/**
 * NIST SP 800-56A Concat KDF (used by JWE ECDH-ES per RFC 7518 §4.6.2).
 * Pinned by `tests/unit/jweConcatKdf.test.ts` against the RFC 7518
 * Appendix C reference vector.
 */
/**
 * Derive `keyDataLen / 8` bytes from `sharedSecret`. `keyDataLen` is
 * **bits** (RFC 7518 §4.6.2). OtherInfo is the spec layout:
 * AlgorithmID || PartyUInfo || PartyVInfo || SuppPubInfo, each
 * length-prefixed with a 4-byte big-endian count.
 */
export declare function concatKdf({ sharedSecret, algorithmId, partyUInfo, partyVInfo, keyDataLen, supplPubInfo, }: {
    sharedSecret: Uint8Array;
    algorithmId: string;
    partyUInfo: Uint8Array;
    partyVInfo: Uint8Array;
    keyDataLen: number;
    supplPubInfo?: Uint8Array;
}): Uint8Array;