Are the nodejs methods crypto.createCipheriv, crypto.createCipheriv.update, and crypto.createCipheriv.final able to made async?

const crypto = require('crypto');
const util = require('util');

class AES {
    constructor(key, iv) {
        if (!key) throw new Error('A 32 byte / 256 bit key is required.');
        if (!iv) throw new Error('Initialization vector is required.');

        this.key = key;
        this.iv = iv;
    }

    encrypt(data) {
        let cipher = crypto.createCipheriv('aes-256-cbc', this.key, this.iv);
        let encrypted = cipher.update(data, 'utf-8', 'hex');
        encrypted += cipher.final('hex');

        return encrypted;
    }

    decrypt(data) {
        let decipher = crypto.createDecipheriv('aes-256-cbc', this.key, this.iv);
        let decrypted = decipher.update(data, 'hex', 'utf-8');
        decrypted += decipher.final('utf-8');

        return decrypted;
    }

    static randomBytes = async bytes => {
        let result;
        result = await util.promisify(crypto.randomBytes)(bytes);

        return result;
    }

    sha256(data) {
        return crypto.createHash('sha256').update(data).digest('hex');
    }
}

The above is my code and I'm wondering if the encrypt and decrypt methods should be made async? It takes less than 1 ms to execute using my test data, but w/thousands of concurrent users, would it be better to build these methods using async? I wasn't able to promisify them in earlier tests so I thought maybe the module can't be async'd?