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Jack O'Connor 64747d48ff do another saturating_add for consistency
This one is less security/correctness-critical than the other one I just
added, but I might as well be consistent.
2 months ago
src do another saturating_add for consistency 2 months ago
tests suppress expected stderr prints in b3sum tests 2 months ago
.gitignore check in the Cargo.lock for b3sum 1 year ago
Cargo.lock version 1.3.3 4 months ago
Cargo.toml version 1.3.3 4 months ago grammar fix in b3sum help output 4 months ago fix a typo in the check doc 1 year ago


A command line utility for calculating BLAKE3 hashes, similar to Coreutils tools like b2sum or md5sum.

Usage: b3sum [OPTIONS] [FILE]...

  [FILE]...  Files to hash, or checkfiles to check

  -l, --length <LEN>          The number of output bytes, before hex encoding [default: 32]
      --num-threads <NUM>     The maximum number of threads to use
      --keyed                 Use the keyed mode
      --derive-key <CONTEXT>  Use the key derivation mode, with the given context string
      --no-mmap               Disable memory mapping
      --no-names              Omit filenames in the output
      --raw                   Write raw output bytes to stdout, rather than hex
  -c, --check                 Read BLAKE3 sums from the [FILE]s and check them
      --quiet                 Skip printing OK for each successfully verified file
  -h, --help                  Print help information (use `--help` for more detail)
  -V, --version               Print version information

See also this document about how the --check flag works.


Hash the file foo.txt:

b3sum foo.txt

Time hashing a gigabyte of data, to see how fast it is:

# Create a 1 GB file.
head -c 1000000000 /dev/zero > /tmp/bigfile
# Hash it with SHA-256.
time openssl sha256 /tmp/bigfile
# Hash it with BLAKE3.
time b3sum /tmp/bigfile


Prebuilt binaries are available for Linux, Windows, and macOS (requiring the unidentified developer workaround) on the releases page. If you've installed Rust and Cargo, you can also build b3sum yourself with:

cargo install b3sum

On Linux for example, Cargo will put the compiled binary in ~/.cargo/bin. You might want to add that directory to your $PATH, or rustup might have done it for you when you installed Cargo.

If you want to install directly from this directory, you can run cargo install --path .. Or you can just build with cargo build --release, which puts the binary at ./target/release/b3sum.