您可以将加密的文件写回磁盘，而不是将整个文件缓冲在内存中：

var fs = require('fs');
var crypto = require('crypto');

var key = '14189dc35ae35e75ff31d7502e245cd9bc7803838fbfd5c773cdcd79b8a28bbd';
var cipher = crypto.createCipher('aes-256-cbc', key);
var input = fs.createReadStream('test.txt');
var output = fs.createWriteStream('test.txt.enc');

input.pipe(cipher).pipe(output);

output.on('finish', function() {
  console.log('Encrypted file written to disk!');
});

不推荐使用没有初始化向量的crypto.createCipher（），因为NodeJS v10.0.0使用crypto.createCipheriv（）。
您还可以使用stream.pipeline（）而不是pipe方法来管道流，然后promisify它（因此代码将很容易适应promise-like和async/await流）。

const {createReadStream, createWriteStream} = require('fs');
const {pipeline} = require('stream');
const {randomBytes, createCipheriv} = require('crypto');
const {promisify} = require('util');

const key = randomBytes(32); // ... replace with your key
const iv = randomBytes(16); // ... replace with your initialization vector

promisify(pipeline)(
        createReadStream('./text.txt'),
        createCipheriv('aes-256-cbc', key, iv),
        createWriteStream('./text.txt.enc')
)
.then(() => {/* ... */})
.catch(err => {/* ... */});

使用NodeJS 15+可以简化它（跳过promisify部分）

const {createReadStream, createWriteStream} = require('fs');
const {pipeline} = require('stream/promises');
const {randomBytes, createCipheriv} = require('crypto');

const key = randomBytes(32); // ... replace with your key
const iv = randomBytes(16); // ... replace with your initialization vector

pipeline(
  createReadStream('./text.txt'),
  createCipheriv('aes-256-cbc', key, iv),
  createWriteStream('./text.txt.enc')
)
.then(() => {/* ... */})
.catch(err => {/* ... */});

我会简单地使用Fileger来实现，它是一个基于promise的包，是NodeJS文件系统的一个干净的替代品。

const fileger = require("fileger")
const file = new fileger.File("./your-file-path.txt");

file.encrypt("your-password") // this will encrypt the file
   .then(() => {
      file.decrypt("your-password") // this will decrypt the file
   })