quak/README.md

quak

quak is a WTFPL-licensed TypeScript client library and CLI by @sneak for the Ente end-to-end encrypted photo hosting service. It logs in, enumerates collections and files, and downloads individual images while decrypting them on the way to disk.

quak also includes a resilient backup command that downloads every file in the account into a deduplicated local directory tree, skipping files that already exist on disk and continuing past individual download failures instead of crashing. It decrypts and persists all three metadata layers (basic, private magic, public magic) per file, including camera info, GPS coordinates, captions, and any face/keyword labels the Ente clients have added. A helper subcommand can detect and regenerate missing thumbnails, encrypting and uploading them back to the server.

Getting Started

git clone https://git.eeqj.de/sneak/quak.git
cd quak
yarn install
yarn build

# Log in (prompts for email, password, and OTP/TOTP if required).
yarn quak login

# List the user's collections (albums).
yarn quak collections

# List files in a collection.
yarn quak files --collection 12345

# Download and decrypt a single file.
yarn quak get 67890 --out ./photo.jpg

# Back up every file in the account.
yarn quak backup ./my-backup

For library use:

import { Client } from "quak";

const client = await Client.login({
    email: "you@example.com",
    password: "your-password",
});

for (const c of await client.listCollections()) {
    console.log(c.id, c.name);
    const files = await client.listFiles(c.id, c.key);
    for (const f of files) {
        console.log(`  ${f.metadata.title} [${f.metadata.fileType}]`);
    }
}

// Download a file
const files = await client.listFiles(collectionID, collectionKey);
await client.downloadFile(files[0], "./photo.jpg");

// Serialize session for later (consumer handles persistence)
const snapshot = client.toJSON();
// ... later:
const restored = Client.fromJSON(snapshot);

Entrypoints

This repository adheres to the Scripts to Rule Them All standard: normalized scripts in script/ are the entrypoints for the development workflow, and the Makefile targets are thin shims that call them. The scripts are POSIX sh (not bash) so they run in minimal containers such as alpine. We provide:

• script/bootstrap — install all dependencies (node/yarn if missing, then yarn install --frozen-lockfile)
• script/setup — set up the repo for development after a fresh clone: runs script/bootstrap, then script/install-precommit
• script/projectname — output the project name (our own extension); used by script/docker for the image tag
• script/build — compile the TypeScript sources into dist/, then verify that the entrypoints package.json declares (main, types, bin) are among the files the compiler wrote, and make the CLI executable (our own extension)
• script/test — run the test suite (vitest, hard-capped at 30s where timeout is available, verbose rerun on failure)
• script/lint — run eslint and a prettier check, by building Dockerfile.lint; requires docker (see Linting below)
• script/fmt — format all files with prettier (writes)
• script/fmt-check — check formatting (read-only)
• script/check — run all checks: test, lint, fmt-check (our own extension)
• script/docker — build the test and build image, tagged via script/projectname
• script/cibuild — cd to the repo root and build both images (what CI runs): script/lint first, then the Dockerfile image, which runs make test and make build
• script/precommit — run by the git pre-commit hook (our own extension); runs script/lint and script/fmt-check but deliberately not the tests, so the TDD red-phase commit can land
• script/install-precommit — installs the git pre-commit hook (our own extension); make hooks shims to it

make hooks installs the pre-commit hook that runs script/precommit.

Linting

Linting runs in a container, one way, everywhere. script/lint builds Dockerfile.lint, which copies the repo into a digest-pinned node image and runs eslint and prettier as build steps, so a successful build is a clean lint. There is no host lint path: docker is required to lint, and that also works where the docker daemon is remote and bind mounts are impossible.

Lint happens in exactly one place, which constrains the rest of the build. script/check calls script/lint, so make check cannot run inside a container without asking for docker inside docker. The image built from Dockerfile therefore runs make test and make build and does not lint; script/cibuild builds Dockerfile.lint first and that image second, so CI gets both verdicts.

Build epochs

script/lint passes --build-arg LINT_EPOCH="$(date +%s)", and script/docker and script/cibuild pass --build-arg CHECK_EPOCH="$(date +%s)". Both Dockerfiles refuse to build without their argument. This is deliberate: on an unchanged tree Docker would otherwise serve the linter and test layers from cache, so nothing would run and the build would still exit 0 — a lint build over an untouched tree returns success in well under a second, having linted nothing. A changing epoch invalidates every layer below the guard on every invocation while leaving the dependency layers above them cached, and the missing-argument guard means a bare docker build . fails loudly instead of quietly reporting a green it did not earn: an unset build argument is the empty string, which is a perfectly stable cache key.

Rationale

Ente is one of very few photo services with a credible end-to-end encryption story. The shipping clients (mobile Flutter, web React, desktop Electron, and Go CLI) work, but they are slow, buggy, and difficult to script against. The Flutter app fails to sync reliably. The web app is heavy. The desktop app is the web app inside a slow Electron wrapper. The Go CLI is the closest thing to a usable tool, but it is awkward to integrate from anything that is not a shell. The Go CLI's backup mode crashes entirely when a single file download fails, which makes it useless as an actual backup tool.

quak fixes these problems. This repo ships a correct, well-tested implementation of Ente's cryptographic protocol and API surface, plus a CLI that proves the library is enough to do real work without a UI. The backup command is resilient by design: per-file errors are logged and the run continues.

The longer-term goal of this project is a simple desktop client for Ente, built on this library in Electron (or a comparable runtime), with two priorities above everything else: correctness and stability. Performance and simplicity follow from those. Features will be added only after the protocol layer is correct, the local cache is reliable, and the UI is responsive on a five-year-old laptop.

Development workflow

All work on quak is test-driven. No exceptions.

1. Every change starts on a feature branch off main.
2. The first commit on the branch is the test suite for what is being added or changed. Those tests must fail at that commit; the branch is red until the implementation lands.
3. Subsequent commits add the implementation and any refactors needed to make the tests pass.
4. A feature branch can only be merged into main when make check is green. main is always green. CI runs script/cibuild, which lints via Dockerfile.lint and then runs make test and make build in the Dockerfile image, so neither a red branch nor one that does not compile can pass CI.
5. Tests are the canonical API documentation for this library. Every test file is commented thoroughly enough that a reader who has never seen quak can learn how to use it from the tests alone. Comments explain why a behavior matters, not just what the assertion checks.
6. Test fixtures (cryptographic vectors, recorded HTTP responses, sample files) are committed alongside their tests. Where possible they are generated by deterministic helpers in the test/ tree so any reviewer can reproduce them by running the helper.
7. git rebase -i is allowed on a feature branch before merge to clean up the test-then-implementation sequence into reviewable commits, but the final history must still show tests landing before (or with) the matching implementation.
8. The pre-commit hook installed by make hooks runs script/precommit, which runs the lint and format checks but not the full make check. This is deliberate so the TDD red-phase commit (failing tests, no implementation yet) can land. The suite runs as part of the image build, which is what CI executes via script/cibuild, so a red branch still cannot reach main.

Design

quak is a TypeScript library with a thin CLI wrapper. The library does the work; the CLI is for humans.

Layout

quak/
    src/
        crypto/         libsodium primitives (boxes, secretstreams, KDF, SRP)
        api/            HTTP client (ApiClient class)
        auth/           login flow (SRP + email OTP + TOTP), key unwrap
        model/          decrypted Collection, File, Metadata types + decrypt fns
        download/       streaming file/thumbnail download + decryption
        backup.ts       resilient full-account backup with dedup
        errors.ts       error types shared across layers
        retry.ts        retry classifier + exponential backoff with jitter
        thumbnails.ts   detect + regenerate missing thumbnails
        client.ts       high-level Client class assembled from the above
        index.ts        public library exports
    bin/
        quak.ts         CLI entrypoint (commander.js)
    test/               unit + integration tests (vitest)
    Makefile
    Dockerfile          test suite and compile
    Dockerfile.lint     eslint and prettier, as build steps
    package.json
    tsconfig.json

make build compiles that tree into dist/, preserving its shape: the library lands in dist/src/ and the CLI in dist/bin/quak.js, which is what package.json points main, types and bin at. The compiler's rootDir is the repository root rather than src/, because bin/ is compiled too and rootDir has to contain everything that is compiled.

Cryptography

All cryptography is done by libsodium-wrappers-sumo (the "sumo" build is required for crypto_pwhash / Argon2id). No hand-rolled crypto.

The key hierarchy, derived during login, is:

1. The user enters their password.
2. Argon2id (crypto_pwhash) over the password and a server-issued kekSalt, with server-issued memLimit and opsLimit, produces a 32-byte Key Encryption Key (KEK).
3. SRP login: a 16-byte SRP login subkey is derived from the KEK using crypto_kdf_derive_from_key (BLAKE2b) with subkey id 1 and context loginctx. That 16-byte value is the SRP password.
4. After SRP completes (or after email-OTP fallback), the server returns a blob of "key attributes" plus an encrypted auth token.
5. crypto_secretbox_open_easy over the encrypted master key with the KEK yields the 32-byte master key.
6. crypto_secretbox_open_easy over the encrypted secret key with the master key yields the user's X25519 private key. The matching public key is delivered in cleartext.
7. crypto_box_seal_open over the encrypted token with the user's keypair yields the URL-safe base64 auth token used in X-Auth-Token for all subsequent calls.

Per-collection keys are decrypted with crypto_secretbox_open_easy using the master key (for owned collections). Per-file keys are decrypted with crypto_secretbox_open_easy using the collection key. File metadata is a secretstream blob (single chunk, TAG_FINAL) under the file key. File content is a chunked crypto_secretstream_xchacha20poly1305 stream under the file key, with a 4 MiB plaintext chunk size and a 17-byte authentication overhead per chunk. Thumbnails use the same secretstream blob format as metadata.

For upload (thumbnail repair), encryptBlob performs the push side: a single secretstream chunk with TAG_FINAL, returning the header and ciphertext.

HTTP API

Production endpoints:

• API: https://api.ente.io
• File download CDN: https://files.ente.io/?fileID=<id>
• Thumbnail CDN: https://thumbnails.ente.io/?fileID=<id>

A custom API endpoint is configurable for self-hosted servers via the constructor option apiOrigin. When set, file downloads route through <apiOrigin>/files/download/<id> instead of the dedicated CDN host.

Required request headers on every authenticated call:

• X-Auth-Token: the decrypted auth token from login.
• X-Client-Package: identifies the client. quak uses berlin.sneak.quak.

Endpoints used:

• GET /users/srp/attributes?email=<email>: fetch SRP and KDF parameters.
• POST /users/srp/create-session: begin SRP handshake.
• POST /users/srp/verify-session: complete SRP, receive 2FA challenge or the encrypted token plus key attributes.
• POST /users/ott and POST /users/verify-email: email OTP fallback path.
• POST /users/two-factor/verify: TOTP second factor.
• GET /collections/v2?sinceTime=<usec>: list collections changed since microsecond timestamp; pass 0 for a full enumeration.
• GET /collections/v2/diff?collectionID=<id>&sinceTime=<usec>: list files in a collection; paginate while hasMore is true.
• GET https://files.ente.io/?fileID=<id>: download encrypted file bytes.
• POST /files/upload-url: mint a presigned upload URL (for thumbnail repair).
• PUT /files/thumbnail: register an uploaded thumbnail's object key.

Retries and timeouts

Every request in the library goes through one policy, in src/retry.ts. A request is repeated only when repeating it could produce a different answer:

• ApiError with a 5xx status: retried. So are 408 and 429, the two 4xx codes that are statements about timing rather than about the request.
• Every other 4xx: not retried. A 404 in particular is an answer, and listMissingThumbnails depends on getting it promptly and once.
• Transport failures — a fetch rejection, ECONNRESET, ETIMEDOUT, a DNS or TLS failure — and deadline aborts: retried. The errno is looked for in the error's cause chain, because that is where Node's fetch puts it.
• A truncated download: retried.
• Anything else, including a secretstream authentication failure that is not truncation: not retried. The default answer is no. For a backup tool, retrying a permanent failure spends round trips and delays every remaining file, while declining to retry a transient one costs a single file that the next run picks up.

Backoff is exponential with full jitter: the delay before retry n is random() * min(maxDelayMs, baseDelayMs * 2 ** (n - 1)). The exponential term is the ceiling and the wait is drawn below it, so a client that lost many parallel downloads to one CDN blip does not send them all again at the same instant. Defaults, configurable through ApiClientOptions.retry:

Option	Default	Meaning
attempts	4	total calls, not retries
baseDelayMs	500	ceiling for the first retry's delay
maxDelayMs	10000	upper bound on that ceiling

With those defaults a file that is going to fail gives up after at most three and a half seconds of waiting. sleep and random are injectable through the same option, which is how the test suite exercises the whole policy without waiting.

Two deadlines, applied with AbortSignal.timeout() and renewed for each attempt:

Option	Default	Applies to
requestTimeoutMs	30000	getJSON, postJSON, putJSON, putFile
downloadTimeoutMs	600000	file and thumbnail body transfers

They are separate because one number cannot serve both: a value short enough to keep a hung API call from stalling a backup would cancel a legitimate multi-gigabyte download. The download deadline covers the body, not just the headers — getFileStream returns as soon as headers arrive, so a deadline that only guarded the initial request would leave the same hang one layer down.

Non-idempotent requests are not blindly replayed. postJSON and putJSON reach /users/srp/create-session, /users/two-factor/verify — which consumes one of a small number of second-factor attempts — and /files/thumbnail. They are retried only on the three failures that establish no TCP connection to the server ever existed, so no request byte can have been transmitted: ENOTFOUND and EAI_AGAIN (name resolution produced no address) and ECONNREFUSED (the peer refused the connection). A 5xx, a mid-flight reset and a deadline are all left to the caller, because each of them can happen after the server has already acted. The routing errnos EHOSTUNREACH, ENETUNREACH and ENETDOWN are excluded for the same reason, despite looking like connect-time failures: on Linux an ICMP unreachable arriving mid-flight, or a local interface going down after the request was written, delivers them on an already-established socket. They stay retryable for the idempotent calls. putFile is exempt: a presigned PUT stores one whole object at one key in one request, so replaying it has no partial state to damage.

A download is retried as a whole — request, stream consumption, and decryption — because a socket reset after the response headers have arrived surfaces in the download layer rather than in ApiClient, and that is the common failure for multi-megabyte photos over a CDN. The secretstream pull state is not resumable and these endpoints have no Range support, so a retry starts the file over. The atomic write stays outside the retry, so a download that needed three attempts still performs exactly one write and one rename. runBackup and runMetadataBackup are unchanged: the retry sits below them, and a file that fails after exhausting it is still logged, counted, and stepped over.

One imprecision is deliberate and worth knowing about. When a body ends part-way through a secretstream chunk, Poly1305 fails and carries no framing signal, so a cut connection and genuinely corrupt bytes are indistinguishable. quak reports that as truncation, which means it is retried. For a body of more than one chunk the distinction is real — a chunk that failed while the stream carried on past it stays an authentication failure and is not retried — but for a single-chunk body, which is most thumbnails and every small file, a wrong key, server-side corruption and a mid-chunk cutoff all present alike and all get retried. The cost is bounded by the attempt count, and it buys never silently keeping a truncated file.

Session handling

The Client class holds the auth token, master key, secret key, and public key in memory. There is no on-disk session store in the library; the consumer decides how to persist sessions.

client.toJSON() returns a ClientSnapshot (a plain serializable object with base64-encoded keys) that the consumer can write to disk, a database, or whatever else fits their use case. Client.fromJSON(snapshot) restores a working client from that snapshot without re-authenticating.

The CLI stores the snapshot at the platform-appropriate data directory via env-paths: ~/Library/Application Support/quak/session.json on macOS, $XDG_DATA_HOME/quak/session.json on Linux. The file is written with mode 0600. The key material is stored in cleartext in the JSON; treat this file as you would treat the password itself.

CLI surface

quak login                                      interactive or QUAK_EMAIL/QUAK_PASSWORD
quak whoami                                     print logged-in account as JSON
quak logout                                     delete saved session
quak collections [--json]                       list all collections
quak files --collection <id> [--json]           list files in a collection
quak get <fileID> [--out path] [--collection]   download and decrypt a file
quak get-thumb <fileID> [--out] [--collection]  download and decrypt a thumbnail
quak backup <dir> [--json]                      full incremental backup
quak helper list-missing-thumbnails [--json]    find files with missing thumbnails
quak helper fix-missing-thumbnails [--file ids] generate + upload missing thumbnails

get and get-thumb search all collections for the file ID when --collection is not specified. All listing and backup commands support --json for machine-readable output.

Backup layout

quak backup <dir> produces:

<dir>/
    originals/
        <fileID>.<ext>          actual file content (one per unique file)
        <fileID>.json           all decrypted metadata for that file
    collections/
        <name>/
            <title> -> ../../originals/<fileID>.<ext>   (symlink)
        <name>.json             collection metadata + file list

Each file is downloaded exactly once regardless of how many collections it appears in. On subsequent runs, existing originals are skipped. If a download fails, the error is logged and the backup continues with the next file. The exit code is non-zero if any files failed.

TODO

• Retry policy: no retry on 4xx, exponential backoff on 5xx and network errors
• Update the API reference section below to match the current implementation
• make docker green
• Tag v1.0.0

Future (desktop client, separate repo):

• Electron app skeleton consuming this library
• Local cache (SQLite) keyed on (collectionID, fileID, updationTime)
• Background sync worker that streams new files into the cache
• Gallery UI: thumbnails, full-image view, basic search
• Upload, delete, and share operations in the library

API reference

The API reference section below is from an earlier draft and does not fully reflect the current implementation. The authoritative API documentation is in the test files, particularly test/client/usage.test.ts which is a literate tutorial walking through every operation. Run yarn test to verify the examples are correct.

The key types and their actual signatures can be found in:

• src/client.ts: Client, LoginOptions, ClientSnapshot
• src/api/client.ts: ApiClient, ApiClientOptions, ApiError, StreamOptions
• src/errors.ts: ApiError, TruncatedStreamError
• src/retry.ts: withRetry, isRetryable, isSafeToReplay, RetryOptions
• src/auth/types.ts: KeyAttributes, SRPAttributes, AuthorizationResponse, LoginChallenge
• src/model/types.ts: Collection, EnteFile, FileMetadata, FileBlob, RawCollection, RawEnteFile, RawMagicMetadata
• src/download/index.ts: DownloadResult
• src/backup.ts: BackupResult, BackupError
• src/thumbnails.ts: MissingThumbnailInfo, ThumbnailFixResult

Source attribution

The cryptographic protocol and wire format implemented here are Ente's, taken from the Ente open source clients at https://github.com/ente-io/ente. No code is imported or vendored from those projects; any reference code that is copied is rewritten in TypeScript in this repository. Protocol fidelity is verified against the upstream implementations in web/packages/base/, mobile/apps/photos/lib/, and cli/.

For LLMs

If you are an LLM agent working on this repository, read and follow these documents:

• REPO_POLICIES.md in the repo root. It is copied from https://git.eeqj.de/sneak/prompts and covers repository structure, tooling, Makefile targets, Dockerfile conventions, dependency pinning, and commit hygiene. All external dependencies must be pinned by cryptographic hash in yarn.lock. Never git add -A. Never force-push to main.

• The "Development workflow" section above. All changes go on feature branches. Tests are written first and committed in a failing state before the implementation. Tests are the canonical API documentation and must be commented thoroughly. main is always green.

• Required checks before every commit: make lint (eslint + prettier check, which builds Dockerfile.lint and therefore needs docker) and make fmt-check must pass. The pre-commit hook enforces this. make check (which also runs tests) must pass before merging to main. Never invoke eslint or prettier directly; linting runs in the container only.

• Formatting: prettier with 4-space indents and proseWrap: always for markdown. Use make fmt to format. Use yarn not npm.

• Testing: vitest. Tests go in test/ mirroring the src/ structure. make test must complete in under 20 seconds. Use mkdtempSync for temporary directories, never manual timestamp paths.

• Code style: const for everything, let if reassignment is needed, never var. Avoid unnecessary comments. No hand-rolled crypto. The LLM_PROSE_TELLS.md document in the prompts repo applies to any prose written in this repository (README, comments, commit messages).

License

WTFPL. See LICENSE.

Author

@sneak