SubtleCrypto: decrypt() method
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
decrypt(algorithm, key, data)
Parameters
algorithm

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.
key

A CryptoKey
containing the key to be used for decryption. If using RSAOAEP, this is the privateKey
property of the CryptoKeyPair
object.
data

An ArrayBuffer
, a TypedArray
, or a DataView
containing the data to be decrypted (also known as ciphertext).
Return value
A Promise
that fulfills with an ArrayBuffer
containing the plaintext.
Exceptions
The promise is rejected when the following exceptions are encountered:

InvalidAccessError
DOMException

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
DOMException

Raised when the operation failed for an operationspecific 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
RSAOAEP
This code decrypts ciphertext
using RSAOAEP. See the complete code on GitHub.
function decryptMessage(privateKey, ciphertext) {
return window.crypto.subtle.decrypt(
{ name: "RSAOAEP" },
privateKey,
ciphertext,
);
}
AESCTR
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: "AESCTR", counter, length: 64 },
key,
ciphertext,
);
}
AESCBC
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: "AESCBC", iv }, key, ciphertext);
}
AESGCM
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: "AESGCM", iv }, key, ciphertext);
}
Specifications
Browser compatibility

Desktop 
Mobile 

Chrome 
Edge 
Firefox 
Internet Explorer 
Opera 
Safari 
WebView Android 
Chrome Android 
Firefox for Android 
Opera Android 
Safari on IOS 
Samsung Internet 
decrypt 
37 
7912–79Not supported: AESCTR.

34 
11Returns CryptoOperation instead of Promise 
24 
7 
37 
37 
34 
24 
7 
3.0 
See also