/**
 * MultiModalGuard (L8)
 *
 * Detects hidden instructions and malicious content in multi-modal inputs
 * (images, audio, documents, base64 payloads).
 *
 * Threat Model:
 * - ASI01: Agent Goal Hijack via manipulated media
 * - Multi-Modal Injection: Hidden text in images, audio with embedded instructions
 *
 * Detection Capabilities:
 * - Image metadata (EXIF) injection
 * - Steganographic patterns
 * - Hidden text detection (white-on-white, etc.)
 * - Base64 embedded payloads
 * - Document macro/script detection
 * - Audio transcript injection markers
 */
export interface MultiModalGuardConfig {
    /** Enable EXIF/metadata scanning */
    scanMetadata?: boolean;
    /** Enable base64 payload detection */
    detectBase64Payloads?: boolean;
    /** Enable steganography detection heuristics */
    detectSteganography?: boolean;
    /** Maximum allowed metadata size in bytes */
    maxMetadataSize?: number;
    /** Suspicious patterns to detect in extracted text */
    customPatterns?: RegExp[];
    /** Allowed MIME types */
    allowedMimeTypes?: string[];
    /** Block all multi-modal content (strict mode) */
    strictMode?: boolean;
}
export interface MultiModalContent {
    /** Content type: image, audio, document, base64 */
    type: "image" | "audio" | "document" | "base64" | "url";
    /** Raw content or base64 string */
    content?: string;
    /** MIME type if known */
    mimeType?: string;
    /** URL if remote content */
    url?: string;
    /** Filename if provided */
    filename?: string;
    /** Extracted metadata */
    metadata?: Record<string, any>;
    /** Any extracted text (OCR, transcripts, etc.) */
    extractedText?: string;
}
export interface MultiModalGuardResult {
    allowed: boolean;
    reason: string;
    violations: string[];
    request_id: string;
    content_analysis: {
        type: string;
        threats_detected: string[];
        metadata_suspicious: boolean;
        hidden_content_detected: boolean;
        injection_patterns_found: string[];
        risk_score: number;
    };
    recommendations: string[];
}
export declare class MultiModalGuard {
    private config;
    private readonly INJECTION_PATTERNS;
    private readonly SUSPICIOUS_METADATA_FIELDS;
    private readonly DANGEROUS_MIME_TYPES;
    private readonly STEGO_MARKERS;
    constructor(config?: MultiModalGuardConfig);
    /**
     * Analyze multi-modal content for hidden instructions or malicious payloads
     */
    check(content: MultiModalContent, requestId?: string): MultiModalGuardResult;
    /**
     * Batch check multiple content items
     */
    checkBatch(contents: MultiModalContent[], requestId?: string): MultiModalGuardResult;
    /**
     * Extract and analyze image metadata (EXIF simulation)
     * In production, use a proper EXIF parser
     */
    parseImageMetadata(base64Image: string): Record<string, any>;
    private scanMetadata;
    /**
     * @param rawHeuristics - Whether to run the invisible-character and
     * intra-token-homoglyph-mixing heuristics, which look for anomalies
     * introduced by an attacker in the ORIGINAL text. Must be false when
     * scanning an already-decoded/normalized variant: partial homoglyph
     * normalization (only the small set of commonly-spoofed letters) applied
     * to genuinely non-English text (e.g. a plain Cyrillic sentence) creates
     * artificial intra-token script mixing that isn't an attack, and would
     * otherwise false-positive on legitimate non-English content.
     */
    private scanText;
    private detectBase64Payloads;
    private detectSteganography;
    private checkUrl;
    private generateRecommendations;
}