  This paper considers a three-receiver broadcast channel with degraded message
sets and message cognition. The model consists of a common message for all
three receivers, a private common message for only two receivers and two
additional private messages for these two receivers, such that each receiver is
only interested in one message, while being fully cognizant of the other one.
First, this model is investigated without any secrecy constraints, where the
capacity region is established, showing that the straightforward extension of
the K\"orner and Marton inner bound to the investigated scenario is optimal. In
particular, this agrees with Nair and Wang's result, which states that the idea
of indirect decoding - introduced to improve the K\"orner and Marton inner
bound - does not provide a better region for this scenario. Further, some
secrecy constraints are introduced by letting the private messages to be
confidential ones. Two different secrecy criteria are considered: joint secrecy
and individual secrecy. For both criteria, a general achievable rate region is
provided. Moreover, the joint and individual secrecy capacity regions are
established, if the two legitimate receivers are more capable than the
eavesdropper. The established capacity regions indicate that the individual
secrecy criterion can provide a larger capacity region as compared to the joint
one, because each cognizant message can be used as a secret key for the other
individual message. Further, the joint secrecy capacity is established for a
more general class of more capable channels, where only one of the two
legitimate receivers is more capable than the eavesdropper. This was done by
showing that principle of indirect decoding introduced by Nair and El Gamal is
optimal for this class of channels. This result is in contrast with the
nonsecrecy case, where the indirect decoding does not provide any gain.
