Add conversions From our keys

src/pubkey/ecdsa.rs

@@ -35,6 +35,9 @@ pub static ECDSA_SHA2_NISTP384: PubkeyAlgo = PubkeyAlgo {
 ///
 /// - `EcdsaPubkey<p256::NistP256>` is compatible with [`ECDSA_SHA2_NISTP256`].
 /// - `EcdsaPubkey<p384::NistP384>` is compatible with [`ECDSA_SHA2_NISTP384`].
+///
+/// You can convert it to and from [`ecdsa::VerifyingKey<C>`] and [`elliptic_curve::PublicKey<C>`]
+/// using `from()`/`into()`.
 #[derive(Debug, Clone)]
 pub struct EcdsaPubkey<C> 
     where C: ecdsa::PrimeCurve + elliptic_curve::ProjectiveArithmetic,
@@ -46,6 +49,9 @@ pub struct EcdsaPubkey<C>
 ///
 /// - `EcdsaPrivkey<p256::NistP256>` is compatible with [`ECDSA_SHA2_NISTP256`].
 /// - `EcdsaPrivkey<p384::NistP384>` is compatible with [`ECDSA_SHA2_NISTP384`].
+///
+/// You can convert it to and from [`ecdsa::SigningKey<C>`] and [`elliptic_curve::SecretKey<C>`]
+/// using `from()`/`into()`.
 #[derive(Clone)]
 pub struct EcdsaPrivkey<C>
     where C: ecdsa::PrimeCurve + elliptic_curve::ProjectiveArithmetic,
@@ -247,37 +253,49 @@ impl Curve for p384::NistP384 {
 impl<C> From<ecdsa::VerifyingKey<C>> for EcdsaPubkey<C>
     where C: ecdsa::PrimeCurve + elliptic_curve::ProjectiveArithmetic,
 {
-    fn from(verifying: ecdsa::VerifyingKey<C>) -> Self {
-        Self { verifying }
-    }
+    fn from(verifying: ecdsa::VerifyingKey<C>) -> Self { Self { verifying } }
+}
+
+impl<C> From<elliptic_curve::PublicKey<C>> for EcdsaPubkey<C>
+    where C: ecdsa::PrimeCurve + elliptic_curve::ProjectiveArithmetic,
+{
+    fn from(public: elliptic_curve::PublicKey<C>) -> Self { Self { verifying: public.into() } }
+}
+
+impl<C> From<EcdsaPubkey<C>> for ecdsa::VerifyingKey<C>
+    where C: ecdsa::PrimeCurve + elliptic_curve::ProjectiveArithmetic,
+{
+    fn from(pubkey: EcdsaPubkey<C>) -> Self { pubkey.verifying }
+}
+
+impl<C> From<EcdsaPubkey<C>> for elliptic_curve::PublicKey<C>
+    where C: ecdsa::PrimeCurve + elliptic_curve::ProjectiveArithmetic,
+{
+    fn from(pubkey: EcdsaPubkey<C>) -> Self { pubkey.verifying.into() }
 }
 
 impl<C> From<ecdsa::SigningKey<C>> for EcdsaPrivkey<C>
     where C: ecdsa::PrimeCurve + elliptic_curve::ProjectiveArithmetic,
           <C as elliptic_curve::ScalarArithmetic>::Scalar: ecdsa::hazmat::SignPrimitive<C>,
           ecdsa::SignatureSize<C>: generic_array::ArrayLength<u8>,
 {
-    fn from(signing: ecdsa::SigningKey<C>) -> Self {
-        Self { signing }
-    }
+    fn from(signing: ecdsa::SigningKey<C>) -> Self { Self { signing } }
 }
 
-impl<C> From<elliptic_curve::PublicKey<C>> for EcdsaPubkey<C>
+impl<C> From<elliptic_curve::SecretKey<C>> for EcdsaPrivkey<C>
     where C: ecdsa::PrimeCurve + elliptic_curve::ProjectiveArithmetic,
+          <C as elliptic_curve::ScalarArithmetic>::Scalar: ecdsa::hazmat::SignPrimitive<C>,
+          ecdsa::SignatureSize<C>: generic_array::ArrayLength<u8>,
 {
-    fn from(public: elliptic_curve::PublicKey<C>) -> Self {
-        Self { verifying: public.into() }
-    }
+    fn from(secret: elliptic_curve::SecretKey<C>) -> Self { Self { signing: secret.into() } }
 }
 
-impl<C> From<elliptic_curve::SecretKey<C>> for EcdsaPrivkey<C>
+impl<C> From<EcdsaPrivkey<C>> for ecdsa::SigningKey<C>
     where C: ecdsa::PrimeCurve + elliptic_curve::ProjectiveArithmetic,
           <C as elliptic_curve::ScalarArithmetic>::Scalar: ecdsa::hazmat::SignPrimitive<C>,
           ecdsa::SignatureSize<C>: generic_array::ArrayLength<u8>,
 {
-    fn from(secret: elliptic_curve::SecretKey<C>) -> Self {
-        Self { signing: secret.into() }
-    }
+    fn from(privkey: EcdsaPrivkey<C>) -> Self { privkey.signing }
 }
 
 impl fmt::Display for EcdsaPubkey<p256::NistP256> {

src/pubkey/ed25519.rs

@@ -16,15 +16,17 @@ pub static SSH_ED25519: PubkeyAlgo = PubkeyAlgo {
 
 /// Ed25519 public key from RFC 8032.
 ///
-/// This key is compatible with [`SSH_ED25519`].
+/// This key is compatible with [`SSH_ED25519`]. You can convert it to and from
+/// [`ed25519_dalek::PublicKey`] using `from()`/`into()`.
 #[derive(Debug, Clone)]
 pub struct Ed25519Pubkey {
     pub(crate) pubkey: ed25519_dalek::PublicKey,
 }
 
 /// Ed25519 keypair from RFC 8032.
 ///
-/// This key is compatible with [`SSH_ED25519`].
+/// This key is compatible with [`SSH_ED25519`]. You can convert it to and from
+/// [`ed25519_dalek::Keypair`] using `from()`/`into()`.
 pub struct Ed25519Privkey {
     pub(crate) keypair: ed25519_dalek::Keypair,
 }
@@ -80,15 +82,19 @@ pub(super) fn decode(blob: &mut PacketDecode) -> Result<Ed25519Pubkey> {
 
 
 impl From<ed25519_dalek::PublicKey> for Ed25519Pubkey {
-    fn from(pubkey: ed25519_dalek::PublicKey) -> Self {
-        Self { pubkey }
-    }
+    fn from(pubkey: ed25519_dalek::PublicKey) -> Self { Self { pubkey } }
+}
+
+impl From<Ed25519Pubkey> for ed25519_dalek::PublicKey {
+    fn from(pubkey: Ed25519Pubkey) -> Self { pubkey.pubkey }
 }
 
 impl From<ed25519_dalek::Keypair> for Ed25519Privkey {
-    fn from(keypair: ed25519_dalek::Keypair) -> Self {
-        Self { keypair }
-    }
+    fn from(keypair: ed25519_dalek::Keypair) -> Self { Self { keypair } }
+}
+
+impl From<Ed25519Privkey> for ed25519_dalek::Keypair {
+    fn from(privkey: Ed25519Privkey) -> Self { privkey.keypair }
 }
 
 impl fmt::Display for Ed25519Pubkey {

src/pubkey/rsa.rs

@@ -37,15 +37,17 @@ pub static RSA_SHA2_512: PubkeyAlgo = PubkeyAlgo {
 
 /// RSA public key.
 ///
-/// This key is compatible with [`SSH_RSA_SHA1`], [`RSA_SHA2_256`] and [`RSA_SHA2_512`].
+/// This key is compatible with [`SSH_RSA_SHA1`], [`RSA_SHA2_256`] and [`RSA_SHA2_512`]. You can
+/// convert it to and from [`rsa::RsaPublicKey`] using `from()`/`into()`.
 #[derive(Debug, Clone)]
 pub struct RsaPubkey {
     pub(crate) pubkey: rsa::RsaPublicKey,
 }
 
 /// RSA whole key (private and public parts).
 ///
-/// This key is compatible with [`SSH_RSA_SHA1`], [`RSA_SHA2_256`] and [`RSA_SHA2_512`].
+/// This key is compatible with [`SSH_RSA_SHA1`], [`RSA_SHA2_256`] and [`RSA_SHA2_512`]. You can
+/// convert it to and from [`rsa::RsaPrivateKey`] using `from()`/`into()`.
 #[derive(Clone)]
 pub struct RsaPrivkey {
     pub(crate) privkey: rsa::RsaPrivateKey,
@@ -134,17 +136,20 @@ impl RsaHash for sha2::Sha512 {
 }
 
 impl From<rsa::RsaPublicKey> for RsaPubkey {
-    fn from(pubkey: rsa::RsaPublicKey) -> Self {
-        Self { pubkey }
-    }
+    fn from(pubkey: rsa::RsaPublicKey) -> Self { Self { pubkey } }
+}
+
+impl From<RsaPubkey> for rsa::RsaPublicKey {
+    fn from(pubkey: RsaPubkey) -> Self { pubkey.pubkey }
 }
 
 impl From<rsa::RsaPrivateKey> for RsaPrivkey {
-    fn from(privkey: rsa::RsaPrivateKey) -> Self {
-        Self { privkey }
-    }
+    fn from(privkey: rsa::RsaPrivateKey) -> Self { Self { privkey } }
 }
 
+impl From<RsaPrivkey> for rsa::RsaPrivateKey {
+    fn from(privkey: RsaPrivkey) -> Self { privkey.privkey }
+}
 
 impl fmt::Display for RsaPubkey {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {