Format de fichier

À propos des fichiers XZ

XZ (XZ Compressed · Format d'archive)

Lancement 2009 Par Lasse Collin

XZ Compressed (.xz) est un format de fichier pris en charge par KaijuConverter pour l’archivage, l’échange professionnel et la conversion multiplateforme.

Famille

Archives & Compressed

Extension

.xz

Type MIME

application/x-xz

Utilisable comme

Entrée Sortie

L'histoire

COMMENT XZ
A VU LE JOUR.

2009

2024

XZ is a general-purpose compression format released in 2009 by Lasse Collin, based on the LZMA2 algorithm (an evolution of the LZMA Igor Pavlov designed for 7-Zip). The xz-utils suite became the default "best compression ratio" tool on Linux — typically 30% smaller than gzip and 15% smaller than bzip2 at comparable speed.

Every major Linux distribution adopted .tar.xz for kernel and package distribution. Then came March 2024 and the notorious XZ backdoor incident: someone operating under the name Jia Tan spent three years as a trusted xz-utils maintainer, then inserted a malicious payload that would compromise SSH on affected systems. A Microsoft engineer, Andres Freund, caught it by noticing SSH logins were half a second slower than usual. The backdoor was removed, xz-utils went through a governance reshuffle, and the industry learned a hard lesson about single-maintainer supply-chain risk.

CURIOSITÉS ET
ANECDOTES.

The XZ backdoor (CVE-2024-3094) was caught in March 2024 by a Microsoft engineer who noticed SSH logins were ~500 ms slower than usual — arguably the most important security catch of the decade.

XZ compression typically beats gzip by 30% and bzip2 by 15% on general data.

Every modern Linux distribution ships its kernel source as .tar.xz.

XZ supports parallel compression via xz -T flag — essential for utilizing modern many-core CPUs.

The LZMA2 algorithm is a successor to LZMA, originally designed for 7-Zip by Igor Pavlov.

POINTS FORTS ET
LIMITES.

Points forts

Best-in-class compression ratio among mainstream tools.
Streaming-capable — can pipe through network.
Multi-threaded compression available.
Mature on every Linux distribution.
Supports integrity checking (CRC32, CRC64, SHA-256).

Limites

Slow compression at high levels — 3-5× slower than gzip.
Memory-hungry: xz -9 can need 700+ MB to compress.
2024 supply-chain backdoor damaged trust in the project.
Zstandard outperforms xz at similar ratios with less memory.

Tailles et poids typiques

Text/source archive

15-25% of original

Linux kernel (.tar.xz)

~125 MB

Firefox source code

~600 MB

Spécifications techniques

MIME type: application/x-xz
Extensions: .xz, .txz
Algorithm: LZMA2
Standard: The .xz File Format specification 1.1.0
Integrity checks: None, CRC32, CRC64, SHA-256

OUTILS STUDIO POUR XZ

Outils Spécialisés pour Fichiers .XZ

Voir les 45 outils →

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CONVERTIR DEPUIS
XZ

xz zip xz 7z xz tar xz gz xz bz2 xz lzma xz zst xz lz4

CONVERTIR EN
XZ

zip xz 7z xz tar xz gz xz bz2 xz rar xz cab xz tgz xz jar xz war xz lzma xz zst xz lz4 xz cpio xz ar xz apk xz deb xz rpm xz lz xz iso xz dmg xz snap xz

Cas d'usage courants

Linux packages, high compression