ECDSA Support in signer

.github/workflows/rust.yml

@@ -70,7 +70,10 @@ jobs:
             # Subxt-signer has the "subxt" features enabled in the "check all targets" test. Run it on its own to
             # check it without. We can't enable subxt or web features here, so no cargo hack.
             - name: Cargo check subxt-signer
-              run: cargo check -p subxt-signer
+              run: |
+                cargo check -p subxt-signer
+                cargo check -p subxt-signer --no-default-features --features sr25519
+                cargo check -p subxt-signer --no-default-features --features ecdsa
 
             # We can't enable web features here, so no cargo hack.
             - name: Cargo check subxt-lightclient

Cargo.toml

@@ -116,6 +116,7 @@ bip39 = "2.0.0"
 hmac = "0.12.1"
 pbkdf2 = { version = "0.12.2", default-features = false }
 schnorrkel = "0.10.2"
+secp256k1 = "0.27.0"
 secrecy = "0.8.0"
 sha2 = "0.10.6"
-zeroize = { version = "1", default-features = false }
+zeroize = { version = "1", default-features = false }

signer/Cargo.toml

@@ -15,7 +15,14 @@ description = "Sign extrinsics to be submitted by Subxt"
 keywords = ["parity", "subxt", "extrinsic", "signer"]
 
 [features]
-default = []
+default = ["sr25519", "ecdsa"]
+
+# Pick the signer implementation(s) you need by enabling the
+# corresponding features. Note: I had more difficulties getting
+# ecdsa compiling to WASM on my mac; following this comment helped:
+# https://github.com/rust-bitcoin/rust-bitcoin/issues/930#issuecomment-1215538699
+sr25519 = ["schnorrkel"]
+ecdsa = ["secp256k1"]
 
 # Make the keypair algorithms here compatible with Subxt's Signer trait,
 # so that they can be used to sign transactions for compatible chains.
@@ -37,7 +44,8 @@ sha2 = { workspace = true }
 hmac = { workspace = true }
 zeroize = { workspace = true }
 bip39 = { workspace = true }
-schnorrkel = { workspace = true }
+schnorrkel = { workspace = true, optional = true }
+secp256k1 = { workspace = true, features = ["recovery", "global-context"], optional = true }
 secrecy = { workspace = true }
 
 # We only pull this in to enable the JS flag for schnorrkel to use.

signer/src/crypto/seed_from_entropy.rs

@@ -10,6 +10,7 @@ use zeroize::Zeroize;
 /// This is taken from `substrate-bip39` so that we can keep dependencies in line, and
 /// is the same logic that sp-core uses to go from mnemonic entropy to seed. Returns
 /// `None` if invalid length.
+#[allow(dead_code)]
 pub fn seed_from_entropy(entropy: &[u8], password: &str) -> Option<[u8; 64]> {
     if entropy.len() < 16 || entropy.len() > 32 || entropy.len() % 4 != 0 {
         return None;