import { IndexHelperBase } from './IndexHelperBase.js';
/**
 * Version 2 index helper. Blinds attributes in two stages: an unkeyed SHA-256
 * pre-hash of each canonicalized value (cacheable and byte-concatenated for
 * compound indexes), followed by a keyed HMAC pass over the resulting digests.
 * The shared, blinding-agnostic machinery lives in `IndexHelperBase`.
 */
export declare class IndexHelper extends IndexHelperBase {
    _cache: any;
    /**
     * Creates a new IndexHelper instance that can be used to blind EDV
     * document attributes to enable indexing.
     *
     * @returns {IndexHelper} An IndexHelper instance.
     */
    constructor();
    /**
     * Ensures that future documents inserted or updated using this client
     * instance will be indexed according to the given attribute, additionally
     * prewarming the HMAC cache when an `hmac` is supplied. See
     * `IndexHelperBase.ensureIndex` for the indexing semantics.
     *
     * @param {object} options - The options to use.
     * @param {string|string[]} options.attribute - The attribute name or an
     *   array of attribute names to create a unique compound index.
     * @param {boolean} [options.unique=false] - Set to `true` if the index
     *   should be considered unique, `false` if not.
     * @param {object} [options.hmac] - An optional HMAC API with `id`, `sign`,
     *   and `verify` properties for prewarming caches.
     */
    ensureIndex({ attribute, unique, hmac }?: any): void;
    /**
     * Blinds a Uint8Array of bytes using the given HMAC API.
     *
     * @param {object} hmac - An HMAC API with `id`, `sign`, and `verify`
     *   properties.
     * @param {Uint8Array} data - The value to blind.
     *
     * @returns {Promise<string>} - Resolves to the blinded value.
     */
    _blindData(hmac: any, data: any): Promise<string>;
    /**
     * Blinds a hashed attribute (compound or simple) using the given HMAC API.
     *
     * @param {object} options - The options to use.
     * @param {object} options.hmac - An HMAC API with `id`, `sign`, and `verify`
     *   properties.
     * @param {object} options.hashedAttribute - The attribute with `name`,
     *   `value`, and optional `unique` property; `name` and `value` MUST be
     *   Uint8Arrays.
     *
     * @returns {Promise<object>} - Resolves to an object
     *   `{name, value, unique?}`.
     */
    _blindHashedAttribute({ hmac, hashedAttribute }: any): Promise<any>;
    _buildBlindAttributes({ hmac, doc, equal, has }: any): Promise<any[]>;
    /**
     * Hashes a single attribute, converting its name and value into a hashed
     * name and hashed value.
     *
     * @param {object} options - The options to use.
     * @param {string} options.name - A name associated with a value.
     * @param {any} options.value - The value associated with the name for the
     *   attribute.
     *
     * @returns {Promise<object>} - Resolves to an object `{name, value}`.
     */
    _hashAttribute({ name, value }: any): Promise<{
        name: Uint8Array<ArrayBufferLike> & Uint8Array<ArrayBuffer>;
        value: Uint8Array<ArrayBufferLike> & Uint8Array<ArrayBuffer>;
    }>;
    /**
     * Builds a hashed compound attribute from an array of hashed attributes
     * via the given HMAC API.
     *
     * @param {object} options - The options to use.
     * @param {Array} options.hashedAttributes - The hashed attributes that
     *   comprise the compound index.
     * @param {number} [options.length=options.hashedAttributes.length] - The
     *   number of hashed attributes to go into the compound attribute
     *   (<= `hashedAttributes.length`).
     *
     * @returns {Promise<string>} - Resolves to the hashed compound attribute.
     */
    _hashCompoundAttribute({ hashedAttributes, length }: any): Promise<{
        name: Uint8Array<ArrayBufferLike> & Uint8Array<ArrayBuffer>;
        value: Uint8Array<ArrayBufferLike> & Uint8Array<ArrayBuffer>;
    }>;
    _prewarmCache({ attributes, hmac }: any): Promise<any[]>;
    _cachedHmac({ hmac, data }: any): Promise<any>;
}
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