PurpleMind RSA Cracker

(function() {
    const E = 65537n;
    const N = 1000000000100000000002379n;
    const D = 773700352548471672492113n;

    function pow_mod(base, exp, mod) {
        let n = 1n;
        while(exp > 0n) {
            if(exp % 2n === 1n) {
                n *= base;
                exp -= 1n;
            }

            base = base ** 2n % mod;
            exp /= 2n;

            n %= mod;
        }

        return n;
    }

    function crack(cyphertext, d, e, n) {
        let start_plain = cyphertext.substring(0, 30);
        let rest_cypher = cyphertext.substring(30);

        let rest_plain = rest_cypher
            // Text pre-processing to strip interwoven words and concatenate and parse lines
            .split("\n").map(line => line.split(" ").filter((_, i) => i % 2 == 0).join("")).map(n => BigInt(n))
            // Decrypting using `d`
            .map(x => pow_mod(x, d, n))
            // Converting the decrypted numbers to ASCII
            .map(n => n.toString().padStart(3 * 8, "0").match(/.{3}/g).map(n => String.fromCharCode(parseInt(n))).join("")).join("");

        return start_plain + rest_plain;
    }

    for(let comment of document.querySelectorAll("ytd-comment-thread-renderer #content-text")) {
        if(/^(.|\n){30}((\d{3}\s+\w+\s*){8}\n?)+$/g.test(comment.innerText)) {
            comment.innerText = `DECRYPTED: [[[ ${crack(comment.innerText, D, E, N)} ]]]`;
        }
        else if(/(\b\d{3}\b.*){8}/g.test(comment.innerText) && !/^FAILED TO DECRYPT \(invalid format\): \[\[\[ (.|\n)* \]\]\]$/g.test(comment.innerText)) {
            comment.innerText = `FAILED TO DECRYPT (invalid format): [[[ ${comment.innerText} ]]]`;
        }
    }
})();