import { webcrypto } from "crypto";

const subtle = webcrypto.subtle;

type EncryptedData = {
    iv: ArrayBuffer;
    ciphertext: ArrayBuffer; //tag 포함
}


export async function AES_GCM_Encrypt(key: ArrayBuffer, msg: ArrayBuffer, aad?: ArrayBuffer): Promise<EncryptedData> {
    const iv = webcrypto.getRandomValues(new Uint8Array(12));
    const keyObj = await subtle.importKey("raw", key, {
        name: "AES-GCM",
    }, false, ["encrypt"]);

    const ciphertext = await subtle.encrypt({
        name: "AES-GCM",
        iv,
        additionalData: aad
    }, keyObj, msg);

    return {
        iv,
        ciphertext
    }
}


export async function AES_GCM_Decrypt(key: ArrayBuffer, data: EncryptedData, aad?: ArrayBuffer): Promise<ArrayBuffer> {
    const keyObj = await subtle.importKey("raw", key, {
        name: "AES-GCM",
    }, false, ["decrypt"]);

    const plaintext = await subtle.decrypt({
        name: "AES-GCM",
        iv: data.iv,
        additionalData: aad
    }, keyObj, data.ciphertext);
    //아마도 tag 검증 실패시 예외가 발생할 것으로 예상

    return plaintext;
}