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SubtleCrypto.unwrapKey()

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

Syntax

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

Parameters

  • format is an enumerated value describing the data format of the key to unwrapped. 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.
Candidate Recommendation Initial definition.

Browser compatibility

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari
Basic support 37 (Yes) 34 (34) No support ? No support
Feature Android Chrome for Android Edge Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support (Yes) 37 (Yes) 34.0 (34) No support ? No support

See also

Document Tags and Contributors

 Contributors to this page: abbycar, bergr01, teoli
 Last updated by: abbycar,