The computational soundness of formal encryption is studied extensively following the work of Abadi and Rogaway[1]. Recent work considers the scenario in which secret sharing is needed, and separately, the scenario when key cycles are present. The novel technique is the use of a co-induction definition of the adversarial knowledge. In this paper, we prove a computational soundness theorem of formal encryption in the presence of both key cycles and secret shares at the same time, which is a non-trivial extension of former approaches.
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