feat: add xiami crypto & have a working decryption workflow (#2, #9)

This commit is contained in:
鲁树人 2023-05-09 01:23:35 +01:00
parent 6afc825222
commit 68e4aef4c6
6 changed files with 109 additions and 7 deletions

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@ -24,7 +24,7 @@ export function SelectFile() {
fileName,
})
);
dispatch(processFile(fileId));
dispatch(processFile({ fileId }));
}
}

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@ -1,3 +1,7 @@
export enum DECRYPTION_WORKER_ACTION_NAME {
DECRYPT = 'DECRYPT',
}
export interface DecryptionResult {
decrypted: string; // blob uri
}

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@ -0,0 +1,6 @@
export interface CryptoBase {
isSupported(blob: Blob): Promise<boolean>;
decrypt(blob: Blob): Promise<Blob>;
}
export type CryptoFactory = () => CryptoBase;

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@ -0,0 +1,47 @@
// Xiami file header
// offset description
// 0x00 "ifmt"
// 0x04 Format name, e.g. "FLAC".
// 0x08 0xfe, 0xfe, 0xfe, 0xfe
// 0x0C (3 bytes) Little-endian, size of data to copy without modification.
// e.g. [ 8a 19 00 ] = 6538 bytes of plaintext data.
// 0x0F (1 byte) File key, applied to
// 0x10 Plaintext data
// ???? Encrypted data
import type { CryptoBase } from '../CryptoBase';
const XIAMI_FILE_MAGIC = new Uint8Array('ifmt'.split('').map((x) => x.charCodeAt(0)));
const XIAMI_EXPECTED_PADDING = new Uint8Array([0xfe, 0xfe, 0xfe, 0xfe]);
const u8Sub = (a: number, b: number) => {
if (a > b) {
return a - b;
}
return a + 0xff - b;
};
export class XiamiCrypto implements CryptoBase {
async isSupported(blob: Blob): Promise<boolean> {
const headerBuffer = await blob.slice(0, 0x10).arrayBuffer();
const header = new Uint8Array(headerBuffer);
return (
header.slice(0x00, 0x04).every((b, i) => b === XIAMI_FILE_MAGIC[i]) &&
header.slice(0x08, 0x0c).every((b, i) => b === XIAMI_EXPECTED_PADDING[i])
);
}
async decrypt(blob: Blob): Promise<Blob> {
const headerBuffer = await blob.slice(0, 0x10).arrayBuffer();
const header = new Uint8Array(headerBuffer);
const key = u8Sub(header[0x0f], 1);
const plainTextSize = header[0x0c] | (header[0x0d] << 8) | (header[0x0e] << 16);
const decrypted = new Uint8Array(await blob.slice(0x10).arrayBuffer());
for (let i = decrypted.byteLength - 1; i >= plainTextSize; i--) {
decrypted[i] = u8Sub(key, decrypted[i]);
}
return new Blob([decrypted]);
}
}

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@ -1,12 +1,27 @@
import { WorkerServerBus } from '~/util/WorkerEventBus';
import { DECRYPTION_WORKER_ACTION_NAME } from './constants';
import type { CryptoFactory } from './crypto/CryptoBase';
import { XiamiCrypto } from './crypto/xiami/xiami';
const bus = new WorkerServerBus();
onmessage = bus.onmessage;
const decryptorFactories: CryptoFactory[] = [
// Xiami (*.xm)
() => new XiamiCrypto(),
];
bus.addEventHandler(DECRYPTION_WORKER_ACTION_NAME.DECRYPT, async (blobURI) => {
const blob = await fetch(blobURI).then((r) => r.arrayBuffer());
// TODO: Implement decryptor for blob received here.
console.log(blob);
return { hello: true };
const blob = await fetch(blobURI).then((r) => r.blob());
for (const factory of decryptorFactories) {
const decryptor = factory();
if (await decryptor.isSupported(blob)) {
const decrypted = await decryptor.decrypt(blob);
return { decrypted: URL.createObjectURL(decrypted) };
}
}
throw new Error('could not decrypt file: no working decryptor found');
});

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@ -3,6 +3,8 @@ import type { PayloadAction } from '@reduxjs/toolkit';
import type { RootState } from '~/store';
import { decryptionQueue } from '~/decrypt-worker/client';
import type { DecryptionResult } from '~/decrypt-worker/constants';
export enum ProcessState {
UNTOUCHED = 'UNTOUCHED',
COMPLETE = 'COMPLETE',
@ -40,10 +42,15 @@ const initialState: FileListingState = {
displayMode: ListingMode.LIST,
};
export const processFile = createAsyncThunk('fileListing/processFile', async (fileId: string, thunkAPI) => {
export const processFile = createAsyncThunk<
DecryptionResult,
{ fileId: string },
{ rejectValue: { message: string; stack?: string } }
>('fileListing/processFile', async ({ fileId }, thunkAPI) => {
const file = selectFiles(thunkAPI.getState() as RootState)[fileId];
if (!file) {
return thunkAPI.rejectWithValue('ERROR: File not found');
const { message, stack } = new Error('ERROR: File not found');
return thunkAPI.rejectWithValue({ message, stack });
}
return decryptionQueue.add({ id: fileId, blobURI: file.raw });
@ -76,6 +83,29 @@ export const fileListingSlice = createSlice({
}
},
},
extraReducers(builder) {
builder.addCase(processFile.fulfilled, (state, action) => {
const { fileId } = action.meta.arg;
const file = state.files[fileId];
if (!file) return;
file.state = ProcessState.COMPLETE;
file.decrypted = action.payload.decrypted;
// TODO: populate file metadata
});
builder.addCase(processFile.rejected, (state, action) => {
const { fileId } = action.meta.arg;
const file = state.files[fileId];
if (!file) return;
if (action.payload) {
file.errorMessage = action.payload.message;
} else {
file.errorMessage = action.error.message || 'unknown error';
}
});
},
});
export const { addNewFile, setDecryptedContent } = fileListingSlice.actions;