KeysInterface: add new ecdh method

This method will help us avoid retrieving our node secret, something we want to
get rid of entirely.  It will be used in upcoming commits when decoding the
onion message packet, and in future PRs to help us get rid of
KeysInterface::get_node_secret usages across the codebase

diff --git a/fuzz/src/chanmon_consistency.rs b/fuzz/src/chanmon_consistency.rs
index 615f3aad995ce054d9b073923bf31e23725b7bef..c511e4ff31c886dd829fb33c7bcd46af7cbbce7c 100644 (file)
--- a/fuzz/src/chanmon_consistency.rs
+++ b/fuzz/src/chanmon_consistency.rs
@@ -54,6 +54,7 @@ use utils::test_logger::{self, Output};
 use utils::test_persister::TestPersister;
 
 use bitcoin::secp256k1::{PublicKey,SecretKey};
+use bitcoin::secp256k1::ecdh::SharedSecret;
 use bitcoin::secp256k1::ecdsa::RecoverableSignature;
 use bitcoin::secp256k1::Secp256k1;
 
@@ -165,6 +166,14 @@ impl KeysInterface for KeyProvider {
                Ok(SecretKey::from_slice(&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, self.node_id]).unwrap())
        }
 
+       fn ecdh(&self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&[u8; 32]>) -> Result<SharedSecret, ()> {
+               let mut node_secret = self.get_node_secret(recipient)?;
+               if let Some(tweak) = tweak {
+                       node_secret.mul_assign(tweak).map_err(|_| ())?;
+               }
+               Ok(SharedSecret::new(other_key, &node_secret))
+       }
+
        fn get_inbound_payment_key_material(&self) -> KeyMaterial {
                KeyMaterial([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, self.node_id])
        }

diff --git a/fuzz/src/full_stack.rs b/fuzz/src/full_stack.rs
index b4ca316ed0dbba1f695a913e747239dca3ffef90..40c77f066628270cb920b8741e26b53325432ac5 100644 (file)
--- a/fuzz/src/full_stack.rs
+++ b/fuzz/src/full_stack.rs
@@ -51,6 +51,7 @@ use utils::test_logger;
 use utils::test_persister::TestPersister;
 
 use bitcoin::secp256k1::{PublicKey,SecretKey};
+use bitcoin::secp256k1::ecdh::SharedSecret;
 use bitcoin::secp256k1::ecdsa::RecoverableSignature;
 use bitcoin::secp256k1::Secp256k1;
 
@@ -269,6 +270,14 @@ impl KeysInterface for KeyProvider {
                Ok(self.node_secret.clone())
        }
 
+       fn ecdh(&self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&[u8; 32]>) -> Result<SharedSecret, ()> {
+               let mut node_secret = self.get_node_secret(recipient)?;
+               if let Some(tweak) = tweak {
+                       node_secret.mul_assign(tweak).map_err(|_| ())?;
+               }
+               Ok(SharedSecret::new(other_key, &node_secret))
+       }
+
        fn get_inbound_payment_key_material(&self) -> KeyMaterial {
                self.inbound_payment_key.clone()
        }

diff --git a/lightning/src/chain/keysinterface.rs b/lightning/src/chain/keysinterface.rs
index 4231d08259abcbe1e4c50550f4b40aa7d7064faa..9a3baea8bb442a3c6928cca83559606a66de95ff 100644 (file)
--- a/lightning/src/chain/keysinterface.rs
+++ b/lightning/src/chain/keysinterface.rs
@@ -27,6 +27,7 @@ use bitcoin::hash_types::WPubkeyHash;
 
 use bitcoin::secp256k1::{SecretKey, PublicKey};
 use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature, Signing};
+use bitcoin::secp256k1::ecdh::SharedSecret;
 use bitcoin::secp256k1::ecdsa::RecoverableSignature;
 use bitcoin::{secp256k1, Witness};
 
@@ -404,6 +405,12 @@ pub trait KeysInterface {
        /// This method must return the same value each time it is called with a given `Recipient`
        /// parameter.
        fn get_node_secret(&self, recipient: Recipient) -> Result<SecretKey, ()>;
+       /// Gets the ECDH shared secret of our [`node secret`] and `other_key`, multiplying by `tweak` if
+       /// one is provided. Note that this tweak can be applied to `other_key` instead of our node
+       /// secret, though this is less efficient.
+       ///
+       /// [`node secret`]: Self::get_node_secret
+       fn ecdh(&self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&[u8; 32]>) -> Result<SharedSecret, ()>;
        /// Get a script pubkey which we send funds to when claiming on-chain contestable outputs.
        ///
        /// This method should return a different value each time it is called, to avoid linking
@@ -1133,6 +1140,14 @@ impl KeysInterface for KeysManager {
                }
        }
 
+       fn ecdh(&self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&[u8; 32]>) -> Result<SharedSecret, ()> {
+               let mut node_secret = self.get_node_secret(recipient)?;
+               if let Some(tweak) = tweak {
+                       node_secret.mul_assign(tweak).map_err(|_| ())?;
+               }
+               Ok(SharedSecret::new(other_key, &node_secret))
+       }
+
        fn get_inbound_payment_key_material(&self) -> KeyMaterial {
                self.inbound_payment_key.clone()
        }
@@ -1217,6 +1232,14 @@ impl KeysInterface for PhantomKeysManager {
                }
        }
 
+       fn ecdh(&self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&[u8; 32]>) -> Result<SharedSecret, ()> {
+               let mut node_secret = self.get_node_secret(recipient)?;
+               if let Some(tweak) = tweak {
+                       node_secret.mul_assign(tweak).map_err(|_| ())?;
+               }
+               Ok(SharedSecret::new(other_key, &node_secret))
+       }
+
        fn get_inbound_payment_key_material(&self) -> KeyMaterial {
                self.inbound_payment_key.clone()
        }

diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs
index c5133a850584fd5b6e91d9c91e43a087c3c268d3..2da743033d3596f5176b17ee6b864f8fa7416679 100644 (file)
--- a/lightning/src/ln/channel.rs
+++ b/lightning/src/ln/channel.rs
@@ -6583,6 +6583,7 @@ mod tests {
        use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature};
        use bitcoin::secp256k1::ffi::Signature as FFISignature;
        use bitcoin::secp256k1::{SecretKey,PublicKey};
+       use bitcoin::secp256k1::ecdh::SharedSecret;
        use bitcoin::secp256k1::ecdsa::RecoverableSignature;
        use bitcoin::hashes::sha256::Hash as Sha256;
        use bitcoin::hashes::Hash;
@@ -6621,6 +6622,7 @@ mod tests {
                type Signer = InMemorySigner;
 
                fn get_node_secret(&self, _recipient: Recipient) -> Result<SecretKey, ()> { panic!(); }
+               fn ecdh(&self, _recipient: Recipient, _other_key: &PublicKey, _tweak: Option<&[u8; 32]>) -> Result<SharedSecret, ()> { panic!(); }
                fn get_inbound_payment_key_material(&self) -> KeyMaterial { panic!(); }
                fn get_destination_script(&self) -> Script {
                        let secp_ctx = Secp256k1::signing_only();

diff --git a/lightning/src/util/test_utils.rs b/lightning/src/util/test_utils.rs
index 4f3d800be5dd8479f79a7999318fc627017e7078..92383c91e8fc29c6da1b45a6d735f4fe0280485a 100644 (file)
--- a/lightning/src/util/test_utils.rs
+++ b/lightning/src/util/test_utils.rs
@@ -36,6 +36,7 @@ use bitcoin::network::constants::Network;
 use bitcoin::hash_types::{BlockHash, Txid};
 
 use bitcoin::secp256k1::{SecretKey, PublicKey, Secp256k1, ecdsa::Signature};
+use bitcoin::secp256k1::ecdh::SharedSecret;
 use bitcoin::secp256k1::ecdsa::RecoverableSignature;
 
 use regex;
@@ -74,6 +75,7 @@ impl keysinterface::KeysInterface for OnlyReadsKeysInterface {
        type Signer = EnforcingSigner;
 
        fn get_node_secret(&self, _recipient: Recipient) -> Result<SecretKey, ()> { unreachable!(); }
+       fn ecdh(&self, _recipient: Recipient, _other_key: &PublicKey, _tweak: Option<&[u8; 32]>) -> Result<SharedSecret, ()> { unreachable!(); }
        fn get_inbound_payment_key_material(&self) -> KeyMaterial { unreachable!(); }
        fn get_destination_script(&self) -> Script { unreachable!(); }
        fn get_shutdown_scriptpubkey(&self) -> ShutdownScript { unreachable!(); }
@@ -599,6 +601,9 @@ impl keysinterface::KeysInterface for TestKeysInterface {
        fn get_node_secret(&self, recipient: Recipient) -> Result<SecretKey, ()> {
                self.backing.get_node_secret(recipient)
        }
+       fn ecdh(&self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&[u8; 32]>) -> Result<SharedSecret, ()> {
+               self.backing.ecdh(recipient, other_key, tweak)
+       }
        fn get_inbound_payment_key_material(&self) -> keysinterface::KeyMaterial {
                self.backing.get_inbound_payment_key_material()
        }