# Process message into chunks
def chunkMessage( str )
    nblk = ((str.length + 8) >> 6) + 1
    blks = Array.new(nblk * 16) { 0 }

    i = 0
    while i < str.length do
        blks[i >> 2] |= str[i].ord << ((i % 4) * 8)
        i += 1
    end

    blks[i >> 2] |= 0x80 << ((i % 4) * 8)
    blks[nblk * 16 - 2] = str.length * 8

    return blks
end