/**
 * @module
 *
 * Implements the `client_secret_post` client authentication method, where the
 * client authenticates by including its `client_id` and `client_secret` in the
 * request body as form-urlencoded or JSON parameters.
 *
 * @see https://datatracker.ietf.org/doc/html/rfc6749#section-2.3.1
 */
import { ClientAuthMethod, ClientAuthMethodResponse } from "./types.js";
/**
 * {@link ClientAuthMethod} implementation for the `client_secret_post` authentication method.
 *
 * Extracts client credentials from the request body (`client_id` and `client_secret`
 * parameters), supporting both `application/x-www-form-urlencoded` and `application/json`
 * content types.
 *
 * @see https://datatracker.ietf.org/doc/html/rfc6749#section-2.3.1
 */
export declare class ClientSecretPost implements ClientAuthMethod {
    /**
     * The identifier for this authentication method.
     * Always `"client_secret_post"`.
     */
    get method(): "client_secret_post";
    /**
     * Whether the client secret is optional for this method.
     * Always `false` - a client secret is required for `client_secret_post`.
     */
    get secretIsOptional(): boolean;
    /**
     * Extracts the `client_id` and `client_secret` from the request body.
     *
     * Sets `hasAuthMethod` to `true` only when both `client_id` and `client_secret`
     * fields are present in the body, allowing the caller to distinguish between
     * "this method was attempted" and "no credentials provided".
     *
     * Supports `application/x-www-form-urlencoded` and `application/json` content types.
     * Returns `{ hasAuthMethod: false }` for any other content type.
     *
     * @param req - The incoming HTTP request.
     * @returns The extracted client credentials, or `{ hasAuthMethod: false }` if the
     *   body does not contain `client_id` and `client_secret` fields.
     */
    extractClientCredentials(req: Request): Promise<ClientAuthMethodResponse>;
}
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