base256.js

// http://hewo.xedoloh.com/2015/04/base-256/
const BASE_START = "bghjklnpqrstvwyz";
const BASE_MID = "aeio";
const BASE_END = "cdfm";

const b256_encode = (source) => {
    let buffer = '';
    for (let byte of source) {
        buffer += BASE_START[(byte >> 4)];
        buffer += BASE_MID[((byte >> 2) & 0b11)];
        buffer += BASE_END[(byte & 0b11)];
    }
    return buffer;
}

base256.rs

// http://hewo.xedoloh.com/2015/04/base-256/
const BASE_START: &[u8] = b"bghjklnpqrstvwyz";
const BASE_MID: &[u8] = b"aeio";
const BASE_END: &[u8] = b"cdfm";

fn b256_encode(source: &[u8]) -> String {
    let mut buffer = String::with_capacity(source.len() * 3);
    for &byte in source {
        buffer.push(BASE_START[(byte >> 4) as usize] as char);
        buffer.push(BASE_MID[((byte >> 2) & 0b11) as usize] as char);
        buffer.push(BASE_END[(byte & 0b11) as usize] as char);
    }
    buffer
}

fn main() {
    println!("{}", b256_encode(b"\x00\x01"));
}