/**
 * CogmemAi Local Encryption — AES-256-GCM with quantum-resistant symmetric key.
 *
 * AES-256 is quantum-resistant: Grover's algorithm halves effective key strength
 * to ~AES-128, which remains computationally secure against quantum attack.
 *
 * Format: QE1:<base64(iv + authTag + ciphertext)>
 * - QE1 prefix = Quantum Encryption v1 (format identifier)
 * - IV: 12 bytes (96-bit, GCM standard)
 * - Auth tag: 16 bytes (128-bit, integrity verification)
 * - Ciphertext: variable length
 */
/**
 * Check if local encryption is enabled.
 */
export declare function isEncryptionEnabled(): boolean;
/**
 * Encrypt plaintext with AES-256-GCM.
 * Returns: QE1:<base64(iv + authTag + ciphertext)>
 */
export declare function encrypt(plaintext: string): string;
/**
 * Decrypt a QE1-prefixed ciphertext.
 * Returns plaintext, or the original string if not encrypted or decryption fails.
 */
export declare function decrypt(data: string): string;
/**
 * Check if a string is encrypted (has QE1: prefix).
 */
export declare function isEncrypted(data: string): boolean;
/**
 * Get encryption status info (for diagnostics, never expose the key).
 */
export declare function getEncryptionInfo(): {
    enabled: boolean;
    algorithm: string;
    keySource: string;
    quantumSafe: boolean;
};