Unlike my recent BLAKE3 implementation, this one should be valid up to 4GB of data - more than you could ever have in a Scratch project! This implementation should match RFC-7693. If you enter the string "abc", it matches the test vector given in the RFC: 508C5E8C327C14E2E1A72BA34EEB452F37458B209ED63A294D999B4C86675982 Kudos to https://scratch.mit.edu/projects/281984950/ for implementing BLAKE2s in Scratch first, although my implementation is not based on theirs (and I think mine is faster, although I haven't checked)
