sequoia-keystore-backend-0.2.0/.cargo_vcs_info.json0000644000000001450000000000100157310ustar { "git": { "sha1": "05e35c2c80cc21938497fd4d291f3dd8b10b1518" }, "path_in_vcs": "backend" }sequoia-keystore-backend-0.2.0/Cargo.toml0000644000000030560000000000100137330ustar # THIS FILE IS AUTOMATICALLY GENERATED BY CARGO # # When uploading crates to the registry Cargo will automatically # "normalize" Cargo.toml files for maximal compatibility # with all versions of Cargo and also rewrite `path` dependencies # to registry (e.g., crates.io) dependencies. # # If you are reading this file be aware that the original Cargo.toml # will likely look very different (and much more reasonable). # See Cargo.toml.orig for the original contents. [package] edition = "2021" rust-version = "1.70" name = "sequoia-keystore-backend" version = "0.2.0" authors = ["Neal H. Walfield "] description = "Traits for private key store backends." homepage = "https://sequoia-pgp.org/" readme = "README.md" keywords = [ "cryptography", "openpgp", ] categories = ["cryptography"] license = "LGPL-2.0-or-later" repository = "https://gitlab.com/sequoia-pgp/sequoia-keystore" [package.metadata.docs.rs] features = ["sequoia-openpgp/default"] [dependencies.anyhow] version = "1.0.18" [dependencies.blanket] version = "0.3" [dependencies.sequoia-openpgp] version = "1.17" default-features = false [dependencies.thiserror] version = "1.0.2" [target."cfg(not(windows))".dev-dependencies.sequoia-openpgp] version = "1" features = [ "crypto-nettle", "__implicit-crypto-backend-for-tests", ] default-features = false [target."cfg(windows)".dev-dependencies.sequoia-openpgp] version = "1" features = [ "crypto-cng", "__implicit-crypto-backend-for-tests", ] default-features = false [badges.maintenance] status = "actively-developed" sequoia-keystore-backend-0.2.0/Cargo.toml.orig000064400000000000000000000022331046102023000174100ustar 00000000000000[package] name = "sequoia-keystore-backend" description = "Traits for private key store backends." version = "0.2.0" authors = ["Neal H. Walfield "] homepage = "https://sequoia-pgp.org/" repository = "https://gitlab.com/sequoia-pgp/sequoia-keystore" readme = "README.md" keywords = ["cryptography", "openpgp" ] categories = ["cryptography"] license = "LGPL-2.0-or-later" edition = "2021" rust-version = "1.70" [badges] maintenance = { status = "actively-developed" } [dependencies] anyhow = "1.0.18" blanket = "0.3" sequoia-openpgp = { version = "1.17", default-features = false } thiserror = "1.0.2" # Enables a crypto backend for the tests: [target.'cfg(not(windows))'.dev-dependencies] sequoia-openpgp = { version = "1", default-features = false, features = ["crypto-nettle", "__implicit-crypto-backend-for-tests"] } # Enables a crypto backend for the tests: [target.'cfg(windows)'.dev-dependencies] sequoia-openpgp = { version = "1", default-features = false, features = ["crypto-cng", "__implicit-crypto-backend-for-tests"] } # Enables a crypto backend for the docs.rs generation: [package.metadata.docs.rs] features = ["sequoia-openpgp/default"] sequoia-keystore-backend-0.2.0/LICENSE.txt000064400000000000000000000627341046102023000163600ustar 00000000000000Sequoia PGP is free software; you can redistribute it and/or modify it under the terms of the GNU Library General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. Sequoia PGP is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. --- GNU LIBRARY GENERAL PUBLIC LICENSE Version 2, June 1991 Copyright (C) 1991 Free Software Foundation, Inc. 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. [This is the first released version of the library GPL. It is numbered 2 because it goes with version 2 of the ordinary GPL.] Preamble The licenses for most software are designed to take away your freedom to share and change it. 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To apply these terms, attach the following notices to the library. It is safest to attach them to the start of each source file to most effectively convey the exclusion of warranty; and each file should have at least the "copyright" line and a pointer to where the full notice is found. Copyright (C) This library is free software; you can redistribute it and/or modify it under the terms of the GNU Library General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License for more details. You should have received a copy of the GNU Library General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA Also add information on how to contact you by electronic and paper mail. You should also get your employer (if you work as a programmer) or your school, if any, to sign a "copyright disclaimer" for the library, if necessary. Here is a sample; alter the names: Yoyodyne, Inc., hereby disclaims all copyright interest in the library `Frob' (a library for tweaking knobs) written by James Random Hacker. , 1 April 1990 Ty Coon, President of Vice That's all there is to it! sequoia-keystore-backend-0.2.0/README.md000064400000000000000000000005651046102023000160060ustar 00000000000000The `sequoia-keystore` crate implements a server that manages secret key material. Secret key material can be stored in files, on hardware devices like smartcards, or accessed via the network. `sequoia-keystore` doesn't implement these access methods. This is taken care of by various backends. The backends implement a common interface, which is defined by this crate. sequoia-keystore-backend-0.2.0/src/lib.rs000064400000000000000000000606021046102023000164300ustar 00000000000000//! Defines the traits that keystore backends need to implement. //! //! Sequoia's keystore is a service, which manages and multiplexes //! access to secret key material. Conceptually, keys live on //! devices, and devices are managed by backends. A device may be as //! simple as an on-disk file, it may be a smartcard, or it could be //! another keystore server that is accessed over the network. //! //! A backend implements the traits defined in this crate. The traits //! abstract away the details of the various devices. They are mostly //! concerned with enumerating keys, and executing the low-level //! decrypt and sign operations. The backend interfaces are different //! from, and more low level than the general-purpose interface //! exposed to applications. //! //! The following figure illustrates the architecture. The squares //! represent different address spaces. //! //! ```text //! +---------------+ +---------------+ //! | Application | | Application | //! +---------------+ +---------------+ //! \ / //! +----------------------------------------------+ //! | Keystore | //! | / \ | //! | soft key openpgp card | //! | backend backend | //! +----------------------------------------------+ //! ``` //! //! The keystore does not have to run as a server; it is also possible //! to co-locate the keystore in an application, as shown here: //! //! ```text //! +----------------------------------------------+ //! | Application | //! | | | //! | Keystore | //! | / \ | //! | soft key openpgp card | //! +----------------------------------------------+ //! ``` //! //! Using a daemon instead of a library or a sub-process, which is //! spawned once per application and is terminated when the //! application terminates, offers several advantages. //! //! The main user-visible advantage is that the daemon is able to hold //! state. In the case of soft keys, the daemon can cache an //! unencrypted key in memory so that the user doesn't have to unlock //! the key as frequently. This is particularly helpful when a //! command-line tool like `sq` is executed multiple times in a row //! and each time accesses the same password-protected key. Likewise, //! a daemon can cache a PIN needed to access an HSM. It can also //! keep the HSM open thereby avoiding the initialization overhead. //! This also applies to remote keys: an ssh tunnel, for instance, can //! be held open, and reused as required. //! //! A separate daemon also simplifies an important non-functional security //! property: process separation. Since soft keys aren't managed by the //! application, but by the daemon, an attacker is not able to use a //! [heartbleed]-style attack to exfiltrate secret key material. //! //! [heartbleed]: https://heartbleed.com/ //! //! The traits model backends as collections of devices each of which //! contains zero or more keys. The following figure illustrates a //! possible configuration. The keystore uses two backends, the //! softkey backend, and the openpgp card backend, and each backend //! has two devices. The softkey backend models certificates as //! devices; the openpgp card backend has one device for each physical //! device. Each device contains between 1 and 3 keys. The interface //! does not impose a limit on the number of devices per backend, or //! the number of keys per device. As such, a TPM managing thousands //! of keys is conceivable, and in scope. //! //! ```text //! +----------------------------------------------------+ //! | Keystore | //! | / \ | //! | soft key openpgp card | //! | / \ / \ | //! | 0x1234 0xABCE Gnuk Nitro Key | //! | / \ | #123456 #234567 | //! | 0x10 0x23 0x34 / | \ / | \ | //! | 0x31 0x49 0x5A 0x64 0x71 0x88 | //! +----------------------------------------------------+ //! ``` //! //! The different devices may or may not be connected at any given //! time. For instance, the user may remove a smartcard, but if the //! backend has recorded the configuration, the keystore still knows //! about the //! //! When the keystore starts, it eagerly initializes the various //! backends that it knows about. At this time, backends are //! statically linked to the keystore, and have to be explicitly //! listed in the keystore initialization function. //! //! When a backend is initialized, the initialization function is //! passed a directory. The backend should read any required state //! from a subdirectory, which is named after the backend. For //! instance, the soft keys backend uses the "softkeys" subdirectory. //! //! A backend must be extremely careful when using state stored //! somewhere else. If a user selects a different home directory, //! then they usually want a different configuration, which is //! isolated from the main configuration. This is not entirely //! possible in the case where a backend uses a physical resource, for //! example. //! //! # Keys and Devices //! //! At its simplest, a device contains zero or more OpenPGP keys. A //! device may also be locked or unlocked, registered or not //! registered, and available or unavailable. //! //! If a device is locked, it first has to be unlocked before it can //! be used. Sometimes a device can be unlocked by supplying a //! password via the [`DeviceHandle::unlock`] interface. Other times, //! the device has to be manually unlocked by the user. If a device //! is locked, it may or may not be possible to enumerate the keys //! stored on the device. //! //! If a device is registered, then the device's configuration has //! been cached locally. In this case, the keys on the device can be //! enumerated even if the device is not connected to the host. For //! instance, when an OpenPGP card is registered, the OpenPGP card //! backend records the serial number of device, the list of keys that //! are stored on the smartcard, and their attributes. When the user //! enumerates the keys managed by the key store, these keys are //! returned, even if the smartcard is not attached. The user cannot, //! of course, use the keys. //! //! If a device is registered, but is not attached to the system, then //! it is considered unavailable. If the user attempts to use a key //! on an unavailable device, then an error is returned. In this //! case, the application could normally prompt the user to make the //! corresponding device available. //! //! These states are documented in more detail in the documentation //! for [`DeviceHandle`]. //! //! Whether a key is registered or available is purely a function of //! the device. If a device contains multiple keys, and they can be //! registered, or available independent of the other keys, then the //! backend must model the keys as separate devices. use std::cell::OnceCell; use sequoia_openpgp as openpgp; use openpgp::Fingerprint; use openpgp::KeyID; use openpgp::Result; use openpgp::crypto::Password; use openpgp::crypto::SessionKey; use openpgp::crypto::mpi; use openpgp::packet::PKESK; use openpgp::types::HashAlgorithm; use openpgp::types::PublicKeyAlgorithm; use openpgp::types::SymmetricAlgorithm; /// Errors used in this crate. /// /// Note: This enum cannot be exhaustively matched to allow for future /// extensions. #[non_exhaustive] #[derive(thiserror::Error, Debug)] pub enum Error { /// Invalid argument. #[error("Invalid argument: {0}")] InvalidArgument(String), /// Not found. #[error("Not found: {0}")] NotFound(String), /// Operation not supported. #[error("Operation not supported: {0}")] OperationNotSupported(String), /// The device or key is locked. /// /// A device is locked when a pin, password, or some other /// interaction is needed to unlock the device. /// /// When this error is received, the caller should prompt the user /// for the password, unlock the object, and then retry the /// operation. #[error("Object is locked: {0}")] Locked(String), /// The device or key is not available. /// /// When this error is received, the caller may prompt the user to /// insert the device, and then retry the operation. #[error("Object is not available: {0}")] Unavailable(String), /// The device is not registered. #[error("Device is not registered: {0}")] Unregistered(String), /// The device is not configured. /// /// The device may contain keys, but it first needs to be /// configured before it can be used. #[error("Device needs to be configured: {0}")] Unconfigured(String), /// The device or key is already unlocked. /// /// Returned by [`DeviceHandle::unlock`] and [`KeyHandle::unlock`] /// if a device or key is already unlocked or doesn't need to be /// unlocked. #[error("Device is already unlocked: {0}")] AlreadyUnlocked(String), } /// The backend interface for the sequoia key store. /// /// This is the the interface that each device driver needs to /// implement. pub trait Backend: Send { /// Returns the backend's identifier. /// /// This should be an identifier that uniquely identifies the /// device driver, is human readable, and is stable across /// restarts. fn id(&self) -> String; /// Causes the backend to look for devices. /// /// This function should perform a lightweight scan. In /// particular, it should: /// /// - Read in the configuration of any devices that have been /// registered. /// /// - Look for locally connected devices with OpenPGP keys, /// e.g., smartcards, TPMs, etc. /// /// This function should not search for devices that may take a /// long time to find. For instance, it should not scan the /// network, or prompt the user for a password. Instead, a /// separate utility should be used to discover and register those /// devices. /// /// The backend should cache information about any devices that it /// finds in memory, but it should not register them. /// /// This function should not initialize registered devices for /// use, e.g., the ssh tunnel needed to access a remote key should /// not be brought up. /// /// In the terminology of [`DeviceHandle`], this should look for /// devices that are available or registered. fn scan(&mut self) -> Result<()> { Err(Error::OperationNotSupported("Backend::scan".into()).into()) } /// Lists all devices that are available or registered. /// /// This does not actively perform a scan. It simply returns the /// devices that were available or registered as of the last scan. /// /// In the terminology of [`DeviceHandle`], it returns devices /// that are available or are registered. fn list<'a>(&'a self) -> Box> + Send + Sync + 'a>; /// Returns a handle for the specified device. /// /// id is a string as returned by [`DeviceHandle::id`]. /// /// If the device is not available or not registered, then this /// should return [`Error::NotFound`]. fn find_device<'a>(&self, id: &str) -> Result>; /// Returns a handle for the specified key. /// /// `id` is a string as returned by [`KeyHandle::id`]. /// /// If the key is not available or not registered, then this /// should return [`Error::NotFound`]. fn find_key<'a>(&self, id: &str) -> Result>; } /// A device that contains zero or more keys. /// /// # Device Properties /// /// A device has three properties: it can be available or not, /// configured or not, and registered or not. /// /// ## Available /// /// A device is available if the secret key material can be used. /// (This is independent of whether the secret key material is /// locked.) A smart card, for instance, is available when it is /// inserted, and it is not available when it is not inserted. /// Devices that are available are always returned by /// [`Backend::list`]. /// /// ## Configured /// /// A device is configured if it can be used without further /// configuration. (This is independent of whether the secret key /// material is locked.) To use the secret key material on a /// smartcard or a TPM, the user may first need to load the OpenPGP /// certificate corresponding to the secret keys. Most devices, /// however, are already configured, or are able to configure /// themselves without the user's intervention. For instance, OpenPGP /// smartcards don't normally contain the OpenPGP certificate /// corresponding to the secret keys, but they do contain the keys' /// OpenPGP fingerprints, and an OpenPGP card backend could fetch /// the certificate's without user intervention. /// /// Devices that are available, but not configured should still be /// returned by [`Backend::list`]. However, because the keys may not /// be known, the keys may not be enumerable or not usable. In this /// case, [`DeviceHandle::list`] should return /// [`Error::Unconfigured`]. /// /// If a device contains multiple keys, and some can be configured /// while others aren't, then each key should be exposed as a separate /// device; this API assumes that either no key or all keys on a given /// device are configured. /// /// ## Registered /// /// A device that is registered is a device whose meta-data has been /// saved locally. Devices that are registered are returned by /// [`Backend::list`] even if they are not available. Likewise, the /// keys on a registered device are returned by [`DeviceHandle::list`] /// even when the device is not available. When the key store /// attempts to decrypt a message, it may prompt the user to insert an /// unavailable, registered device. /// /// When a backend scans for devices, it should not automatically /// register devices. Once a device has been successfully used, /// however, a backend may register the device. For instance, a smart /// card that is discovered by a scan should not automatically be /// registered. However, when the smart card is successfully used to /// create a signature or decrypt a message, then it may be registered /// without further intervention from the user. /// /// ## Alternate View /// /// Another, less precise view, is that a device may be in one of the /// following states: /// /// - Ready: The device is available and configured. /// /// The device can be used immediately. For instance, a soft key, /// or a smartcard that is inserted. /// /// A device that is ready may still need to be unlocked. /// /// - Disconnected: A device that was registered, but is not /// available. /// /// The device is not available, but the user may be prompted to /// make it available. For instance, if a key needed to decrypt a /// message is on a smartcard that is unavailable, the user may be /// prompted to insert the smartcard. Similarly, if a key is /// accessible via an ssh tunnel, but the ssh tunnel cannot be /// established, the user may be prompted to connect to the /// network. /// /// The backend should still expose all of an unavailable device's /// keys (insofar as they are known), however, the decrypt and /// sign operations should fail with [`Error::Unavailable`]. /// /// - Unusable: A device that was discovered, but that cannot be /// used without some additional configuration. For instance, a /// smartcard or a TPM key may need the corresponding certificate /// before it can be used. /// /// - Unknown: A device that is not available, and not registered. /// /// The aforementioned three properties map onto these states as /// follows: /// /// ```text /// Available, Configured, Registered: Ready /// Available, Configured, Not Registered: Ready /// Available, Not Configured, Registered: Unusable /// Available, Not Configured, Not Registered: Unusable /// Not Available, Configured, Registered: Disconnected /// Not Available, Configured, Not Registered: Unknown /// Not Available, Not Configured, Registered: Disconnected /// Not Available, Not Configured, Not Registered: Unknown /// ``` /// /// A device is only ever instantiated if it is available or registered. #[blanket::blanket(derive(Box, Mut))] pub trait DeviceHandle { /// Returns the device's id. /// /// The id is a globally unique, stable, and mostly human readable /// identifier. fn id(&self) -> String; /// Returns the device's description. /// /// The description is a human readable string, e.g., "GnuK with /// certificate FINGERPRINT". fn description(&self) -> String { self.id() } /// Sets the device's human readable description. /// /// This should fail if the device is not registered. fn set_description(&self, _description: String) -> Result<()> { Err(Error::Unregistered(self.id()).into()) } /// Returns whether the device is available. /// /// A device is available if it is plugged-in. fn available(&self) -> bool; /// Returns whether the device is configured. /// /// A device is configured if the keys can be used without further /// configuration. fn configured(&self) -> bool; /// Returns whether the device is registered. /// /// A device is registered if the device is locally memorized. In /// this case, the user may be prompted to insert the device. fn registered(&self) -> bool; /// Registers the device. /// /// This explicitly registers the device. The backend should /// memorize the device and should return it during a scan even if /// it is not available. If the device is already registered, /// this should silently succeed. fn register(&mut self) -> Result<()> { Err(Error::OperationNotSupported("DeviceHandle::register".into()).into()) } /// Unregisters the device from the backend. /// /// This should not destroy any secret key material stored on the /// device. It should just remove any cached state about the /// device. For instance, if the device is an ssh tunnel, then /// the ssh tunnel's configuration should be forgotten. If the /// device is a smart card, then the smart card should be /// forgotten. Note: if the smart card is inserted, it is still /// available and thus still usable. /// /// Note: devices that are not available can only be registered /// using a backend-specific tool. For instance, a device /// accessible via an ssh tunnel is never available. fn unregister(&mut self) -> Result<()> { Err(Error::OperationNotSupported("DeviceHandle::unregister".into()).into()) } /// Connects to and unlocks the device. /// /// Some devices need to be initialized. For instance, to access /// a remote key, it may be necessary to create an ssh tunnel. /// Some devices need to be unlocked before the keys can be /// enumerated. For instance, if soft keys are stored in a /// database and the database is encrypted, it may be necessary to /// supply a password to decrypt the database. fn unlock(&mut self, _password: &Password) -> Result<()> { Err(Error::AlreadyUnlocked("DeviceHandle::unlock".into()).into()) } /// Locks the device and any keys in contains. /// /// Locks the device if it has been previously unlocked as well as /// any keys managed by the device. If the device is locked or /// can't be locked, this is a noop. If the device needs to be /// deinitialized, it MAY be deinitialized lazily if doing so /// cannot result in a user-visible error. For instance, if the /// device uses an ssh tunnel, the ssh tunnel may be closed later. fn lock(&mut self) -> Result<()> { Ok(()) } /// Lists keys on the device. /// /// Returns the keys on the device. If the device is not usable, /// then this should return [`Error::Unconfigured`]. fn list<'a>(&'a self) -> Box> + Send + Sync + 'a>; } /// A Key on a Device. /// /// A key may or may not be available. This is a function of the /// device. #[blanket::blanket(derive(Box, Mut))] pub trait KeyHandle { /// Returns the key's id. /// /// The id is a globally unique, stable, and mostly human readable /// identifier. An example of a good id is the concatenation of /// the the key's fingerprint, and the device's serial number, /// e.g., "Key 8F17777118A33DDA9BA48E62AACB3243630052D9 on Yubikey /// 5 #217813388320." fn id(&self) -> String; /// Returns whether the key is available. fn available(&self) -> bool; /// Returns whether the key is locked. fn locked(&self) -> bool; /// Returns whether the key is decryption capable. fn decryption_capable(&self) -> bool; /// Returns whether the key is signing capable. fn signing_capable(&self) -> bool; /// Unlocks a key. /// /// A key is typically unlocked by providing a password or pin. /// Not all keys are locked. If the key is not available, this /// should attempt to connect to the device. If the device is not /// available or cannot be initialized, then this should fail. fn unlock(&mut self, _password: &Password) -> Result<()> { Err(Error::AlreadyUnlocked("KeyHandle::unlock".into()).into()) } /// Lock a key. /// /// Relocks the key. This usually causes the backend to forget the /// key's password. fn lock(&mut self) -> Result<()> { Ok(()) } /// Returns the key's fingerprint. fn fingerprint(&self) -> Fingerprint; /// Returns the key's key ID. fn keyid(&self) -> KeyID { KeyID::from(self.fingerprint()) } /// Returns the corresponding public key. /// /// The backend SHOULD ensure that the secret key material is /// removed. fn public_key(&self) -> openpgp::packet::Key; /// Decrypts a PKESK. /// fn decrypt_pkesk(&mut self, pkesk: &PKESK) -> Option<(SymmetricAlgorithm, SessionKey)> { // We want to use `PKESK::decrypt`. For that, we need // something that implements the `Decryptor` interface. We // could implement `Decryptor` for `KeyHandle`, but then that // is part of our public API. Instead, we do a bit of // acrobatics here. struct Decryptor where T: KeyHandle { slf: T, pk: OnceCell< openpgp::packet::Key< openpgp::packet::key::PublicParts, openpgp::packet::key::UnspecifiedRole>>, } impl openpgp::crypto::Decryptor for Decryptor where T: KeyHandle { fn public(&self) -> &openpgp::packet::Key< openpgp::packet::key::PublicParts, openpgp::packet::key::UnspecifiedRole> { self.pk.get_or_init(|| self.slf.public_key()) } fn decrypt(&mut self, ciphertext: &mpi::Ciphertext, plaintext_len: Option) -> Result { self.slf.decrypt_ciphertext(ciphertext, plaintext_len) } } let mut decryptor = Decryptor { slf: self, pk: OnceCell::new(), }; pkesk.decrypt(&mut decryptor, None) } /// Decrypts a ciphertext. /// /// This method has the same semantics as /// [`sequoia_openpgp::crypto::Decryptor::decrypt`]. /// /// Returns the session key. fn decrypt_ciphertext(&mut self, ciphertext: &mpi::Ciphertext, plaintext_len: Option) -> Result; /// Signs a message. /// /// `text` is the message to sign. fn sign(&mut self, hash_algo: HashAlgorithm, text: &[u8]) -> Result<(PublicKeyAlgorithm, mpi::Signature)>; }