feat(convert): tdata conversion

packages/convert/package.json

@@ -10,10 +10,12 @@
     "exports": "./src/index.ts",
     "dependencies": {
         "@mtcute/core": "workspace:^",
-        "@fuman/utils": "https://pkg.pr.new/teidesu/fuman/@fuman/utils@6017eb4",
+        "@fuman/utils": "https://pkg.pr.new/teidesu/fuman/@fuman/utils@b0c74cb",
-        "@fuman/net": "https://pkg.pr.new/teidesu/fuman/@fuman/net@6017eb4"
+        "@fuman/net": "https://pkg.pr.new/teidesu/fuman/@fuman/net@b0c74cb",
+        "@fuman/io": "https://pkg.pr.new/teidesu/fuman/@fuman/io@b0c74cb" 
     },
     "devDependencies": {
-        "@mtcute/test": "workspace:^"
+        "@mtcute/test": "workspace:^",
+        "@mtcute/node": "workspace:^"
     }
 }

packages/convert/src/index.ts

@@ -3,3 +3,4 @@ export * from './gramjs/index.js'
 export * from './mtkruto/index.js'
 export * from './pyrogram/index.js'
 export * from './telethon/index.js'
+export * from './tdesktop/index.js'

packages/convert/src/tdesktop/convert.ts

@@ -0,0 +1,73 @@
+import { type StringSessionData, readStringSession } from '@mtcute/core/utils.js'
+import type { MaybeArray } from '@fuman/utils'
+import { Long } from '@mtcute/core'
+
+import { DC_MAPPING_PROD } from '../dcs.js'
+
+import type { TdataOptions } from './tdata.js'
+import { Tdata } from './tdata.js'
+import type { InputTdKeyData } from './types.js'
+
+export async function convertFromTdata(tdata: Tdata | TdataOptions, accountIdx = 0): Promise<StringSessionData> {
+    if (!(tdata instanceof Tdata)) {
+        tdata = await Tdata.open(tdata)
+    }
+
+    const auth = await tdata.readMtpAuthorization(accountIdx)
+    const authKey = auth.authKeys.find(it => it.dcId === auth.mainDcId)
+    if (!authKey) throw new Error('Failed to find auth key')
+
+    return {
+        version: 3,
+        primaryDcs: DC_MAPPING_PROD[auth.mainDcId],
+        authKey: authKey.key,
+        self: {
+            userId: auth.userId.toNumber(),
+            isBot: false,
+            isPremium: false,
+            usernames: [],
+        },
+    }
+}
+
+export async function convertToTdata(
+    sessions: MaybeArray<StringSessionData | string>,
+    tdata: Tdata | TdataOptions,
+): Promise<void> {
+    if (!Array.isArray(sessions)) {
+        sessions = [sessions]
+    }
+
+    if (!(tdata instanceof Tdata)) {
+        const keyData: InputTdKeyData = {
+            count: sessions.length,
+            order: Array.from({ length: sessions.length }, (_, i) => i),
+            active: 0,
+        }
+        tdata = await Tdata.create({
+            keyData,
+            ...tdata,
+        })
+    }
+
+    for (let i = 0; i < sessions.length; i++) {
+        let session = sessions[i]
+
+        if (typeof session === 'string') {
+            session = readStringSession(session)
+        }
+
+        await tdata.writeMtpAuthorization({
+            userId: Long.fromNumber(session.self?.userId ?? 0),
+            mainDcId: session.primaryDcs.main.id,
+            authKeys: [
+                {
+                    dcId: session.primaryDcs.main.id,
+                    key: session.authKey,
+                },
+            ],
+            authKeysToDestroy: [],
+        }, i)
+        await tdata.writeEmptyMapFile(i)
+    }
+}

packages/convert/src/tdesktop/docs.md

@@ -0,0 +1,55 @@
+## How it works
+
+### Data name
+
+TDesktop allows for multiple "data names", which is basically
+a prefix for data storage. Default one is `data`, but you can choose
+any using `-key` CLI parameter.
+
+### Local key
+
+TDesktop uses something called "local key" to encrypt most of the files.
+The local key itself is stored in `key_datas`, where `data` is the default 
+data name. That file can be passcode-protected, in which case you will
+need a correct passcode to decrypt it.
+
+### Encryption
+
+Without going too deep into details, encryption used is the same
+as the one used in MTProto v1 for message encryption (see 
+[Telegram docs](https://core.telegram.org/mtproto/description_v1#defining-aes-key-and-initialization-vector) 
+for details). 
+
+There, instead of `auth_key` a local key is used, and instead of
+`msg_key` lower 16 bytes of sha1 of the contents are used.
+
+Before encrypting (and computing sha1), content size is prepended, and
+the result is padded.
+
+### File naming
+
+To name different files, TDesktop uses 8 lower bytes of md5 hash,
+with nibbles switched (i.e. `0xFE => 0xEF`).
+
+So, for example:
+
+```typescript
+const filename = 'data'
+const md5 = crypto.md5(filename) // 8d777f385d3dfec8815d20f7496026dc 
+const md5Lower = md5.slice(0, 8) // 8d777f385d3dfec8
+const result = swap8(md5Lower).toUpperHex() // D877F783D5D3EF8C
+```
+
+`D877F783D5D3EF8C` is the folder that is most likely present in your
+`tdata` folder, which is derived simply from `data` and is used
+for your first account data.
+
+### Multi accounts
+
+For second, third, etc. accounts, TDesktop appends `#2`, `#3` etc. 
+to the base data name respectively.
+
+### MTProto auth keys
+
+Auth keys are stored in a file named same as account data folder but with
+`s` appended. So, for the first account that would be `D877F783D5D3EF8Cs`.

packages/convert/src/tdesktop/index.ts

@@ -0,0 +1,6 @@
+import * as qt from './qt-bundle.js'
+
+export { qt }
+export * from './convert.js'
+export * from './tdata.js'
+export * from './types.js'

packages/convert/src/tdesktop/qt-bundle.ts

@@ -0,0 +1,4 @@
+import * as read from './qt-reader.js'
+import * as write from './qt-writer.js'
+
+export { read, write }

packages/convert/src/tdesktop/qt-reader.ts

@@ -0,0 +1,35 @@
+import { Long } from '@mtcute/core'
+import { type ISyncReadable, read } from '@fuman/io'
+import { u8 } from '@fuman/utils'
+
+export function readQByteArray(readable: ISyncReadable): Uint8Array {
+    const length = read.uint32be(readable)
+    if (length === 0 || length === 0xFFFFFFFF) {
+        return u8.empty
+    }
+
+    return read.exactly(readable, length)
+}
+
+export function readLong(readable: ISyncReadable): Long {
+    const high = read.int32be(readable)
+    const low = read.int32be(readable)
+
+    return new Long(low, high)
+}
+
+export function readCharArray(readable: ISyncReadable): Uint8Array {
+    const buf = readQByteArray(readable)
+
+    if (buf.length > 0) {
+        // drop the last byte, which is always 0
+        return buf.subarray(0, buf.length - 1)
+    }
+    return buf
+}
+
+const u16Decoder = new TextDecoder('utf-16be')
+export function readQString(readable: ISyncReadable): string {
+    const bytes = readQByteArray(readable)
+    return u16Decoder.decode(bytes)
+}

packages/convert/src/tdesktop/qt-writer.ts

@@ -0,0 +1,31 @@
+import type { ISyncWritable } from '@fuman/io'
+import { write } from '@fuman/io'
+import { u8 } from '@fuman/utils'
+import type { Long } from '@mtcute/core'
+
+export function writeQByteArray(into: ISyncWritable, buf: Uint8Array): void {
+    write.uint32be(into, buf.length)
+    write.bytes(into, buf)
+}
+
+export function writeLong(into: ISyncWritable, long: Long): void {
+    write.int32be(into, long.high)
+    write.int32be(into, long.low)
+}
+
+export function writeCharArray(into: ISyncWritable, buf: Uint8Array): void {
+    const bytes = u8.alloc(buf.length + 1)
+    bytes.set(buf)
+    bytes[buf.length] = 0
+
+    writeQByteArray(into, bytes)
+}
+
+export function writeQString(into: ISyncWritable, str: string): void {
+    const length = str.length * 2
+    write.uint32be(into, length)
+
+    for (let i = 0; i < length; i++) {
+        write.uint16be(into, str.charCodeAt(i))
+    }
+}

packages/convert/src/tdesktop/tdata.test.ts

@@ -0,0 +1,106 @@
+import { fileURLToPath } from 'node:url'
+
+import { describe, expect, it } from 'vitest'
+import { Long } from '@mtcute/core'
+
+import type { INodeFsLike } from '../utils/fs.js'
+import { getDefaultCryptoProvider } from '../utils/crypto.js'
+
+import { Tdata } from './tdata.js'
+
+class FakeFs implements INodeFsLike {
+    readonly files = new Map<string, Uint8Array>()
+
+    async readFile(path: string): Promise<Uint8Array> {
+        return this.files.get(path)!
+    }
+
+    async writeFile(path: string, data: Uint8Array): Promise<void> {
+        this.files.set(path, data)
+    }
+
+    async stat(path: string): Promise<{ size: number, lastModified: number }> {
+        return {
+            size: this.files.get(path)!.length,
+            lastModified: 0,
+        }
+    }
+
+    mkdir(): Promise<void> {
+        return Promise.resolve()
+    }
+}
+
+describe('tdata', () => {
+    it('should read simple tdata', async () => {
+        const tdata = await Tdata.open({
+            path: fileURLToPath(new URL('./__fixtures__/simple', import.meta.url)),
+        })
+
+        const auth = await tdata.readMtpAuthorization()
+
+        expect({ auth, key: tdata.keyData }).toMatchSnapshot()
+    })
+
+    it('should read passcode-protected tdata', async () => {
+        const tdata = await Tdata.open({
+            path: fileURLToPath(new URL('./__fixtures__/passcode', import.meta.url)),
+            passcode: '123123',
+        })
+
+        const auth = await tdata.readMtpAuthorization()
+
+        expect({ auth, key: tdata.keyData }).toMatchSnapshot()
+    })
+
+    it('should throw on invalid passcode', async () => {
+        await expect(Tdata.open({
+            path: fileURLToPath(new URL('./__fixtures__/passcode', import.meta.url)),
+            passcode: '123',
+        })).rejects.toThrow('Failed to decrypt, invalid password?')
+    })
+
+    it('should read multi-account tdata', async () => {
+        const tdata = await Tdata.open({
+            path: fileURLToPath(new URL('./__fixtures__/multiacc', import.meta.url)),
+        })
+
+        const auth0 = await tdata.readMtpAuthorization(0)
+        const auth1 = await tdata.readMtpAuthorization(1)
+
+        expect({ auth0, auth1, key: tdata.keyData }).toMatchSnapshot()
+    })
+
+    it('should write simple tdata', async () => {
+        const fs = new FakeFs()
+        const crypto = await getDefaultCryptoProvider()
+        crypto.randomBytes = size => new Uint8Array(size)
+
+        const tdata = await Tdata.create({
+            path: '/',
+            fs,
+            crypto,
+            keyData: {
+                count: 1,
+                order: [0],
+                active: 0,
+            },
+        })
+
+        const key = new Uint8Array(256)
+        key.fill(1)
+        await tdata.writeMtpAuthorization({
+            userId: Long.fromNumber(12345678),
+            mainDcId: 2,
+            authKeys: [
+                {
+                    dcId: 2,
+                    key,
+                },
+            ],
+            authKeysToDestroy: [],
+        })
+
+        expect(fs.files).toMatchSnapshot()
+    })
+})

packages/convert/src/tdesktop/tdata.ts

@@ -0,0 +1,494 @@
+import { dirname, join } from 'node:path/posix'
+
+import { Bytes, read, write } from '@fuman/io'
+import type { UnsafeMutable } from '@fuman/utils'
+import { typed, u8, utf8 } from '@fuman/utils'
+import { createAesIgeForMessageOld } from '@mtcute/core/utils.js'
+import { Long, MtUnsupportedError } from '@mtcute/core'
+
+import type { INodeFsLike } from '../utils/fs.js'
+import { type IExtendedCryptoProvider, getDefaultCryptoProvider } from '../utils/crypto.js'
+
+import { readLong, readQByteArray } from './qt-reader.js'
+import type { InputTdKeyData, TdAuthKey, TdKeyData, TdMtpAuthorization } from './types.js'
+import { writeLong, writeQByteArray } from './qt-writer.js'
+
+const TDF_MAGIC = /* #__PURE__ */ utf8.encoder.encode('TDF$')
+const TDF_VERSION = 5008003
+const MTP_AUTHORIZATION_BLOCK = 0x4B // see https://github.com/telegramdesktop/tdesktop/blob/dev/Telegram/SourceFiles/storage/details/storage_settings_scheme.h
+const HEX_ALPHABET = '0123456789ABCDEF'
+
+function toFilePart(key: Uint8Array): string {
+    let str = ''
+    // we need to swap nibbles for whatever reason
+    for (let i = 0; i < 8; i++) {
+        const b = key[i]
+        const low = b & 0x0F
+        const high = b >> 4
+        str += HEX_ALPHABET[low] + HEX_ALPHABET[high]
+    }
+    return str
+}
+
+export interface TdataOptions {
+    /** Full path to the tdata directory */
+    path: string
+
+    /**
+     * File system to use for reading/writing.
+     *
+     * @default  `import('node:fs/promises')`
+     */
+    fs?: INodeFsLike
+
+    /**
+     * Crypto functions to use for encryption/decryption.
+     *
+     * @default  `node:crypto`-based implementation
+     */
+    crypto?: IExtendedCryptoProvider
+
+    /**
+     * Whether to ignore TDF version mismatch.
+     * If set to `true`, the version will be ignored and the file will be read as is,
+     * however the probability of errors is higher.
+     */
+    ignoreVersion?: boolean
+
+    /**
+     * Whether the host machine has LE processor (default true, try changing in case of errors)
+     */
+    le?: boolean
+
+    /**
+     * Value of -key cli parameter.
+     * Defaults to `data`
+     */
+    dataKey?: string
+
+    /**
+     * Local passcode
+     */
+    passcode?: string
+}
+
+export class Tdata {
+    private constructor(
+        readonly options: TdataOptions,
+        readonly fs: INodeFsLike,
+        readonly crypto: IExtendedCryptoProvider,
+    ) {}
+
+    readonly keyData!: TdKeyData
+
+    static async open(options: TdataOptions): Promise<Tdata> {
+        const fs: INodeFsLike = options.fs ?? (await import('node:fs/promises') as unknown as INodeFsLike)
+        const crypto: IExtendedCryptoProvider = options.crypto ?? (await getDefaultCryptoProvider())
+        await crypto.initialize?.()
+
+        const tdata = new Tdata(options, fs, crypto)
+        ;(tdata as UnsafeMutable<Tdata>).keyData = await tdata.readKeyData()
+
+        return tdata
+    }
+
+    static async create(options: TdataOptions & { keyData: InputTdKeyData }): Promise<Tdata> {
+        const fs: INodeFsLike = options.fs ?? (await import('node:fs/promises') as unknown as INodeFsLike)
+        const crypto: IExtendedCryptoProvider = options.crypto ?? (await getDefaultCryptoProvider())
+        await crypto.initialize?.()
+
+        const tdata = new Tdata(options, fs, crypto)
+        const keyData: TdKeyData = {
+            ...options.keyData,
+            localKey: options.keyData.localKey ?? crypto.randomBytes(256),
+            version: options.keyData.version ?? TDF_VERSION,
+        }
+        ;(tdata as UnsafeMutable<Tdata>).keyData = keyData
+
+        await tdata.writeKeyData(keyData)
+
+        return tdata
+    }
+
+    #readInt32(buf: Uint8Array): number {
+        return (this.options.le ?? true) ? read.int32le(buf) : read.int32be(buf)
+    }
+
+    #writeInt32(buf: Uint8Array, val: number): Uint8Array {
+        if (this.options.le ?? true) {
+            write.int32le(buf, val)
+        } else {
+            write.int32be(buf, val)
+        }
+
+        return buf
+    }
+
+    getDataName(idx: number): string {
+        let res = this.options.dataKey ?? 'data'
+
+        if (idx > 0) {
+            res += `#${idx + 1}`
+        }
+
+        return res
+    }
+
+    async readFile(filename: string): Promise<[number, Uint8Array]> {
+        const order: string[] = []
+
+        const modern = `${filename}s`
+        if (await this.fs.stat(join(this.options.path, modern))) {
+            order.push(modern)
+        } else {
+            const try0 = `${filename}0`
+            const try1 = `${filename}1`
+
+            const try0s = await this.fs.stat(join(this.options.path, try0))
+            const try1s = await this.fs.stat(join(this.options.path, try1))
+
+            if (try0s) {
+                order.push(try0)
+
+                if (try1s) {
+                    order.push(try1)
+                    if (try0s.lastModified < try1s.lastModified) {
+                        order.reverse()
+                    }
+                }
+            } else if (try1s) {
+                order.push(try1)
+            }
+        }
+
+        let lastError = 'file not found'
+
+        for (const file of order) {
+            const data = await this.fs.readFile(join(this.options.path, file))
+            const magic = data.subarray(0, 4)
+
+            if (!typed.equal(magic, TDF_MAGIC)) {
+                lastError = 'invalid magic'
+                continue
+            }
+
+            const versionBytes = data.subarray(4, 8)
+            const version = this.#readInt32(versionBytes)
+            if (version > TDF_VERSION && !this.options.ignoreVersion) {
+                lastError = `Unsupported version: ${version}`
+                continue
+            }
+
+            const dataSize = data.length - 24
+            const bytes = data.subarray(8, dataSize + 8)
+
+            const md5 = await this.crypto.createHash('md5')
+            await md5.update(bytes)
+            await md5.update(this.#writeInt32(u8.alloc(4), dataSize))
+            await md5.update(versionBytes)
+            await md5.update(magic)
+
+            const hash = await md5.digest()
+            if (!typed.equal(hash, data.subarray(dataSize + 8))) {
+                lastError = 'md5 mismatch'
+                continue
+            }
+
+            return [version, bytes]
+        }
+
+        throw new Error(`failed to read ${filename}, last error: ${lastError}`)
+    }
+
+    async writeFile(
+        filename: string,
+        data: Uint8Array,
+        mkdir = false,
+    ): Promise<void> {
+        filename = join(this.options.path, `${filename}s`)
+
+        const version = this.#writeInt32(u8.alloc(4), TDF_VERSION)
+        const dataSize = this.#writeInt32(u8.alloc(4), data.length)
+        const md5 = await this.crypto.createHash('md5')
+        await md5.update(data)
+        await md5.update(dataSize)
+        await md5.update(version)
+        await md5.update(TDF_MAGIC)
+
+        if (mkdir) {
+            await this.fs.mkdir(dirname(filename), { recursive: true })
+        }
+
+        await this.fs.writeFile(
+            filename,
+            u8.concat([TDF_MAGIC, version, data, await md5.digest()]),
+        )
+    }
+
+    async createLocalKey(
+        salt: Uint8Array,
+        passcode: string = this.options.passcode ?? '',
+    ): Promise<Uint8Array> {
+        const hasher = await this.crypto.createHash('sha512')
+        hasher.update(salt)
+        hasher.update(utf8.encoder.encode(passcode))
+        hasher.update(salt)
+        const hash = await hasher.digest()
+
+        return this.crypto.pbkdf2(
+            hash,
+            salt,
+            passcode === '' ? 1 : 100000,
+            256,
+            'sha512',
+        )
+    }
+
+    async decryptLocal(encrypted: Uint8Array, key: Uint8Array): Promise<Uint8Array> {
+        const encryptedKey = encrypted.subarray(0, 16)
+        const encryptedData = encrypted.subarray(16)
+
+        const ige = createAesIgeForMessageOld(
+            this.crypto,
+            key,
+            encryptedKey,
+            false,
+        )
+        const decrypted = ige.decrypt(encryptedData)
+
+        if (
+            !typed.equal(
+                this.crypto.sha1(decrypted).subarray(0, 16),
+                encryptedKey,
+            )
+        ) {
+            throw new Error('Failed to decrypt, invalid password?')
+        }
+
+        const fullLen = encryptedData.length
+        const dataLen = this.#readInt32(decrypted)
+
+        if (
+            dataLen > decrypted.length
+            || dataLen <= fullLen - 16
+            || dataLen < 4
+        ) {
+            throw new Error('Failed to decrypt, invalid data length')
+        }
+
+        return decrypted.subarray(4, dataLen)
+    }
+
+    async encryptLocal(data: Uint8Array, key: Uint8Array): Promise<Uint8Array> {
+        const dataSize = data.length + 4
+        const padding: Uint8Array
+            = dataSize & 0x0F
+                ? this.crypto.randomBytes(0x10 - (dataSize & 0x0F))
+                : u8.empty
+
+        const toEncrypt = u8.alloc(dataSize + padding.length)
+        this.#writeInt32(toEncrypt, dataSize)
+        toEncrypt.set(data, 4)
+        toEncrypt.set(padding, dataSize)
+
+        const encryptedKey = this.crypto.sha1(toEncrypt).subarray(0, 16)
+
+        const ige = createAesIgeForMessageOld(
+            this.crypto,
+            key,
+            encryptedKey,
+            false,
+        )
+        const encryptedData = ige.encrypt(toEncrypt)
+
+        return u8.concat2(encryptedKey, encryptedData)
+    }
+
+    async readKeyData(): Promise<TdKeyData> {
+        const [version, data] = await this.readFile(`key_${this.options.dataKey ?? 'data'}`)
+        const bytes = Bytes.from(data)
+
+        const salt = readQByteArray(bytes)
+        const keyEncrypted = readQByteArray(bytes)
+        const infoEncrypted = readQByteArray(bytes)
+
+        const passcodeKey = await this.createLocalKey(salt)
+        const keyInnerData = await this.decryptLocal(keyEncrypted, passcodeKey)
+        const infoDecrypted = await this.decryptLocal(
+            infoEncrypted,
+            keyInnerData,
+        )
+        const info = Bytes.from(infoDecrypted)
+
+        const localKey = keyInnerData
+        const count = read.int32be(info)
+        const order = [...Array(count)].map(() => read.int32be(info))
+        const active = read.int32be(info)
+
+        return {
+            version,
+            localKey,
+            count,
+            order,
+            active,
+        }
+    }
+
+    async writeKeyData(keyData: TdKeyData): Promise<void> {
+        const info = Bytes.alloc()
+        write.int32be(info, keyData.count)
+        keyData.order.forEach(i => write.int32be(info, i))
+        write.int32be(info, keyData.active)
+        const infoDecrypted = info.result()
+
+        const infoEncrypted = await this.encryptLocal(infoDecrypted, keyData.localKey)
+
+        const salt = this.crypto.randomBytes(32)
+        const passcodeKey = await this.createLocalKey(salt)
+
+        const keyEncrypted = await this.encryptLocal(keyData.localKey, passcodeKey)
+
+        const data = Bytes.alloc()
+        writeQByteArray(data, salt)
+        writeQByteArray(data, keyEncrypted)
+        writeQByteArray(data, infoEncrypted)
+
+        await this.writeFile(`key_${this.options.dataKey ?? 'data'}`, data.result(), true)
+    }
+
+    async computeDataNameKey(accountIdx: number): Promise<Uint8Array> {
+        const md5 = await this.crypto.createHash('md5')
+        await md5.update(utf8.encoder.encode(this.getDataName(accountIdx)))
+        const r = await md5.digest()
+        return r.subarray(0, 8)
+    }
+
+    async computeDataNameKeyHex(accountIdx: number): Promise<string> {
+        return toFilePart(await this.computeDataNameKey(accountIdx))
+    }
+
+    async readEncryptedFile(filename: string): Promise<[number, Uint8Array]> {
+        const [version, data] = await this.readFile(filename)
+
+        const encrypted = readQByteArray(Bytes.from(data))
+        const decrypted = await this.decryptLocal(encrypted, this.keyData.localKey)
+
+        return [version, decrypted]
+    }
+
+    async writeEncryptedFile(
+        filename: string,
+        data: Uint8Array,
+        mkdir = false,
+    ): Promise<void> {
+        const encryptedInner = await this.encryptLocal(data, this.keyData.localKey)
+
+        const writer = Bytes.alloc(data.length + 4)
+        writeQByteArray(writer, encryptedInner)
+
+        await this.writeFile(filename, writer.result(), mkdir)
+    }
+
+    async readMtpAuthorization(accountIdx: number = 0): Promise<TdMtpAuthorization> {
+        const [, mtpData] = await this.readEncryptedFile(
+            await this.computeDataNameKeyHex(accountIdx),
+        )
+
+        // nb: this is pretty much a hack that relies on the fact that
+        // most of the time the mtp auth data is in the first setting
+        // since the settings are not length-prefixed, we can't skip unknown settings,
+        // as we need to know their type.
+        // and this is very much tied to the actual tdesktop version, and would be a nightmare to maintain
+        let bytes = Bytes.from(mtpData)
+
+        const header = read.int32be(bytes)
+        if (header !== MTP_AUTHORIZATION_BLOCK) {
+            throw new MtUnsupportedError(`expected first setting to be mtp auth data, got 0x${header.toString(16)}`)
+        }
+
+        const mtpAuthBlock = readQByteArray(bytes)
+
+        bytes = Bytes.from(mtpAuthBlock)
+
+        const legacyUserId = read.int32be(bytes)
+        const legacyMainDcId = read.int32be(bytes)
+
+        let userId, mainDcId
+        if (legacyMainDcId === -1 && legacyMainDcId === -1) {
+            userId = readLong(bytes)
+            mainDcId = read.int32be(bytes)
+        } else {
+            userId = Long.fromInt(legacyUserId)
+            mainDcId = legacyMainDcId
+        }
+
+        function readKeys(target: TdAuthKey[]) {
+            const count = read.uint32be(bytes)
+
+            for (let i = 0; i < count; i++) {
+                const dcId = read.int32be(bytes)
+                const key = read.exactly(bytes, 256)
+                target.push({ dcId, key })
+            }
+        }
+
+        const authKeys: TdAuthKey[] = []
+        const authKeysToDestroy: TdAuthKey[] = []
+
+        readKeys(authKeys)
+        readKeys(authKeysToDestroy)
+
+        return {
+            userId,
+            mainDcId,
+            authKeys,
+            authKeysToDestroy,
+        }
+    }
+
+    async writeMtpAuthorization(auth: TdMtpAuthorization, accountIdx = 0): Promise<void> {
+        const bytes = Bytes.alloc()
+
+        // legacy user id & dc id
+        write.int32be(bytes, -1)
+        write.int32be(bytes, -1)
+        writeLong(bytes, auth.userId)
+        write.int32be(bytes, auth.mainDcId)
+
+        function writeKeys(keys: TdAuthKey[]) {
+            write.uint32be(bytes, keys.length)
+            keys.forEach((k) => {
+                write.int32be(bytes, k.dcId)
+                write.bytes(bytes, k.key)
+            })
+        }
+
+        writeKeys(auth.authKeys)
+        writeKeys(auth.authKeysToDestroy)
+
+        const file = Bytes.alloc()
+        write.int32be(file, MTP_AUTHORIZATION_BLOCK)
+        writeQByteArray(file, bytes.result())
+
+        await this.writeEncryptedFile(
+            await this.computeDataNameKeyHex(accountIdx),
+            file.result(),
+        )
+    }
+
+    async writeEmptyMapFile(accountIdx: number): Promise<void> {
+        // without this file tdesktop will not "see" the account
+        // however just creating an empty file seems to be enough to make it happy
+
+        const writer = Bytes.alloc()
+        writeQByteArray(writer, u8.empty) // legacySalt
+        writeQByteArray(writer, u8.empty) // legacyKeyEncrypted
+        writeQByteArray(writer, await this.encryptLocal(u8.empty, this.keyData.localKey))
+
+        await this.writeFile(
+            join(await this.computeDataNameKeyHex(accountIdx), 'map'),
+            writer.result(),
+            true,
+        )
+    }
+}

packages/convert/src/tdesktop/types.ts

@@ -0,0 +1,26 @@
+import type { Long } from '@mtcute/core'
+
+export interface TdAuthKey {
+    dcId: number
+    key: Uint8Array
+}
+
+export interface TdMtpAuthorization {
+    userId: Long
+    mainDcId: number
+    authKeys: TdAuthKey[]
+    authKeysToDestroy: TdAuthKey[]
+}
+
+export interface InputTdKeyData {
+    localKey?: Uint8Array
+    version?: number
+    count: number
+    order: number[]
+    active: number
+}
+
+export interface TdKeyData extends InputTdKeyData {
+    version: number
+    localKey: Uint8Array
+}

packages/convert/src/utils/crypto.ts

@@ -0,0 +1,29 @@
+import type { MaybePromise } from '@fuman/utils'
+import type { ICryptoProvider } from '@mtcute/core/utils.js'
+
+export interface IExtendedCryptoProvider extends ICryptoProvider {
+    createHash(algorithm: 'md5' | 'sha512'): MaybePromise<{
+        update(data: Uint8Array): MaybePromise<void>
+        digest(): MaybePromise<Uint8Array>
+    }>
+}
+
+export async function getDefaultCryptoProvider(): Promise<IExtendedCryptoProvider> {
+    const crypto = /* @vite-ignore */ await import('node:crypto')
+    const { NodeCryptoProvider } = /* @vite-ignore */ await import('@mtcute/node/utils.js')
+
+    return new (class extends NodeCryptoProvider implements IExtendedCryptoProvider {
+        createHash(algorithm: 'md5' | 'sha512') {
+            const hasher = crypto.createHash(algorithm)
+
+            return {
+                update(data: Uint8Array) {
+                    hasher.update(data)
+                },
+                digest() {
+                    return hasher.digest() as unknown as Uint8Array
+                },
+            }
+        }
+    })()
+}

packages/convert/src/utils/fs.ts

@@ -0,0 +1,6 @@
+export interface INodeFsLike {
+    readFile(path: string): Promise<Uint8Array>
+    writeFile(path: string, data: Uint8Array): Promise<void>
+    mkdir(path: string, options?: { recursive?: boolean }): Promise<void>
+    stat(path: string): Promise<{ size: number, lastModified: number }>
+}