/**
 * @octomil/browser — Secure aggregation (SecAgg / SecAgg+)
 *
 * Implements pairwise masking using ECDH key exchange and Shamir's
 * secret sharing, all via the Web Crypto API. Ensures the server
 * only sees the aggregate of client updates, never individual deltas.
 */
import type { WeightMap } from "./types.js";
export declare class SecureAggregation {
    private keyPair;
    /** Generate an ECDH key pair for this round. */
    generateKeyPair(): Promise<{
        publicKey: JsonWebKey;
    }>;
    /** Derive a shared secret with a peer using ECDH. */
    deriveSharedSecret(peerPublicKeyJwk: JsonWebKey): Promise<ArrayBuffer>;
    /**
     * Generate a deterministic PRG mask from a shared secret.
     * Uses the secret as a seed to produce `length` float values.
     */
    createMask(secret: ArrayBuffer, length: number): Promise<Float32Array>;
    /** Add masks to a weight update: masked = delta + sum(masks). */
    maskUpdate(delta: WeightMap, masks: Map<string, Float32Array>): WeightMap;
    /** Remove masks of dropped peers from the aggregated sum. */
    unmask(maskedSum: WeightMap, droppedMasks: Map<string, Float32Array>): WeightMap;
}
export interface SecretShare {
    x: number;
    y: number;
}
/**
 * Split a secret into `numShares` shares requiring `threshold` to reconstruct.
 */
export declare function shamirSplit(secret: number, threshold: number, numShares: number): SecretShare[];
/**
 * Reconstruct a secret from `threshold` shares via Lagrange interpolation.
 */
export declare function shamirReconstruct(shares: SecretShare[]): number;
export declare class SecAggPlus extends SecureAggregation {
    private readonly threshold;
    constructor(threshold: number);
    /**
     * Split a shared secret into Shamir shares so that any `threshold`
     * surviving peers can reconstruct the mask of a dropped peer.
     */
    splitSecret(secret: number, numPeers: number): SecretShare[];
    /** Reconstruct a dropped peer's secret from collected shares. */
    reconstructSecret(shares: SecretShare[]): number;
}
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