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Custom Parameters

When integrating with ALTCHA Sentinel, the challenge generation endpoint GET /v1/challenge allows you to pass custom parameters that are included with the verification data returned at the final submission step.

Custom parameters let you attach additional metadata that your server can process or validate during verification.

Usage

Custom parameters are provided as URL query parameters prefixed with params.:

?params.param_name=param_value

All custom parameters:

  • are incorporated into the challenge salt (signed and verifiable via the challenge signature)
  • appear in the verificationData object returned by the API

Limits

  • Maximum of 10 custom parameters
  • Maximum of 20 characters per parameter name
  • Maximum of 100 characters per parameter value

Example

Challenge request

GET /v1/challenge?params.abc=123&params.def=456

Verification data

The custom parameters are included in the verificationData object:

{
  "id": "...",
  "classification": "...",
  "score": 0,
  "params.abc": "123",
  "params.def": "456"
}