Where are the digital certificates storage location on Mac OS X
Apple's Mac OS X includes a built-in key and password manager, Keychain, which stores user passwords, user and server certificates, and keys.
Source Certificate and Key Management in Mac OS X (Link no longer available)
Where is the Keychain data stored?
The keychain data is stored in ~/Library/Keychains/,
/Library/Keychains/, and /Network/Library/Keychains/.
The first location is where my personal keychain is stored. To access
their data, I need the Keychain Utility located in the Utilities
folder in the Applications folder.
I like using spotlight to access the Keychain Utility as it only takes
a few keys to get there – click on the spotlight icon in the top right
corner and type “keychain”. Spotlight is quick and will predict what
you are looking for and get it on top of the search quickly, so you
don’t even need to type the whole word. Once you open it, you have
access to your Keychain.
Understanding Local Keychain Files
I will briefly explain the purpose of the most important files in
these directories.
/Users/${OS_USERNAME}/Library/Keychains/login.keychain-db – This keychain is created
when your user account in Mac OS X is created and normally has its
password synchronised with your login password. It is unlocked at
login and locked a logout. This is where most of your passwords will
end up in. Its password is changed when you change your login password
or using the Keychain Access utility.
/Users/${OS_USERNAME}/Library/Keychains/${HARDWARE_UUID}/ – UUID stands for Universally Unique Identifier and this value is unique to your device. In the Keychain Access app, it appears as “Local Items” and is where your iCloud keychain is stored, when the service is enabled. The iCloud keychain service
allows passwords and other types of data from it to be synchronised
with your other Apple devices like you iPad, iPhone or another Mac.
The only requirements are that all these devices are using the same
Apple ID account, and the OS supports the iCloud keychain service (Mac
OS X 10.9 and above, iOS 7.0.3 and above).
/Library/Keychains/System.keychain – The System keychain stores
items that are accessed by the OS and shared between users, for example, to allow everyone on the Mac to be able to connect to a WiFi
network. Only administrators can change its content.
/Library/Keychains/FileVaultMaster.keychain – This file is created
by the system when FileVault encryption service is enabled on your
Mac. The OS manages its content.
/System/Library/Keychains/ – This is another location that can store
loads of keychain files. Its content is managed by the system and
other applications. Most of them will not appear in the Keychain Access
utility however, all users benefit from it.
Source Understanding the Mac OS X Keychain (Link updated) by Ivaylo Mihaylov
Further Reading
