Available in all subroutines.

Returns a SHA-256-based message authentication code based on the supplied key and string s. The returned code is Base64-encoded.


declare local var.hmac_sha256_base64 STRING;
set var.hmac_sha256_base64 = digest.hmac_sha256_base64("key", "input");
# var.hmac_sha256_base64 is now "ngiewTr4gaisInpzbD58SQ6jtK/KDF+D3/Y5O2g6cuM="

Try it out

digest.hmac_sha256_base64 is used in the following solution recipes, which show real world use cases. Click RUN to provision a Fastly service, execute the code on Fastly, and see how the function behaves.

JSON web tokens

Decode the popular JWT format to verify user session tokens before forwarding trusted authentication data to your origin.

User contributed notes

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