import { KeyObject } from 'node:crypto';
import type { Receipt, ReceiptStatus } from './domain.js';
import type { Currency } from './money.js';
export declare const RECEIPT_SIGNATURE_VERSION: 1;
export interface SignatureBundle {
    readonly signature: string;
    readonly signatureVersion: number;
    readonly signingKeyId: string;
}
/**
 * A signer scoped to a single Stipend key id. Production deployments may
 * rotate keys by switching the signer at startup; receipts record which key
 * id signed them so verification can find the right public key later.
 */
export interface Signer {
    readonly keyId: string;
    readonly signatureVersion: number;
    sign(payload: string): SignatureBundle;
}
export interface Verifier {
    readonly keyId: string;
    verify(payload: string, signature: string): boolean;
}
interface Ed25519SignerOptions {
    readonly keyId: string;
    readonly privateKey: KeyObject | string | Buffer;
    readonly signatureVersion?: number;
}
interface Ed25519VerifierOptions {
    readonly keyId: string;
    readonly publicKey: KeyObject | string | Buffer;
}
export declare class Ed25519Signer implements Signer {
    readonly keyId: string;
    readonly signatureVersion: number;
    private readonly key;
    constructor(options: Ed25519SignerOptions);
    sign(payload: string): SignatureBundle;
}
export declare class Ed25519Verifier implements Verifier {
    readonly keyId: string;
    private readonly key;
    constructor(options: Ed25519VerifierOptions);
    verify(payload: string, signature: string): boolean;
}
/**
 * Generate a fresh Ed25519 keypair. Used by the keygen CLI helper.
 * Returns PEM-encoded keys, suitable for env / secret manager storage.
 */
export declare function generateEd25519Keypair(): {
    readonly privateKey: string;
    readonly publicKey: string;
};
/**
 * Inputs required to derive a receipt's canonical signed payload. Both the
 * signer (when issuing a receipt) and the verifier (when re-deriving for
 * comparison) build the canonical string from exactly these fields.
 */
export interface ReceiptCanonicalInput {
    readonly id: string;
    readonly paymentId: string;
    readonly accountId: string;
    readonly status: ReceiptStatus;
    readonly amountCents: bigint;
    readonly currency: Currency;
    readonly providerRef: string | null;
    readonly entitlementsGranted: readonly string[];
    readonly signedAt: string;
}
/**
 * Build the canonical JSON string for a receipt signature.
 *
 * Fields are snake_cased to match the TDD §5.1 signed-payload schema, even
 * though TypeScript uses camelCase internally. Any change to the field set
 * or its naming is a signature version bump.
 */
export declare function buildReceiptSignedPayload(receipt: ReceiptCanonicalInput): string;
export interface VerifyReceiptResult {
    readonly valid: boolean;
    readonly keyId: string;
    readonly signatureVersion: number;
    readonly signedAt: string;
    readonly reason?: string;
}
export type PublicKeyResolver = (keyId: string) => KeyObject | string | Buffer | undefined;
/**
 * Verify a receipt's signature without database access.
 *
 * Pass either a single public key (when the caller knows which key signed
 * the receipt) or a resolver function that maps the receipt's
 * `signingKeyId` to the matching public key (when supporting key
 * rotation).
 *
 * The function re-derives the canonical payload from the receipt's
 * fields, so an attacker cannot pass a tampered receipt with a matching
 * pre-canonicalized payload — the verifier always trusts the receipt's
 * fields as input and never trusts a payload string provided by the
 * caller.
 */
export declare function verifyReceipt(receipt: Receipt, keyOrResolver: KeyObject | string | Buffer | PublicKeyResolver): VerifyReceiptResult;
export {};
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