/**
 * In-memory nonce cache implementation
 *
 * WARNING: This implementation is only suitable for single-instance deployments.
 * For multi-instance deployments, use Redis, DynamoDB, or Cloudflare KV implementations.
 */
import { NonceCache } from "@kya-os/contracts/handshake";
/**
 * In-memory nonce cache with TTL support
 */
export declare class MemoryNonceCache implements NonceCache {
    private cache;
    private cleanupInterval?;
    constructor(cleanupIntervalMs?: number);
    /**
     * Check if a nonce exists in the cache
     */
    has(nonce: string, agentDid?: string): Promise<boolean>;
    /**
     * Add a nonce to the cache with TTL
     * MUST ensure atomic add-if-absent semantics for replay prevention
     */
    add(nonce: string, ttlSeconds: number, agentDid?: string): Promise<void>;
    /**
     * Clean up expired entries
     * Safe to call frequently and should be no-op for backends that auto-expire
     */
    cleanup(): Promise<void>;
    /**
     * Get cache statistics
     */
    getStats(): {
        size: number;
        expired: number;
    };
    /**
     * Clear all entries (useful for testing)
     */
    clear(): void;
    /**
     * Destroy the cache and stop cleanup interval
     */
    destroy(): void;
}