You open the Keychain Access program, available in the "Applications / Utilities" section. In the category list on the right, select "My Certificates."
This gives you a list of all the certificates installed in your keychain. If you are not familiar with what a keychain is. It is basically a secure database containing login passwords, certificates, private keys, etc.
When downloading a certificate, double-click it to import it into the keychain.
You can then find your certificate in the My Certificates list. If you expand the certificate that interests you to search for the private key, it should be shown right below the certificate.
I bet you just followed the guide and took steps, and it’s not exactly what you did. We are doing everything right :-)
How it works, you first create the public and private keys together in the keychain access program. Typically, in encryption, how you use them, you provide your public key to someone, and then you can encrypt the message and send it. Only the person with the private key that was created with this public key can decrypt the message.
But anyone who receives your public key cannot know for sure if this is really from you. There are certificates here. A third party, such as Apple, which most people trust, will sign your public key, which creates the certificate. So, what you probably did before, sent your public key to Apple, which signed it and thereby created a certificate that you could download.
Let me give a short version:
- Keychain access is used to create a public / private key
- You create a certificate signing request with your public key. This is basically a public key file in which Apple asks to create a certificate from this public key.
- Apple adds a ton of information about you and the purpose of the public key, and also adds the public key to the file, which becomes a certificate. Then the apple signs it.
- You are uploading a certificate.
- Double-click and import the certificate into the keychain.