import { PrivateKey } from '../auth/ecc/src/key_private';
import { PublicKey } from '../auth/ecc/src/key_public';
export interface MemoData {
    from: string;
    to: string;
    nonce: string;
    check: number;
    encrypted: string;
}
export declare function encode(private_key: string | PrivateKey | null, public_key: string | PublicKey | null, memo: string, testNonce?: string): string;
/**
 * Decode an encrypted memo.
 * @param private_key - Our private key (WIF or PrivateKey)
 * @param memo - Encrypted memo string (leading #)
 * @param expectedRecipientPubKey - If we are the sender, optionally verify the memo's 'to' matches this (prevents wrong-recipient decryption)
 * @returns Decrypted memo with leading #, or original string on failure
 */
export declare function decode(private_key: string | PrivateKey | null, memo: string, expectedRecipientPubKey?: string | PublicKey): string;