declare const PROTOCOL_VERSION = "rtm-ecdh-v1";
declare const HANDSHAKE_CLIENT_OK = "rtm-handshake-ok";
declare const HANDSHAKE_SERVER_OK = "rtm-handshake-server-ok";
export declare const HANDSHAKE_EVENTS: {
    readonly INIT: "key_exchange_init";
    readonly RESPONSE: "key_exchange_response";
    readonly COMPLETE: "key_exchange_complete";
    readonly ACK: "key_exchange_ack";
    readonly ERROR: "key_exchange_error";
};
export interface EncryptedEnvelope {
    encrypted: true;
    seq: number;
    iv: string;
    ciphertext: string;
    tag: string;
}
export interface DirectionalKeys {
    k_c2s: CryptoKey;
    k_s2c: CryptoKey;
}
declare function encodeBase64(buffer: ArrayBuffer | Uint8Array): string;
declare function decodeBase64(value: string): Uint8Array;
export declare function isEncryptedEnvelope(data: unknown): data is EncryptedEnvelope;
export declare function generateEphemeralKeyPair(): Promise<CryptoKeyPair>;
export declare function exportUncompressedPublicKey(publicKey: CryptoKey): Promise<Uint8Array>;
export declare function importUncompressedPublicKey(bytes: Uint8Array): Promise<CryptoKey>;
export declare function computeSharedSecret(privateKey: CryptoKey, peerPublicKey: CryptoKey): Promise<Uint8Array>;
export declare function deriveDirectionalKeys(sharedSecret: Uint8Array, c2sNonce: Uint8Array, s2cNonce: Uint8Array): Promise<DirectionalKeys>;
export declare function buildSignaturePayload(clientPublicKey: Uint8Array, serverPublicKey: Uint8Array, c2sNonce: Uint8Array, s2cNonce: Uint8Array, sessionId: string): Uint8Array;
export declare function importSigningPublicKey(pem: string): Promise<CryptoKey>;
export declare function verifyHandshakeSignature(signatureB64: string, clientPublicKey: Uint8Array, serverPublicKey: Uint8Array, c2sNonce: Uint8Array, s2cNonce: Uint8Array, sessionId: string, signingPublicKey: CryptoKey): Promise<boolean>;
export declare function encrypt(key: CryptoKey, plaintext: string, seq: number): Promise<EncryptedEnvelope>;
export declare function decrypt(key: CryptoKey, envelope: EncryptedEnvelope, seq: number): Promise<string>;
export declare function encryptPayload(key: CryptoKey, payload: unknown, seq: number): Promise<EncryptedEnvelope>;
export declare function decryptPayload(key: CryptoKey, envelope: EncryptedEnvelope, seq: number): Promise<any>;
export declare function randomNonce4(): Uint8Array;
export { PROTOCOL_VERSION, HANDSHAKE_CLIENT_OK, HANDSHAKE_SERVER_OK, encodeBase64, decodeBase64, };