BLAKE3/b3sum/README.md

b3sum

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

b3sum 0.2.1

USAGE:
    b3sum [FLAGS] [OPTIONS] [file]...

FLAGS:
    -h, --help        Prints help information
        --keyed       Uses the keyed mode, with the raw 32-byte key read from stdin
        --no-mmap     Disables memory mapping
        --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
    -V, --version     Prints version information

OPTIONS:
        --derive-key <CONTEXT>    Uses the key derivation mode, with the input as key material
    -l, --length <LEN>            The number of output bytes, prior to hex encoding (default 32)

ARGS:
    <file>...

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

The standard way to install b3sum is:

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.

By default, b3sum enables the assembly implementations, AVX-512 support, and multi-threading features of the underlying blake3 crate. To avoid this (for example, if your C compiler does not support AVX-512), you can use Cargo's --no-default-features flag.