# `Challenge.from` Creates a challenge from the given parameters. If `secretKey` option is provided, the challenge ID is computed as HMAC-SHA256 over the challenge parameters (realm|method|intent|request|expires|digest|opaque), cryptographically binding the ID to its contents. ## Usage ```ts twoslash import { Challenge } from 'mppx' // With HMAC-bound ID (recommended for servers) const challenge = Challenge.from( { realm: 'mpp.dev', method: 'tempo', intent: 'charge', request: { amount: '1000000', currency: '0x...', recipient: '0x...' }, secretKey: 'my-secret', }, ) ``` ### With explicit ID Use an explicit ID when you don't need HMAC-bound challenge verification. ```ts twoslash import { Challenge } from 'mppx' const challenge = Challenge.from({ id: 'abc123', realm: 'mpp.dev', method: 'tempo', intent: 'charge', request: { amount: '1000000', currency: '0x...', recipient: '0x...' }, }) ``` ## Return type ```ts type ReturnType = Challenge ``` A challenge object. ## Parameters ### parameters Challenge parameters. Must include either `id` or `secretKey`. #### description (optional) * **Type:** `string` Human-readable description of the payment. #### digest (optional) * **Type:** `string` Digest of the request body. #### expires (optional) * **Type:** `string` Expiration timestamp (ISO 8601). #### id (when not using secretKey) * **Type:** `string` Explicit challenge ID. #### intent * **Type:** `string` Intent type (for example, `"charge"`, `"session"`). #### meta (optional) * **Type:** `Record` Server-defined correlation data, serialized as `opaque` on the Challenge. #### method * **Type:** `string` Payment method (for example, "tempo", "stripe"). #### realm * **Type:** `string` Server realm (for example, hostname). #### request * **Type:** `Record` Method-specific request data. #### secretKey (when not using id) * **Type:** `string` Secret key for HMAC-bound challenge ID.