Add Flow Action: HMAC Signature Generator (scoped-safe)

[isaac-vicentini]

HMAC Signature Generator (Flow Action)

This Flow Action computes a keyed hash (HMAC) of the input payload.
It supports common algorithms and handles raw or Base64-encoded secrets.

Inputs

• payload (String) — Text to sign (e.g., request body or signedPayload).
• secret (String) — Shared secret used to compute the HMAC.
• algorithm (Choice) — HmacSHA256 (default), HmacSHA1, HmacSHA512.
• secret_encoding (Choice) — raw (default) or base64.

  The underlying API expects the secret in Base64. If you pass a raw secret, this action converts it for you.

Output

• signature (String, Base64) — The computed HMAC in Base64.

Example

1. Default (HmacSHA256, secret as raw)
   payload: {"id":123,"ok":true}
   secret: mysecret
   algorithm: HmacSHA256
   secret_encoding: raw

Result → Base64 signature (compare with your provider/tool).

[github-actions]

✅ Valid PR for ActionPack

Thank you for your contribution. This PR complies with the CONTRIBUTING.md.
A maintainer will review this shortly. In the meantime, Happy Hacking!

[SapphicFire]

Looks good to me!