h i g h l i g h t s • A searchable encryption is presented against both data and access pattern leakage. • A homomorphic exclusive-or (XOR) function is defined to enable the evaluation key to be calculated instead of storing. • An effective and feasible approach performs with a query of less than 60 milliseconds among 100,000 entries.

In this paper, we present a thorough and comprehensive study for bit-patterned media recording (BPMR), from a signal processing and coding perspective. We first propose a recording-physics-based generic channel model for BPMR, which includes all the major characteristics and impairments of the system. It also provides a fair basis for the performance comparison of different coding and detection schemes. We further propose various channel algorithms and techniques for BPMR, including a two-dimensional (2D) equalization scheme with onedimensional (1D) generalized partial response (GPR) target to mitigate inter-track interference (ITI) and media noise, a maximum a posteriori (MAP) detector for BPMR with write errors, various low-density parity-check (LDPC) codes, as well as the iterative detection and decoding schemes. The corresponding performance gains are illustrated at 4Tb/in 2 .

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