import { Cache } from 'cache-manager';
export interface CaptchaResult {
    svg: string;
    key: string;
}
export declare class CaptchaService {
    private cacheManager;
    constructor(cacheManager: Cache);
    generate(options?: {
        size?: number;
        charPreset?: string;
        noise?: number;
        width?: number;
        height?: number;
        fontSize?: number;
        color?: string;
    }): Promise<CaptchaResult>;
    validate(key: string, code: string): Promise<boolean>;
}