import { Header } from './header';
import { Value, type Label } from './map';
import { Key, type KeyWrapper } from './key';
/**
 * Recipient represents a COSE_recipient structure used by {@link EncryptMessage}
 * and {@link MacMessage} to carry the content encryption/MAC key for a recipient.
 *
 * Build recipients with the static factories rather than the constructor:
 *   - {@link Recipient.direct} — the caller-provided key is the content key; no
 *     key bytes are transported in the recipient.
 *   - {@link Recipient.keyWrap} — the content key is wrapped by a recipient
 *     key-encryption key (KEK), e.g. an {@link AesKwKey}.
 *
 * Unsupported recipient algorithms can be parsed and kept in the object graph,
 * but `recoverCEK()` only works for the supported helper modes.
 *
 * @see https://datatracker.ietf.org/doc/html/rfc9052#name-enveloped-cose-structure
 */
export declare class Recipient {
    protected: Header | null;
    unprotected: Header | null;
    ciphertext: Uint8Array | null;
    recipients: Recipient[];
    key: (Key & KeyWrapper) | null;
    /**
     * Creates a recipient for the direct content-key distribution method
     * (RFC 9052 §8.5.1): the content encryption key is the preshared secret and
     * no key is transported. A direct recipient must be the only recipient.
     *
     * @param kid - Optional key-selection hint placed in the unprotected header.
     */
    static direct(kid?: Uint8Array): Recipient;
    /**
     * Creates a recipient for the AES Key Wrap content-key distribution method
     * (RFC 9052 §8.5.2). The `alg` header parameter is taken from the KEK. If the
     * KEK has a `kid` and no `kid` is passed, it is copied as an unprotected
     * key-selection hint.
     *
     * @param kek - The recipient's key-encryption key, e.g. an {@link AesKwKey}.
     * @param kid - Optional key-selection hint that overrides the KEK's kid.
     */
    static keyWrap(kek: Key & KeyWrapper, kid?: Uint8Array): Recipient;
    static fromCBORValue(value: unknown, understoodCriticalLabels?: Iterable<Label>): Recipient;
    constructor(protectedHeader?: Header, unprotected?: Header);
    alg(): number | string | undefined;
    encode(cek: Uint8Array): Value[];
    recoverCEK(kek: Key & Partial<KeyWrapper>): Uint8Array;
}