/**
 * Cryptographic utilities for bundle verification
 */
export declare class CryptoUtils {
    /**
     * Calculate SHA-256 checksum of data
     */
    static calculateChecksum(data: ArrayBuffer | string): Promise<string>;
    /**
     * Verify signature using public key
     */
    static verifySignature(data: ArrayBuffer | string, signature: string, publicKey: string): Promise<boolean>;
    /**
     * Convert base64 string to ArrayBuffer
     */
    private static base64ToArrayBuffer;
    /**
     * Generate a random nonce
     */
    static generateNonce(length?: number): string;
    /**
     * Validate checksum format
     */
    static isValidChecksum(checksum: string, algorithm?: 'SHA-256' | 'SHA-512'): boolean;
}