BLAKE3/b3sum

b3sum

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

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

Arguments:
  [FILE]...  Files to hash, or checkfiles to check. When no file is given,
             or when - is given, read standard input.

Options:
  -l, --length <LEN>          The number of output bytes, prior to hex
                              encoding [default: 32]
      --num-threads <NUM>     The maximum number of threads to use. By
                              default, this is the number of logical cores.
                              If this flag is omitted, or if its value is 0,
                              RAYON_NUM_THREADS is also respected.
      --keyed                 Uses the keyed mode. The secret key is read from standard
                              input, and it must be exactly 32 raw bytes.
      --derive-key <CONTEXT>  Uses the key derivation mode, with the given
                              context string. Cannot be used with --keyed.
      --no-mmap               Disables memory mapping. Currently this also disables
                              multithreading.
      --no-names              Omits filenames in the output
      --raw                   Writes raw output bytes to stdout, rather than hex.
                              --no-names is implied. In this case, only a single
                              input is allowed.
  -c, --check                 Reads BLAKE3 sums from the [FILE]s and checks them
      --quiet                 Skips printing OK for each successfully verified file.
                              Must be used with --check.
  -h, --help                  Print help information
  -V, --version               Print version information

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

Example

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

Installation

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.