PEE/src/jpg.ts

import { Buffer } from "buffer";
import type { ImageProcessor } from "./processor.worker";
import { f5stego } from './f5stego';
import { settings } from "./stores";
import { decodeCoom3Payload } from "./utils";

const key = Buffer.from("CUNNYCUNNYCUNNY");
const f5inst = new f5stego(key);

const inject = async (b: File, links: string[]) => {
    // TODO: maybe do a lossless crop/embed/concat?
    if (b.size / 20 < links.join(' ').length)
        throw "Image too small to embed.";
    const arr = new Uint8Array(new Uint8Array(await b.arrayBuffer()));
    const buff = f5inst.embed(arr, new TextEncoder().encode(links.join(' ')), 1);
    return Buffer.from(buff);
};

// unfortunately, because of the way f5 work, we can't determine
// if there's an embedded message until we have the complete file
// but the way PEE was designed forces us to just try to extract something until it works
const has_embed = (b: Uint8Array) => {
    try {
        const res = f5inst.extract(b);
        if (!res)
            return false; // unsure
        if (res.length > 1024) // probably garbage, allows for ~20 links from take-me-to.space, should be enough
            return false; // unsure
        const str = Buffer.from(res).toString();
        if (!str.match(/^[a-zA-Z0-9:/.\-_ ]+$/))
            return false; // unsure
        return str; // sure
    } catch {
        return false; // unsure
    }
};

const extract = (b: Uint8Array, ex: string) => {
    // if we reached here then ex is heckin cute and valid
    return decodeCoom3Payload(Buffer.from(ex));
};

export default {
    match: fn => !!fn.match(/\.jpe?g$/),
    has_embed,
    extract,
    inject
} as ImageProcessor;