I was out on Key Haven doing an on-site consultation with a customer who was interested in learning about the Keychain. This is the secure location where the Mac OS stores all saved passwords, tokens, certificates and more. He had changed his login password some time ago and had two active Keychains. One of the questions we addressed was: How do I merge these Keychains?
Well, it turns out that I have a couple of Keychains, too. One was my login Keychain and the other was some random “donmayer” Keychain that I have just been too lazy to address. But here was an excuse and I set about merging them. There really is not a true “merge” command so the best option is to copy all (or the important parts) of the Keychain you don’t want to the Keychain you do want. Then you can go ahead and delete the unwanted Keychain.
But, there is a trick here. If you were to simply “Select All” and drag them into the destination Keychain you would be asked for the password for that Keychain for every item you are moving. The way around this is to temporarily eliminate the password for your Keychain. You do this by going to Keychain Access >Edit >Change password for …. It will ask for your original password and then if you leave the new password prompts blank it will warn you about not protecting this vital information. You can ignore that because you are only doing this for a short time.
Once you have the destination password set to nothing, you can simply drag the contents from the Keychain you are deleting by selecting all and dragging it onto the destination Keychain. You may get some warnings about duplicates which you can ignore. Once you have copied all the contents to the destination Keychain you can delete that old Keychain.
Now, don’t forget to go back into the Edit menu to set your password for the Keychain. In most cases, it is simplest to just use your Mac’s Admin password for the Login Keychain.