Unable to export private and public keys under Mac

I have a public and private key in one machine, I tried to export them under the name of key.cer, I mean what other option is there besides .certificate extension.

Now I moved that key.cer which supposedly contain the private and public keys to another machine. but no luck, the two keys did not show up in the keychain o开发者_运维百科f the new machine.

That's because .cer is just the certificate. When exporting a certificate that includes a private key, you should stick with the default export option, which is a .p12 file.

You should only export your private key..