aead-stream/dist/webcrypto/web-decrypt.js

Authenticated encryption on arbitrary large files

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.webDecrypt = void 0;
const chunkify_1 = require("../chunkify");
const util_1 = require("./util");
const profiles = { "AES-GCM": 1 };
const defaultOptions = {};
async function* webDecrypt(key, ciphertext, options = defaultOptions) {
    const [header, chunkStream] = await (0, util_1.shift)(9, ciphertext);
    if (new TextDecoder().decode(header.slice(0, 4)) !== "aead") {
        throw new Error("invalid input: magic number mismatch");
    }
    const profile = header[4];
    const chunksize = (0, util_1.decodeUint32)(header.slice(5));
    switch (profile) {
        case profiles["AES-GCM"]:
            yield* aesGcmDecrypt(key, (0, chunkify_1.chunkify)(chunksize, chunkStream), options);
            return;
        default:
            throw new Error("unsupported profile: " + profile);
    }
}
exports.webDecrypt = webDecrypt;
async function* aesGcmDecrypt(key, ciphertext, options) {
    const nonceLength = 12;
    const authTagLength = 16;
    const crypto = await (0, util_1.webcrypto)();
    let chunkIndex = 0;
    for await (const chunk of ciphertext) {
        let aad = (0, util_1.encodeUint32)(chunkIndex++);
        if (options.associatedData) {
            aad = (0, util_1.concat)(aad, options.associatedData);
        }
        const nonce = chunk.slice(0, nonceLength);
        const ciphertext = await crypto.subtle.decrypt({
            name: "AES-GCM",
            iv: nonce,
            additionalData: aad,
            tagLength: authTagLength * 8,
        }, key, chunk.slice(nonceLength));
        yield new Uint8Array(ciphertext);
    }
}