Format guide
SHA-1 checksum
Secure Hash Algorithm 1 (FIPS 180-4)
SHA-1 produces a 160-bit (40 hex character) fingerprint. Standardized by NIST in 1995 and deprecated for cryptographic use since the SHAttered collision attack (2017). Still used widely in non-security contexts: Git uses SHA-1 to identify every commit, blob, and tree. Output matches the `shasum` CLI format.
How to open a SHA-1 checksum file
Any text editor. Verify with `shasum -c file.sha1` (`-a 1` for explicit algorithm). Git's plumbing commands (`git cat-file -p <sha1>`) all reference SHA-1 hashes.
Primary use
Git's content-addressable storage and legacy file integrity.
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