SubtleCrypto.unwrapKey()

The SubtleCrypto.unwrapKey() method returns a Promise of a CryptoKey corresponding to the wrapped key given in parameter.

Syntax

var result = crypto.subtle.unwrapKey(format, wrappedKey, unwrappingKey, unwrapAlgo, unwrappedKeyAlgo, extractable, keyUsages);

Parameters

  • format is an enumerated value describing the data format of the key to unwrap. It can be one of the following:
  • wrappedKey is a ArrayBuffer or a ... containing the wrapped key in the given format.
  • unwrappingKey is the CryptoKey to use to unwrap.
  • unwrapAlgo is the DOMString representing the algorithm used to perform the unwrapping. It is one of the following: AES-CBC, AES-CTR, AES-GCM, RSA-OAEP, and AES-KW.
  • unwrappedKeyAlgo is the DOMString representing the algorithm of the wrapped key.
  • extractable is a Boolean indicating if the key can be extracted from the CryptoKey object at a later stage.
  • keyUsages  is an Array indicating what can be done with the unwrapped key. Possible values of the array are:
    • "encrypt", allowing the key to be used for encrypting messages.
    • "decrypt", allowing the key to be used for decrypting messages.
    • "sign", allowing the key to be used for signing messages.
    • "verify", allowing the key to be used for verifying the signature of messages.
    • "deriveKey", allowing the key to be used as a base key when deriving a new key.
    • "deriveBits", allowing the key to be used as a base key when deriving bits of data for use in cryptographic primitives.
    • "wrapKey", allowing the key to wrap a symmetric key for usage (transfer, storage) in unsecure environments.
    • "unwrapKey", allowing the key to unwrap a symmetric key for usage (transfer, storage) in unsecure environments.

Return value

Exceptions

The promise is rejected when one of the following exceptions is encountered:

  • InvalidAccessError when the unwrapping key is not a key for the requested unwrap algorithm or if the CryptoKey.usages value of that key doesn't contain "unwrap".
  • NotSupported when trying to use an algorithm that is either unknown or isn't suitable for encryption or wrapping.
  • SyntaxError when keyUsages is empty but the unwrapped key is of type "secret" or "private".
  • TypeError when trying to use an invalid format.

Specifications

Specification Status Comment
Web Cryptography API
The definition of 'SubtleCrypto.unwrapKey()' in that specification.
Recommendation Initial definition.

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidiOS SafariSamsung Internet
Basic supportChrome Full support 37Edge Full support 12Firefox 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 KeyOperation instead of Promise
Opera Full support 24Safari Full support 7WebView Android ? Chrome Android Full support 37Edge Mobile Full support 12Firefox 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 24Safari iOS Full support 7Samsung Internet Android Full support 6.0

Legend

Full support  
Full support
Partial support  
Partial support
Compatibility unknown  
Compatibility unknown
See implementation notes.
See implementation notes.
User must explicitly enable this feature.
User must explicitly enable this feature.

See also

Document Tags and Contributors

Contributors to this page: fscholz, fabrice.desre, darlesson, Dans24, abbycar, bergr01, teoli
Last updated by: fscholz,