Thedecrypt() method of theSubtleCrypto interface decrypts some encrypted data.It takes as arguments akey to decrypt with, some optional extra parameters, and the data to decrypt (also known as "ciphertext").It returns aPromise which will be fulfilled with the decrypted data (also known as "plaintext").

Syntax

decrypt(algorithm, key, data)

Parameters

algorithm

An object specifying thealgorithm to be used, and any extra parameters as required.The values given for the extra parameters must match those passed into the correspondingencrypt() call.

• To useRSA-OAEP, pass anRsaOaepParams object.
• To useAES-CTR, pass anAesCtrParams object.
• To useAES-CBC, pass anAesCbcParams object.
• To useAES-GCM, pass anAesGcmParams object.

key

ACryptoKey containing the key to be used for decryption.If using RSA-OAEP, this is theprivateKey property of theCryptoKeyPair object.

data

AnArrayBuffer, aTypedArray, or aDataView containing the data to be decrypted (also known asciphertext).

Return value

APromise that fulfills with anArrayBuffer containing the plaintext.

Exceptions

The promise is rejected when the following exceptions are encountered:

InvalidAccessErrorDOMException

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).

OperationErrorDOMException

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

Thedecrypt() method supports the same algorithms as theencrypt() method.

Examples

RSA-OAEP

This code decryptsciphertext 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 decryptsciphertext using AES in CTR mode.Note thatcounter 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 decryptsciphertext using AES in CBC mode. Note thativ must match the value that was used for encryption.See the complete code on GitHub.

function decryptMessage(key, ciphertext) {  // The iv value is the same as that used for encryption  return window.crypto.subtle.decrypt({ name: "AES-CBC", iv }, key, ciphertext);}

AES-GCM

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

function decryptMessage(key, ciphertext) {  // The iv value is the same as that used for encryption  return window.crypto.subtle.decrypt({ name: "AES-GCM", iv }, key, ciphertext);}

Specifications

Browser compatibility

See also

• SubtleCrypto.encrypt().
• RFC 3447 specifies RSAOAEP.
• NIST SP800-38A specifies CTR mode.
• NIST SP800-38A specifies CBC mode.
• NIST SP800-38D specifies GCM mode.
• FIPS 198-1 specifies HMAC.