Add ecdsa module to openvm_p256

Author: Avaneesh-axiom

guest-libs/p256/guest/Cargo.toml

@@ -21,6 +21,12 @@ ecdsa = { workspace = true }
 serde = { workspace = true }
 hex-literal = { workspace = true }
 ff = { workspace = true }
+p256 = { workspace = true }
+
+[features]
+default = ["ecdsa"]
+ecdsa = ["p256/ecdsa", "ecdsa-core"]
+ecdsa-core = ["p256/ecdsa-core"]
 
 [target.'cfg(not(target_os = "zkvm"))'.dependencies]
 num-bigint = { workspace = true }

guest-libs/p256/guest/src/ecdsa.rs

@@ -0,0 +1,14 @@
+// re-export types that are visible in the p256 crate for API compatibility
+
+pub use p256::ecdsa::Error;
+
+/// ECDSA/secp256k1 signature (fixed-size)
+pub type Signature = ecdsa::Signature<crate::P256>;
+
+/// ECDSA/secp256k1 signing key
+#[cfg(feature = "ecdsa")]
+pub type SigningKey = ecdsa::SigningKey<crate::P256>;
+
+/// ECDSA/secp256k1 verification key (i.e. public key)
+#[cfg(feature = "ecdsa")]
+pub type VerifyingKey = ecdsa::VerifyingKey<crate::P256>;

guest-libs/p256/guest/src/lib.rs

@@ -13,6 +13,9 @@ mod internal;
 mod point;
 mod scalar;
 
+#[cfg(feature = "ecdsa-core")]
+pub mod ecdsa;
+
 // Needs to be public so that the `sw_init` macro can access it
 pub use internal::{
     P256Point, P256Point as AffinePoint, P256Point as ProjectivePoint, P256Scalar as Scalar,
@@ -34,8 +37,7 @@ impl Curve for P256 {
     /// 32-byte serialized field elements.
     type FieldBytesSize = U32;
 
-    // I don't think any arithmetic is done on Curve::Uint, so it's fine to use the U256 type
-    // instead of the OpenVM ruint impl
+    // Perf: Use the U256 type from openvm_ruint here
     type Uint = U256;
 
     /// Curve order.