gzipencoded

Gzipencoded refers to data that has been compressed using the gzip format, typically employing the DEFLATE algorithm and wrapped in a gzip container. Gzip encoding is designed for efficient transmission and storage, and is commonly used to reduce the size of text-based data such as HTML, CSS, and JSON before transfer over networks, or stored as files with a .gz extension.

The gzip container, defined in RFC 1952, consists of a header, a compressed data stream, and a trailer containing a CRC32 checksum and the uncompressed input size. The DEFLATE algorithm combines Huffman coding and LZ77 to achieve compression. The format supports streaming, allowing decompression to begin before the entire input is available.

In practice, gzip encoding is widely used in HTTP via the Content-Encoding: gzip header, enabling servers to compress responses and clients to transparently decompress them. It is also common to distribute single-file archives as .gz, and as part of tar.gz or tgz archives when multiple files must be packaged together.

Performance considerations include good compression for plain text and moderate to poor results on already compressed data. Compression and decompression are CPU-bound, with throughput influenced by data type and hardware. Some environments require careful handling of streaming boundaries, content-length, and compatibility with intermediaries that may compress or modify content.

Security and operational caveats include the risk of compression-based attacks (such as CRIME/BREACH with TLS) and the potential for decompression bombs if untrusted data is not size-limited. Mitigations include proper input validation, size limits, and avoiding redundant compression on already compressed content.

See also: DEFLATE, RFC 1952, HTTP content encoding, gzip file, zlib.