  We establish a one-shot strong converse bound for privacy amplification
against quantum side information using trace distance as a security criterion.
This strong converse bound implies that in the independent and identical
scenario, the trace distance exponentially converges to one in every finite
blocklength when the rate of the extracted randomness exceeds the quantum
conditional entropy. The established one-shot bound has an application to
bounding the information leakage of classical-quantum wiretap channel coding
and private communication over quantum channels. That is, the trace distance
between Alice and Eavesdropper's joint state and its decoupled state vanishes
as the rate of randomness used in hashing exceeds the quantum mutual
information. On the other hand, the trace distance converges to one when the
rate is below the quantum mutual information, resulting in an exponential
strong converse. Our result also leads to an exponential strong converse for
entropy accumulation, which complements a recent result by Dupuis
[arXiv:2105.05342]. Lastly, our result and its applications apply to the
moderate deviation regime. Namely, we characterize the asymptotic behaviors of
the trace distances when the associated rates approach the fundamental
thresholds with speeds slower than $O(1/\sqrt{n})$.
