1 files changed, 20 insertions, 2 deletions
diff --git a/openpgp/src/crypto/backend/interface.rs b/openpgp/src/crypto/backend/interface.rs
index f96e9a6c..81343c6c 100644
--- a/openpgp/src/crypto/backend/interface.rs
+++ b/openpgp/src/crypto/backend/interface.rs
@@ -1,9 +1,12 @@
 //! The crypto-backend abstraction.
 
-use crate::Result;
+use crate::{
+    Result,
+    crypto::mem::Protected,
+};
 
 /// Abstracts over the cryptographic backends.
-pub trait Backend {
+pub trait Backend: Asymmetric {
     /// Returns a short, human-readable description of the backend.
     ///
     /// This starts with the name of the backend, possibly a version,
@@ -19,3 +22,18 @@ pub trait Backend {
     /// long-term cryptographic keys from.
     fn random(buf: &mut [u8]) -> Result<()>;
 }
+
+/// Public-key cryptography interface.
+pub trait Asymmetric {
+    /// Generates an X25519 key pair.
+    ///
+    /// Returns a tuple containing the secret and public key.
+    fn x25519_generate_key() -> Result<(Protected, [u8; 32])>;
+
+    /// Computes the public key for a given secret key.
+    fn x25519_derive_public(secret: &Protected) -> Result<[u8; 32]>;
+
+    /// Computes the shared point.
+    fn x25519_shared_point(secret: &Protected, public: &[u8; 32])
+                           -> Result<Protected>;
+}