The HmacImportParams dictionary of the Web Crypto API represents the object that should be passed as the algorithm parameter into SubtleCrypto.importKey() or SubtleCrypto.unwrapKey(), when generating a key for the HMAC algorithm.



A DOMString. This should be set to HMAC.


A DOMString representing the name of the digest function to use. The can take a value of SHA-256, SHA-384, or SHA-512.

Warning: Although you can technically pass SHA-1 here, this is strongly discouraged as it is considered vulnerable.

length Optional

A Number representing the length in bits of the key. If this is omitted the length of the key is equal to the length of the digest generated by the digest function you have chosen. Unless you have a good reason to use a different length, omit this property and use the default.


See the examples for SubtleCrypto.importKey().


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

Browser compatibility

Browsers that support the "HMAC" algorithm for the SubtleCrypto.importKey(), SubtleCrypto.unwrapKey() methods will support this type.

See also