Node.js v26.0.0 documentation

Console#

The node:console module provides a simple debugging console that is similar to the JavaScript console mechanism provided by web browsers.

The module exports two specific components:

• A Console class with methods such as console.log(), console.error(), and console.warn() that can be used to write to any Node.js stream.
• A global console instance configured to write to process.stdout and process.stderr. The global console can be used without calling require('node:console').

Warning: The global console object's methods are neither consistently synchronous like the browser APIs they resemble, nor are they consistently asynchronous like all other Node.js streams. Programs that desire to depend on the synchronous / asynchronous behavior of the console functions should first figure out the nature of console's backing stream. This is because the stream is dependent on the underlying platform and standard stream configuration of the current process. See the note on process I/O for more information.

Example using the global console:

console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s', 'world');
// Prints: hello world, to stdout
console.error(new Error('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
//   Error: Whoops, something bad happened
//     at [eval]:5:15
//     at Script.runInThisContext (node:vm:132:18)
//     at Object.runInThisContext (node:vm:309:38)
//     at node:internal/process/execution:77:19
//     at [eval]-wrapper:6:22
//     at evalScript (node:internal/process/execution:76:60)
//     at node:internal/main/eval_string:23:3

const name = 'Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
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Example using the Console class:

const out = getStreamSomehow();
const err = getStreamSomehow();
const myConsole = new console.Console(out, err);

myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s', 'world');
// Prints: hello world, to out
myConsole.error(new Error('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err

const name = 'Will Robinson';
myConsole.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to err
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Class: Console#

The Console class can be used to create a simple logger with configurable output streams and can be accessed using either require('node:console').Console or console.Console (or their destructured counterparts):

import { Console } from 'node:console';
const { Console } = require('node:console');
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const { Console } = console;
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new Console(stdout[, stderr][, ignoreErrors])#

new Console(options)#

• options <Object>
  • stdout <stream.Writable>
  • stderr <stream.Writable>
  • ignoreErrors <boolean> Ignore errors when writing to the underlying streams. Default: true.
  • colorMode <boolean> | <string> Set color support for this Console instance. Setting to true enables coloring while inspecting values. Setting to false disables coloring while inspecting values. Setting to 'auto' makes color support depend on the value of the isTTY property and the value returned by getColorDepth() on the respective stream. This option can not be used, if inspectOptions.colors is set as well. Default: 'auto'.
  • inspectOptions <Object> | <Map> Specifies options that are passed along to util.inspect(). Can be an options object or, if different options for stdout and stderr are desired, a Map from stream objects to options.
  • groupIndentation <number> Set group indentation. Default: 2.

Creates a new Console with one or two writable stream instances. stdout is a writable stream to print log or info output. stderr is used for warning or error output. If stderr is not provided, stdout is used for stderr.

import { createWriteStream } from 'node:fs';
import { Console } from 'node:console';
// Alternatively
// const { Console } = console;

const output = createWriteStream('./stdout.log');
const errorOutput = createWriteStream('./stderr.log');
// Custom simple logger
const logger = new Console({ stdout: output, stderr: errorOutput });
// use it like console
const count = 5;
logger.log('count: %d', count);
// In stdout.log: count 5
const fs = require('node:fs');
const { Console } = require('node:console');
// Alternatively
// const { Console } = console;

const output = fs.createWriteStream('./stdout.log');
const errorOutput = fs.createWriteStream('./stderr.log');
// Custom simple logger
const logger = new Console({ stdout: output, stderr: errorOutput });
// use it like console
const count = 5;
logger.log('count: %d', count);
// In stdout.log: count 5
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The global console is a special Console whose output is sent to process.stdout and process.stderr. It is equivalent to calling:

new Console({ stdout: process.stdout, stderr: process.stderr });
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console.assert(value[, ...message])#

• value <any> The value tested for being truthy.
• ...message <any> All arguments besides value are used as error message.

console.assert() writes a message if value is falsy or omitted. It only writes a message and does not otherwise affect execution. The output always starts with "Assertion failed". If provided, message is formatted using util.format().

If value is truthy, nothing happens.

console.assert(true, 'does nothing');

console.assert(false, 'Whoops %s work', 'didn\'t');
// Assertion failed: Whoops didn't work

console.assert();
// Assertion failed
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console.clear()#

When stdout is a TTY, calling console.clear() will attempt to clear the TTY. When stdout is not a TTY, this method does nothing.

The specific operation of console.clear() can vary across operating systems and terminal types. For most Linux operating systems, console.clear() operates similarly to the clear shell command. On Windows, console.clear() will clear only the output in the current terminal viewport for the Node.js binary.

console.count([label])#

• label <string> The display label for the counter. Default: 'default'.

Maintains an internal counter specific to label and outputs to stdout the number of times console.count() has been called with the given label.

> console.count()
default: 1
undefined
> console.count('default')
default: 2
undefined
> console.count('abc')
abc: 1
undefined
> console.count('xyz')
xyz: 1
undefined
> console.count('abc')
abc: 2
undefined
> console.count()
default: 3
undefined
>
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console.countReset([label])#

• label <string> The display label for the counter. Default: 'default'.

Resets the internal counter specific to label.

> console.count('abc');
abc: 1
undefined
> console.countReset('abc');
undefined
> console.count('abc');
abc: 1
undefined
>
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console.debug(data[, ...args])#

• data <any>
• ...args <any>

The console.debug() function is an alias for console.log().

console.dir(obj[, options])#

• obj <any>
• options <Object>
  • showHidden <boolean> If true then the object's non-enumerable and symbol properties will be shown too. Default: false.
  • depth <number> Tells util.inspect() how many times to recurse while formatting the object. This is useful for inspecting large complicated objects. To make it recurse indefinitely, pass null. Default: 2.
  • colors <boolean> If true, then the output will be styled with ANSI color codes. Colors are customizable; see customizing util.inspect() colors. Default: false.

Uses util.inspect() on obj and prints the resulting string to stdout. This function bypasses any custom inspect() function defined on obj.

console.dirxml(...data)#

• ...data <any>

This method calls console.log() passing it the arguments received. This method does not produce any XML formatting.

console.error([data][, ...args])#

• data <any>
• ...args <any>

Prints to stderr with newline. Multiple arguments can be passed, with the first used as the primary message and all additional used as substitution values similar to printf(3) (the arguments are all passed to util.format()).

const code = 5;
console.error('error #%d', code);
// Prints: error #5, to stderr
console.error('error', code);
// Prints: error 5, to stderr
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If formatting elements (e.g. %d) are not found in the first string then util.inspect() is called on each argument and the resulting string values are concatenated. See util.format() for more information.

console.group([...label])#

• ...label <any>

Increases indentation of subsequent lines by spaces for groupIndentation length.

If one or more labels are provided, those are printed first without the additional indentation.

console.groupCollapsed()#

An alias for console.group().

console.groupEnd()#

Decreases indentation of subsequent lines by spaces for groupIndentation length.

console.info([data][, ...args])#

• data <any>
• ...args <any>

The console.info() function is an alias for console.log().

console.log([data][, ...args])#

• data <any>
• ...args <any>

Prints to stdout with newline. Multiple arguments can be passed, with the first used as the primary message and all additional used as substitution values similar to printf(3) (the arguments are all passed to util.format()).

const count = 5;
console.log('count: %d', count);
// Prints: count: 5, to stdout
console.log('count:', count);
// Prints: count: 5, to stdout
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See util.format() for more information.

console.table(tabularData[, properties])#

• tabularData <any>
• properties <string[]> Alternate properties for constructing the table.

Try to construct a table with the columns of the properties of tabularData (or use properties) and rows of tabularData and log it. Falls back to just logging the argument if it can't be parsed as tabular.

// These can't be parsed as tabular data
console.table(Symbol());
// Symbol()

console.table(undefined);
// undefined

console.table([{ a: 1, b: 'Y' }, { a: 'Z', b: 2 }]);
// ┌─────────┬─────┬─────┐
// │ (index) │ a   │ b   │
// ├─────────┼─────┼─────┤
// │ 0       │ 1   │ 'Y' │
// │ 1       │ 'Z' │ 2   │
// └─────────┴─────┴─────┘

console.table([{ a: 1, b: 'Y' }, { a: 'Z', b: 2 }], ['a']);
// ┌─────────┬─────┐
// │ (index) │ a   │
// ├─────────┼─────┤
// │ 0       │ 1   │
// │ 1       │ 'Z' │
// └─────────┴─────┘
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console.time([label])#

• label <string> Default: 'default'

Starts a timer that can be used to compute the duration of an operation. Timers are identified by a unique label. Use the same label when calling console.timeEnd() to stop the timer and output the elapsed time in suitable time units to stdout. For example, if the elapsed time is 3869ms, console.timeEnd() displays "3.869s".

console.timeEnd([label])#

• label <string> Default: 'default'

Stops a timer that was previously started by calling console.time() and prints the result to stdout:

console.time('bunch-of-stuff');
// Do a bunch of stuff.
console.timeEnd('bunch-of-stuff');
// Prints: bunch-of-stuff: 225.438ms
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console.timeLog([label][, ...data])#

• label <string> Default: 'default'
• ...data <any>

For a timer that was previously started by calling console.time(), prints the elapsed time and other data arguments to stdout:

console.time('process');
const value = expensiveProcess1(); // Returns 42
console.timeLog('process', value);
// Prints "process: 365.227ms 42".
doExpensiveProcess2(value);
console.timeEnd('process');
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console.trace([message][, ...args])#

• message <any>
• ...args <any>

Prints to stderr the string 'Trace: ', followed by the util.format() formatted message and stack trace to the current position in the code.

console.trace('Show me');
// Prints: (stack trace will vary based on where trace is called)
//  Trace: Show me
//    at repl:2:9
//    at REPLServer.defaultEval (repl.js:248:27)
//    at bound (domain.js:287:14)
//    at REPLServer.runBound [as eval] (domain.js:300:12)
//    at REPLServer.<anonymous> (repl.js:412:12)
//    at emitOne (events.js:82:20)
//    at REPLServer.emit (events.js:169:7)
//    at REPLServer.Interface._onLine (readline.js:210:10)
//    at REPLServer.Interface._line (readline.js:549:8)
//    at REPLServer.Interface._ttyWrite (readline.js:826:14)
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console.warn([data][, ...args])#

• data <any>
• ...args <any>

The console.warn() function is an alias for console.error().

Inspector only methods#

The following methods are exposed by the V8 engine in the general API but do not display anything unless used in conjunction with the inspector (--inspect flag).

console.profile([label])#

• label <string>

This method does not display anything unless used in the inspector. The console.profile() method starts a JavaScript CPU profile with an optional label until console.profileEnd() is called. The profile is then added to the Profile panel of the inspector.

console.profile('MyLabel');
// Some code
console.profileEnd('MyLabel');
// Adds the profile 'MyLabel' to the Profiles panel of the inspector.
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console.profileEnd([label])#

• label <string>

This method does not display anything unless used in the inspector. Stops the current JavaScript CPU profiling session if one has been started and prints the report to the Profiles panel of the inspector. See console.profile() for an example.

If this method is called without a label, the most recently started profile is stopped.

console.timeStamp([label])#

• label <string>

This method does not display anything unless used in the inspector. The console.timeStamp() method adds an event with the label 'label' to the Timeline panel of the inspector.

Crypto#

The node:crypto module provides cryptographic functionality that includes a set of wrappers for OpenSSL's hash, HMAC, cipher, decipher, sign, and verify functions.

const { createHmac } = await import('node:crypto');

const secret = 'abcdefg';
const hash = createHmac('sha256', secret)
               .update('I love cupcakes')
               .digest('hex');
console.log(hash);
// Prints:
//   c0fa1bc00531bd78ef38c628449c5102aeabd49b5dc3a2a516ea6ea959d6658e
const { createHmac } = require('node:crypto');

const secret = 'abcdefg';
const hash = createHmac('sha256', secret)
               .update('I love cupcakes')
               .digest('hex');
console.log(hash);
// Prints:
//   c0fa1bc00531bd78ef38c628449c5102aeabd49b5dc3a2a516ea6ea959d6658e
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Determining if crypto support is unavailable#

It is possible for Node.js to be built without including support for the node:crypto module. In such cases, attempting to import from crypto or calling require('node:crypto') will result in an error being thrown.

When using CommonJS, the error thrown can be caught using try/catch:

let crypto;
try {
  crypto = require('node:crypto');
} catch (err) {
  console.error('crypto support is disabled!');
}
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When using the lexical ESM import keyword, the error can only be caught if a handler for process.on('uncaughtException') is registered before any attempt to load the module is made (using, for instance, a preload module).

When using ESM, if there is a chance that the code may be run on a build of Node.js where crypto support is not enabled, consider using the import() function instead of the lexical import keyword:

let crypto;
try {
  crypto = await import('node:crypto');
} catch (err) {
  console.error('crypto support is disabled!');
}
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Asymmetric key types#

The following table lists the asymmetric key types recognized by the KeyObject API:

Class: Certificate#

SPKAC is a Certificate Signing Request mechanism originally implemented by Netscape and was specified formally as part of HTML5's keygen element.

<keygen> is deprecated since HTML 5.2 and new projects should not use this element anymore.

The node:crypto module provides the Certificate class for working with SPKAC data. The most common usage is handling output generated by the HTML5 <keygen> element. Node.js uses OpenSSL's SPKAC implementation internally.

Static method: Certificate.exportChallenge(spkac[, encoding])#

• spkac <string> | <ArrayBuffer> | <Buffer> | <TypedArray> | <DataView>
• encoding <string> The encoding of the spkac string.
• Returns: <Buffer> The challenge component of the spkac data structure, which includes a public key and a challenge.

const { Certificate } = await import('node:crypto');
const spkac = getSpkacSomehow();
const challenge = Certificate.exportChallenge(spkac);
console.log(challenge.toString('utf8'));
// Prints: the challenge as a UTF8 string
const { Certificate } = require('node:crypto');
const spkac = getSpkacSomehow();
const challenge = Certificate.exportChallenge(spkac);
console.log(challenge.toString('utf8'));
// Prints: the challenge as a UTF8 string
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Static method: Certificate.exportPublicKey(spkac[, encoding])#

• spkac <string> | <ArrayBuffer> | <Buffer> | <TypedArray> | <DataView>
• encoding <string> The encoding of the spkac string.
• Returns: <Buffer> The public key component of the spkac data structure, which includes a public key and a challenge.

const { Certificate } = await import('node:crypto');
const spkac = getSpkacSomehow();
const publicKey = Certificate.exportPublicKey(spkac);
console.log(publicKey);
// Prints: the public key as <Buffer ...>
const { Certificate } = require('node:crypto');
const spkac = getSpkacSomehow();
const publicKey = Certificate.exportPublicKey(spkac);
console.log(publicKey);
// Prints: the public key as <Buffer ...>
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Static method: Certificate.verifySpkac(spkac[, encoding])#

• spkac <string> | <ArrayBuffer> | <Buffer> | <TypedArray> | <DataView>
• encoding <string> The encoding of the spkac string.
• Returns: <boolean> true if the given spkac data structure is valid, false otherwise.

import { Buffer } from 'node:buffer';
const { Certificate } = await import('node:crypto');

const spkac = getSpkacSomehow();
console.log(Certificate.verifySpkac(Buffer.from(spkac)));
// Prints: true or false
const { Buffer } = require('node:buffer');
const { Certificate } = require('node:crypto');

const spkac = getSpkacSomehow();
console.log(Certificate.verifySpkac(Buffer.from(spkac)));
// Prints: true or false
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Legacy API#

As a legacy interface, it is possible to create new instances of the crypto.Certificate class as illustrated in the examples below.

new crypto.Certificate()#

Instances of the Certificate class can be created using the new keyword or by calling crypto.Certificate() as a function:

const { Certificate } = await import('node:crypto');

const cert1 = new Certificate();
const cert2 = Certificate();
const { Certificate } = require('node:crypto');

const cert1 = new Certificate();
const cert2 = Certificate();
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certificate.exportChallenge(spkac[, encoding])#

• spkac <string> | <ArrayBuffer> | <Buffer> | <TypedArray> | <DataView>
• encoding <string> The encoding of the spkac string.
• Returns: <Buffer> The challenge component of the spkac data structure, which includes a public key and a challenge.

const { Certificate } = await import('node:crypto');
const cert = Certificate();
const spkac = getSpkacSomehow();
const challenge = cert.exportChallenge(spkac);
console.log(challenge.toString('utf8'));
// Prints: the challenge as a UTF8 string
const { Certificate } = require('node:crypto');
const cert = Certificate();
const spkac = getSpkacSomehow();
const challenge = cert.exportChallenge(spkac);
console.log(challenge.toString('utf8'));
// Prints: the challenge as a UTF8 string
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certificate.exportPublicKey(spkac[, encoding])#

• spkac <string> | <ArrayBuffer> | <Buffer> | <TypedArray> | <DataView>
• encoding <string> The encoding of the spkac string.
• Returns: <Buffer> The public key component of the spkac data structure, which includes a public key and a challenge.

const { Certificate } = await import('node:crypto');
const cert = Certificate();
const spkac = getSpkacSomehow();
const publicKey = cert.exportPublicKey(spkac);
console.log(publicKey);
// Prints: the public key as <Buffer ...>
const { Certificate } = require('node:crypto');
const cert = Certificate();
const spkac = getSpkacSomehow();
const publicKey = cert.exportPublicKey(spkac);
console.log(publicKey);
// Prints: the public key as <Buffer ...>
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certificate.verifySpkac(spkac[, encoding])#

• spkac <string> | <ArrayBuffer> | <Buffer> | <TypedArray> | <DataView>
• encoding <string> The encoding of the spkac string.
• Returns: <boolean> true if the given spkac data structure is valid, false otherwise.

import { Buffer } from 'node:buffer';
const { Certificate } = await import('node:crypto');

const cert = Certificate();
const spkac = getSpkacSomehow();
console.log(cert.verifySpkac(Buffer.from(spkac)));
// Prints: true or false
const { Buffer } = require('node:buffer');
const { Certificate } = require('node:crypto');

const cert = Certificate();
const spkac = getSpkacSomehow();
console.log(cert.verifySpkac(Buffer.from(spkac)));
// Prints: true or false
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Class: Cipheriv#

• Extends: <stream.Transform>

Instances of the Cipheriv 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.createCipheriv() method is used to create Cipheriv instances. Cipheriv objects are not to be created directly using the new keyword.

Example: Using Cipheriv objects as streams:

const {
  scrypt,
  randomFill,
  createCipheriv,
} = await import('node:crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';

// First, we'll generate the key. The key length is dependent on the algorithm.
// In this case for aes192, it is 24 bytes (192 bits).
scrypt(password, 'salt', 24, (err, key) => {
  if (err) throw err;
  // Then, we'll generate a random initialization vector
  randomFill(new Uint8Array(16), (err, iv) => {
    if (err) throw err;

    // Once we have the key and iv, we can create and use the cipher...
    const cipher = createCipheriv(algorithm, key, iv);

    let encrypted = '';
    cipher.setEncoding('hex');

    cipher.on('data', (chunk) => encrypted += chunk);
    cipher.on('end', () => console.log(encrypted));

    cipher.write('some clear text data');
    cipher.end();
  });
});
const {
  scrypt,
  randomFill,
  createCipheriv,
} = require('node:crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';

// First, we'll generate the key. The key length is dependent on the algorithm.
// In this case for aes192, it is 24 bytes (192 bits).
scrypt(password, 'salt', 24, (err, key) => {
  if (err) throw err;
  // Then, we'll generate a random initialization vector
  randomFill(new Uint8Array(16), (err, iv) => {
    if (err) throw err;

    // Once we have the key and iv, we can create and use the cipher...
    const cipher = createCipheriv(algorithm, key, iv);

    let encrypted = '';
    cipher.setEncoding('hex');

    cipher.on('data', (chunk) => encrypted += chunk);
    cipher.on('end', () => console.log(encrypted));

    cipher.write('some clear text data');
    cipher.end();
  });
});
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Example: Using Cipheriv and piped streams:

import {
  createReadStream,
  createWriteStream,
} from 'node:fs';

import {
  pipeline,
} from 'node:stream';

const {
  scrypt,
  randomFill,
  createCipheriv,
} = await import('node:crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';

// First, we'll generate the key. The key length is dependent on the algorithm.
// In this case for aes192, it is 24 bytes (192 bits).
scrypt(password, 'salt', 24, (err, key) => {
  if (err) throw err;
  // Then, we'll generate a random initialization vector
  randomFill(new Uint8Array(16), (err, iv) => {
    if (err) throw err;

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

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

    pipeline(input, cipher, output, (err) => {
      if (err) throw err;
    });
  });
});
const {
  createReadStream,
  createWriteStream,
} = require('node:fs');

const {
  pipeline,
} = require('node:stream');

const {
  scrypt,
  randomFill,
  createCipheriv,
} = require('node:crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';

// First, we'll generate the key. The key length is dependent on the algorithm.
// In this case for aes192, it is 24 bytes (192 bits).
scrypt(password, 'salt', 24, (err, key) => {
  if (err) throw err;
  // Then, we'll generate a random initialization vector
  randomFill(new Uint8Array(16), (err, iv) => {
    if (err) throw err;

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

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

    pipeline(input, cipher, output, (err) => {
      if (err) throw err;
    });
  });
});
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Example: Using the cipher.update() and cipher.final() methods:

const {
  scrypt,
  randomFill,
  createCipheriv,
} = await import('node:crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';

// First, we'll generate the key. The key length is dependent on the algorithm.
// In this case for aes192, it is 24 bytes (192 bits).
scrypt(password, 'salt', 24, (err, key) => {
  if (err) throw err;
  // Then, we'll generate a random initialization vector
  randomFill(new Uint8Array(16), (err, iv) => {
    if (err) throw err;

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

    let encrypted = cipher.update('some clear text data', 'utf8', 'hex');
    encrypted += cipher.final('hex');
    console.log(encrypted);
  });
});
const {
  scrypt,
  randomFill,
  createCipheriv,
} = require('node:crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';

// First, we'll generate the key. The key length is dependent on the algorithm.
// In this case for aes192, it is 24 bytes (192 bits).
scrypt(password, 'salt', 24, (err, key) => {
  if (err) throw err;
  // Then, we'll generate a random initialization vector
  randomFill(new Uint8Array(16), (err, iv) => {
    if (err) throw err;

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

    let encrypted = cipher.update('some clear text data', 'utf8', 'hex');
    encrypted += cipher.final('hex');
    console.log(encrypted);
  });
});
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cipher.final([outputEncoding])#

• outputEncoding <string> The encoding of the return value.
• Returns: <Buffer> | <string> Any remaining enciphered contents. If outputEncoding is specified, a string is returned. If an outputEncoding is not provided, a Buffer is returned.

Once the cipher.final() method has been called, the Cipheriv object can no longer be used to encrypt data. Attempts to call cipher.final() more than once will result in an error being thrown.

cipher.getAuthTag()#

• Returns: <Buffer> When using an authenticated encryption mode (GCM, CCM, OCB, and chacha20-poly1305 are currently supported), the cipher.getAuthTag() method returns a Buffer containing the authentication tag that has been computed from the given data.

The cipher.getAuthTag() method should only be called after encryption has been completed using the cipher.final() method.

If the authTagLength option was set during the cipher instance's creation, this function will return exactly authTagLength bytes.

cipher.setAAD(buffer[, options])#

• buffer <string> | <ArrayBuffer> | <Buffer> | <TypedArray> | <DataView>
• options <Object> stream.transform options
  • plaintextLength <number>
  • encoding <string> The string encoding to use when buffer is a string.
• Returns: <Cipheriv> The same Cipheriv instance for method chaining.

When using an authenticated encryption mode (GCM, CCM, OCB, and chacha20-poly1305 are currently supported), the cipher.setAAD() method sets the value used for the additional authenticated data (AAD) input parameter.

The plaintextLength option is optional for GCM and OCB. When using CCM, the plaintextLength option must be specified and its value must match the length of the plaintext in bytes. See CCM mode.

The cipher.setAAD() method must be called before cipher.update().

cipher.setAutoPadding([autoPadding])#

• autoPadding <boolean> Default: true
• Returns: <Cipheriv> The same Cipheriv instance for method chaining.

When using block encryption algorithms, the Cipheriv class will automatically add padding to the input data to the appropriate block size. To disable the default padding call cipher.setAutoPadding(false).

When autoPadding is false, the length of the entire input data must be a multiple of the cipher's block size or cipher.final() will throw an error. Disabling automatic padding is useful for non-standard padding, for instance using 0x0 instead of PKCS padding.

The cipher.setAutoPadding() method must be called before cipher.final().

cipher.update(data[, inputEncoding][, outputEncoding])#

• data <string> | <Buffer> | <TypedArray> | <DataView>
• inputEncoding <string> The encoding of the data.
• outputEncoding <string> The encoding of the return value.
• Returns: <Buffer> | <string>

Updates the cipher with data. If the inputEncoding argument is given, the data argument is a string using the specified encoding. If the inputEncoding argument is not given, data must be a Buffer, TypedArray, or DataView. If data is a Buffer, TypedArray, or DataView, then inputEncoding is ignored.

The outputEncoding specifies the output format of the enciphered data. If the outputEncoding is specified, a string using the specified encoding is returned. If no outputEncoding is provided, a Buffer is returned.

The cipher.update() method can be called multiple times with new data until cipher.final() is called. Calling cipher.update() after cipher.final() will result in an error being thrown.

Class: Decipheriv#

• Extends: <stream.Transform>

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

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

The crypto.createDecipheriv() method is used to create Decipheriv instances. Decipheriv objects are not to be created directly using the new keyword.

Example: Using Decipheriv objects as streams:

import { Buffer } from 'node:buffer';
const {
  scryptSync,
  createDecipheriv,
} = await import('node: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 the async `crypto.scrypt()` instead.
const key = scryptSync(password, 'salt', 24);
// The IV is usually passed along with the ciphertext.
const iv = Buffer.alloc(16, 0); // Initialization vector.

const decipher = createDecipheriv(algorithm, key, iv);

let decrypted = '';
decipher.on('readable', () => {
  let chunk;
  while (null !== (chunk = decipher.read())) {
    decrypted += chunk.toString('utf8');
  }
});
decipher.on('end', () => {
  console.log(decrypted);
  // Prints: some clear text data
});

// Encrypted with same algorithm, key and iv.
const encrypted =
  'e5f79c5915c02171eec6b212d5520d44480993d7d622a7c4c2da32f6efda0ffa';
decipher.write(encrypted, 'hex');
decipher.end();
const {
  scryptSync,
  createDecipheriv,
} = require('node:crypto');
const { Buffer } = require('node:buffer');

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 the async `crypto.scrypt()` instead.
const key = scryptSync(password, 'salt', 24);
// The IV is usually passed along with the ciphertext.
const iv = Buffer.alloc(16, 0); // Initialization vector.

const decipher = createDecipheriv(algorithm, key, iv);

let decrypted = '';
decipher.on('readable', () => {
  let chunk;
  while (null !== (chunk = decipher.read())) {
    decrypted += chunk.toString('utf8');
  }
});
decipher.on('end', () => {
  console.log(decrypted);
  // Prints: some clear text data
});

// Encrypted with same algorithm, key and iv.
const encrypted =
  'e5f79c5915c02171eec6b212d5520d44480993d7d622a7c4c2da32f6efda0ffa';
decipher.write(encrypted, 'hex');
decipher.end();
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Example: Using Decipheriv and piped streams:

import {
  createReadStream,
  createWriteStream,
} from 'node:fs';
import { Buffer } from 'node:buffer';
const {
  scryptSync,
  createDecipheriv,
} = await import('node:crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';
// Use the async `crypto.scrypt()` instead.
const key = scryptSync(password, 'salt', 24);
// The IV is usually passed along with the ciphertext.
const iv = Buffer.alloc(16, 0); // Initialization vector.

const decipher = createDecipheriv(algorithm, key, iv);

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

input.pipe(decipher).pipe(output);
const {
  createReadStream,
  createWriteStream,
} = require('node:fs');
const {
  scryptSync,
  createDecipheriv,
} = require('node:crypto');
const { Buffer } = require('node:buffer');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';
// Use the async `crypto.scrypt()` instead.
const key = scryptSync(password, 'salt', 24);
// The IV is usually passed along with the ciphertext.
const iv = Buffer.alloc(16, 0); // Initialization vector.

const decipher = createDecipheriv(algorithm, key, iv);

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

input.pipe(decipher).pipe(output);
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Example: Using the decipher.update() and decipher.final() methods:

import { Buffer } from 'node:buffer';
const {
  scryptSync,
  createDecipheriv,
} = await import('node:crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';
// Use the async `crypto.scrypt()` instead.
const key = scryptSync(password, 'salt', 24);
// The IV is usually passed along with the ciphertext.
const iv = Buffer.alloc(16, 0); // Initialization vector.

const decipher = createDecipheriv(algorithm, key, iv);

// Encrypted using same algorithm, key and iv.
const encrypted =
  'e5f79c5915c02171eec6b212d5520d44480993d7d622a7c4c2da32f6efda0ffa';
let decrypted = decipher.update(encrypted, 'hex', 'utf8');
decrypted += decipher.final('utf8');
console.log(decrypted);
// Prints: some clear text data
const {
  scryptSync,
  createDecipheriv,
} = require('node:crypto');
const { Buffer } = require('node:buffer');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';
// Use the async `crypto.scrypt()` instead.
const key = scryptSync(password, 'salt', 24);
// The IV is usually passed along with the ciphertext.
const iv = Buffer.alloc(16, 0); // Initialization vector.

const decipher = createDecipheriv(algorithm, key, iv);

// Encrypted using same algorithm, key and iv.
const encrypted =
  'e5f79c5915c02171eec6b212d5520d44480993d7d622a7c4c2da32f6efda0ffa';
let decrypted = decipher.update(encrypted, 'hex', 'utf8');
decrypted += decipher.final('utf8');
console.log(decrypted);
// Prints: some clear text data
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decipher.final([outputEncoding])#

• outputEncoding <string> The encoding of the return value.
• Returns: <Buffer> | <string> Any remaining deciphered contents. If outputEncoding is specified, a string is returned. If an outputEncoding is not provided, a Buffer is returned.

Once the decipher.final() method has been called, the Decipheriv object can no longer be used to decrypt data. Attempts to call decipher.final() more than once will result in an error being thrown.

decipher.setAAD(buffer[, options])#

• buffer <string> | <ArrayBuffer> | <Buffer> | <TypedArray> | <DataView>
• options <Object> stream.transform options
  • plaintextLength <number>
  • encoding <string> String encoding to use when buffer is a string.
• Returns: <Decipheriv> The same Decipher for method chaining.

When using an authenticated encryption mode (GCM, CCM, OCB, and chacha20-poly1305 are currently supported), the decipher.setAAD() method sets the value used for the additional authenticated data (AAD) input parameter.

The options argument is optional for GCM. When using CCM, the plaintextLength option must be specified and its value must match the length of the ciphertext in bytes. See CCM mode.

The decipher.setAAD() method must be called before decipher.update().

When passing a string as the buffer, please consider caveats when using strings as inputs to cryptographic APIs.

decipher.setAuthTag(buffer[, encoding])#

• buffer <string> | <Buffer> | <ArrayBuffer> | <TypedArray> | <DataView>
• encoding <string> String encoding to use when buffer is a string.
• Returns: <Decipheriv> The same Decipher for method chaining.

When using an authenticated encryption mode (GCM, CCM, OCB, and chacha20-poly1305 are currently supported), the decipher.setAuthTag() method is used to pass in the received authentication tag. If no tag is provided, or if the cipher text has been tampered with, decipher.final() will throw, indicating that the cipher text should be discarded due to failed authentication. If the tag length is invalid according to NIST SP 800-38D or does not match the value of the authTagLength option, decipher.setAuthTag() will throw an error.

The decipher.setAuthTag() method must be called before decipher.update() for CCM mode or before decipher.final() for GCM and OCB modes and chacha20-poly1305. decipher.setAuthTag() can only be called once.

When passing a string as the authentication tag, please consider caveats when using strings as inputs to cryptographic APIs.

decipher.setAutoPadding([autoPadding])#

• autoPadding <boolean> Default: true
• Returns: <Decipheriv> The same Decipher for method chaining.

When data has been encrypted without standard block padding, calling decipher.setAutoPadding(false) will disable automatic padding to prevent decipher.final() from checking for and removing padding.

Turning auto padding off will only work if the input data's length is a multiple of the ciphers block size.

The decipher.setAutoPadding() method must be called before decipher.final().

decipher.update(data[, inputEncoding][, outputEncoding])#

• data <string> | <Buffer> | <TypedArray> | <DataView>
• inputEncoding <string> The encoding of the data string.
• outputEncoding <string> The encoding of the return value.
• Returns: <Buffer> | <string>

Updates the decipher with data. If the inputEncoding argument is given, the data argument is a string using the specified encoding. If the inputEncoding argument is not given, data must be a Buffer. If data is a Buffer then inputEncoding is ignored.

The outputEncoding specifies the output format of the enciphered data. If the outputEncoding is specified, a string using the specified encoding is returned. If no outputEncoding is provided, a Buffer is returned.

The decipher.update() method can be called multiple times with new data until decipher.final() is called. Calling decipher.update() after decipher.final() will result in an error being thrown.

Even if the underlying cipher implements authentication, the authenticity and integrity of the plaintext returned from this function may be uncertain at this time. For authenticated encryption algorithms, authenticity is generally only established when the application calls decipher.final().

Class: DiffieHellman#

The DiffieHellman class is a utility for creating Diffie-Hellman key exchanges.

Instances of the DiffieHellman class can be created using the crypto.createDiffieHellman() function.

import assert from 'node:assert';

const {
  createDiffieHellman,
} = await import('node:crypto');

// Generate Alice's keys...
const alice = createDiffieHellman(2048);
const aliceKey = alice.generateKeys();

// Generate Bob's keys...
const bob = createDiffieHellman(alice.getPrime(), alice.getGenerator());
const bobKey = bob.generateKeys();

// Exchange and generate the secret...
const aliceSecret = alice.computeSecret(bobKey);
const bobSecret = bob.computeSecret(aliceKey);

// OK
assert.strictEqual(aliceSecret.toString('hex'), bobSecret.toString('hex'));
const assert = require('node:assert');

const {
  createDiffieHellman,
} = require('node:crypto');

// Generate Alice's keys...
const alice = createDiffieHellman(2048);
const aliceKey = alice.generateKeys();

// Generate Bob's keys...
const bob = createDiffieHellman(alice.getPrime(), alice.getGenerator());
const bobKey = bob.generateKeys();

// Exchange and generate the secret...
const aliceSecret = alice.computeSecret(bobKey);
const bobSecret = bob.computeSecret(aliceKey);

// OK
assert.strictEqual(aliceSecret.toString('hex'), bobSecret.toString('hex'));
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diffieHellman.computeSecret(otherPublicKey[, inputEncoding][, outputEncoding])#

• otherPublicKey <string> | <ArrayBuffer> | <Buffer> | <TypedArray> | <DataView>
• inputEncoding <string> The encoding of an otherPublicKey string.
• outputEncoding <string> The encoding of the return value.
• Returns: <Buffer> | <string>

Computes the shared secret using otherPublicKey as the other party's public key and returns the computed shared secret. The supplied key is interpreted using the specified inputEncoding, and secret is encoded using specified outputEncoding. If the inputEncoding is not provided, otherPublicKey is expected to be a Buffer, TypedArray, or DataView.

If outputEncoding is given a string is returned; otherwise, a Buffer is returned.

diffieHellman.generateKeys([encoding])#

• encoding <string> The encoding of the return value.
• Returns: <Buffer> | <string>

Generates private and public Diffie-Hellman key values unless they have been generated or computed already, and returns the public key in the specified encoding. This key should be transferred to the other party. If encoding is provided a string is returned; otherwise a Buffer is returned.

This function is a thin wrapper around DH_generate_key(). In particular, once a private key has been generated or set, calling this function only updates the public key but does not generate a new private key.

diffieHellman.getGenerator([encoding])#

• encoding <string> The encoding of the return value.
• Returns: <Buffer> | <string>

Returns the Diffie-Hellman generator in the specified encoding. If encoding is provided a string is returned; otherwise a Buffer is returned.

diffieHellman.getPrime([encoding])#

• encoding <string> The encoding of the return value.
• Returns: <Buffer> | <string>

Returns the Diffie-Hellman prime in the specified encoding. If encoding is provided a string is returned; otherwise a Buffer is returned.

diffieHellman.getPrivateKey([encoding])#

• encoding <string> The encoding of the return value.
• Returns: <Buffer> | <string>

Returns the Diffie-Hellman private key in the specified encoding. If encoding is provided a string is returned; otherwise a Buffer is returned.

diffieHellman.getPublicKey([encoding])#

• encoding <string> The encoding of the return value.
• Returns: <Buffer> | <string>

Returns the Diffie-Hellman public key in the specified encoding. If encoding is provided a string is returned; otherwise a Buffer is returned.

diffieHellman.setPrivateKey(privateKey[, encoding])#

• privateKey <string> | <ArrayBuffer> | <Buffer> | <TypedArray> | <DataView>
• encoding <string> The encoding of the privateKey string.

Sets the Diffie-Hellman private key. If the encoding argument is provided, privateKey is expected to be a string. If no encoding is provided, privateKey is expected to be a Buffer, TypedArray, or DataView.

This function does not automatically compute the associated public key. Either diffieHellman.setPublicKey() or diffieHellman.generateKeys() can be used to manually provide the public key or to automatically derive it.

diffieHellman.setPublicKey(publicKey[, encoding])#

• publicKey <string> | <ArrayBuffer> | <Buffer> | <TypedArray> | <DataView>
• encoding <string> The encoding of the publicKey string.

Sets the Diffie-Hellman public key. If the encoding argument is provided, publicKey is expected to be a string. If no encoding is provided, publicKey is expected to be a Buffer, TypedArray, or DataView.

diffieHellman.verifyError#

A bit field containing any warnings and/or errors resulting from a check performed during initialization of the DiffieHellman object.

The following values are valid for this property (as defined in node:constants module):

• DH_CHECK_P_NOT_SAFE_PRIME
• DH_CHECK_P_NOT_PRIME
• DH_UNABLE_TO_CHECK_GENERATOR
• DH_NOT_SUITABLE_GENERATOR

Class: DiffieHellmanGroup#

The DiffieHellmanGroup class takes a well-known modp group as its argument. It works the same as DiffieHellman, except that it does not allow changing its keys after creation. In other words, it does not implement setPublicKey() or setPrivateKey() methods.

const { createDiffieHellmanGroup } = await import('node:crypto');
const dh = createDiffieHellmanGroup('modp16');
const { createDiffieHellmanGroup } = require('node:crypto');
const dh = createDiffieHellmanGroup('modp16');
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The following groups are supported:

• 'modp14' (2048 bits, RFC 3526 Section 3)
• 'modp15' (3072 bits, RFC 3526 Section 4)
• 'modp16' (4096 bits, RFC 3526 Section 5)
• 'modp17' (6144 bits, RFC 3526 Section 6)
• 'modp18' (8192 bits, RFC 3526 Section 7)

The following groups are still supported but deprecated (see Caveats):

• 'modp1' (768 bits, RFC 2409 Section 6.1)
• 'modp2' (1024 bits, RFC 2409 Section 6.2)
• 'modp5' (1536 bits, RFC 3526 Section 2)

These deprecated groups might be removed in future versions of Node.js.

Class: ECDH#

The ECDH class is a utility for creating Elliptic Curve Diffie-Hellman (ECDH) key exchanges.

Instances of the ECDH class can be created using the crypto.createECDH() function.

import assert from 'node:assert';

const {
  createECDH,
} = await import('node:crypto');

// Generate Alice's keys...
const alice = createECDH('secp521r1');
const aliceKey = alice.generateKeys();

// Generate Bob's keys...
const bob = createECDH('secp521r1');
const bobKey = bob.generateKeys();

// Exchange and generate the secret...
const aliceSecret = alice.computeSecret(bobKey);
const bobSecret = bob.computeSecret(aliceKey);

assert.strictEqual(aliceSecret.toString('hex'), bobSecret.toString('hex'));
// OK
const assert = require('node:assert');

const {
  createECDH,
} = require('node:crypto');

// Generate Alice's keys...
const alice = createECDH('secp521r1');
const aliceKey = alice.generateKeys();

// Generate Bob's keys...
const bob = createECDH('secp521r1');
const bobKey = bob.generateKeys();

// Exchange and generate the secret...
const aliceSecret = alice.computeSecret(bobKey);
const bobSecret = bob.computeSecret(aliceKey);

assert.strictEqual(aliceSecret.toString('hex'), bobSecret.toString('hex'));
// OK
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Static method: ECDH.convertKey(key, curve[, inputEncoding[, outputEncoding[, format]]])#

• key <string> | <ArrayBuffer> | <Buffer> | <TypedArray> | <DataView>
• curve <string>
• inputEncoding <string> The encoding of the key string.
• outputEncoding <string> The encoding of the return value.
• format <string> Default: 'uncompressed'
• Returns: <Buffer> | <string>

Converts the EC Diffie-Hellman public key specified by key and curve to the format specified by format. The format argument specifies point encoding and can be 'compressed', 'uncompressed' or 'hybrid'. The supplied key is interpreted using the specified inputEncoding, and the returned key is encoded using the specified outputEncoding.

Use crypto.getCurves() to obtain a list of available curve names. On recent OpenSSL releases, openssl ecparam -list_curves will also display the name and description of each available elliptic curve.

If format is not specified the point will be returned in 'uncompressed' format.

If the inputEncoding is not provided, key is expected to be a Buffer, TypedArray, or DataView.

Example (uncompressing a key):

const {
  createECDH,
  ECDH,
} = await import('node:crypto');

const ecdh = createECDH('secp256k1');
ecdh.generateKeys();

const compressedKey = ecdh.getPublicKey('hex', 'compressed');

const uncompressedKey = ECDH.convertKey(compressedKey,
                                        'secp256k1',
                                        'hex',
                                        'hex',
                                        'uncompressed');

// The converted key and the uncompressed public key should be the same
console.log(uncompressedKey === ecdh.getPublicKey('hex'));
const {
  createECDH,
  ECDH,
} = require('node:crypto');

const ecdh = createECDH('secp256k1');
ecdh.generateKeys();

const compressedKey = ecdh.getPublicKey('hex', 'compressed');

const uncompressedKey = ECDH.convertKey(compressedKey,
                                        'secp256k1',
                                        'hex',
                                        'hex',
                                        'uncompressed');

// The converted key and the uncompressed public key should be the same
console.log(uncompressedKey === ecdh.getPublicKey('hex'));
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ecdh.computeSecret(otherPublicKey[, inputEncoding][, outputEncoding])#

• otherPublicKey <string> | <ArrayBuffer> | <Buffer> | <TypedArray> | <DataView>
• inputEncoding <string> The encoding of the otherPublicKey string.
• outputEncoding <string> The encoding of the return value.
• Returns: <Buffer> | <string>

Computes the shared secret using otherPublicKey as the other party's public key and returns the computed shared secret. The supplied key is interpreted using specified inputEncoding, and the returned secret is encoded using the specified outputEncoding. If the inputEncoding is not provided, otherPublicKey is expected to be a Buffer, TypedArray, or DataView.

If outputEncoding is given a string will be returned; otherwise a Buffer is returned.

ecdh.computeSecret will throw an ERR_CRYPTO_ECDH_INVALID_PUBLIC_KEY error when otherPublicKey lies outside of the elliptic curve. Since otherPublicKey is usually supplied from a remote user over an insecure network, be sure to handle this exception accordingly.

ecdh.generateKeys([encoding[, format]])#

• encoding <string> The encoding of the return value.
• format <string> Default: 'uncompressed'
• Returns: <Buffer> | <string>

Generates private and public EC Diffie-Hellman key values, and returns the public key in the specified format and encoding. This key should be transferred to the other party.

The format argument specifies point encoding and can be 'compressed' or 'uncompressed'. If format is not specified, the point will be returned in 'uncompressed' format.

If encoding is provided a string is returned; otherwise a Buffer is returned.

ecdh.getPrivateKey([encoding])#

• encoding <string> The encoding of the return value.
• Returns: <Buffer> | <string> The EC Diffie-Hellman in the specified encoding.

If encoding is specified, a string is returned; otherwise a Buffer is returned.

ecdh.getPublicKey([encoding][, format])#

• encoding <string> The encoding of the return value.
• format <string> Default: 'uncompressed'
• Returns: <Buffer> | <string> The EC Diffie-Hellman public key in the specified encoding and format.

The format argument specifies point encoding and can be 'compressed' or 'uncompressed'. If format is not specified the point will be returned in 'uncompressed' format.

If encoding is specified, a string is returned; otherwise a Buffer is returned.

ecdh.setPrivateKey(privateKey[, encoding])#

• privateKey <string> | <ArrayBuffer> | <Buffer> | <TypedArray> | <DataView>
• encoding <string> The encoding of the privateKey string.

Sets the EC Diffie-Hellman private key. If encoding is provided, privateKey is expected to be a string; otherwise privateKey is expected to be a Buffer, TypedArray, or DataView.

If privateKey is not valid for the curve specified when the ECDH object was created, an error is thrown. Upon setting the private key, the associated public point (key) is also generated and set in the ECDH object.

ecdh.setPublicKey(publicKey[, encoding])#

• publicKey <string> | <ArrayBuffer> | <Buffer> | <TypedArray> | <DataView>
• encoding <string> The encoding of the publicKey string.

Sets the EC Diffie-Hellman public key. If encoding is provided publicKey is expected to be a string; otherwise a Buffer, TypedArray, or DataView is expected.

There is not normally a reason to call this method because ECDH only requires a private key and the other party's public key to compute the shared secret. Typically either ecdh.generateKeys() or ecdh.setPrivateKey() will be called. The ecdh.setPrivateKey() method attempts to generate the public point/key associated with the private key being set.

Example (obtaining a shared secret):

const {
  createECDH,
  createHash,
} = await import('node:crypto');

const alice = createECDH('secp256k1');
const bob = createECDH('secp256k1');

// This is a shortcut way of specifying one of Alice's previous private
// keys. It would be unwise to use such a predictable private key in a real
// application.
alice.setPrivateKey(
  createHash('sha256').update('alice', 'utf8').digest(),
);

// Bob uses a newly generated cryptographically strong
// pseudorandom key pair
bob.generateKeys();

const aliceSecret = alice.computeSecret(bob.getPublicKey(), null, 'hex');
const bobSecret = bob.computeSecret(alice.getPublicKey(), null, 'hex');

// aliceSecret and bobSecret should be the same shared secret value
console.log(aliceSecret === bobSecret);
const {
  createECDH,
  createHash,
} = require('node:crypto');

const alice = createECDH('secp256k1');
const bob = createECDH('secp256k1');

// This is a shortcut way of specifying one of Alice's previous private
// keys. It would be unwise to use such a predictable private key in a real
// application.
alice.setPrivateKey(
  createHash('sha256').update('alice', 'utf8').digest(),
);

// Bob uses a newly generated cryptographically strong
// pseudorandom key pair
bob.generateKeys();

const aliceSecret = alice.computeSecret(bob.getPublicKey(), null, 'hex');
const bobSecret = bob.computeSecret(alice.getPublicKey(), null, 'hex');

// aliceSecret and bobSecret should be the same shared secret value
console.log(aliceSecret === bobSecret);
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Class: Hash#

• Extends: <stream.Transform>

The Hash class is a utility for creating hash digests of data. It can be used in one of two ways:

• As a stream that is both readable and writable, where data is written to produce a computed hash digest on the readable side, or
• Using the hash.update() and hash.digest() methods to produce the computed hash.

The crypto.createHash() method is used to create Hash instances. Hash objects are not to be created directly using the new keyword.

Example: Using Hash objects as streams:

const {
  createHash,
} = await import('node:crypto');

const hash = createHash('sha256');

hash.on('readable', () => {
  // Only one element is going to be produced by the
  // hash stream.
  const data = hash.read();
  if (data) {
    console.log(data.toString('hex'));
    // Prints:
    //   6a2da20943931e9834fc12cfe5bb47bbd9ae43489a30726962b576f4e3993e50
  }
});

hash.write('some data to hash');
hash.end();
const {
  createHash,
} = require('node:crypto');

const hash = createHash('sha256');

hash.on('readable', () => {
  // Only one element is going to be produced by the
  // hash stream.
  const data = hash.read();
  if (data) {
    console.log(data.toString('hex'));
    // Prints:
    //   6a2da20943931e9834fc12cfe5bb47bbd9ae43489a30726962b576f4e3993e50
  }
});

hash.write('some data to hash');
hash.end();
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Example: Using Hash and piped streams:

import { createReadStream } from 'node:fs';
import { stdout } from 'node:process';
const { createHash } = await import('node:crypto');

const hash = createHash('sha256');

const input = createReadStream('test.js');
input.pipe(hash).setEncoding('hex').pipe(stdout);
const { createReadStream } = require('node:fs');
const { createHash } = require('node:crypto');
const { stdout } = require('node:process');

const hash = createHash('sha256');

const input = createReadStream('test.js');
input.pipe(hash).setEncoding('hex').pipe(stdout);
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Example: Using the hash.update() and hash.digest() methods:

const {
  createHash,
} = await import('node:crypto');

const hash = createHash('sha256');

hash.update('some data to hash');
console.log(hash.digest('hex'));
// Prints:
//   6a2da20943931e9834fc12cfe5bb47bbd9ae43489a30726962b576f4e3993e50
const {
  createHash,
} = require('node:crypto');

const hash = createHash('sha256');

hash.update('some data to hash');
console.log(hash.digest('hex'));
// Prints:
//   6a2da20943931e9834fc12cfe5bb47bbd9ae43489a30726962b576f4e3993e50
copy

hash.copy([options])#

• options <Object> stream.transform options
• Returns: <Hash>

Creates a new Hash object that contains a deep copy of the internal state of the current Hash object.

The optional options argument controls stream behavior. For XOF hash functions such as 'shake256', the outputLength option can be used to specify the desired output length in bytes.

An error is thrown when an attempt is made to copy the Hash object after its hash.digest() method has been called.

// Calculate a rolling hash.
const {
  createHash,
} = await import('node:crypto');

const hash = createHash('sha256');

hash.update('one');
console.log(hash.copy().digest('hex'));

hash.update('two');
console.log(hash.copy().digest('hex'));

hash.update('three');
console.log(hash.copy().digest('hex'));

// Etc.
// Calculate a rolling hash.
const {
  createHash,
} = require('node:crypto');

const hash = createHash('sha256');

hash.update('one');
console.log(hash.copy().digest('hex'));

hash.update('two');
console.log(hash.copy().digest('hex'));

hash.update('three');
console.log(hash.copy().digest('hex'));

// Etc.
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hash.digest([encoding])#

• encoding <string> The encoding of the return value.
• Returns: <Buffer> | <string>

Calculates the digest of all of the data passed to be hashed (using the hash.update() method). If encoding is provided a string will be returned; otherwise a Buffer is returned.

The Hash object can not be used again after hash.digest() method has been called. Multiple calls will cause an error to be thrown.

hash.update(data[, inputEncoding])#

• data <string> | <Buffer> | <TypedArray> | <DataView>
• inputEncoding <string> The encoding of the data string.

Updates the hash content with the given data, the encoding of which is given in inputEncoding. If encoding is not provided, and the data is a string, an encoding of 'utf8' is enforced. If data is a Buffer, TypedArray, or DataView, then inputEncoding is ignored.

This can be called many times with new data as it is streamed.

Class: Hmac#

• Extends: <stream.Transform>

The Hmac class is a utility for creating cryptographic HMAC digests. It can be used in one of two ways:

• As a stream that is both readable and writable, where data is written to produce a computed HMAC digest on the readable side, or
• Using the hmac.update() and hmac.digest() methods to produce the computed HMAC digest.

The crypto.createHmac() method is used to create Hmac instances. Hmac objects are not to be created directly using the new keyword.

Example: Using Hmac objects as streams:

const {
  createHmac,
} = await import('node:crypto');

const hmac = createHmac('sha256', 'a secret');

hmac.on('readable', () => {
  // Only one element is going to be produced by the
  // hash stream.
  const data = hmac.read();
  if (data) {
    console.log(data.toString('hex'));
    // Prints:
    //   7fd04df92f636fd450bc841c9418e5825c17f33ad9c87c518115a45971f7f77e
  }
});

hmac.write('some data to hash');
hmac.end();
const {
  createHmac,
} = require('node:crypto');

const hmac = createHmac('sha256', 'a secret');

hmac.on('readable', () => {
  // Only one element is going to be produced by the
  // hash stream.
  const data = hmac.read();
  if (data) {
    console.log(data.toString('hex'));
    // Prints:
    //   7fd04df92f636fd450bc841c9418e5825c17f33ad9c87c518115a45971f7f77e
  }
});

hmac.write('some data to hash');
hmac.end();
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Example: Using Hmac and piped streams:

import { createReadStream } from 'node:fs';
import { stdout } from 'node:process';
const {
  createHmac,
} = await import('node:crypto');

const hmac = createHmac('sha256', 'a secret');

const input = createReadStream('test.js');
input.pipe(hmac).pipe(stdout);
const {
  createReadStream,
} = require('node:fs');
const {
  createHmac,
} = require('node:crypto');
const { stdout } = require('node:process');

const hmac = createHmac('sha256', 'a secret');

const input = createReadStream('test.js');
input.pipe(hmac).pipe(stdout);
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Example: Using the hmac.update() and hmac.digest() methods:

const {
  createHmac,
} = await import('node:crypto');

const hmac = createHmac('sha256', 'a secret');

hmac.update('some data to hash');
console.log(hmac.digest('hex'));
// Prints:
//   7fd04df92f636fd450bc841c9418e5825c17f33ad9c87c518115a45971f7f77e
const {
  createHmac,
} = require('node:crypto');

const hmac = createHmac('sha256', 'a secret');

hmac.update('some data to hash');
console.log(hmac.digest('hex'));
// Prints:
//   7fd04df92f636fd450bc841c9418e5825c17f33ad9c87c518115a45971f7f77e
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