feat: add p2p::k1 module

Cargo.toml

@@ -43,6 +43,7 @@ base64 = { version = "0.22.1" }
 sha3 = { version = "0.10.8" }
 k256 = { version = "0.13.4", features = ["ecdsa", "sha256"] }
 criterion = "0.7.0"
+tempfile = "3.10.0"
 tracing = "0.1.32"
 tracing-subscriber = { version = "0.3.9", features = ["env-filter"] }
 tracing-loki = "0.2.6"

crates/charon-k1util/Cargo.toml

@@ -14,6 +14,7 @@ libp2p.workspace = true
 
 [dev-dependencies]
 criterion.workspace = true
+tempfile.workspace = true
 
 [[bench]]
 name = "k1util"

crates/charon-k1util/src/k1util.rs

@@ -2,6 +2,8 @@
 //!
 //! Helper functions for working with secp256k1 keys.
 
+use std::path::Path;
+
 use k256::{
     AffinePoint, FieldBytes, PublicKey, SecretKey,
     ecdsa::{self, RecoveryId, Signature, SigningKey, hazmat::VerifyPrimitive},
@@ -185,9 +187,30 @@ pub fn recover(hash: &[u8], sig: &[u8]) -> Result<PublicKey> {
     Ok(pubkey.into())
 }
 
+/// Load loads a secret key from a file.
+pub fn load(file: &Path) -> Result<SecretKey> {
+    let contents = std::fs::read_to_string(file).map_err(K1UtilError::FailedToReadFile)?;
+
+    let decoded = hex::decode(contents.trim())?;
+
+    let key = SecretKey::from_slice(&decoded).map_err(K1UtilError::FailedToParseSecretKey)?;
+
+    Ok(key)
+}
+
+/// Save saves a secret key to a file.
+pub fn save(key: &SecretKey, file: &Path) -> Result<()> {
+    let encoded = hex::encode(key.to_bytes());
+
+    std::fs::write(file, encoded).map_err(K1UtilError::FailedToWriteFile)?;
+
+    Ok(())
+}
+
 #[cfg(test)]
 mod tests {
     use k256::elliptic_curve::rand_core::OsRng;
+    use std::io::Write;
 
     use super::*;
 
@@ -258,4 +281,50 @@ mod tests {
             "Recovered public key should match"
         );
     }
+
+    #[test]
+    fn test_load_nonexistent_file() {
+        let file = Path::new("nonexistent-file");
+        let result = load(file);
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn test_invalid_hex_encoded_file() {
+        let mut temp_file = tempfile::NamedTempFile::new().unwrap();
+        write!(temp_file, "abcXYZ123").unwrap(); // invalid hex encoded file
+
+        let result = load(temp_file.path());
+        assert!(result.is_err());
+        assert!(matches!(
+            result.unwrap_err(),
+            K1UtilError::FailedToDecodeHex(_)
+        ));
+    }
+
+    #[test]
+    fn test_valid_hex_strings() {
+        let key = SecretKey::random(&mut OsRng);
+        let key_str = hex::encode(key.to_bytes()).to_string();
+
+        let hex_strs = vec![
+            format!("{}\n", key_str.clone()),
+            format!("{}\r\n", key_str.clone()),
+            format!("{} ", key_str.clone()),
+            key_str.clone(),
+        ];
+
+        for hex_str in hex_strs {
+            let mut temp_file = tempfile::NamedTempFile::new().unwrap();
+            write!(temp_file, "{}", hex_str).unwrap();
+
+            let result = load(Path::new(&temp_file.path()));
+            assert!(
+                result.is_ok(),
+                "Failed to load key from file: {:?}",
+                &hex_str[hex_str.len().saturating_sub(2)..].to_string()
+            );
+            assert_eq!(result.unwrap(), key, "Key should match");
+        }
+    }
 }

crates/charon-p2p/Cargo.toml

@@ -12,9 +12,12 @@ thiserror.workspace = true
 k256.workspace = true
 charon-eth2.workspace = true
 charon-k1util.workspace = true
+chrono.workspace = true
+rand.workspace = true
 
 [dev-dependencies]
 charon-testutil.workspace = true
+tempfile.workspace = true
 
 [lints]
 workspace = true

crates/charon-p2p/src/k1.rs

@@ -0,0 +1,229 @@
+//! # Charon P2P K1
+
+use std::path::{Path, PathBuf};
+
+use charon_k1util as k1util;
+use k256::{SecretKey, elliptic_curve::rand_core::OsRng};
+use rand::RngCore;
+
+const KEY_FILE_NAME: &str = "charon-enr-private-key";
+const KEY_BACKUP_DIR: &str = "charon-enr-private-key-backups";
+
+type Result<T> = std::result::Result<T, K1Error>;
+
+/// An error that can occur when loading a private key.
+#[derive(Debug, thiserror::Error)]
+pub enum K1Error {
+    /// K1 utility error.
+    #[error("K1 utility error: {0}")]
+    K1UtilError(#[from] k1util::K1UtilError),
+
+    /// IOError.
+    #[error("IO error: {0}")]
+    IoError(#[from] std::io::Error),
+}
+
+/// Returns the charon-enr-private-key path relative to the data dir.
+pub fn key_path(data_dir: &Path) -> PathBuf {
+    data_dir.join(KEY_FILE_NAME)
+}
+
+/// Loads the private key from the data dir.
+pub fn load_priv_key(data_dir: &Path) -> Result<SecretKey> {
+    k1util::load(&key_path(data_dir)).map_err(K1Error::K1UtilError)
+}
+
+/// Generates a new private key and saves it to the data dir.
+pub fn new_saved_priv_key(data_dir: &Path) -> Result<SecretKey> {
+    backup_priv_key(data_dir)?;
+
+    std::fs::create_dir_all(data_dir)?;
+
+    let key = SecretKey::random(&mut OsRng);
+
+    k1util::save(&key, &key_path(data_dir)).map_err(K1Error::K1UtilError)?;
+
+    Ok(key)
+}
+
+/// Backs up the private key to the backup directory.
+///
+/// The backup directory is created if it doesn't exist.
+fn backup_priv_key(data_dir: &Path) -> Result<()> {
+    let key_path = key_path(data_dir);
+
+    if !key_path.exists() {
+        // Nothing to backup
+        return Ok(());
+    }
+
+    let current_time = chrono::Utc::now();
+    let nonce = OsRng.next_u64();
+    let backup_path = data_dir.join(KEY_BACKUP_DIR).join(format!(
+        "{}_{}",
+        current_time.format("%Y-%m-%d_%H-%M-%S_%f"),
+        nonce
+    ));
+    std::fs::create_dir_all(
+        backup_path
+            .parent()
+            .expect("Backup path parent should exist"),
+    )
+    .map_err(K1Error::IoError)?;
+    if backup_path.is_dir() {
+        panic!("Backup path is a directory: {:?}", backup_path);
+    }
+    std::fs::copy(key_path, backup_path).map_err(K1Error::IoError)?;
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use k256::elliptic_curve::rand_core::OsRng;
+    use std::{collections::HashSet, fs};
+    use tempfile::TempDir;
+
+    fn setup_temp_dir() -> TempDir {
+        tempfile::tempdir().expect("Failed to create temp dir")
+    }
+
+    fn create_test_key_file(data_dir: &Path) -> Result<SecretKey> {
+        let key = SecretKey::random(&mut OsRng);
+        k1util::save(&key, &key_path(data_dir))?;
+        Ok(key)
+    }
+
+    #[test]
+    fn test_key_path() {
+        let data_dir = Path::new("/test/data");
+        let path = key_path(data_dir);
+        assert_eq!(path, PathBuf::from("/test/data/charon-enr-private-key"));
+    }
+
+    #[test]
+    fn test_new_saved_priv_key_creates_key() -> Result<()> {
+        let temp_dir = setup_temp_dir();
+        let data_dir = temp_dir.path();
+
+        let key = new_saved_priv_key(data_dir)?;
+
+        let key_file = key_path(data_dir);
+        assert!(key_file.exists());
+
+        let loaded_key = load_priv_key(data_dir)?;
+        assert_eq!(key.to_bytes(), loaded_key.to_bytes());
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_new_saved_priv_key_creates_data_dir() -> Result<()> {
+        let temp_dir = setup_temp_dir();
+        let data_dir = temp_dir.path().join("new_dir");
+
+        assert!(!data_dir.exists());
+
+        new_saved_priv_key(&data_dir)?;
+
+        assert!(data_dir.exists());
+        assert!(data_dir.is_dir());
+
+        assert!(key_path(&data_dir).exists());
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_load_priv_key_success() -> Result<()> {
+        let temp_dir = setup_temp_dir();
+        let data_dir = temp_dir.path();
+
+        let original_key = create_test_key_file(data_dir)?;
+
+        let loaded_key = load_priv_key(data_dir)?;
+
+        assert_eq!(original_key.to_bytes(), loaded_key.to_bytes());
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_load_priv_key_file_not_found() {
+        let temp_dir = setup_temp_dir();
+        let data_dir = temp_dir.path();
+
+        let result = load_priv_key(data_dir);
+
+        assert!(result.is_err());
+        assert!(matches!(result, Err(K1Error::K1UtilError(_))));
+    }
+
+    #[test]
+    fn test_backup_priv_key_creates_backup() -> Result<()> {
+        let temp_dir = setup_temp_dir();
+        let data_dir = temp_dir.path();
+
+        create_test_key_file(data_dir)?;
+
+        backup_priv_key(data_dir)?;
+
+        let backup_dir = data_dir.join(KEY_BACKUP_DIR);
+        assert!(backup_dir.exists());
+        assert!(backup_dir.is_dir());
+
+        let entries: Vec<_> = fs::read_dir(&backup_dir)?.filter_map(|e| e.ok()).collect();
+        assert_eq!(entries.len(), 1);
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_new_saved_priv_key_with_existing_key() -> Result<()> {
+        let temp_dir = setup_temp_dir();
+        let data_dir = temp_dir.path();
+
+        let first_key = new_saved_priv_key(data_dir)?;
+
+        let second_key = new_saved_priv_key(data_dir)?;
+
+        assert_ne!(first_key.to_bytes(), second_key.to_bytes());
+
+        let loaded_key = load_priv_key(data_dir)?;
+        assert_eq!(second_key.to_bytes(), loaded_key.to_bytes());
+
+        let backup_dir = data_dir.join(KEY_BACKUP_DIR);
+        assert!(backup_dir.exists());
+
+        let entries: Vec<_> = fs::read_dir(&backup_dir)?.filter_map(|e| e.ok()).collect();
+        assert_eq!(entries.len(), 1);
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_backup_uniqueness() -> Result<()> {
+        const NUM_BACKUPS: usize = 5;
+
+        let temp_dir = setup_temp_dir();
+        let data_dir = temp_dir.path();
+
+        create_test_key_file(data_dir)?;
+
+        for _ in 0..NUM_BACKUPS {
+            backup_priv_key(data_dir)?;
+        }
+
+        let backup_dir = data_dir.join(KEY_BACKUP_DIR);
+        let entries: Vec<_> = fs::read_dir(&backup_dir)?.filter_map(|e| e.ok()).collect();
+        let backup_names: HashSet<_> = entries.iter().map(|e| e.file_name()).collect();
+
+        assert_eq!(
+            backup_names.len(),
+            NUM_BACKUPS,
+            "Should have 5 unique backup names"
+        );
+
+        Ok(())
+    }
+}

crates/charon-p2p/src/lib.rs

@@ -13,3 +13,6 @@ pub mod name;
 
 /// P2P configuration.
 pub mod config;
+
+/// K1 utilities.
+pub mod k1;