The SubtleCrypto.sign() method returns a Promise containing the signature corresponding to the text, algorithm and key given as parameters.


var signature = crypto.subtle.sign(algorithm, key, text2sign);


  • algorithm is an object specifying the signature function to be used and its parameters; if there are no parameters, algorithm can be a DOMString with the algorithm name. Supported values are: HMAC, RSASSA-PKCS1-v1_5, and ECDSA.
  • key is a CryptoKey containing the private key to be used for signing.
  • text2sign is a ArrayBuffer or an ArrayBufferView containing the data to be signed.

Return value

  • signature is a Promise that returns the signature on success.


The promise is rejected when the following exception is encountered:

  • InvalidAccessError when the signing key is not a key for the request signing algorithm or when trying to use an algorithm that is either unknown or isn't suitable for signing.


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

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support3712


32 — 341

FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support373712


32 — 341


1. 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.

2. Returns CryptoOperation instead of Promise

See also

Document Tags and Contributors

Contributors to this page: jvmccarthy, fscholz, Dans24, abbycar, groovecoder, dskloet, teoli
Last updated by: jvmccarthy,