Banerjee, Pradeep KumarPradeep KumarBanerjee2025-01-242025-01-242025-01-01Entropy 27 (1): 29 (2025)https://tore.tuhh.de/handle/11420/53535The problem of constructing information measures with a well-defined interpretation is of fundamental significance in information theory. A good definition of an information measure entails certain desirable properties while also providing answers to operational problems. In this work, we investigate the properties of the unique information, an information measure that quantifies a deviation from the Blackwell order. Beyond providing an accessible introduction to the topic from a channel ordering perspective, we present a novel resource-theoretic characterization of unique information in a cryptographic task related to secret key agreement. Our operational view of unique information entails rich physical intuition that leads to new insights into secret key agreement in the context of non-negative decompositions of the mutual information into redundant and synergistic contributions. Through this lens, we illuminate new directions for research in partial information decompositions and information-theoretic cryptography.en1099-43002025Multidisciplinary Digital Publishing Institutehttps://creativecommons.org/licenses/by/4.0/Computer Science, Information and General Works::004: Computer SciencesJournal Article2025-01-24https://doi.org/10.15480/882.1448710.3390/e2701002910.15480/882.14487Journal Article