Reverse Engineering Samsung NX mini Firmware Compression: Uncovering Fujitsu RELC
This post details the reverse engineering of a proprietary LZSS compression algorithm used in the firmware of Samsung NX mini, NX3000/NX3300, and Galaxy K Zoom cameras. The initial goal was to understand enough of the algorithm to extract and disassemble the ARM code, but it turned out to be Fujitsu's RELC (Rapid Embedded Lossless Data Compression), a hardware IP block on their ARM SoCs. By meticulously analyzing the compressed stream, the researchers determined the bitmask, offset, and length encoding schemes, ultimately creating a complete decompressor that successfully decompressed all firmware files. This research not only reveals the compression mechanism of the Samsung camera firmware but also highlights the challenges and techniques involved in reverse engineering unknown compression algorithms.