Web/API/SubtleCrypto/decrypt

Secure contextThis feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

The decrypt() method of the SubtleCrypto interface decrypts some encrypted data. It takes as arguments a key to decrypt with, some optional extra parameters, and the data to decrypt (also known as "ciphertext"). It returns a Promise which will be fulfilled with the decrypted data (also known as "plaintext").

Syntax

const result = crypto.subtle.decrypt(algorithm, key, data);

Parameters

algorithm is an object specifying the algorithm to be used, and any extra parameters as required. The values given for the extra parameters must match those passed into the corresponding encrypt() call.
- To use RSA-OAEP, pass an RsaOaepParams object.
- To use AES-CTR, pass an AesCtrParams object.
- To use AES-CBC, pass an AesCbcParams object.
- To use AES-GCM, pass an AesGcmParams object.
key is a CryptoKey containing the key to be used for decryption. If using RSA-OAEP, this is the privateKey property of the CryptoKeyPair object.
data is a BufferSource containing the data to be decrypted (also known as ciphertext).

Return value

result is a Promise that fulfills with an ArrayBuffer containing the plaintext.

Exceptions

The promise is rejected when the following exceptions are encountered:

InvalidAccessError: Raised when the requested operation is not valid for the provided key (e.g. invalid encryption algorithm, or invalid key for the specified encryption algorithm).
OperationError: Raised when the operation failed for an operation-specific reason (e.g. algorithm parameters of invalid sizes, or there was an error decrypting the ciphertext).

Supported algorithms

The decrypt() method supports the same algorithms as the encrypt() method.

Examples

Note: You can [[../../../../../../../mdn.github.io/dom-examples/web-crypto/encrypt-decrypt/index|try the working examples]] on GitHub.

RSA-OAEP

This code decrypts ciphertext using RSA-OAEP. See the complete code on GitHub.

function decryptMessage(privateKey, ciphertext) {
  return window.crypto.subtle.decrypt(
    {
      name: "RSA-OAEP"
    },
    privateKey,
    ciphertext
  );
}

AES-CTR

This code decrypts ciphertext using AES in CTR mode. Note that counter must match the value that was used for encryption. See the complete code on GitHub.

function decryptMessage(key, ciphertext) {
  return window.crypto.subtle.decrypt(
    {
      name: "AES-CTR",
      counter,
      length: 64
    },
    key,
    ciphertext
  );
}

AES-CBC

This code decrypts ciphertext using AES in CBC mode. Note that iv must match the value that was used for encryption. See the complete code on GitHub.

function decryptMessage(key, ciphertext) {
  return window.crypto.subtle.decrypt(
    {
      name: "AES-CBC",
      iv: iv
    },
    key,
    ciphertext
  );
}

AES-GCM

This code decrypts ciphertext using AES in GCM mode. Note that iv must match the value that was used for encryption. See the complete code on GitHub.

function decryptMessage(key, ciphertext) {
  return window.crypto.subtle.decrypt(
    {
      name: "AES-GCM",
      iv: iv
    },
    key,
    ciphertext
  );
}

Specifications

Specification	Status	Comment
Web Cryptography APIThe definition of 'SubtleCrypto.decrypt()' in that specification.	Recommendation	Initial definition.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`decrypt`	Chrome Full support 37	Edge Partial support 12 Notes' Partial support 12 Notes' Notes' Not supported: AES-CTR.	Firefox Full support 34 Full support 34 No support 32 — 34 Disabled' Disabled' From version 32 until version 34 (exclusive): this feature is behind the `dom.webcrypto.enabled` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	IE Partial support 11 Notes' Partial support 11 Notes' Notes' Returns `CryptoOperation` instead of `Promise`	Opera Full support 24	Safari Full support 7	WebView Android Full support 37	Chrome Android Full support 37	Firefox Android Full support 34 Full support 34 No support 32 — 34 Disabled' Disabled' From version 32 until version 34 (exclusive): this feature is behind the `dom.webcrypto.enabled` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	Opera Android Full support 24	Safari iOS Full support 7	Samsung Internet Android Full support 6.0

Legend

Full support: Full support
Partial support: Partial support
See implementation notes.': See implementation notes.
User must explicitly enable this feature.': User must explicitly enable this feature.