mimc implementation in js

mimc.js

    forward_mimc: (input_data, steps) => {
        const encoder = new TextEncoder();
        const decoder = new TextDecoder();
        const inputBytes = encoder.encode(input_data);
        let inp = BigInt('0x' + Array.from(inputBytes, byte => byte.toString(16).padStart(2, '0')).join(''));

        for (let i = 1n; i < BigInt(steps); i++) {
            inp = (inp ** 3n + _round_constants[Number(i % BigInt(_round_constants.length))]) % _modulus;
        }

        const byteLength = Math.ceil(inp.toString(2).length / 8);
        const resultArray = new Uint8Array(byteLength);
        for (let i = 0; i < byteLength; i++) {
            resultArray[i] = Number((inp >> (8n * BigInt(i))) & 0xffn);
        }

        return decoder.decode(resultArray);
    },
    reverse_mimc: (input_data, steps) => {

        const inputBytes = input_data
        let rtrace = BigInt('0x' + Array.from(inputBytes, byte => byte.toString(16).padStart(2, '0')).join(''));

        for (let i = BigInt(steps) - 1n; i > 0n; i--) {
            rtrace = onionrVDF.powerMod(rtrace - _round_constants[Number(i % BigInt(_round_constants.length))], _little_fermat_expt, _modulus);
        }


        const byteLength = Math.ceil(rtrace.toString(2).length / 8);
        const resultArray = new Uint8Array(byteLength);
        for (let i = 0; i < byteLength; i++) {
            resultArray[i] = Number((rtrace >> (8n * BigInt(i))) & 0xffn);
        }

        return resultArray.reverse()
    }