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The SubtleCrypto interface of the Web Crypto API provides a number of low-level cryptographic functions. It is accessed via the Crypto.subtle properties available in a window context (via Window.crypto).

Warning: This API provides a number of low-level cryptographic primitives. It's very easy to misuse them, and the pitfalls involved can be very subtle.

Even assuming you use the basic cryptographic functions correctly, secure key management and overall security system design are extremely hard to get right, and are generally the domain of specialist security experts.

Errors in security system design and implementation can make the security of the system completely ineffective.

If you're not sure you know what you are doing, you probably shouldn't be using this API.

Overview

We can split the functions implemented by this API into two groups: cryptography functions and key management functions.

Cryptography functions

These are the functions you can use to implement security features such as privacy and authentication in a system. The SubtleCrypto API provides the following cryptography functions:

* sign() and verify(): create and verify digital signatures.
* encrypt() and decrypt(): encrypt and decrypt data.
* digest(): create a fixed-length, collision-resistant digest of some data.

Key management functions

Except for digest(), all the cryptography functions in the API use cryptographic keys. In the SubtleCrypto API a cryptographic key is represented using a CryptoKey object. To perform operations like signing and encrypting, you pass a CryptoKey object into the sign() or encrypt() function.

Generating and deriving keys

The generateKey() and deriveKey() functions both create a new CryptoKey object.

The difference is that generateKey() will generate a new distinct key value each time you call it, while deriveKey() derives a key from some initial keying material. If you provide the same keying material to two separate calls to deriveKey(), you will get two CryptoKey objects that have the same underlying value. This is useful if, for example, you want to derive an encryption key from a password and later derive the same key from the same password to decrypt the data.

Importing and exporting keys

To make keys available outside your app, you need to export the key, and that's what exportKey() is for. You can choose one of a number of export formats.

The inverse of exportKey() is importKey(). You can import keys from other systems, and support for standard formats like PKCS #8 and JSON Web Key helps you do this. The exportKey() function exports the key in an unencrypted format.

If the key is sensitive you should use wrapKey(), which exports the key and then encrypts it using another key; the API calls a "key-wrapping key".

The inverse of wrapKey() is unwrapKey(), which decrypts then imports the key.

Storing keys

CryptoKey objects can be stored using the structured clone algorithm, meaning that you can store and retrieve them using standard web storage APIs. The specification expects that most developers will use the IndexedDB API to store CryptoKey objects.

Supported algorithms

The cryptographic functions provided by the Web Crypto API can be performed by one or more different cryptographic algorithms: the algorithm argument to the function indicates which algorithm to use. Some algorithms need extra parameters: in these cases the algorithm argument is a dictionary object that includes the extra parameters.

The table below summarises which algorithms are suitable for which cryptographic operations:

 

sign()

verify()

encrypt()

decrypt()

digest()

deriveBits()

deriveKey()

wrapKey()

unwrapKey()

RSASSA-PKCS1-v1_5        
RSA-PSS        
ECDSA        
HMAC        
RSA-OAEP      
AES-CTR      
AES-CBC      
AES-GCM      
SHA-1        
SHA-256        
SHA-384        
SHA-512        
ECDH        
HKDF        
PBKDF2        
AES-KW        

Properties

This interface neither inherits, nor implements, any property.

Methods

This interface doesn't inherit any method.

SubtleCrypto.encrypt()
Returns a Promise that fufills with the encrypted data corresponding to the clear text, algorithm, and key given as parameters.
SubtleCrypto.decrypt()
Returns a Promise that fulfills with the clear data corresponding to the encrypted text, algorithm, and key given as parameters.
SubtleCrypto.sign()
Returns a Promise that fulfills with the signature corresponding to the text, algorithm, and key given as parameters.
SubtleCrypto.verify()
Returns a Promise that fulfills with a Boolean value indicating if the signature given as a parameter matches the text, algorithm, and key that are also given as parameters.
SubtleCrypto.digest()
Returns a Promise that fulfills with a digest generated from the algorithm and text given as parameters.
SubtleCrypto.generateKey()
Returns a Promise that fulfills with a newly-generated CryptoKey, for symmetrical algorithms, or a CryptoKeyPair, containing two newly generated keys, for asymmetrical algorithms. These will match the algorithm, usages, and extractability given as parameters.
SubtleCrypto.deriveKey()
Returns a Promise that fulfills with a newly generated CryptoKey derived from the master key and specific algorithm given as parameters.
SubtleCrypto.deriveBits()
Returns a Promise that fulfills with a newly generated buffer of pseudo-random bits derived from the master key and specific algorithm given as parameters.
SubtleCrypto.importKey()
Returns a Promise that fulfills with a CryptoKey corresponding to the format, the algorithm, raw key data, usages, and extractability given as parameters.
SubtleCrypto.exportKey()
Returns a Promise that fulfills with a buffer containing the key in the requested format.
SubtleCrypto.wrapKey()
Returns a Promise that fulfills with a wrapped symmetric key for usage (transfer and storage) in insecure environments. The wrapped key matches the format specified in the given parameters, and wrapping is done by the given wrapping key, using the specified algorithm.
SubtleCrypto.unwrapKey()
Returns a Promise that fulfills with a CryptoKey corresponding to the wrapped key given in the parameter.

Specifications

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

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Basic supportChrome Full support 37Edge Partial 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 11Opera Full support 24Safari Full support 10.1
Full support 10.1
Full support 7
Prefixed
Prefixed Implemented with the vendor prefix: WebKit
WebView Android Full support 37Chrome 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 10.1
Full support 10.1
Full support 7
Prefixed
Prefixed Implemented with the vendor prefix: WebKit
Samsung Internet Android Full support 6.0
encryptChrome Full support 37Edge Partial support 12
Notes
Partial support 12
Notes
Notes Not supported: AES-CTR.
Firefox 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 CryptoOperation instead of Promise
Opera Full support 24Safari Full support 7WebView Android Full support 37Chrome 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
decryptChrome Full support 37Edge Partial support 12
Notes
Partial support 12
Notes
Notes Not supported: AES-CTR.
Firefox 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 CryptoOperation instead of Promise
Opera Full support 24Safari Full support 7WebView Android Full support 37Chrome 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
signChrome Full support 37Edge Partial support 12
Notes
Partial support 12
Notes
Notes Not supported: RSA-PSS, ECDSA.
Firefox 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 CryptoOperation instead of Promise
Opera Full support 24Safari Full support 7WebView Android Full support 37Chrome 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
verifyChrome Full support 37Edge Partial support 12
Notes
Partial support 12
Notes
Notes Not supported: RSA-PSS, ECDSA.
Firefox 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 CryptoOperation instead of Promise
Opera Full support 24Safari Full support 7WebView Android Full support 37Chrome 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
digestChrome Full support 37Edge Partial support 12
Notes
Partial support 12
Notes
Notes Not supported: SHA-1.
Firefox 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 CryptoOperation instead of Promise
Opera Full support 24Safari Full support 7WebView Android Full support 37Chrome 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
generateKeyChrome Full support 37Edge Partial support 12
Notes
Partial support 12
Notes
Notes Not supported: RSA-PSS, ECDSA, ECDH.
Notes Not supported: AES-CTR.
Firefox 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 Full support 37Chrome 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
deriveKeyChrome Full support 37Edge Partial support 12
Notes
Partial support 12
Notes
Notes Not supported: ECDH.
Notes Not supported: HKDF, PBKDF2.
Firefox 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 No support NoOpera Full support 24Safari Full support 7WebView Android Full support 37Chrome 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
deriveBitsChrome Full support 37Edge Partial support 12
Notes
Partial support 12
Notes
Notes Not supported: ECDH.
Notes Not supported: HKDF, PBKDF2.
Firefox 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 No support NoOpera Full support 24Safari Full support 7WebView Android Full support 37Chrome 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
importKeyChrome Full support 37Edge Partial support 12
Notes
Partial support 12
Notes
Notes Not supported: RSA-PSS, ECDSA, ECDH.
Notes Not supported: AES-CTR, HKDF, PBKDF2.
Firefox 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 Full support 37Chrome 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
exportKeyChrome Full support 37Edge Partial support 12
Notes
Partial support 12
Notes
Notes Not supported: RSA-PSS, ECDSA, ECDH.
Notes Not supported: AES-CTR.
Firefox 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 Full support 37Chrome 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
wrapKeyChrome Full support 37Edge Partial support 12
Notes
Partial support 12
Notes
Notes Not supported: AES-CTR.
Firefox 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 Full support 37Chrome 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
unwrapKeyChrome Full support 37Edge Partial support 12
Notes
Partial support 12
Notes
Notes Not supported: AES-CTR.
Firefox 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
Available in workersChrome ? Edge No support NoFirefox Full support 48IE ? Opera ? Safari ? WebView Android ? Chrome Android ? Edge Mobile ? Firefox Android ? Opera Android ? Safari iOS ? Samsung Internet Android ?

Legend

Full support  
Full support
Partial support  
Partial support
No support  
No support
Compatibility unknown  
Compatibility unknown
See implementation notes.
See implementation notes.
User must explicitly enable this feature.
User must explicitly enable this feature.
Requires a vendor prefix or different name for use.
Requires a vendor prefix or different name for use.

See also