ecdsa: add serialization methods to SigningKey/VerifyKey

ecdsa/src/sign.rs

@@ -12,20 +12,17 @@ use crate::{
 use core::convert::TryInto;
 use elliptic_curve::{
     generic_array::ArrayLength, ops::Invert, scalar::NonZeroScalar, weierstrass::Curve,
-    zeroize::Zeroize, Arithmetic, FromBytes, FromDigest, SecretKey,
+    zeroize::Zeroize, Arithmetic, ElementBytes, FromBytes, FromDigest, SecretKey,
 };
 use signature::{
     digest::{BlockInput, Digest, FixedOutput, Reset, Update},
     DigestSigner,
 };
 
 #[cfg(feature = "rand")]
-use {
-    elliptic_curve::ElementBytes,
-    signature::{
-        rand_core::{CryptoRng, RngCore},
-        RandomizedDigestSigner, RandomizedSigner,
-    },
+use signature::{
+    rand_core::{CryptoRng, RngCore},
+    RandomizedDigestSigner, RandomizedSigner,
 };
 
 #[cfg(feature = "verify")]
@@ -77,6 +74,11 @@ where
             public_key: C::AffinePoint::generator() * self.secret_scalar,
         }
     }
+
+    /// Serialize this [`SigningKey`] as bytes
+    pub fn to_bytes(&self) -> ElementBytes<C> {
+        self.secret_scalar.to_bytes()
+    }
 }
 
 impl<C, D> DigestSigner<D, Signature<C>> for SigningKey<C>

ecdsa/src/verify.rs

@@ -11,7 +11,9 @@ use core::ops::Add;
 use elliptic_curve::{
     consts::U1,
     generic_array::ArrayLength,
-    sec1::{EncodedPoint, FromEncodedPoint, UncompressedPointSize, UntaggedPointSize},
+    sec1::{
+        EncodedPoint, FromEncodedPoint, ToEncodedPoint, UncompressedPointSize, UntaggedPointSize,
+    },
     weierstrass::Curve,
     Arithmetic, FromDigest,
 };
@@ -50,6 +52,15 @@ where
             Err(Error::new())
         }
     }
+
+    /// Serialize this [`VerifyKey`] as a SEC1 [`EncodedPoint`], optionally
+    /// applying point compression.
+    pub fn to_encoded_point(&self, compress: bool) -> EncodedPoint<C>
+    where
+        C::AffinePoint: ToEncodedPoint<C>,
+    {
+        self.public_key.to_encoded_point(compress)
+    }
 }
 
 impl<C, D> DigestVerifier<D, Signature<C>> for VerifyKey<C>