Aspects include encrypting data based at least in part on a session key to generate encrypted data. The session key is encrypted based at least in part on a sender key to generate an encrypted session key. A request for an encrypted sender key index is transmitted to the key management system (KMS), the request includes an index of the sender key and an index of each of one or more additional keys. The encrypted sender key index is received from the KMS. An object that includes the encrypted data, the encrypted session key, the index of each of the one or more additional keys, and the encrypted sender key index is generated. Access to the data via the object is controlled based at least in part on whether a receiver has access to the sender key and to the one or more additional keys.