/**
 * Enum defining the type of storage to use.
 */
export declare enum PowerAuthStorageType {
    /**
     * Secure storage: PowerAuth Keychain (iOS & Android)
     */
    SECURE = "SECURE",
    /**
     * Standard storage: UserDefaults (iOS) / SharedPreferences (Android)
     */
    STANDARD = "STANDARD"
}
/**
 * The `PowerAuthStorageUtils` class provides utility methods for storing and retrieving
 * string values in platform-specific secure and standard storage.
 */
export declare class PowerAuthStorageUtils {
    /**
     * Stores a string value for the given key in the specified storage type.
     * @param key The key to store the value under.
     * @param value The string value to store.
     * @param storageType The type of storage to use (SECURE or STANDARD).
     * @throws `PowerAuthErrorCode.WRONG_PARAMETER` if key or value is invalid.
     */
    static setString(key: string, value: string, storageType: PowerAuthStorageType): Promise<void>;
    /**
     * Retrieves a string value for the given key from the specified storage type.
     * @param key The key to retrieve the value for.
     * @param storageType The type of storage to use (SECURE or STANDARD).
     * @returns The stored string value, or undefined if the key does not exist.
     * @throws `PowerAuthErrorCode.WRONG_PARAMETER` if key is invalid.
     */
    static getString(key: string, storageType: PowerAuthStorageType): Promise<string | undefined>;
    /**
     * Checks if a value exists for the given key in the specified storage type.
     * @param key The key to check.
     * @param storageType The type of storage to use (SECURE or STANDARD).
     * @returns True if the key exists, false otherwise.
     * @throws `PowerAuthErrorCode.WRONG_PARAMETER` if key is invalid.
     */
    static exists(key: string, storageType: PowerAuthStorageType): Promise<boolean>;
    /**
     * Removes the value for the given key from the specified storage type.
     * @param key The key to remove.
     * @param storageType The type of storage to use (SECURE or STANDARD).
     * @returns True if the key was removed, false if the key did not exist.
     * @throws `PowerAuthErrorCode.WRONG_PARAMETER` if key is invalid.
     */
    static remove(key: string, storageType: PowerAuthStorageType): Promise<boolean>;
}