openpgp: Move KeyPair to crypto.

1 files changed, 150 insertions, 3 deletions

diff --git a/openpgp/src/crypto/asymmetric.rs b/openpgp/src/crypto/asymmetric.rs
index 9c8a1ae6..51d95934 100644
--- a/openpgp/src/crypto/asymmetric.rs
+++ b/openpgp/src/crypto/asymmetric.rs
@@ -1,9 +1,12 @@
-//! Asymmetric crypto operations.
+//! Asymmetric crypt operations.
+
+use nettle::{dsa, ecdsa, ed25519, rsa, Yarrow};
 
 use packet::Key;
-use crypto::mpis;
-use constants::HashAlgorithm;
+use crypto::mpis::{self, MPI};
+use constants::{Curve, HashAlgorithm};
 
+use Error;
 use Result;
 
 /// Creates a signature.
@@ -20,3 +23,147 @@ pub trait Signer {
     fn sign(&mut self, hash_algo: HashAlgorithm, digest: &[u8])
             -> Result<mpis::Signature>;
 }
+
+/// A cryptographic key pair.
+pub struct KeyPair {
+    public: Key,
+    secret: mpis::SecretKey,
+}
+
+impl KeyPair {
+    /// Creates a new key pair.
+    pub fn new(public: Key, secret: mpis::SecretKey) -> Result<Self> {
+        Ok(Self {
+            public: public,
+            secret: secret,
+        })
+    }
+}
+
+impl Signer for KeyPair {
+    fn public(&self) -> &Key {
+        &self.public
+    }
+
+    fn sign(&mut self, hash_algo: HashAlgorithm, digest: &[u8])
+            -> Result<mpis::Signature>
+    {
+        use PublicKeyAlgorithm::*;
+        use crypto::mpis::PublicKey;
+        use memsec;
+
+        let mut rng = Yarrow::default();
+
+        #[allow(deprecated)]
+        match (self.public.pk_algo(), self.public.mpis(), &self.secret)
+        {
+            (RSASign,
+             &PublicKey::RSA { ref e, ref n },
+             &mpis::SecretKey::RSA { ref p, ref q, ref d, .. }) |
+            (RSAEncryptSign,
+             &PublicKey::RSA { ref e, ref n },
+             &mpis::SecretKey::RSA { ref p, ref q, ref d, .. }) => {
+                let public = rsa::PublicKey::new(&n.value, &e.value)?;
+                let secret = rsa::PrivateKey::new(&d.value, &p.value,
+                                                  &q.value, Option::None)?;
+
+                // The signature has the length of the modulus.
+                let mut sig = vec![0u8; n.value.len()];
+
+                // As described in [Section 5.2.2 and 5.2.3 of RFC 4880],
+                // to verify the signature, we need to encode the
+                // signature data in a PKCS1-v1.5 packet.
+                //
+                //   [Section 5.2.2 and 5.2.3 of RFC 4880]:
+                //   https://tools.ietf.org/html/rfc4880#section-5.2.2
+                rsa::sign_digest_pkcs1(&public, &secret, digest,
+                                       hash_algo.oid()?,
+                                       &mut rng, &mut sig)?;
+
+                Ok(mpis::Signature::RSA {
+                    s: MPI::new(&sig),
+                })
+            },
+
+            (DSA,
+             &PublicKey::DSA { ref p, ref q, ref g, .. },
+             &mpis::SecretKey::DSA { ref x }) => {
+                let params = dsa::Params::new(&p.value, &q.value, &g.value);
+                let secret = dsa::PrivateKey::new(&x.value);
+
+                let sig = dsa::sign(&params, &secret, digest, &mut rng)?;
+
+                Ok(mpis::Signature::DSA {
+                    r: MPI::new(&sig.r()),
+                    s: MPI::new(&sig.s()),
+                })
+            },
+
+            (EdDSA,
+             &PublicKey::EdDSA { ref curve, ref q },
+             &mpis::SecretKey::EdDSA { ref scalar }) => match curve {
+                Curve::Ed25519 => {
+                    let public = q.decode_point(&Curve::Ed25519)?.0;
+
+                    let mut sig = vec![0; ed25519::ED25519_SIGNATURE_SIZE];
+
+                    // Nettle expects the private key to be exactly
+                    // ED25519_KEY_SIZE bytes long but OpenPGP allows leading
+                    // zeros to be stripped.
+                    // Padding has to be unconditionaly, otherwise we have a
+                    // secret-dependant branch.
+                    let missing = ed25519::ED25519_KEY_SIZE
+                        .saturating_sub(scalar.value.len());
+                    let mut sec = [0u8; ed25519::ED25519_KEY_SIZE];
+                    sec[missing..].copy_from_slice(&scalar.value[..]);
+
+                    let res = ed25519::sign(public, &sec[..], digest, &mut sig);
+                    unsafe {
+                        memsec::memzero(sec.as_mut_ptr(),
+                                        ed25519::ED25519_KEY_SIZE);
+                    }
+                    res?;
+
+                    Ok(mpis::Signature::EdDSA {
+                        r: MPI::new(&sig[..32]),
+                        s: MPI::new(&sig[32..]),
+                    })
+                },
+                _ => Err(
+                    Error::UnsupportedEllipticCurve(curve.clone()).into()),
+            },
+
+            (ECDSA,
+             &PublicKey::ECDSA { ref curve, .. },
+             &mpis::SecretKey::ECDSA { ref scalar }) => {
+                let secret = match curve {
+                    Curve::NistP256 =>
+                        ecdsa::PrivateKey::new::<ecdsa::Secp256r1>(
+                            &scalar.value)?,
+                    Curve::NistP384 =>
+                        ecdsa::PrivateKey::new::<ecdsa::Secp384r1>(
+                            &scalar.value)?,
+                    Curve::NistP521 =>
+                        ecdsa::PrivateKey::new::<ecdsa::Secp521r1>(
+                            &scalar.value)?,
+                    _ =>
+                        return Err(
+                            Error::UnsupportedEllipticCurve(curve.clone())
+                                .into()),
+                };
+
+                let sig = ecdsa::sign(&secret, digest, &mut rng);
+
+                Ok(mpis::Signature::ECDSA {
+                    r: MPI::new(&sig.r()),
+                    s: MPI::new(&sig.s()),
+                })
+            },
+
+            (pk_algo, _, _) => Err(Error::InvalidArgument(format!(
+                "unsupported combination of algorithm {:?}, key {:?}, \
+                 and secret key {:?}",
+                pk_algo, self.public, self.secret)).into()),
+        }
+    }
+}