Function blake2b 

pub fn blake2b(out: &mut [u8], input: &[u8]) -> Result<(), Error>

blake2b(out, outlen, in, inlen, NULL, 0): the one-shot unkeyed digest.

The digest length is out.len().

Errors

Error::IncorrectParameter if out.len() is 0 or greater than 64 (BLAKE2b’s digest size).