You can use your keychain to securely store sensitive information unrelated to your computer, such as personal identification numbers (PINs) for a bank account, credit card numbers, confidential notes, cryptographic keys, and any other information that you want to keep private.
Storing information in your keychain:
Open Keychain Access, located in the Utilites folder in the Applications folder.
Open Keychain Access
If keychains are hidden, choose View > Show Keychains.
Select the keychain you want to use.
If the keychain is locked, click the lock icon, and then enter your keychain password to unlock it.
Choose File > New Secure Note Item.
Type a name for the note that will help you remember what it is.
Type or paste the information you want to preserve in the Note field.
Click Add.
Enter a password if required.
To view the contents of the note, select Secure Notes in the Category list and double-click the note. Select Show Note. You’ll be asked for your keychain password if you haven’t selected “Always allow access to this item” in the Access Control pane.
NOTE: It’s a good idea to leave “Always allow access to this item” unselected for most items in your keychain. This provides greater security for your information.