A method for storing data items in a data repository that allows a client storing a data item to lose the ability to either retrieve the stored data item or enable its retrieval, while preserving controlled access to the stored data item indefinitely. The client storing the data item encrypts it using an encryption key that it creates, which may be derived from the content of the data item. The encryption key is also stored in the data repository in an encrypted form, with its encryption making use of a public key. The method allows storage space to be shared for identical data items encrypted and stored by independent clients of the data repository.