Add EcdsaCurve trait impls (#1019)

This is a marker trait added in RustCrypto/signatures#787 which marks an
elliptic curve as being intended for use with ECDSA.

It's the intended successor of the `SignPrimitive` and `VerifyPrimitive`
traits, carrying with it the one bit of information needed to eliminate
the need for custom impls: a flag for low-S normalization.

`bp256`, `bp384`, `k256`, `p192`, `p224`, `p256`, `p384`, and `p521`
have all received trait impls.

Of those, only `k256` has the `NORMALIZE_S` flag set to `true`.

Cargo.toml

@@ -17,3 +17,6 @@ members = [
 
 [profile.dev]
 opt-level = 2
+
+[patch.crates-io.ecdsa]
+git = "https://github.com/rustcrypto/signatures.git"

bp256/src/r1/ecdsa.rs

@@ -8,6 +8,10 @@ pub type Signature = ecdsa::Signature<BrainpoolP256r1>;
 /// ECDSA/brainpoolP256r1 signature (ASN.1 DER encoded)
 pub type DerSignature = ecdsa::der::Signature<BrainpoolP256r1>;
 
+impl ecdsa::EcdsaCurve for BrainpoolP256r1 {
+    const NORMALIZE_S: bool = false;
+}
+
 #[cfg(feature = "sha256")]
 impl ecdsa::hazmat::DigestPrimitive for BrainpoolP256r1 {
     type Digest = sha2::Sha256;

bp256/src/t1/ecdsa.rs

@@ -8,6 +8,10 @@ pub type Signature = ecdsa::Signature<BrainpoolP256t1>;
 /// ECDSA/brainpoolP256t1 signature (ASN.1 DER encoded)
 pub type DerSignature = ecdsa::der::Signature<BrainpoolP256t1>;
 
+impl ecdsa::EcdsaCurve for BrainpoolP256t1 {
+    const NORMALIZE_S: bool = false;
+}
+
 #[cfg(feature = "sha256")]
 impl ecdsa::hazmat::DigestPrimitive for BrainpoolP256t1 {
     type Digest = sha2::Sha256;

bp384/src/r1/ecdsa.rs

@@ -8,6 +8,10 @@ pub type Signature = ecdsa::Signature<BrainpoolP384r1>;
 /// ECDSA/brainpoolP384r1 signature (ASN.1 DER encoded)
 pub type DerSignature = ecdsa::der::Signature<BrainpoolP384r1>;
 
+impl ecdsa::EcdsaCurve for BrainpoolP384r1 {
+    const NORMALIZE_S: bool = false;
+}
+
 #[cfg(feature = "sha384")]
 impl ecdsa::hazmat::DigestPrimitive for BrainpoolP384r1 {
     type Digest = sha2::Sha384;

bp384/src/t1/ecdsa.rs

@@ -8,6 +8,10 @@ pub type Signature = ecdsa::Signature<BrainpoolP384t1>;
 /// ECDSA/brainpoolP384t1 signature (ASN.1 DER encoded)
 pub type DerSignature = ecdsa::der::Signature<BrainpoolP384t1>;
 
+impl ecdsa::EcdsaCurve for BrainpoolP384t1 {
+    const NORMALIZE_S: bool = false;
+}
+
 #[cfg(feature = "sha384")]
 impl ecdsa::hazmat::DigestPrimitive for BrainpoolP384t1 {
     type Digest = sha2::Sha384;

k256/src/ecdsa.rs

@@ -144,7 +144,7 @@
 
 pub use ecdsa_core::{
     signature::{self, Error},
-    RecoveryId,
+    EcdsaCurve, RecoveryId,
 };
 
 #[cfg(any(feature = "ecdsa", feature = "sha256"))]
@@ -165,6 +165,10 @@ pub type Signature = ecdsa_core::Signature<Secp256k1>;
 /// ECDSA/secp256k1 signature (ASN.1 DER encoded)
 pub type DerSignature = ecdsa_core::der::Signature<Secp256k1>;
 
+impl EcdsaCurve for Secp256k1 {
+    const NORMALIZE_S: bool = true;
+}
+
 /// ECDSA/secp256k1 signing key
 #[cfg(feature = "ecdsa")]
 pub type SigningKey = ecdsa_core::SigningKey<Secp256k1>;

p192/src/ecdsa.rs

@@ -32,17 +32,23 @@
 //! [NIST Special Publication 800-131A Revision 2]: https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-131Ar2.pdf
 
 pub use ecdsa_core::signature::{self, Error};
-#[cfg(feature = "ecdsa")]
-use {crate::AffinePoint, ecdsa_core::hazmat::VerifyPrimitive};
 
 use super::NistP192;
+use ecdsa_core::EcdsaCurve;
+
+#[cfg(feature = "ecdsa")]
+use {crate::AffinePoint, ecdsa_core::hazmat::VerifyPrimitive};
 
 /// ECDSA/P-192 signature (fixed-size)
 pub type Signature = ecdsa_core::Signature<NistP192>;
 
 /// ECDSA/P-192 signature (ASN.1 DER encoded)
 pub type DerSignature = ecdsa_core::der::Signature<NistP192>;
 
+impl EcdsaCurve for NistP192 {
+    const NORMALIZE_S: bool = false;
+}
+
 /// ECDSA/P-192 verification key (i.e. public key)
 #[cfg(feature = "ecdsa")]
 pub type VerifyingKey = ecdsa_core::VerifyingKey<NistP192>;

p224/src/ecdsa.rs

@@ -38,20 +38,26 @@
 //! ```
 
 pub use ecdsa_core::signature::{self, Error};
+
+use super::NistP224;
+use ecdsa_core::EcdsaCurve;
+
 #[cfg(feature = "ecdsa")]
 use {
     crate::{AffinePoint, Scalar},
     ecdsa_core::hazmat::{SignPrimitive, VerifyPrimitive},
 };
 
-use super::NistP224;
-
 /// ECDSA/P-224 signature (fixed-size)
 pub type Signature = ecdsa_core::Signature<NistP224>;
 
 /// ECDSA/P-224 signature (ASN.1 DER encoded)
 pub type DerSignature = ecdsa_core::der::Signature<NistP224>;
 
+impl EcdsaCurve for NistP224 {
+    const NORMALIZE_S: bool = false;
+}
+
 /// ECDSA/P-224 signing key
 #[cfg(feature = "ecdsa")]
 pub type SigningKey = ecdsa_core::SigningKey<NistP224>;

p256/src/ecdsa.rs

@@ -42,6 +42,7 @@
 pub use ecdsa_core::signature::{self, Error};
 
 use super::NistP256;
+use ecdsa_core::EcdsaCurve;
 
 #[cfg(feature = "ecdsa")]
 use {
@@ -55,6 +56,10 @@ pub type Signature = ecdsa_core::Signature<NistP256>;
 /// ECDSA/P-256 signature (ASN.1 DER encoded)
 pub type DerSignature = ecdsa_core::der::Signature<NistP256>;
 
+impl EcdsaCurve for NistP256 {
+    const NORMALIZE_S: bool = false;
+}
+
 /// ECDSA/P-256 signing key
 #[cfg(feature = "ecdsa")]
 pub type SigningKey = ecdsa_core::SigningKey<NistP256>;

p384/src/ecdsa.rs

@@ -38,20 +38,26 @@
 //! ```
 
 pub use ecdsa_core::signature::{self, Error};
+
+use super::NistP384;
+use ecdsa_core::EcdsaCurve;
+
 #[cfg(feature = "ecdsa")]
 use {
     crate::{AffinePoint, Scalar},
     ecdsa_core::hazmat::{SignPrimitive, VerifyPrimitive},
 };
 
-use super::NistP384;
-
 /// ECDSA/P-384 signature (fixed-size)
 pub type Signature = ecdsa_core::Signature<NistP384>;
 
 /// ECDSA/P-384 signature (ASN.1 DER encoded)
 pub type DerSignature = ecdsa_core::der::Signature<NistP384>;
 
+impl EcdsaCurve for NistP384 {
+    const NORMALIZE_S: bool = false;
+}
+
 /// ECDSA/P-384 signing key
 #[cfg(feature = "ecdsa")]
 pub type SigningKey = ecdsa_core::SigningKey<NistP384>;

p521/src/ecdsa.rs

@@ -38,20 +38,26 @@
 //! ```
 
 pub use ecdsa_core::signature::{self, Error};
+
+use super::NistP521;
+use ecdsa_core::EcdsaCurve;
+
 #[cfg(feature = "ecdsa")]
 use {
     crate::{AffinePoint, Scalar},
     ecdsa_core::hazmat::{SignPrimitive, VerifyPrimitive},
 };
 
-use super::NistP521;
-
 /// ECDSA/P-521 signature (fixed-size)
 pub type Signature = ecdsa_core::Signature<NistP521>;
 
 /// ECDSA/P-521 signature (ASN.1 DER encoded)
 pub type DerSignature = ecdsa_core::der::Signature<NistP521>;
 
+impl EcdsaCurve for NistP521 {
+    const NORMALIZE_S: bool = false;
+}
+
 /// ECDSA/P-521 signing key
 #[cfg(feature = "ecdsa")]
 pub type SigningKey = ecdsa_core::SigningKey<NistP521>;