/**
 * Maximum number of message keys we will derive-and-cache to support out-of-order delivery.
 *
 * This mirrors the Rust implementation and is intentionally higher than the 1:1 ratchet MAX_SKIP.
 */
export declare const SENDER_KEY_MAX_SKIP = 10000;
/** Bound the amount of cached skipped message keys to limit memory/CPU DoS. */
export declare const SENDER_KEY_MAX_STORED_SKIPPED_KEYS = 2000;
export interface SenderKeyDistribution {
    groupId: string;
    keyId: number;
    /** Hex-encoded 32-byte chain key */
    chainKey: string;
    iteration: number;
    /** UNIX seconds */
    createdAt: number;
    /** Per-sender outer pubkey used to publish group messages */
    senderEventPubkey?: string;
}
export interface SenderKeyStateSerialized {
    keyId: number;
    /** Hex-encoded 32-byte chain key */
    chainKey: string;
    iteration: number;
    /** messageNumber -> hex-encoded 32-byte key */
    skippedMessageKeys?: Record<string, string>;
}
/**
 * Signal-style "sender key" state (symmetric chain) for efficient one-to-many group messages.
 *
 * A sender distributes a fresh SenderKeyDistribution to each group member over a 1:1 Double Ratchet
 * session (forward-secure), then publishes group messages once using OneToManyChannel.
 */
export declare class SenderKeyState {
    readonly keyId: number;
    private chainKey;
    private iteration;
    private skippedMessageKeys;
    constructor(keyId: number, chainKey: Uint8Array, iteration: number);
    chainKeyBytes(): Uint8Array;
    iterationNumber(): number;
    skippedLen(): number;
    encryptToBytes(plaintext: string): {
        messageNumber: number;
        ciphertext: Uint8Array;
    };
    encrypt(plaintext: string): {
        messageNumber: number;
        ciphertext: string;
    };
    decryptFromBytes(messageNumber: number, ciphertextBytes: Uint8Array): string;
    decrypt(messageNumber: number, ciphertext: string): string;
    toJSON(): SenderKeyStateSerialized;
    static fromJSON(data: SenderKeyStateSerialized): SenderKeyState;
    static fromDistribution(dist: SenderKeyDistribution): SenderKeyState;
    private pruneSkipped;
}
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