forked from um/web
95 lines
3.1 KiB
TypeScript
95 lines
3.1 KiB
TypeScript
|
import QMCCryptoModule from '@jixun/qmc2-crypto';
|
|||
|
|
|
|||
|
|
// EOF Magic detection.
|
|||
|
|
const DETECTION_SIZE = 40;
|
|||
|
|
|
|||
|
|
// Process in 2m buffer size
|
|||
|
|
const DECRYPTION_BUF_SIZE = 2 * 1024 * 1024;
|
|||
|
|
|
|||
|
|
/**
|
|||
|
|
* 解密一个 QMC2 加密的文件。
|
|||
|
|
*
|
|||
|
|
* 如果检测并解密成功，返回解密后的 Uint8Array 数组，按顺序拼接即可得到完整文件。
|
|||
|
|
* 若失败，返回 `null`。
|
|||
|
|
* @param {ArrayBuffer} mggBlob 读入的文件 Blob
|
|||
|
|
* @param {string} name 文件名
|
|||
|
|
* @return {Promise<Uint8Array[]|null>}
|
|||
|
|
*/
|
|||
|
|
export async function decryptMGG(mggBlob: ArrayBuffer) {
|
|||
|
|
// 初始化模组
|
|||
|
|
const QMCCrypto = await QMCCryptoModule();
|
|||
|
|
|
|||
|
|
// 申请内存块，并文件末端数据到 WASM 的内存堆
|
|||
|
|
const detectionBuf = new Uint8Array(mggBlob.slice(-DETECTION_SIZE));
|
|||
|
|
const pDetectionBuf = QMCCrypto._malloc(detectionBuf.length);
|
|||
|
|
QMCCrypto.writeArrayToMemory(detectionBuf, pDetectionBuf);
|
|||
|
|
|
|||
|
|
// 检测结果内存块
|
|||
|
|
const pDetectionResult = QMCCrypto._malloc(QMCCrypto.sizeof_qmc_detection());
|
|||
|
|
|
|||
|
|
// 进行检测
|
|||
|
|
const detectOK = QMCCrypto.detectKeyEndPosition(
|
|||
|
|
pDetectionResult,
|
|||
|
|
pDetectionBuf,
|
|||
|
|
detectionBuf.length
|
|||
|
|
);
|
|||
|
|
|
|||
|
|
// 提取结构体内容：
|
|||
|
|
// (pos: i32; len: i32; error: char[??])
|
|||
|
|
const position = QMCCrypto.getValue(pDetectionResult, "i32");
|
|||
|
|
const len = QMCCrypto.getValue(pDetectionResult + 4, "i32");
|
|||
|
|
const detectionError = QMCCrypto.UTF8ToString(pDetectionResult + 8);
|
|||
|
|
|
|||
|
|
// 释放内存
|
|||
|
|
QMCCrypto._free(pDetectionBuf);
|
|||
|
|
QMCCrypto._free(pDetectionResult);
|
|||
|
|
|
|||
|
|
if (detectOK) {
|
|||
|
|
// 计算解密后文件的大小。
|
|||
|
|
// 之前得到的 position 为相对当前检测数据起点的偏移。
|
|||
|
|
const decryptedSize = mggBlob.byteLength - DETECTION_SIZE + position;
|
|||
|
|
// $prog.max = decryptedSize;
|
|||
|
|
|
|||
|
|
// 提取嵌入到文件的 EKey
|
|||
|
|
const ekey = new Uint8Array(
|
|||
|
|
mggBlob.slice(decryptedSize, decryptedSize + len)
|
|||
|
|
);
|
|||
|
|
|
|||
|
|
// 解码 UTF-8 数据到 string
|
|||
|
|
const decoder = new TextDecoder();
|
|||
|
|
const ekey_b64 = decoder.decode(ekey);
|
|||
|
|
|
|||
|
|
// 初始化加密与缓冲区
|
|||
|
|
const hCrypto = QMCCrypto.createInstWidthEKey(ekey_b64);
|
|||
|
|
const buf = QMCCrypto._malloc(DECRYPTION_BUF_SIZE);
|
|||
|
|
|
|||
|
|
const decryptedParts = [];
|
|||
|
|
let offset = 0;
|
|||
|
|
let bytesToDecrypt = decryptedSize;
|
|||
|
|
while (bytesToDecrypt > 0) {
|
|||
|
|
const blockSize = Math.min(bytesToDecrypt, DECRYPTION_BUF_SIZE);
|
|||
|
|
|
|||
|
|
// 解密一些片段
|
|||
|
|
const blockData = new Uint8Array(
|
|||
|
|
mggBlob.slice(offset, offset + blockSize)
|
|||
|
|
);
|
|||
|
|
QMCCrypto.writeArrayToMemory(blockData, buf);
|
|||
|
|
QMCCrypto.decryptStream(hCrypto, buf, offset, blockSize);
|
|||
|
|
decryptedParts.push(QMCCrypto.HEAPU8.slice(buf, buf + blockSize));
|
|||
|
|
|
|||
|
|
offset += blockSize;
|
|||
|
|
bytesToDecrypt -= blockSize;
|
|||
|
|
// $prog.value = offset;
|
|||
|
|
|
|||
|
|
// 避免网页卡死，让 event loop 处理一下其它事件。
|
|||
|
|
// Worker 应该不需要等待也可以？
|
|||
|
|
// await new Promise((resolve) => setTimeout(resolve));
|
|||
|
|
}
|
|||
|
|
QMCCrypto._free(buf);
|
|||
|
|
hCrypto.delete();
|
|||
|
|
|
|||
|
|
return decryptedParts;
|
|||
|
|
} else {
|
|||
|
|
throw new Error("ERROR: could not decrypt\n " + detectionError);
|
|||
|
|
}
|
|||
|
|
}
|