After a successful verification, the shopper will be redirected to your gated content using what we call a “magic link”. This magic link could include an optional signature parameter that will let you validate its authenticity, giving you the confidence to provide secure access to private content or storefronts with the discounts pre-applied.
If you don’t need to validate the authenticity of the magic link, then it can simply be the destination URL of your gated content.You don’t need to keep reading this section.

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Requirements for signature validation

You need to ask your Customer Success Manager to set a Signature Key to your brand. If you manage more than one brand (one per territory, for example), you will need a different signature key for each brand. Important: Don’t share nor use this signature key in any public-facing code.

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Setup

You will need to build a small page that will act as a proxy between the shopper and the gated content. Gocertify will then use this page as the magic link destination. When redirecting the shopper to this proxy page, Gocertify will add the following query parameters:
  • signed_token: A unique identifier of the reward flow (related to the shopper and the specific campaign).
  • clicktimestamp: The time (UTC timestamp) when the shopper clicked the magic link.
  • signature: The SHA256 hash of gocertify{{clicktimestamp}}{{signed_token}}{{signature_key}}
An example of the full URL would be, assuming the signature key is 1234567890: 
https://your-page.com/proxy?clicktimestamp=20250326143831&signedtoken=af551f61&signature=21a07e72ef34d9546e1f41c56171f2990f5fa083a9f516ee891a394838062eca
The proxy page will need to recreate the signature using the same parameters and then confirm it’s the same one that was received as query string. Optionally, you can also validate the clicktimestamp is no older than X seconds (10 seconds is a good default). Here’s a sample implementation: 
    clicktimestamp = params[:clicktimestamp]
    signed_token = params[:signed_token]
    signature = params[:signature]
    signature_key = ENV['GOCERTIFY_SIGNATURE_KEY']

    input = ["gocertify", clicktimestamp, signed_token, signature_key].compact_blank.join
    computed_signature = Digest::SHA256.hexdigest(input)

    if computed_signature == params[:signature] && clicktimestamp.to_time > 10.seconds.ago
        # The signature is valid
    end