CPIO to 7Z Converter

7Z is the native archive format of 7-Zip, an open-source file archiver created by Igor Pavlov in 1999. The format uses an open, modular architecture that supports multiple compression algorithms — LZMA and LZMA2 (the defaults), PPMd for text-heavy data, BWT, and Deflate — selectable per file within the same archive. LZMA typically achieves 30-70% better compression ratios than Deflate-based ZIP files on comparable data, making 7Z one of the most space-efficient general-purpose archive formats available. The container structure stores files with full directory hierarchy, timestamps, and attributes, while supporting solid compression (treating multiple files as a continuous data stream) for additional ratio gains on archives with many similar files. Encryption uses AES-256 with key derivation based on iterative SHA-256 hashing, and both file contents and filenames can be encrypted. One advantage is superior compression density — 7Z consistently produces smaller archives than ZIP or RAR on most data types, valuable when minimizing storage or bandwidth matters. The open architecture is another strength: the format specification and 7-Zip source code are publicly available under the GNU LGPL, enabling any developer to implement 7Z support without licensing constraints. Cross-platform tools supporting 7Z exist for Windows, macOS, Linux, and mobile platforms, and the format has gained widespread recognition as the preferred choice when maximum compression is the priority.