First of all I don`t use iMessage. I log out of iMessage on my iDevices.
Today I took a look of my login Keychain Access and there were 366 items. All of them were iMessage Encryption Key and iMessage Signing Key.
I delete it, reboot my Mac and open Keychain Access again. In the reboot 8 keys (see screenshot) were create. Is this behaviour normal?
Best Answer
That's not abnormal. The system makes these and there's not much detail Keychain Assistant will show so it's a bit difficult to know which is used where.
Also, iMessages establishes a different key for each device you sign in to. The four key pairs you have could be one Mac, one iPad, one iPhone one and one watch.
I wouldn't worry about it - they are so small, deleting them seems more risky than the benefit of clearing out "old" ones.