Sha1sum

SHA1 is a broken and proven vulnerable algorithm. The article may be rewritten with SHA256 (unbroken, as of Jan 2022), or some other safer alternative as the title and the main focus.

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sha1sum is a computer program that calculates and verifies SHA-1 hashes. It is commonly used to verify the integrity of files. It (or a variant) is installed by default on most Linux distributions. Typically distributed alongside sha1sum are sha224sum, sha256sum, sha384sum and sha512sum, which use a specific SHA-2 hash function and b2sum,^[1] which uses the BLAKE2 cryptographic hash function.

The SHA-1 variants are proven vulnerable to collision attacks, and users should instead use, for example, a SHA-2 variant such as sha256sum or the BLAKE2 variant b2sum to prevent tampering by an adversary.^[2][3]

It is included in GNU Core Utilities,^[4] Busybox (excluding b2sum),^[5] and Toybox (excluding b2sum).^[6] Ports to a wide variety of systems are available, including Microsoft Windows.