keyring-rs: A Rust repository from brotskydotcom

Keyring-rs

A cross-platform library to manage storage and retrieval of passwords (and other secrets) in the underlying platform secure store, with a fully-developed example that provides a command-line interface.

Usage

To use this crate in your project, you must include it in your Cargo.toml and specify a feature for each supported credential store you want to use. For example, if you want to use the platform credential stores on Mac and Win, and use the Secret Service (synchronously) on Linux and *nix platforms, you would add a snippet such as this to your [dependencies] section:

keyring = { version = "3", features = ["apple-native", "windows-native", "sync-secret-service"] }

This will give you access to the keyring crate in your code. Now you can use the Entry::new function to create a new keyring entry. The new function takes a service name and a user's name which together identify the entry.

Passwords (strings) or secrets (binary data) can be added to an entry using its set_password or set_secret methods, respectively. (These methods create an entry in the underlying credential store.) The password or secret can then be read back using the get_password or get_secret methods. The underlying credential (with its password/secret data) can then be removed using the delete_credential method.

use keyring::{Entry, Result};

fn main() -> Result<()> {
    let entry = Entry::new("my-service", "my-name")?;
    entry.set_password("topS3cr3tP4$$w0rd")?;
    let password = entry.get_password()?;
    println!("My password is '{}'", password);
    entry.delete_credential()?;
    Ok(())
}

Errors

Creating and operating on entries can yield a keyring::Error which provides both a platform-independent code that classifies the error and, where relevant, underlying platform errors or more information about what went wrong.

Examples

The keychain-rs project contains a sample application (keyring-cli) and a sample library (ios).

The keyring-cli application is a command-line interface to the full functionality of the keyring. Invoke it without arguments to see usage information. It handles binary data input and output using base64 encoding. It can be installed using cargo install and used to experiment with library functionality. It can also be used when debugging keyring-based applications to probe the contents of the credential store; just be sure to build it using the same features/credential stores that are used by your application.

The ios library is a full exercise of all the iOS functionality; it's meant to be loaded into an iOS test harness such as the one found in this project. While the library can be compiled and linked to on macOS as well, doing so doesn't provide any advantages over using the crate directly.

Client Testing

This crate comes with a mock credential store that can be used by clients who want to test without accessing the native platform store. The mock store is cross-platform and allows mocking errors as well as successes.

Extensibility

This crate allows clients to "bring their own credential store" by providing traits that clients can implement. See the developer docs for details.

Platforms

This crate provides built-in implementations of the following platform-specific credential stores:

Linux: The DBus-based Secret Service and the kernel keyutils.
FreeBSD, OpenBSD: The DBus-based Secret Service.
macOS, iOS: The local keychain.
Windows: The Windows Credential Manager.

To enable the stores you want, you use features: there is one feature for each possibly-included credential store. If you specify a feature (e.g., dbus-secret-service) and your target platform (e.g., freebsd) supports that credential store, it will be included as the default credential store in that build. That way you can have a build command that specifies a single credential store for each of your target platforms, and use that same build command for all targets.

If you don't enable any credential stores that are supported on a specific target, the mock keystore will be the default on that target. If you enable multiple credential stores for a specific target, you will get a compile error. See the developer docs for details of which features control the inclusion of which credential stores (and which platforms each credential store targets).

Platform-specific issues

Since neither the maintainers nor GitHub do testing on BSD variants, we rely on contributors to support these platforms. Thanks for your help!

If you use the Secret Service as your credential store, be aware of the following:

Access to credential stores via this crate is always synchronous; that is, it blocks the thread on which it was invoked. This is true even if your feature set specifies using the Zbus-based secret-service crate, which offers an async interface, because this crate always uses the blocking interface. If your application is using an async runtime already, and you build with the async-secret-service feature in this crate, you should (1) specify the same async runtime you are using as a feature for this crate, and (2) be sure to have a separate thread that is used for all keyring calls that access the credential store. Failure to use a separate thread is known to cause deadlocks.
Because credential store access from this crate is always synchronous, there is really no reason not to use the sync-secret-service feature (rather than async-secret-service) with this crate, even if your code is already using one of the async runtimes. Yes, this feature requires that libdbus be installed on your user’s machines, but it is by default in all desktop OS installs that include a Secret Service implementation (such as the Gnome Keyring or the KWallet). If you want to be extra careful, you can use the additional vendored feature to this crate to statically link the dbus library with your app so it’s not required on user machines. Just keep in mind that, in the event of an update to libdbus, using the vendored feature will require a rebuild of your app to get the libdbus update to your users.
Every call to the Secret Service is done via an inter-process call, which takes time (typically tens if not hundreds of milliseconds). If, for some reason, your code is pounding on the Secret Service like a database, you will want to implement a write-through transactional backing cache to protect your users from slowdowns. The mock credential store can be adapted for this purpose.

If you use the Windows-native credential store, be careful about multi-threaded access, because the Windows credential store does not guarantee your calls will be serialized in the order they are made. Always access any single credential from just one thread at a time, and if you are doing operations on multiple credentials that require a particular serialization order, perform all those operations from the same thread.

The macOS and iOS credential stores do not allow service or user names to be empty, because empty fields are treated as wildcards on lookup. Use some default, non-empty value instead.

Upgrading from v2

The major functional change between v2 and v3 is the addition of synchronous support for the Secret Service via the dbus-secret-service crate. This means that keyring users of the Secret Service no longer need to link with an async runtime. (There are other advantages as well; see above for details.)

The main API change between v2 and v3 is the addition of support for non-string (i.e., binary) "password" data. To accommodate this, two changes have been made:

There are two new methods on Entry objects: set_secret and get_secret. These are the analogs of set_password and get_password, but instead of taking or returning strings they take or return binary data (byte arrays/vectors).
The v2 method delete_password has been renamed delete_credential, both to clarify what's actually being deleted and to emphasize that it doesn't matter whether it's holding a "password" or a "secret".

Another API change between v2 and v3 is that the notion of a default feature set has gone away: you must now specify explicitly which crate-supported keystores you want included (other than the mock keystore, which is always present). So all keyring client developers will need to update their Cargo.toml file to use the new features correctly.

All v2 data is fully forward-compatible with v3 data; there have been no changes at all in that respect. However, unlike v2, the v3 implementation of the secret service credential store will not read credentials that were written by the v1 keyring. (For details about why this decision was made, see this issue). Keyring clients who use the secret service and are still using old v1 credentials should replace those credentials with v2/v3 credentials. The CLI has been extended to allow reading and deleting v1 credentials (and thus provides sample code for how to do this).

The MSRV has been moved to 1.75, and all direct dependencies are at their latest stable versions.

License

Licensed under either of

Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contributors

Thanks to the following for helping make this library better, whether through contributing code, discussion, or bug reports!

@Alexei-Barnes
@benwr
@bhkaminski
@Brooooooklyn
@brotskydotcom
@complexspaces
@connor4312
@dario23
@dten
@gondolyr
@hwchen
@jankatins
@jasikpark
@jkhsjdhjs
@jonathanmorley
@jyuch
@klemensn
@landhb
@lexxvir
@MaikKlein
@Phrohdoh
@phlip9
@ReactorScram
@Rukenshia
@russellbanks
@ryanavella
@samuela
@stankec
@steveatinfincia
@Sytten
@thewh1teagle
@tmpfs
@VorpalBlade
@zschreur

If you should be on this list, but don't find yourself, please contact @brotskydotcom.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

brotskydotcom/keyring-rs