I downloaded a personal development certificate from the Apple Developer center and imported it to my keychain. Now, I want to export it as a .p12 file and encrypt it with a password. When I right click the certificate in the Keychain tab Certificates, and press the Export button, the .p12 option is not highlighted/available. Instead of the other 3 options (.cer, .pem, .p7b), which are available.
I tried a couple of things yet, like adding the Apple ID, which was used to create the certificate, to System preferences->Users and Groups->My account, but that didn't solve it. The certificate was created on a different Macbook than I'm using now.
Is it possible to export it as a .p12 in any way?
The missing .p12 option means that you only have either the private key or the certificate on your machine. You need both of these to generate a .p12 (and incidentally, you'll need both the private key and certificate to sign your apps).
So, find out which of these you're missing, add the missing piece to Keychain, and the .p12 option will be available.