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//! Asymmetric crypto operations.
use crate::packet::{self, key, Key};
use crate::crypto::SessionKey;
use crate::crypto::mpi;
use crate::types::{Curve, HashAlgorithm, PublicKeyAlgorithm};
use crate::{Error, Result};
/// Creates a signature.
///
/// Used in the streaming [`Signer`], the methods binding components
/// to certificates (e.g. [`UserID::bind`]), [`SignatureBuilder`]'s
/// signing functions (e.g. [`SignatureBuilder::sign_standalone`]),
/// and likely many more places.
///
/// [`Signer`]: crate::serialize::stream::Signer
/// [`UserID::bind`]: crate::packet::UserID::bind()
/// [`SignatureBuilder`]: crate::packet::signature::SignatureBuilder
/// [`SignatureBuilder::sign_standalone`]: crate::packet::signature::SignatureBuilder::sign_standalone()
///
/// This is a low-level mechanism to produce an arbitrary OpenPGP
/// signature. Using this trait allows Sequoia to perform all
/// operations involving signing to use a variety of secret key
/// storage mechanisms (e.g. smart cards).
///
/// A signer consists of the public key and a way of creating a
/// signature. This crate implements `Signer` for [`KeyPair`], which
/// is a tuple containing the public and unencrypted secret key in
/// memory. Other crates may provide their own implementations of
/// `Signer` to utilize keys stored in various places. Currently, the
/// following implementations exist:
///
/// - [`KeyPair`]: In-memory keys.
/// - [`sequoia_rpc::gnupg::KeyPair`]: Connects to the `gpg-agent`.
///
/// [`sequoia_rpc::gnupg::KeyPair`]: https://docs.sequoia-pgp.org/sequoia_ipc/gnupg/struct.KeyPair.html
pub trait Signer {
/// Returns a reference to the public key.
fn public(&self) -> &Key<key::PublicParts, key::UnspecifiedRole>;
/// Returns a list of hashes that this signer accepts.
///
/// Some cryptographic libraries or hardware modules support signing digests
/// produced with only a limited set of hashing algorithms. This function
/// indicates to callers which algorithm digests are supported by this signer.
///
/// The default implementation of this function allows all hash algorithms to
/// be used. Provide an explicit implementation only when a smaller subset
/// of hashing algorithms is valid for this `Signer` implementation.
fn acceptable_hashes(&self) -> &[HashAlgorithm] {
&crate::crypto::hash::DEFAULT_HASHES_SORTED
}
/// Creates a signature over the `digest` produced by `hash_algo`.
fn sign(&mut self, hash_algo: HashAlgorithm, digest: &[u8])
-> Result<mpi::Signature>;
}
impl Signer for Box<dyn Signer> {
fn public(&self) -> &Key<key::PublicParts, key::UnspecifiedRole> {
self.as_ref().public()
}
fn acceptable_hashes(&self) -> &[HashAlgorithm] {
self.as_ref().acceptable_hashes()
}
fn sign(&mut self, hash_algo: HashAlgorithm, digest: &[u8])
-> Result<mpi::Signature> {
self.as_mut().sign(hash_algo, digest)
}
}
impl Signer for Box<dyn Signer + Send + Sync> {
fn public(&self) -> &Key<key::PublicParts, key::UnspecifiedRole> {
self.as_ref().public()
}
fn acceptable_hashes(&self) -> &[HashAlgorithm] {
self.as_ref().acceptable_hashes()
}
fn sign(&mut self, hash_algo: HashAlgorithm, digest: &[u8])
-> Result<mpi::Signature> {
self.as_mut().sign(hash_algo, digest)
}
}
/// Decrypts a message.
///
/// Used by [`PKESK::decrypt`] to decrypt session keys.
///
/// [`PKESK::decrypt`]: crate::packet::PKESK#method.decrypt
///
/// This is a low-level mechanism to decrypt an arbitrary OpenPGP
/// ciphertext. Using this trait allows Sequoia to perform all
/// operations involving decryption to use a variety of secret key
/// storage mechanisms (e.g. smart cards).
///
/// A decryptor consists of the public key and a way of decrypting a
/// session key. This crate implements `Decryptor` for [`KeyPair`],
/// which is a tuple containing the public and unencrypted secret key
/// in memory. Other crates may provide their own implementations of
/// `Decryptor` to utilize keys stored in various places. Currently, the
/// following implementations exist:
///
/// - [`KeyPair`]: In-memory keys.
/// - [`sequoia_rpc::gnupg::KeyPair`]: Connects to the `gpg-agent`.
///
/// [`sequoia_rpc::gnupg::KeyPair`]: https://docs.sequoia-pgp.org/sequoia_ipc/gnupg/struct.KeyPair.html
pub trait Decryptor {
/// Returns a reference to the public key.
fn public(&self) -> &Key<key::PublicParts, key::UnspecifiedRole>;
/// Decrypts `ciphertext`, returning the plain session key.
fn decrypt(&mut self, ciphertext: &mpi::Ciphertext,
plaintext_len: Option<usize>)
-> Result<SessionKey>;
}
impl Decryptor for Box<dyn Decryptor> {
fn public(&self) -> &Key<key::PublicParts, key::UnspecifiedRole> {
self.as_ref().public()
}
fn decrypt(&mut self, ciphertext: &mpi::Ciphertext,
plaintext_len: Option<usize>)
-> Result<SessionKey> {
self.as_mut().decrypt(ciphertext, plaintext_len)
}
}
impl Decryptor for Box<dyn Decryptor + Send + Sync> {
fn public(&self) -> &Key<key::PublicParts, key::UnspecifiedRole> {
self.as_ref().public()
}
fn decrypt(&mut self, ciphertext: &mpi::Ciphertext,
plaintext_len: Option<usize>)
-> Result<SessionKey> {
self.as_mut().decrypt(ciphertext, plaintext_len)
}
}
/// A cryptographic key pair.
///
/// A `KeyPair` is a combination of public and secret key. If both
/// are available in memory, a `KeyPair` is a convenient
/// implementation of [`Signer`] and [`Decryptor`].
///
///
/// # Examples
///
/// ```
/// # fn main() -> sequoia_openpgp::Result<()> {
/// use sequoia_openpgp as openpgp;
/// use openpgp::types::Curve;
/// use openpgp::cert::prelude::*;
/// use openpgp::packet::prelude::*;
///
/// // Conveniently create a KeyPair from a bare key:
/// let keypair =
/// Key4::<_, key::UnspecifiedRole>::generate_ecc(false, Curve::Cv25519)?
/// .into_keypair()?;
///
/// // Or from a query over a certificate:
/// let (cert, _) =
/// CertBuilder::general_purpose(None, Some("alice@example.org"))
/// .generate()?;
/// let keypair =
/// cert.keys().unencrypted_secret().nth(0).unwrap().key().clone()
/// .into_keypair()?;
/// # Ok(()) }
/// ```
#[derive(Clone)]
pub struct KeyPair {
public: Key<key::PublicParts, key::UnspecifiedRole>,
secret: packet::key::Unencrypted,
}
assert_send_and_sync!(KeyPair);
impl KeyPair {
/// Creates a new key pair.
pub fn new(public: Key<key::PublicParts, key::UnspecifiedRole>,
secret: packet::key::Unencrypted)
-> Result<Self>
{
Ok(Self {
public,
secret,
})
}
/// Returns a reference to the public key.
pub fn public(&self) -> &Key<key::PublicParts, key::UnspecifiedRole> {
&self.public
}
/// Returns a reference to the secret key.
pub fn secret(&self) -> &packet::key::Unencrypted {
&self.secret
}
}
impl From<KeyPair> for Key<key::SecretParts, key::UnspecifiedRole> {
fn from(p: KeyPair) -> Self {
let (key, secret) = (p.public, p.secret);
key.add_secret(secret.into()).0
}
}
impl Signer for KeyPair {
fn public(&self) -> &Key<key::PublicParts, key::UnspecifiedRole> {
KeyPair::public(self)
}
fn sign(&mut self, hash_algo: HashAlgorithm, digest: &[u8])
-> Result<mpi::Signature>
{
use crate::crypto::backend::{Backend, interface::Asymmetric};
self.secret().map(|secret| {
match (self.public().pk_algo(), self.public().mpis(), secret) {
(PublicKeyAlgorithm::EdDSA,
mpi::PublicKey::EdDSA { curve, q },
mpi::SecretKeyMaterial::EdDSA { scalar }) => match curve {
Curve::Ed25519 => {
let public = q.decode_point(&Curve::Ed25519)?.0
.try_into()?;
let secret = scalar.value_padded(32);
let sig =
Backend::ed25519_sign(&secret, &public, digest)?;
Ok(mpi::Signature::EdDSA {
r: mpi::MPI::new(&sig[..32]),
s: mpi::MPI::new(&sig[32..]),
})
|