export interface UnlockCache {
    tryRestoreUserKey(params?: {
        keyVersion?: number;
        origin?: string;
    }): Promise<CryptoKey | null>;
    cacheUserKeyFromMaterial(keyMaterial32: BufferSource, // 32 bytes from HKDF
    opts?: {
        ttlMs?: number;
        keyVersion?: number;
    }): Promise<void>;
    clear(): Promise<void>;
    hardReset(): Promise<void>;
}
/**
 * No-op implementation: never caches, never restores.
 * Useful for tests or environments without IndexedDB.
 */
export declare class NoopUnlockCache implements UnlockCache {
    tryRestoreUserKey(): Promise<CryptoKey | null>;
    cacheUserKeyFromMaterial(): Promise<void>;
    clear(): Promise<void>;
    hardReset(): Promise<void>;
}
export declare class IdbUnlockCache implements UnlockCache {
    private ttlMs;
    constructor(ttlMs?: number);
    cacheUserKeyFromMaterial(keyMaterial32: ArrayBuffer, opts?: {
        ttlMs?: number;
        keyVersion?: number;
    }): Promise<void>;
    tryRestoreUserKey(params?: {
        keyVersion?: number;
        origin?: string;
    }): Promise<CryptoKey | null>;
    clear(): Promise<void>;
    hardReset(): Promise<void>;
}
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