Cryptographic erasure (Crypto Erase) renders data unreadable by irrecoverably destroying the associated encryption key. The encrypted data remains physically on the storage medium but is worthless without the key. This method is especially useful for SSDs and cloud storage where physical overwriting is technically difficult or impossible. The prerequisite is that the data was encrypted from the start and key management is airtight. In your ISMS, document cryptographic erasure as an approved deletion method in your data destruction policy and define for which storage media it applies.