Composably secure device-independent encryption with certified deletion

Composably secure device-independent encryption with certified deletion

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We study the task of encryption with certified deletion (ECD) introduced by Broadbent and Islam (2020), but in a device-independent setting: we show that it is possible to achieve this task even when the honest parties do not trust their quantum devices.Moreover, we define security for the ECD task in a composable manner and show that our ECD protocol satisfies conditions that edgewater shoes lead to composable security.Our protocol is based on device-independent quantum key distribution (DIQKD), and in particular the parallel DIQKD protocol based on the magic square non-local game, given by Jain, Miller and Shi (2020).To achieve certified deletion, we use a property of the magic square game observed by Fu and Miller (2018), namely that a two-round variant of the game can be used to certify deletion of a single random bit.

In order to achieve certified deletion security for arbitrarily long messages from this property, we prove a parallel repetition theorem for two-round non-local games, stuart products emcelle tocopherol which may be of independent interest.