mirror of
https://github.com/BLAKE3-team/BLAKE3
synced 2025-01-21 15:50:01 +01:00
5e82396d80
Changes since 0.3.0:
- The x86 build now automatically falls back to "pure" Rust intrinsics,
under either of two possible conditions:
1. The `cc` crate fails to invoke a C compiler at all, indicating that
nothing of the right name (e.g. "cc" or "$CC" on Unix) is installed.
2. The `cc` crate detects that the compiler doesn't support AVX-512
flags, usually because it's too old.
The end result should be that most callers successfully build the
assembly implementations, and that callers who can't build those see a
warning but not an error. (And note that Cargo suppresses warnings for
non-path depencies.)
79 lines
2.4 KiB
Markdown
79 lines
2.4 KiB
Markdown
# b3sum
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A command line utility for calculating
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[BLAKE3](https://github.com/BLAKE3-team/BLAKE3) hashes, similar to
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Coreutils tools like `b2sum` or `md5sum`.
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```
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b3sum 0.3.1
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USAGE:
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b3sum [FLAGS] [OPTIONS] [file]...
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FLAGS:
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-h, --help Prints help information
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--keyed Uses the keyed mode. The secret key is read from standard
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input, and it must be exactly 32 raw bytes.
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--no-mmap Disables memory mapping
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--no-names Omits filenames in the output
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--raw Writes raw output bytes to stdout, rather than hex.
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--no-names is implied. In this case, only a single
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input is allowed.
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-V, --version Prints version information
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OPTIONS:
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--derive-key <CONTEXT> Uses the key derivation mode, with the given
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context string. Cannot be used with --keyed.
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-l, --length <LEN> The number of output bytes, prior to hex
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encoding (default 32)
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--num-threads <NUM> The maximum number of threads to use. By
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default, this is the number of logical cores.
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If this flag is omitted, or if its value is 0,
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RAYON_NUM_THREADS is also respected.
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ARGS:
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<file>...
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```
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# Example
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Hash the file `foo.txt`:
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```bash
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b3sum foo.txt
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```
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Time hashing a gigabyte of data, to see how fast it is:
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```bash
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# Create a 1 GB file.
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head -c 1000000000 /dev/zero > /tmp/bigfile
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# Hash it with SHA-256.
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time openssl sha256 /tmp/bigfile
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# Hash it with BLAKE3.
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time b3sum /tmp/bigfile
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```
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# Installation
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The standard way to install `b3sum` is:
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```
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cargo install b3sum
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```
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On Linux for example, Cargo will put the compiled binary in
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`~/.cargo/bin`. You might want to add that directory to your `$PATH`, or
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`rustup` might have done it for you when you installed Cargo.
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If you want to install directly from this directory, you can run `cargo
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install --path .`. Or you can just build with `cargo build --release`,
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which puts the binary at `./target/release/b3sum`.
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By default, `b3sum` enables the assembly implementations, AVX-512
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support, and multi-threading features of the underlying
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[`blake3`](https://crates.io/crates/blake3) crate. To avoid this (for
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example, if your C compiler does not support AVX-512), you can use
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Cargo's `--no-default-features` flag.
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