nostr: add PartialEvent struct

crates/nostr/src/event/mod.rs

@@ -16,12 +16,14 @@ use serde_json::Value;
 pub mod builder;
 pub mod id;
 pub mod kind;
+pub mod partial;
 pub mod tag;
 pub mod unsigned;
 
 pub use self::builder::EventBuilder;
 pub use self::id::EventId;
 pub use self::kind::Kind;
+pub use self::partial::PartialEvent;
 pub use self::tag::{Marker, Tag, TagKind};
 pub use self::unsigned::UnsignedEvent;
 #[cfg(feature = "std")]

crates/nostr/src/event/partial.rs

@@ -0,0 +1,83 @@
+// Copyright (c) 2022-2023 Yuki Kishimoto
+// Distributed under the MIT software license
+
+//! Partial Event for fast deserialization and signature verification
+
+use core::fmt;
+
+use bitcoin::secp256k1::schnorr::Signature;
+use bitcoin::secp256k1::{self, Message, Secp256k1, Verification, XOnlyPublicKey};
+
+#[cfg(feature = "std")]
+use crate::SECP256K1;
+use crate::{EventId, JsonUtil};
+
+/// [`PartialEvent`] error
+#[derive(Debug)]
+pub enum Error {
+    /// Error serializing or deserializing JSON data
+    Json(serde_json::Error),
+    /// Secp256k1 error
+    Secp256k1(secp256k1::Error),
+    /// Invalid signature
+    InvalidSignature,
+}
+
+#[cfg(feature = "std")]
+impl std::error::Error for Error {}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Json(e) => write!(f, "Json: {e}"),
+            Self::Secp256k1(e) => write!(f, "Secp256k1: {e}"),
+            Self::InvalidSignature => write!(f, "Invalid signature"),
+        }
+    }
+}
+
+impl From<serde_json::Error> for Error {
+    fn from(e: serde_json::Error) -> Self {
+        Self::Json(e)
+    }
+}
+
+impl From<secp256k1::Error> for Error {
+    fn from(e: secp256k1::Error) -> Self {
+        Self::Secp256k1(e)
+    }
+}
+
+/// Partial event
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
+pub struct PartialEvent {
+    /// Id
+    pub id: EventId,
+    /// Author
+    pub pubkey: XOnlyPublicKey,
+    /// Signature
+    pub sig: Signature,
+}
+
+impl PartialEvent {
+    /// Verify [`Signature`]
+    #[cfg(feature = "std")]
+    pub fn verify_signature(&self) -> Result<(), Error> {
+        self.verify_signature_with_ctx(&SECP256K1)
+    }
+
+    /// Verify [`Signature`]
+    pub fn verify_signature_with_ctx<C>(&self, secp: &Secp256k1<C>) -> Result<(), Error>
+    where
+        C: Verification,
+    {
+        // Verify signature
+        let message = Message::from_slice(self.id.as_bytes())?;
+        secp.verify_schnorr(&self.sig, &message, &self.pubkey)
+            .map_err(|_| Error::InvalidSignature)
+    }
+}
+
+impl JsonUtil for PartialEvent {
+    type Err = Error;
+}

crates/nostr/src/lib.rs

@@ -47,7 +47,7 @@ pub use self::event::tag::{
     ExternalIdentity, HttpMethod, Identity, ImageDimensions, Marker, RelayMetadata, Report, Tag,
     TagKind,
 };
-pub use self::event::{Event, EventBuilder, EventId, Kind, UnsignedEvent};
+pub use self::event::{Event, EventBuilder, EventId, Kind, PartialEvent, UnsignedEvent};
 pub use self::key::Keys;
 pub use self::message::{
     Alphabet, ClientMessage, Filter, RawRelayMessage, RelayMessage, SubscriptionId,