feat: Rust<>JS bindings for Schnorrkel signature verification

android/app/src/main/java/io/parity/signer/EthkeyBridge.java

@@ -155,6 +155,15 @@ public void substrateSign(String seed, String message, Promise promise) {
         }
     }
 
+    @ReactMethod
+    public void schnorrkelVerify(String seed, String message, String signature, Promise promise) {
+        try {
+            promise.resolve(schnorrkelVerify(seed, message, signature));
+        } catch (Exception e) {
+            promise.reject("invalid signature", "invalid signature");
+        }
+    }
+
     private static native String ethkeyBrainwalletAddress(String seed);
     private static native String ethkeyBrainwalletBIP39Address(String seed);
     private static native String ethkeyBrainwalletSign(String seed, String message);
@@ -170,4 +179,5 @@ public void substrateSign(String seed, String message, Promise promise) {
     private static native String ethkeyQrCodeHex(String data);
     private static native String substrateBrainwalletAddress(String seed, int prefix);
     private static native String substrateBrainwalletSign(String seed, String message);
+    private static native boolean schnorrkelVerify(String seed, String message, String signature);
 }

ios/NativeSigner/EthkeyBridge.m

@@ -51,5 +51,6 @@ + (BOOL)requiresMainQueueSetup
 RCT_EXTERN_METHOD(substrateAddress:(NSString*)seed version:(NSUInteger*)version resolve:(RCTPromiseResolveBlock)resolve reject:(RCTPromiseRejectBlock)reject)
 RCT_EXTERN_METHOD(substrateSign:(NSString*)seed message:(NSString*)message resolve:(RCTPromiseResolveBlock)resolve reject:(RCTPromiseRejectBlock)reject)
 RCT_EXTERN_METHOD(blake2b:(NSString*)data resolve:(RCTPromiseResolveBlock)resolve reject:(RCTPromiseRejectBlock)reject)
+RCT_EXTERN_METHOD(schnorrkelVerify: (NSString*)seed message:(NSString*)message signature:(NSString*)signature resolve:(RCTPromiseResolveBlock)resolve reject:(RCTPromiseRejectBlock)reject)
 
 @end

ios/NativeSigner/EthkeyBridge.swift

@@ -199,4 +199,17 @@ class EthkeyBridge: NSObject {
     rust_string_destroy(signature_rust_str)
     resolve(signature)
   }
+
+  @objc func schnorrkelVerify(_ seed: String, message: String, signature: String, resolve: RCTPromiseResolveBlock, reject: RCTPromiseRejectBlock) -> Void {
+    var error: UInt32 = 0
+    var seed_ptr = seed.asPtr()
+    var message_ptr = message.asPtr()
+    var signature_ptr = signature.asPtr()
+    let is_valid = schnorrkel_verify(&error, &seed_ptr, &message_ptr, &signature_ptr)
+    if error == 0 {
+      resolve(is_valid)
+    } else {
+      reject("Failed to verify signature.", nil, nil)
+    }
+  }
 }

rust/signer/signer.h

@@ -76,3 +76,5 @@ struct rust_string* qrcode_hex(unsigned* error, const struct rust_string_ptr* da
 struct rust_string* substrate_brainwallet_address(unsigned* error, const struct rust_string_ptr* seed, const unsigned prefix);
 
 struct rust_string* substrate_brainwallet_sign(unsigned* error, const struct rust_string_ptr* seed, const struct rust_string_ptr* data);
+
+struct rust_string* schnorrkel_verify(unsigned* error, const struct rust_string_ptr* seed, const struct rust_string_ptr* msg, const struct rust_string_ptr* signature);

rust/signer/src/lib.rs

@@ -226,12 +226,24 @@ export! {
 
         Some(signature.to_hex())
     }
+
+    @Java_io_parity_signer_EthkeyBridge_schnorrkelVerify
+    fn schnorrkel_verify(suri: &str, msg: &str, signature: &str) -> Option<bool> {
+        let keypair = sr25519::KeyPair::from_suri(suri)?;
+        let message: Vec<u8> = msg.from_hex().ok()?;
+        let signature: Vec<u8> = signature.from_hex().ok()?;
+        keypair.verify_signature(&message, &signature)
+    }
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
 
+    static SURI: &str = "grant jaguar wish bench exact find voice habit tank pony state salmon";
+
+    static DERIVED_SURI: &str = "grant jaguar wish bench exact find voice habit tank pony state salmon//hard/soft/0";
+
      #[test]
     fn test_blake() {
         let data = "454545454545454545454545454545454545454545454545454545454545454501\
@@ -257,21 +269,29 @@ mod tests {
 
     #[test]
     fn test_substrate_brainwallet_address() {
-        let suri = "grant jaguar wish bench exact find voice habit tank pony state salmon";
         // Secret seed: 0xb139e4050f80172b44957ef9d1755ef5c96c296d63b8a2b50025bf477bd95224
         // Public key (hex): 0x944eeb240615f4a94f673f240a256584ba178e22dd7b67503a753968e2f95761
         let expected = "5FRAPSnpgmnXAnmPVv68fT6o7ntTvaZmkTED8jDttnXs9k4n";
-        let generated = substrate_brainwallet_address(suri, 42).unwrap();
+        let generated = substrate_brainwallet_address(SURI, 42).unwrap();
 
         assert_eq!(expected, generated);
     }
 
     #[test]
     fn test_substrate_brainwallet_address_suri() {
-        let suri = "grant jaguar wish bench exact find voice habit tank pony state salmon//hard/soft/0";
         let expected = "5D4kaJXj5HVoBw2tFFsDj56BjZdPhXKxgGxZuKk4K3bKqHZ6";
-        let generated = substrate_brainwallet_address(suri, 42).unwrap();
+        let generated = substrate_brainwallet_address(DERIVED_SURI, 42).unwrap();
 
         assert_eq!(expected, generated);
     }
+
+    #[test]
+    fn test_substrate_sign() {
+        let msg: String = b"Build The Future".to_hex();
+        let signature = substrate_brainwallet_sign(SURI, &msg).unwrap();
+
+        let is_valid = schnorrkel_verify(SURI, &msg, &signature).unwrap();
+
+        assert!(is_valid);
+    }
 }

rust/signer/src/sr25519.rs

@@ -1,7 +1,7 @@
 use codec::{Encode, Decode};
 use lazy_static::lazy_static;
 use regex::Regex;
-use schnorrkel::{ExpansionMode, SecretKey};
+use schnorrkel::{ExpansionMode, SecretKey, Signature};
 use schnorrkel::derive::{ChainCode, Derivation};
 use substrate_bip39::mini_secret_from_entropy;
 use bip39::{Mnemonic, Language};
@@ -65,6 +65,14 @@ impl KeyPair {
         let context = schnorrkel::signing_context(SIGNING_CTX);
         self.0.sign(context.bytes(message)).to_bytes()
     }
+
+    pub fn verify_signature(&self, message: &[u8], signature: &[u8]) -> Option<bool> {
+        let context = schnorrkel::signing_context(SIGNING_CTX);
+
+        let signature = Signature::from_bytes(signature).ok()?;
+
+        Some(self.0.verify(context.bytes(&message), &signature).is_ok())
+    }
 }
 
 fn derive_hard_junction(secret: &SecretKey, cc: [u8; CHAIN_CODE_LENGTH]) -> SecretKey {

rust/signer/src/util.rs

@@ -17,7 +17,7 @@
 use libc::size_t;
 
 #[cfg(feature = "jni")]
-use jni::{JNIEnv, objects::JString, sys::{jstring, jint}};
+use jni::{JNIEnv, objects::JString, sys::{jboolean, jstring, jint}};
 #[cfg(not(feature = "jni"))]
 use std::cell::Cell;
 
@@ -102,6 +102,16 @@ impl<'a> Argument<'static> for &'a str {
     }
 }
 
+#[cfg(not(feature = "jni"))]
+impl Return<'static> for bool {
+    type Ext = u8;
+    type Env = Cell<u32>;
+
+    fn convert(_: &Self::Env, val: Self) -> Self::Ext {
+        val as u8
+    }
+}
+
 #[cfg(not(feature = "jni"))]
 impl Argument<'static> for String {
     type Ext = *const StringPtr;
@@ -201,6 +211,16 @@ impl<'jni> Return<'jni> for String {
     }
 }
 
+#[cfg(feature = "jni")]
+impl<'jni> Return<'jni> for bool {
+    type Ext = jboolean;
+    type Env = JNIEnv<'jni>;
+
+    fn convert(_: &Self::Env, val: Self) -> Self::Ext {
+        val as jboolean
+    }
+}
+
 #[cfg(feature = "jni")]
 impl<'jni, Inner: Return<'jni, Env = JNIEnv<'jni>> + Default> Return<'jni> for Option<Inner> {
     type Ext = Inner::Ext;

src/util/native.js

@@ -135,3 +135,8 @@ export function substrateAddress(seed, prefix) {
 export function substrateSign(seed, message) {
 	return EthkeyBridge.substrateSign(seed, message);
 }
+
+// Verify a sr25519 signature is valid
+export function schnorrkelVerify(seed, message, signature) {
+	return EthkeyBridge.schnorrkelVerify(seed, message, signature);
+}