nostr: add NostrSigner::backend

Closes rust-nostr#617

Signed-off-by: Yuki Kishimoto <[email protected]>

bindings/nostr-sdk-ffi/src/connect.rs

@@ -13,7 +13,7 @@ use uniffi::Object;
 
 use crate::error::Result;
 use crate::protocol::nips::nip46::{Nip46Request, NostrConnectURI};
-use crate::protocol::signer::NostrSigner;
+use crate::protocol::signer::{NostrSigner, SignerBackend};
 use crate::protocol::{Event, Keys, PublicKey, SecretKey, UnsignedEvent};
 use crate::relay::RelayOptions;
 
@@ -74,6 +74,10 @@ impl NostrConnect {
 #[uniffi::export]
 #[async_trait::async_trait]
 impl NostrSigner for NostrConnect {
+    fn backend(&self) -> SignerBackend {
+        self.inner.backend().into()
+    }
+
     async fn get_public_key(&self) -> Result<Option<Arc<PublicKey>>> {
         Ok(Some(Arc::new(self.inner.get_public_key().await?.into())))
     }

bindings/nostr-sdk-ffi/src/protocol/key/mod.rs

@@ -15,8 +15,8 @@ mod secret_key;
 
 pub use self::public_key::PublicKey;
 pub use self::secret_key::SecretKey;
+use super::signer::{NostrSigner, SignerBackend};
 use crate::error::Result;
-use crate::protocol::signer::NostrSigner;
 use crate::protocol::{Event, UnsignedEvent};
 
 /// Nostr keys
@@ -117,6 +117,10 @@ impl Keys {
 #[uniffi::export]
 #[async_trait::async_trait]
 impl NostrSigner for Keys {
+    fn backend(&self) -> SignerBackend {
+        self.inner.backend().into()
+    }
+
     async fn get_public_key(&self) -> Result<Option<Arc<PublicKey>>> {
         Ok(Some(Arc::new(self.inner.get_public_key().await?.into())))
     }

bindings/nostr-sdk-ffi/src/protocol/signer.rs

@@ -2,19 +2,65 @@
 // Copyright (c) 2023-2024 Rust Nostr Developers
 // Distributed under the MIT software license
 
+use std::borrow::Cow;
 use std::fmt;
 use std::ops::Deref;
 use std::sync::Arc;
 
+use nostr::signer;
+use uniffi::Enum;
+
 use super::event::{Event, UnsignedEvent};
 use super::key::PublicKey;
 use crate::error::Result;
 
+#[derive(Enum)]
+pub enum SignerBackend {
+    /// Secret key
+    Keys,
+    /// Browser extension (NIP07)
+    ///
+    /// <https://github.com/nostr-protocol/nips/blob/master/07.md>
+    BrowserExtension,
+    /// Nostr Connect (NIP46)
+    ///
+    /// <https://github.com/nostr-protocol/nips/blob/master/46.md>
+    NostrConnect,
+    /// Custom
+    Custom { backend: String },
+}
+
+impl<'a> From<signer::SignerBackend<'a>> for SignerBackend {
+    fn from(backend: signer::SignerBackend<'a>) -> Self {
+        match backend {
+            signer::SignerBackend::Keys => Self::Keys,
+            signer::SignerBackend::BrowserExtension => Self::BrowserExtension,
+            signer::SignerBackend::NostrConnect => Self::NostrConnect,
+            signer::SignerBackend::Custom(backend) => Self::Custom {
+                backend: backend.into_owned(),
+            },
+        }
+    }
+}
+
+impl<'a> From<SignerBackend> for signer::SignerBackend<'a> {
+    fn from(backend: SignerBackend) -> Self {
+        match backend {
+            SignerBackend::Keys => Self::Keys,
+            SignerBackend::BrowserExtension => Self::BrowserExtension,
+            SignerBackend::NostrConnect => Self::NostrConnect,
+            SignerBackend::Custom { backend } => Self::Custom(Cow::Owned(backend)),
+        }
+    }
+}
+
 // NOTE: for some weird reason the `Arc<T>` as output must be wrapped inside a `Vec<T>` or an `Option<T>`
 // otherwise compilation will fail.
 #[uniffi::export(with_foreign)]
 #[async_trait::async_trait]
 pub trait NostrSigner: Send + Sync {
+    fn backend(&self) -> SignerBackend;
+
     /// Get signer public key
     async fn get_public_key(&self) -> Result<Option<Arc<PublicKey>>>;
 
@@ -66,6 +112,10 @@ impl NostrSignerRust2FFI {
 
 #[async_trait::async_trait]
 impl NostrSigner for NostrSignerRust2FFI {
+    fn backend(&self) -> SignerBackend {
+        self.inner.backend().into()
+    }
+
     async fn get_public_key(&self) -> Result<Option<Arc<PublicKey>>> {
         Ok(Some(Arc::new(self.inner.get_public_key().await?.into())))
     }
@@ -124,6 +174,10 @@ mod inner {
 
     #[async_trait]
     impl NostrSigner for NostrSignerFFI2Rust {
+        fn backend(&self) -> SignerBackend {
+            self.inner.backend().into()
+        }
+
         async fn get_public_key(&self) -> Result<PublicKey, SignerError> {
             let public_key = self
                 .inner

crates/nostr-connect/src/client.rs

@@ -441,6 +441,10 @@ where
 #[cfg_attr(target_arch = "wasm32", async_trait(?Send))]
 #[cfg_attr(not(target_arch = "wasm32"), async_trait)]
 impl NostrSigner for NostrConnect {
+    fn backend(&self) -> SignerBackend {
+        SignerBackend::NostrConnect
+    }
+
     async fn get_public_key(&self) -> Result<PublicKey, SignerError> {
         self._get_public_key()
             .await

crates/nostr/src/key/mod.rs

@@ -31,7 +31,9 @@ pub mod vanity;
 pub use self::public_key::PublicKey;
 pub use self::secret_key::SecretKey;
 #[cfg(feature = "std")]
-use crate::{Event, NostrSigner, SignerError, UnsignedEvent, SECP256K1};
+use crate::signer::{NostrSigner, SignerBackend, SignerError};
+#[cfg(feature = "std")]
+use crate::{Event, UnsignedEvent, SECP256K1};
 
 /// [`Keys`] error
 #[derive(Debug, PartialEq, Eq)]
@@ -264,6 +266,10 @@ impl FromStr for Keys {
 #[cfg_attr(target_arch = "wasm32", async_trait(?Send))]
 #[cfg_attr(not(target_arch = "wasm32"), async_trait)]
 impl NostrSigner for Keys {
+    fn backend(&self) -> SignerBackend {
+        SignerBackend::Keys
+    }
+
     async fn get_public_key(&self) -> Result<PublicKey, SignerError> {
         Ok(self.public_key)
     }

crates/nostr/src/nips/nip07.rs

@@ -19,7 +19,7 @@ use wasm_bindgen_futures::JsFuture;
 use web_sys::Window;
 
 use crate::event::{self, unsigned};
-use crate::signer::{NostrSigner, SignerError};
+use crate::signer::{NostrSigner, SignerBackend, SignerError};
 use crate::{key, Event, PublicKey, UnsignedEvent};
 
 /// NIP07 error
@@ -315,6 +315,10 @@ impl Nip07Signer {
 
 #[async_trait(?Send)]
 impl NostrSigner for Nip07Signer {
+    fn backend(&self) -> SignerBackend {
+        SignerBackend::BrowserExtension
+    }
+
     async fn get_public_key(&self) -> Result<PublicKey, SignerError> {
         self._get_public_key().await.map_err(SignerError::backend)
     }

crates/nostr/src/signer.rs

@@ -4,6 +4,7 @@
 
 //! Nostr Signer
 
+use alloc::borrow::Cow;
 use alloc::boxed::Box;
 #[cfg(any(not(feature = "std"), feature = "nip04", feature = "nip44"))]
 use alloc::string::String;
@@ -68,11 +69,30 @@ where
     }
 }
 
+/// Signer backend
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum SignerBackend<'a> {
+    /// Secret key
+    Keys,
+    /// Browser extension (NIP07)
+    ///
+    /// <https://github.com/nostr-protocol/nips/blob/master/07.md>
+    BrowserExtension,
+    /// Nostr Connect (NIP46)
+    ///
+    /// <https://github.com/nostr-protocol/nips/blob/master/46.md>
+    NostrConnect,
+    /// Custom
+    Custom(Cow<'a, str>),
+}
+
 /// Nostr signer abstraction
 #[cfg_attr(target_arch = "wasm32", async_trait(?Send))]
 #[cfg_attr(not(target_arch = "wasm32"), async_trait)]
 pub trait NostrSigner: AsyncTraitDeps {
-    // TODO: use `Cow<'a, PublicKey>`?
+    /// Signer backend
+    fn backend(&self) -> SignerBackend;
+
     /// Get signer public key
     async fn get_public_key(&self) -> Result<PublicKey, SignerError>;
 
@@ -115,14 +135,22 @@ pub trait NostrSigner: AsyncTraitDeps {
 #[cfg_attr(target_arch = "wasm32", async_trait(?Send))]
 #[cfg_attr(not(target_arch = "wasm32"), async_trait)]
 impl NostrSigner for Arc<dyn NostrSigner> {
+    #[inline]
+    fn backend(&self) -> SignerBackend {
+        self.as_ref().backend()
+    }
+
+    #[inline]
     async fn get_public_key(&self) -> Result<PublicKey, SignerError> {
         self.as_ref().get_public_key().await
     }
 
+    #[inline]
     async fn sign_event(&self, unsigned: UnsignedEvent) -> Result<Event, SignerError> {
         self.as_ref().sign_event(unsigned).await
     }
 
+    #[inline]
     #[cfg(feature = "nip04")]
     async fn nip04_encrypt(
         &self,
@@ -132,6 +160,7 @@ impl NostrSigner for Arc<dyn NostrSigner> {
         self.as_ref().nip04_encrypt(public_key, content).await
     }
 
+    #[inline]
     #[cfg(feature = "nip04")]
     async fn nip04_decrypt(
         &self,
@@ -143,6 +172,7 @@ impl NostrSigner for Arc<dyn NostrSigner> {
             .await
     }
 
+    #[inline]
     #[cfg(feature = "nip44")]
     async fn nip44_encrypt(
         &self,
@@ -152,6 +182,7 @@ impl NostrSigner for Arc<dyn NostrSigner> {
         self.as_ref().nip44_encrypt(public_key, content).await
     }
 
+    #[inline]
     #[cfg(feature = "nip44")]
     async fn nip44_decrypt(
         &self,