web/src/decrypt/kgm_wasm.ts

68 lines
2.0 KiB
TypeScript

import KgmCryptoModule from '@/KgmWasm/KgmWasmBundle';
import { MergeUint8Array } from '@/utils/MergeUint8Array';
// 每次处理 2M 的数据
const DECRYPTION_BUF_SIZE = 2 *1024 * 1024;
export interface KGMDecryptionResult {
success: boolean;
data: Uint8Array;
error: string;
}
/**
* 解密一个 KGM 加密的文件。
*
* 如果检测并解密成功,返回解密后的 Uint8Array 数据。
* @param {ArrayBuffer} kgmBlob 读入的文件 Blob
*/
export async function DecryptKgmWasm(kgmBlob: ArrayBuffer, ext: string): Promise<KGMDecryptionResult> {
const result: KGMDecryptionResult = { success: false, data: new Uint8Array(), error: '' };
// 初始化模组
let KgmCrypto: any;
try {
KgmCrypto = await KgmCryptoModule();
} catch (err: any) {
result.error = err?.message || 'wasm 加载失败';
return result;
}
if (!KgmCrypto) {
result.error = 'wasm 加载失败';
return result;
}
// 申请内存块,并文件末端数据到 WASM 的内存堆
let kgmBuf = new Uint8Array(kgmBlob);
const pQmcBuf = KgmCrypto._malloc(DECRYPTION_BUF_SIZE);
KgmCrypto.writeArrayToMemory(kgmBuf.slice(0, DECRYPTION_BUF_SIZE), pQmcBuf);
// 进行解密初始化
const headerSize = KgmCrypto.preDec(pQmcBuf, DECRYPTION_BUF_SIZE, ext);
console.log(headerSize);
kgmBuf = kgmBuf.slice(headerSize);
const decryptedParts = [];
let offset = 0;
let bytesToDecrypt = kgmBuf.length;
while (bytesToDecrypt > 0) {
const blockSize = Math.min(bytesToDecrypt, DECRYPTION_BUF_SIZE);
// 解密一些片段
const blockData = new Uint8Array(kgmBuf.slice(offset, offset + blockSize));
KgmCrypto.writeArrayToMemory(blockData, pQmcBuf);
KgmCrypto.decBlob(pQmcBuf, blockSize, offset);
decryptedParts.push(KgmCrypto.HEAPU8.slice(pQmcBuf, pQmcBuf + blockSize));
offset += blockSize;
bytesToDecrypt -= blockSize;
}
KgmCrypto._free(pQmcBuf);
result.data = MergeUint8Array(decryptedParts);
result.success = true;
return result;
}