3 files changed, 109 insertions, 0 deletions
diff --git a/crypto/Cargo.toml b/crypto/Cargo.toml
new file mode 100644
index 0000000..4741b00
--- /dev/null
+++ b/crypto/Cargo.toml
@@ -0,0 +1,15 @@
+[package]
+name = "onioncoin-crypto"
+version.workspace = true
+edition.workspace = true
+authors.workspace = true
+license.workspace = true
+
+[dependencies]
+ed25519-dalek.workspace = true
+curve25519-dalek.workspace = true
+sha3.workspace = true
+blake3.workspace = true
+rand.workspace = true
+serde.workspace = true
+thiserror.workspace = true
diff --git a/crypto/src/keys.rs b/crypto/src/keys.rs
new file mode 100644
index 0000000..4666476
--- /dev/null
+++ b/crypto/src/keys.rs
@@ -0,0 +1,84 @@
+use ed25519_dalek::{Signer, Verifier};
+use serde::{Deserialize, Serialize};
+
+/// Public key wrapper
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PublicKey(pub [u8; 32]);
+
+/// Secret key wrapper
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct SecretKey(pub [u8; 32]);
+
+/// Key pair for signing
+#[derive(Debug, Clone)]
+pub struct KeyPair {
+    pub public: PublicKey,
+    pub secret: SecretKey,
+    signing_key: ed25519_dalek::SigningKey,
+}
+
+impl KeyPair {
+    /// Generate new random keypair
+    pub fn generate() -> Self {
+        use rand::RngCore;
+        let mut rng = rand::thread_rng();
+        let mut secret_bytes = [0u8; 32];
+        rng.fill_bytes(&mut secret_bytes);
+
+        let signing_key = ed25519_dalek::SigningKey::from_bytes(&secret_bytes);
+        let verifying_key = signing_key.verifying_key();
+
+        Self {
+            public: PublicKey(verifying_key.to_bytes()),
+            secret: SecretKey(signing_key.to_bytes()),
+            signing_key,
+        }
+    }
+
+    /// Sign a message
+    pub fn sign(&self, message: &[u8]) -> [u8; 64] {
+        self.signing_key.sign(message).to_bytes()
+    }
+
+    /// Verify a signature
+    pub fn verify(public_key: &PublicKey, message: &[u8], signature: &[u8; 64]) -> bool {
+        let verifying_key = match ed25519_dalek::VerifyingKey::from_bytes(&public_key.0) {
+            Ok(key) => key,
+            Err(_) => return false,
+        };
+
+        let sig = ed25519_dalek::Signature::from_bytes(signature);
+
+        verifying_key.verify(message, &sig).is_ok()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_keypair_generation() {
+        let keypair = KeyPair::generate();
+        assert_ne!(keypair.public.0, [0u8; 32]);
+        assert_ne!(keypair.secret.0, [0u8; 32]);
+    }
+
+    #[test]
+    fn test_sign_verify() {
+        let keypair = KeyPair::generate();
+        let message = b"Hello, OnionCoin!";
+
+        let signature = keypair.sign(message);
+        assert!(KeyPair::verify(&keypair.public, message, &signature));
+    }
+
+    #[test]
+    fn test_verify_invalid_signature() {
+        let keypair = KeyPair::generate();
+        let message = b"Hello, OnionCoin!";
+        let wrong_sig = [0u8; 64];
+
+        assert!(!KeyPair::verify(&keypair.public, message, &wrong_sig));
+    }
+}
diff --git a/crypto/src/lib.rs b/crypto/src/lib.rs
new file mode 100644
index 0000000..92bf68a
--- /dev/null
+++ b/crypto/src/lib.rs
@@ -0,0 +1,10 @@
+// Placeholder crypto module for OnionCoin
+// Production implementation would include:
+// - Ring signatures (Monero-style)
+// - Bulletproofs for confidential transactions
+// - Stealth address generation
+// - Key derivation (HD wallets)
+
+pub mod keys;
+
+pub use keys::{KeyPair, PublicKey, SecretKey};