US Patent 9608813 Key rotation techniques

A plurality of devices have common access to a cryptographic key. The cryptographic key is rotated by providing the devices simultaneous access to both the cryptographic key and a new cryptographic key and then revoking access to the cryptographic key. Keys stored externally and encrypted under the cryptographic key can be reencrypted under the new cryptographic key. Keys intended for electronic shredding can be left encrypted under the old cryptographic key.