Crypto-shredding is the practice of 'deleting' data by deliberately deleting or overwriting the encryption keys.[1] This requires that the data have been encrypted. Data may be considered to exist in three states: data at rest, data in transit and data in use. General data security principles, such as in the CIA triad of confidentiality, integrity, and availability, require that all three states must be adequately protected.
Deleting data at rest on storage media such as backup tapes, data stored in the cloud, computers, phones, or multi-function printers can present challenges when confidentiality of information is of concern. When encryption is in place, data disposal is more secure.