Cipher 类


Cipher类的实例用于加密数据。这个类可以用在以下两种方法中的一种:

  • 作为stream,既可读又可写,未加密数据的编写是为了在可读的方面生成加密的数据,或者
  • 使用cipher.update()cipher.final()方法产生加密的数据。

crypto.createCipher()crypto.createCipheriv()方法用于创建Cipher实例。Cipher对象不能直接使用new关键字创建。

示例:使用Cipher对象作为流:

const crypto = require('crypto');
const cipher = crypto.createCipher('aes192', 'a password');

let encrypted = '';
cipher.on('readable', () => {
  const data = cipher.read();
  if (data)
    encrypted += data.toString('hex');
});
cipher.on('end', () => {
  console.log(encrypted);
  // Prints: ca981be48e90867604588e75d04feabb63cc007a8f8ad89b10616ed84d815504
});

cipher.write('some clear text data');
cipher.end();

示例:使用Cipher和管道流:

const crypto = require('crypto');
const fs = require('fs');
const cipher = crypto.createCipher('aes192', 'a password');

const input = fs.createReadStream('test.js');
const output = fs.createWriteStream('test.enc');

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

示例:使用cipher.update()cipher.final()方法:

const crypto = require('crypto');
const cipher = crypto.createCipher('aes192', 'a password');

let encrypted = cipher.update('some clear text data', 'utf8', 'hex');
encrypted += cipher.final('hex');
console.log(encrypted);
// Prints: ca981be48e90867604588e75d04feabb63cc007a8f8ad89b10616ed84d815504

Instances of the Cipher class are used to encrypt data. The class can be used in one of two ways:

  • As a stream that is both readable and writable, where plain unencrypted data is written to produce encrypted data on the readable side, or
  • Using the cipher.update() and cipher.final() methods to produce the encrypted data.

The crypto.createCipher() or crypto.createCipheriv() methods are used to create Cipher instances. Cipher objects are not to be created directly using the new keyword.

Example: Using Cipher objects as streams:

const crypto = require('crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';
// Key length is dependent on the algorithm. In this case for aes192, it is
// 24 bytes (192 bits).
// Use async `crypto.scrypt()` instead.
const key = crypto.scryptSync(password, 'salt', 24);
// Use `crypto.randomBytes()` to generate a random iv instead of the static iv
// shown here.
const iv = Buffer.alloc(16, 0); // Initialization vector.

const cipher = crypto.createCipheriv(algorithm, key, iv);

let encrypted = '';
cipher.on('readable', () => {
  const data = cipher.read();
  if (data)
    encrypted += data.toString('hex');
});
cipher.on('end', () => {
  console.log(encrypted);
  // Prints: e5f79c5915c02171eec6b212d5520d44480993d7d622a7c4c2da32f6efda0ffa
});

cipher.write('some clear text data');
cipher.end();

Example: Using Cipher and piped streams:

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

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';
// Use the async `crypto.scrypt()` instead.
const key = crypto.scryptSync(password, 'salt', 24);
// Use `crypto.randomBytes()` to generate a random iv instead of the static iv
// shown here.
const iv = Buffer.alloc(16, 0); // Initialization vector.

const cipher = crypto.createCipheriv(algorithm, key, iv);

const input = fs.createReadStream('test.js');
const output = fs.createWriteStream('test.enc');

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

Example: Using the cipher.update() and cipher.final() methods:

const crypto = require('crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';
// Use the async `crypto.scrypt()` instead.
const key = crypto.scryptSync(password, 'salt', 24);
// Use `crypto.randomBytes` to generate a random iv instead of the static iv
// shown here.
const iv = Buffer.alloc(16, 0); // Initialization vector.

const cipher = crypto.createCipheriv(algorithm, key, iv);

let encrypted = cipher.update('some clear text data', 'utf8', 'hex');
encrypted += cipher.final('hex');
console.log(encrypted);
// Prints: e5f79c5915c02171eec6b212d5520d44480993d7d622a7c4c2da32f6efda0ffa