can I permanently add my SSH private key to Keychain so it is automatically available to ssh?

Question

It seems that ssh-add -K ~/.ssh/id_rsa will load your key but will ask for the password each time you reboot.

I am looking for a solution that would not require me to re-enter the key password between logins.

Answer 1

It is not possible to add private key to Keychain, but you can store passphrase for private key in Keychain. On OSX, the native ssh-add command has a special argument to save the private key's passphrase in the OSX Keychain, which means that your normal login will unlock it for use with ssh. On OSX Sierra and later, you also need to configure SSH to always use the Keychain (see Step 2 below).

Alternatively you can use a key without a passphrase, but if you prefer the security that's certainly acceptable with this workflow.

Step 1 - Store passphrase in the Keychain

In the latest version of MacOS (12.0 Monterey), just do this once:

ssh-add --apple-use-keychain ~/.ssh/[your-private-key]

Or in versions of MacOS older than 12.0 Monterey, use:

ssh-add -K ~/.ssh/[your-private-key]

Enter your key passphrase, and you won't be asked for it again.

(If this fails, make sure you are using Apple's version of /usr/bin/ssh-add and not something installed with brew etc.; check with which ssh-add)

Step 2 - Configure SSH-agent to always use the Keychain

(Note: In versions of OSX prior to Sierra, this is not necessary)

It seems that OSX Sierra removed the convenient behavior of persisting your keys between logins, and the update to ssh no longer uses the keychain by default. Because of this, you need to change one more thing for secure persistent key storage.

The solution is outlined in this github thread comment. Here's what you do:

1. Ensure you've completed Step 1 above to store the passphrase in the keychain.

2. If you haven't already, create an ~/.ssh/config file. In other words, in the .ssh directory in your home dir, make a file called config.

3. In that .ssh/config file, add the following lines:

   Host *
       UseKeychain yes
       AddKeysToAgent yes
       IdentityFile ~/.ssh/id_rsa
   

   Change ~/.ssh/id_rsa to the actual filename of your private key. If you have other private keys in your ~/.ssh directory, also add an IdentityFile line for each of them. For example, I have one additional line that reads IdentityFile ~/.ssh/id_ed25519 for a 2nd private key.

   The UseKeychain yes is the key part, which tells SSH to look in your OSX keychain for the key passphrase.

4. That's it! Next time you load any ssh connection, it will try the private keys you've specified, and it will look for their passphrase in the OSX keychain. No passphrase typing required.

Answer 2

I had a similar problem, in that I was being asked every time for my pub-key passphrase. Per suggestion of user "trisweb" above, I turned on these options to ~/.ssh/config:

Host *
  UseKeychain yes
  AddKeysToAgent yes
  IdentityFile ~/.ssh/id_rsa

But it still prompted every time I wanted to use ssh. Eventually I turned on ssh -v and found this debug line:

debug1: key_load_private: incorrect passphrase supplied to decrypt private key

I then opened my keychain in "Keychain Access.app", found the key named "SSH: /Users/username/.ssh/id_rsa" and opened it up. I clicked "Show password" to disclose the password and indeed found that the passphrase in the keyring was an old passphrase. I updated the passphrase in Keychain Access, and now password-free works.

I could have also updated the passphrase with this phrase:

ssh-keygen -p -f ~/.ssh/id_rsa

Answer 3

To all where the above did not work, my issue appears to have been because I was duplicating the UseKeychain yes & AddKeysToAgent yes in all ssh key profiles / shortcuts. I updated my ~/.ssh/config file to declare these only once and they now all load on login without prompting for passwords on startup, e.g:

Host foo
  HostName foo.com
  User fooUser
  IdentityFile ~/.ssh/foo

Host bar
  HostName bar.com
  User barUser
  IdentityFile ~/.ssh/bar

########################
# Keep the default configuration 
#  as the last item in this file
Host *
  UseKeychain yes
  AddKeysToAgent yes
  IdentityFile ~/.ssh/foo
  IdentityFile ~/.ssh/bar

Answer 4

Also, in macOS Sierra and High Sierra (don't know about previous versions), running ssh-add -A will get the agent to load all keys whose passphrases are stored on Keychain... So very handy

Note that these option flags have been renamed and the old ones deprecated in later versions of macOS. From the ssh man page:

APPLE_SSH_ADD_BEHAVIOR
Enables or disables the older processing of the -A and -K options used in earlier macOS releases. These options have been renamed --apple-load-keychain and --apple-use-keychain respectively.
However, -A and -K still behave as in earlier releases except in the following circumstances:

• If a security provider was specified with -S or SSH_SK_PROVIDER, or if APPLE_SSH_ADD_BEHAVIOR is set to the value “openssh”, then ssh-add uses standard OpenSSH behavior: the -A flag is not recognized and the -K flag behaves as documented in the DESCRIPTION section above.
• Otherwise, ssh-add -A and -K will behave as in earlier macOS releases. A warning will be output to standard error unless APPLE_SSH_ADD_BEHAVIOR is set to the value “macos”. Note: Future releases of macOS will not support neither -A nor -K without setting this environment variable.

Answer 5

Answer on OSX 12.0 Monterey

You can now use the flag --apple-use-keychain to accomplish exactly this.

ssh-add --apple-use-keychain ~/.ssh/id_rsa 

Add this to your .zshrc or .bashrc file to have it load from your keychain on new logins / terminal instances.

This replaces the -K and -A flags:

WARNING: The -K and -A flags are deprecated and have been replaced
         by the --apple-use-keychain and --apple-load-keychain
         flags, respectively.  To suppress this warning, set the
         environment variable APPLE_SSH_ADD_BEHAVIOR as described in
         the ssh-add(1) manual page.

Answer 6

See the answer from @Trisweb above - https://apple.stackexchange.com/a/250572/231343. When I try this, for some reason I get the message ssh-add: illegal option when I use the --apple-use-keychain option (I'm using macOS Ventura 13.4.1)

The -K option is in Apple's standard version of ssh-add, I was able to use it, although when I try ssh-add -K ~/.ssh/my_private_key, I'm prompted for a PIN, so I needed:

/usr/bin/ssh-add -K ~/.ssh/my_private_key

Apparently you can also use the -k option instead of -K, which will prompt you for the private key passphrase that you set up when creating the keys.

Answer 7

I have added the two lines below to the ~/.bash_profile file and it worked on macOS Monterey.

eval "$(ssh-agent -s)"
ssh-add --apple-use-keychain ~/.ssh/id_ed25519

Answer 8

One of solutions is to delete .ssh from path. Like this - "ssh-add --apple-use-keychain ~/id_ed25519" or "ssh-add --apple-use-keychain ~/[YOURS ID OF SSH]"

Also you need to change path in ~/.ssh/config by deleting /.ssh

Answer 9

Add the public key in:

.ssh/known_hosts

Public key usually are on:

/home/user/.ssh/id_rsa.pub

Hope that helps