Merge branch 'db' into on-chain-protocol

.github/workflows/ci.yml

@@ -76,4 +76,6 @@ jobs:
       - name: Cargo test
         run: cargo test --workspace --all-features
         env:
+          # To avoid stack overflows
+          RUST_MIN_STACK: 100000000
           MONERO_ADDITIONAL_SLEEP_PERIOD: 60000

LICENSE

@@ -1,21 +1,674 @@
-MIT License
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+versions of the GNU General Public License can be used, that proxy's
+public statement of acceptance of a version permanently authorizes you
+to choose that version for the Program.
+
+  Later license versions may give you additional or different
+permissions.  However, no additional obligations are imposed on any
+author or copyright holder as a result of your choosing to follow a
+later version.
+
+  15. Disclaimer of Warranty.
+
+  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
+OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    <program>  Copyright (C) <year>  <name of author>
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<https://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<https://www.gnu.org/licenses/why-not-lgpl.html>.

xmr-btc/Cargo.toml

@@ -7,16 +7,17 @@ edition = "2018"
 [dependencies]
 anyhow = "1"
 async-trait = "0.1"
-bitcoin = { version = "0.23", features = ["rand"] }
+bitcoin = { version = "0.23", features = ["rand", "serde"] }
-cross-curve-dleq = { git = "https://github.com/comit-network/cross-curve-dleq", rev = "a3e57a70d332b4ce9600663453b9bd02936d76bf" }
+cross-curve-dleq = { git = "https://github.com/comit-network/cross-curve-dleq", rev = "49171f5e08473d46f951fb1fc338fe437d974d3c" }
 curve25519-dalek = "2"
-ecdsa_fun = { version = "0.3.1", features = ["libsecp_compat"] }
+ecdsa_fun = { git = "https://github.com/LLFourn/secp256kfun", rev = "510d48ef6a2b19805f7f5c70c598e5b03f668e7a", features = ["libsecp_compat", "serde", "serialization"] }
-ed25519-dalek = "1.0.0-pre.4" # Cannot be 1 because they depend on curve25519-dalek version 3
+ed25519-dalek = { version = "1.0.0-pre.4", features = ["serde"] }# Cannot be 1 because they depend on curve25519-dalek version 3
 futures = "0.3"
 genawaiter = "0.99.1"
-miniscript = "1"
+miniscript = { version = "1", features = ["serde"] }
-monero = "0.9"
+monero = { version = "0.9", features = ["serde_support"] }
 rand = "0.7"
+serde = { version = "1", features = ["derive"] }
 sha2 = "0.9"
 thiserror = "1"
 tracing = "0.1"
@@ -28,6 +29,8 @@ bitcoin-harness = { git = "https://github.com/coblox/bitcoin-harness-rs", rev =
 futures = "0.3"
 monero-harness = { path = "../monero-harness" }
 reqwest = { version = "0.10", default-features = false }
+serde_cbor = "0.11"
+sled = "0.34"
 testcontainers = "0.10"
 tokio = { version = "0.2", default-features = false, features = ["blocking", "macros", "rt-core", "time", "rt-threaded"] }
 tracing = "0.1"

xmr-btc/src/alice.rs

@@ -3,6 +3,7 @@ use crate::{
     bitcoin::{BroadcastSignedTransaction, WatchForRawTransaction},
     bob, monero,
     monero::{CreateWalletForOutput, Transfer},
+    serde::{bitcoin_amount, cross_curve_dleq_scalar, ecdsa_fun_signature},
     transport::{ReceiveMessage, SendMessage},
 };
 use anyhow::{anyhow, Result};
@@ -11,6 +12,7 @@ use ecdsa_fun::{
     nonce::Deterministic,
 };
 use rand::{CryptoRng, RngCore};
+use serde::{Deserialize, Serialize};
 use sha2::Sha256;
 use std::convert::{TryFrom, TryInto};
 
@@ -129,11 +131,13 @@ impl State {
     }
 }
 
-#[derive(Clone, Debug)]
+#[derive(Debug, Deserialize, Serialize)]
 pub struct State0 {
     a: bitcoin::SecretKey,
+    #[serde(with = "cross_curve_dleq_scalar")]
     s_a: cross_curve_dleq::Scalar,
     v_a: monero::PrivateViewKey,
+    #[serde(with = "bitcoin_amount")]
     btc: bitcoin::Amount,
     xmr: monero::Amount,
     refund_timelock: u32,
@@ -188,7 +192,7 @@ impl State0 {
 
     pub fn receive(self, msg: bob::Message0) -> Result<State1> {
         msg.dleq_proof_s_b.verify(
-            &msg.S_b_bitcoin.clone().into(),
+            msg.S_b_bitcoin.clone().into(),
             msg.S_b_monero
                 .point
                 .decompress()
@@ -215,14 +219,16 @@ impl State0 {
     }
 }
 
-#[derive(Clone, Debug)]
+#[derive(Debug, Deserialize, Serialize)]
 pub struct State1 {
     a: bitcoin::SecretKey,
     B: bitcoin::PublicKey,
+    #[serde(with = "cross_curve_dleq_scalar")]
     s_a: cross_curve_dleq::Scalar,
     S_b_monero: monero::PublicKey,
     S_b_bitcoin: bitcoin::PublicKey,
     v: monero::PrivateViewKey,
+    #[serde(with = "bitcoin_amount")]
     btc: bitcoin::Amount,
     xmr: monero::Amount,
     refund_timelock: u32,
@@ -253,14 +259,16 @@ impl State1 {
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, Deserialize, Serialize)]
 pub struct State2 {
     a: bitcoin::SecretKey,
     B: bitcoin::PublicKey,
+    #[serde(with = "cross_curve_dleq_scalar")]
     s_a: cross_curve_dleq::Scalar,
     S_b_monero: monero::PublicKey,
     S_b_bitcoin: bitcoin::PublicKey,
     v: monero::PrivateViewKey,
+    #[serde(with = "bitcoin_amount")]
     btc: bitcoin::Amount,
     xmr: monero::Amount,
     refund_timelock: u32,
@@ -328,14 +336,16 @@ impl State2 {
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, Deserialize, Serialize)]
 pub struct State3 {
     pub a: bitcoin::SecretKey,
     pub B: bitcoin::PublicKey,
+    #[serde(with = "cross_curve_dleq_scalar")]
     pub s_a: cross_curve_dleq::Scalar,
     pub S_b_monero: monero::PublicKey,
     pub S_b_bitcoin: bitcoin::PublicKey,
     pub v: monero::PrivateViewKey,
+    #[serde(with = "bitcoin_amount")]
     btc: bitcoin::Amount,
     pub xmr: monero::Amount,
     pub refund_timelock: u32,
@@ -344,7 +354,9 @@ pub struct State3 {
     pub redeem_address: bitcoin::Address,
     pub punish_address: bitcoin::Address,
     pub tx_lock: bitcoin::TxLock,
+    #[serde(with = "ecdsa_fun_signature")]
     pub tx_punish_sig_bob: bitcoin::Signature,
+    #[serde(with = "ecdsa_fun_signature")]
     pub tx_cancel_sig_bob: bitcoin::Signature,
 }
 
@@ -381,14 +393,16 @@ impl State3 {
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, Deserialize, Serialize)]
 pub struct State4 {
     a: bitcoin::SecretKey,
     B: bitcoin::PublicKey,
+    #[serde(with = "cross_curve_dleq_scalar")]
     s_a: cross_curve_dleq::Scalar,
     S_b_monero: monero::PublicKey,
     S_b_bitcoin: bitcoin::PublicKey,
     v: monero::PrivateViewKey,
+    #[serde(with = "bitcoin_amount")]
     btc: bitcoin::Amount,
     xmr: monero::Amount,
     refund_timelock: u32,
@@ -397,7 +411,9 @@ pub struct State4 {
     redeem_address: bitcoin::Address,
     punish_address: bitcoin::Address,
     tx_lock: bitcoin::TxLock,
+    #[serde(with = "ecdsa_fun_signature")]
     tx_punish_sig_bob: bitcoin::Signature,
+    #[serde(with = "ecdsa_fun_signature")]
     tx_cancel_sig_bob: bitcoin::Signature,
 }
 
@@ -484,14 +500,16 @@ impl State4 {
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, Deserialize, Serialize)]
 pub struct State5 {
     a: bitcoin::SecretKey,
     B: bitcoin::PublicKey,
+    #[serde(with = "cross_curve_dleq_scalar")]
     s_a: cross_curve_dleq::Scalar,
     S_b_monero: monero::PublicKey,
     S_b_bitcoin: bitcoin::PublicKey,
     v: monero::PrivateViewKey,
+    #[serde(with = "bitcoin_amount")]
     btc: bitcoin::Amount,
     xmr: monero::Amount,
     refund_timelock: u32,
@@ -501,7 +519,9 @@ pub struct State5 {
     punish_address: bitcoin::Address,
     tx_lock: bitcoin::TxLock,
     tx_lock_proof: monero::TransferProof,
+    #[serde(with = "ecdsa_fun_signature")]
     tx_punish_sig_bob: bitcoin::Signature,
+    #[serde(with = "ecdsa_fun_signature")]
     tx_cancel_sig_bob: bitcoin::Signature,
     lock_xmr_fee: monero::Amount,
 }
@@ -575,14 +595,16 @@ impl State5 {
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, Deserialize, Serialize)]
 pub struct State6 {
     a: bitcoin::SecretKey,
     B: bitcoin::PublicKey,
+    #[serde(with = "cross_curve_dleq_scalar")]
     s_a: cross_curve_dleq::Scalar,
     S_b_monero: monero::PublicKey,
     S_b_bitcoin: bitcoin::PublicKey,
     v: monero::PrivateViewKey,
+    #[serde(with = "bitcoin_amount")]
     btc: bitcoin::Amount,
     xmr: monero::Amount,
     refund_timelock: u32,
@@ -591,6 +613,7 @@ pub struct State6 {
     redeem_address: bitcoin::Address,
     punish_address: bitcoin::Address,
     tx_lock: bitcoin::TxLock,
+    #[serde(with = "ecdsa_fun_signature")]
     tx_punish_sig_bob: bitcoin::Signature,
     tx_redeem_encsig: EncryptedSignature,
     lock_xmr_fee: monero::Amount,

xmr-btc/src/bitcoin.rs

@@ -19,6 +19,7 @@ use ecdsa_fun::{
 };
 use miniscript::{Descriptor, Segwitv0};
 use rand::{CryptoRng, RngCore};
+use serde::{Deserialize, Serialize};
 use sha2::Sha256;
 use std::str::FromStr;
 
@@ -28,7 +29,7 @@ pub use ecdsa_fun::{adaptor::EncryptedSignature, Signature};
 
 pub const TX_FEE: u64 = 10_000;
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Deserialize, Serialize, PartialEq)]
 pub struct SecretKey {
     inner: Scalar,
     public: Point,
@@ -83,7 +84,7 @@ impl SecretKey {
     }
 }
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
 pub struct PublicKey(Point);
 
 impl From<PublicKey> for Point<Jacobian> {

xmr-btc/src/bitcoin/transactions.rs

@@ -8,9 +8,10 @@ use bitcoin::{
 };
 use ecdsa_fun::Signature;
 use miniscript::Descriptor;
+use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
 pub struct TxLock {
     inner: Transaction,
     output_descriptor: Descriptor<::bitcoin::PublicKey>,

xmr-btc/src/bob.rs

@@ -5,7 +5,8 @@ use crate::{
         WatchForRawTransaction,
     },
     monero,
-    monero::{CreateWalletForOutput, WatchForTransfer},
+    monero::{CheckTransfer, CreateWalletForOutput, WatchForTransfer},
+    serde::{bitcoin_amount, cross_curve_dleq_scalar, monero_private_key},
     transport::{ReceiveMessage, SendMessage},
 };
 use anyhow::{anyhow, Result};
@@ -15,6 +16,7 @@ use ecdsa_fun::{
     Signature,
 };
 use rand::{CryptoRng, RngCore};
+use serde::{Deserialize, Serialize};
 use sha2::Sha256;
 use std::convert::{TryFrom, TryInto};
 
@@ -102,11 +104,13 @@ impl_from_child_enum!(State3, State);
 impl_from_child_enum!(State4, State);
 impl_from_child_enum!(State5, State);
 
-#[derive(Clone, Debug)]
+#[derive(Debug, Deserialize, Serialize)]
 pub struct State0 {
     b: bitcoin::SecretKey,
+    #[serde(with = "cross_curve_dleq_scalar")]
     s_b: cross_curve_dleq::Scalar,
     v_b: monero::PrivateViewKey,
+    #[serde(with = "bitcoin_amount")]
     btc: bitcoin::Amount,
     xmr: monero::Amount,
     refund_timelock: u32,
@@ -160,7 +164,7 @@ impl State0 {
         W: BuildTxLockPsbt,
     {
         msg.dleq_proof_s_a.verify(
-            &msg.S_a_bitcoin.clone().into(),
+            msg.S_a_bitcoin.clone().into(),
             msg.S_a_monero
                 .point
                 .decompress()
@@ -190,14 +194,16 @@ impl State0 {
     }
 }
 
-#[derive(Clone, Debug)]
+#[derive(Debug, Deserialize, Serialize)]
 pub struct State1 {
     A: bitcoin::PublicKey,
     b: bitcoin::SecretKey,
+    #[serde(with = "cross_curve_dleq_scalar")]
     s_b: cross_curve_dleq::Scalar,
     S_a_monero: monero::PublicKey,
     S_a_bitcoin: bitcoin::PublicKey,
     v: monero::PrivateViewKey,
+    #[serde(with = "bitcoin_amount")]
     btc: bitcoin::Amount,
     xmr: monero::Amount,
     refund_timelock: u32,
@@ -253,14 +259,16 @@ impl State1 {
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, Deserialize, Serialize)]
 pub struct State2 {
     pub A: bitcoin::PublicKey,
     pub b: bitcoin::SecretKey,
+    #[serde(with = "cross_curve_dleq_scalar")]
     pub s_b: cross_curve_dleq::Scalar,
     pub S_a_monero: monero::PublicKey,
     pub S_a_bitcoin: bitcoin::PublicKey,
     pub v: monero::PrivateViewKey,
+    #[serde(with = "bitcoin_amount")]
     btc: bitcoin::Amount,
     pub xmr: monero::Amount,
     pub refund_timelock: u32,
@@ -324,14 +332,16 @@ impl State2 {
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, Serialize, Deserialize)]
 pub struct State3 {
     A: bitcoin::PublicKey,
     b: bitcoin::SecretKey,
+    #[serde(with = "cross_curve_dleq_scalar")]
     s_b: cross_curve_dleq::Scalar,
     S_a_monero: monero::PublicKey,
     S_a_bitcoin: bitcoin::PublicKey,
     v: monero::PrivateViewKey,
+    #[serde(with = "bitcoin_amount")]
     btc: bitcoin::Amount,
     xmr: monero::Amount,
     refund_timelock: u32,
@@ -435,14 +445,16 @@ impl State3 {
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, Deserialize, Serialize)]
 pub struct State4 {
     A: bitcoin::PublicKey,
     b: bitcoin::SecretKey,
+    #[serde(with = "cross_curve_dleq_scalar")]
     s_b: cross_curve_dleq::Scalar,
     S_a_monero: monero::PublicKey,
     S_a_bitcoin: bitcoin::PublicKey,
     v: monero::PrivateViewKey,
+    #[serde(with = "bitcoin_amount")]
     btc: bitcoin::Amount,
     xmr: monero::Amount,
     refund_timelock: u32,
@@ -502,15 +514,18 @@ impl State4 {
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone, Deserialize, Serialize)]
 pub struct State5 {
     A: bitcoin::PublicKey,
     b: bitcoin::SecretKey,
+    #[serde(with = "monero_private_key")]
     s_a: monero::PrivateKey,
+    #[serde(with = "cross_curve_dleq_scalar")]
     s_b: cross_curve_dleq::Scalar,
     S_a_monero: monero::PublicKey,
     S_a_bitcoin: bitcoin::PublicKey,
     v: monero::PrivateViewKey,
+    #[serde(with = "bitcoin_amount")]
     btc: bitcoin::Amount,
     xmr: monero::Amount,
     refund_timelock: u32,

xmr-btc/src/lib.rs

@@ -49,6 +49,7 @@ pub mod alice;
 pub mod bitcoin;
 pub mod bob;
 pub mod monero;
+pub mod serde;
 pub mod transport;
 
 use async_trait::async_trait;

xmr-btc/src/monero.rs

@@ -1,7 +1,10 @@
+use crate::serde::monero_private_key;
+use anyhow::Result;
 use async_trait::async_trait;
 pub use curve25519_dalek::scalar::Scalar;
 pub use monero::{Address, PrivateKey, PublicKey};
 use rand::{CryptoRng, RngCore};
+use serde::{Deserialize, Serialize};
 use std::ops::Add;
 
 pub const MIN_CONFIRMATIONS: u32 = 10;
@@ -12,8 +15,8 @@ pub fn random_private_key<R: RngCore + CryptoRng>(rng: &mut R) -> PrivateKey {
     PrivateKey::from_scalar(scalar)
 }
 
-#[derive(Clone, Copy, Debug)]
+#[derive(Clone, Copy, Debug, Serialize, Deserialize, PartialEq)]
-pub struct PrivateViewKey(PrivateKey);
+pub struct PrivateViewKey(#[serde(with = "monero_private_key")] PrivateKey);
 
 impl PrivateViewKey {
     pub fn new_random<R: RngCore + CryptoRng>(rng: &mut R) -> Self {
@@ -51,7 +54,7 @@ impl From<PublicViewKey> for PublicKey {
 #[derive(Clone, Copy, Debug)]
 pub struct PublicViewKey(PublicKey);
 
-#[derive(Debug, Copy, Clone)]
+#[derive(Debug, Copy, Clone, Deserialize, Serialize, PartialEq)]
 pub struct Amount(u64);
 
 impl Amount {
@@ -73,9 +76,10 @@ impl From<Amount> for u64 {
     }
 }
 
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, Serialize, Deserialize)]
 pub struct TransferProof {
     tx_hash: TxHash,
+    #[serde(with = "monero_private_key")]
     tx_key: PrivateKey,
 }
 
@@ -92,7 +96,7 @@ impl TransferProof {
 }
 
 // TODO: add constructor/ change String to fixed length byte array
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, Serialize, Deserialize)]
 pub struct TxHash(pub String);
 
 impl From<TxHash> for String {

xmr-btc/src/serde.rs

@@ -0,0 +1,210 @@
+pub mod ecdsa_fun_signature {
+    use serde::{de, de::Visitor, Deserializer, Serializer};
+    use std::{convert::TryFrom, fmt};
+
+    struct Bytes64Visitor;
+
+    impl<'de> Visitor<'de> for Bytes64Visitor {
+        type Value = ecdsa_fun::Signature;
+
+        fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+            write!(formatter, "a string containing 64 bytes")
+        }
+
+        fn visit_bytes<E>(self, s: &[u8]) -> Result<Self::Value, E>
+        where
+            E: de::Error,
+        {
+            if let Ok(value) = <[u8; 64]>::try_from(s) {
+                let sig = ecdsa_fun::Signature::from_bytes(value)
+                    .expect("bytes represent an integer greater than or equal to the curve order");
+                Ok(sig)
+            } else {
+                Err(de::Error::invalid_length(s.len(), &self))
+            }
+        }
+    }
+
+    pub fn serialize<S>(x: &ecdsa_fun::Signature, s: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        s.serialize_bytes(&x.to_bytes())
+    }
+
+    pub fn deserialize<'de, D>(
+        deserializer: D,
+    ) -> Result<ecdsa_fun::Signature, <D as Deserializer<'de>>::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        let sig = deserializer.deserialize_bytes(Bytes64Visitor)?;
+        Ok(sig)
+    }
+}
+
+pub mod cross_curve_dleq_scalar {
+    use serde::{de, de::Visitor, Deserializer, Serializer};
+    use std::{convert::TryFrom, fmt};
+
+    struct Bytes32Visitor;
+
+    impl<'de> Visitor<'de> for Bytes32Visitor {
+        type Value = cross_curve_dleq::Scalar;
+
+        fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+            write!(formatter, "a string containing 32 bytes")
+        }
+
+        fn visit_bytes<E>(self, s: &[u8]) -> Result<Self::Value, E>
+        where
+            E: de::Error,
+        {
+            if let Ok(value) = <[u8; 32]>::try_from(s) {
+                Ok(cross_curve_dleq::Scalar::from(value))
+            } else {
+                Err(de::Error::invalid_length(s.len(), &self))
+            }
+        }
+    }
+
+    pub fn serialize<S>(x: &cross_curve_dleq::Scalar, s: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        // Serialise as ed25519 because the inner bytes are private
+        // TODO: Open PR in cross_curve_dleq to allow accessing the inner bytes
+        s.serialize_bytes(&x.into_ed25519().to_bytes())
+    }
+
+    pub fn deserialize<'de, D>(
+        deserializer: D,
+    ) -> Result<cross_curve_dleq::Scalar, <D as Deserializer<'de>>::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        let dleq = deserializer.deserialize_bytes(Bytes32Visitor)?;
+        Ok(dleq)
+    }
+}
+
+pub mod monero_private_key {
+    use serde::{de, de::Visitor, Deserializer, Serializer};
+    use std::fmt;
+
+    struct BytesVisitor;
+
+    impl<'de> Visitor<'de> for BytesVisitor {
+        type Value = monero::PrivateKey;
+
+        fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+            write!(formatter, "a string containing 32 bytes")
+        }
+
+        fn visit_bytes<E>(self, s: &[u8]) -> Result<Self::Value, E>
+        where
+            E: de::Error,
+        {
+            if let Ok(key) = monero::PrivateKey::from_slice(s) {
+                Ok(key)
+            } else {
+                Err(de::Error::invalid_length(s.len(), &self))
+            }
+        }
+    }
+
+    pub fn serialize<S>(x: &monero::PrivateKey, s: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        s.serialize_bytes(x.as_bytes())
+    }
+
+    pub fn deserialize<'de, D>(
+        deserializer: D,
+    ) -> Result<monero::PrivateKey, <D as Deserializer<'de>>::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        let key = deserializer.deserialize_bytes(BytesVisitor)?;
+        Ok(key)
+    }
+}
+
+pub mod bitcoin_amount {
+    use serde::{Deserialize, Deserializer, Serializer};
+
+    pub fn serialize<S>(value: &bitcoin::Amount, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        serializer.serialize_u64(value.as_sat())
+    }
+
+    pub fn deserialize<'de, D>(
+        deserializer: D,
+    ) -> Result<bitcoin::Amount, <D as Deserializer<'de>>::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        let value = u64::deserialize(deserializer)?;
+        let amount = bitcoin::Amount::from_sat(value);
+
+        Ok(amount)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use ::bitcoin::SigHash;
+    use curve25519_dalek::scalar::Scalar;
+    use rand::rngs::OsRng;
+    use serde::{Deserialize, Serialize};
+
+    #[derive(Debug, Serialize, Deserialize, PartialEq)]
+    pub struct CrossCurveDleqScalar(
+        #[serde(with = "cross_curve_dleq_scalar")] cross_curve_dleq::Scalar,
+    );
+
+    #[derive(Debug, Serialize, Deserialize, PartialEq)]
+    pub struct ECDSAFunSignature(#[serde(with = "ecdsa_fun_signature")] ecdsa_fun::Signature);
+
+    #[derive(Debug, Serialize, Deserialize, PartialEq)]
+    pub struct MoneroPrivateKey(#[serde(with = "monero_private_key")] crate::monero::PrivateKey);
+
+    #[derive(Debug, Serialize, Deserialize, PartialEq)]
+    pub struct BitcoinAmount(#[serde(with = "bitcoin_amount")] ::bitcoin::Amount);
+
+    #[test]
+    fn serde_cross_curv_dleq_scalar() {
+        let scalar = CrossCurveDleqScalar(cross_curve_dleq::Scalar::random(&mut OsRng));
+        let encoded = serde_cbor::to_vec(&scalar).unwrap();
+        let decoded: CrossCurveDleqScalar = serde_cbor::from_slice(&encoded).unwrap();
+        assert_eq!(scalar, decoded);
+    }
+
+    #[test]
+    fn serde_ecdsa_fun_sig() {
+        let secret_key = crate::bitcoin::SecretKey::new_random(&mut OsRng);
+        let sig = ECDSAFunSignature(secret_key.sign(SigHash::default()));
+        let encoded = serde_cbor::to_vec(&sig).unwrap();
+        let decoded: ECDSAFunSignature = serde_cbor::from_slice(&encoded).unwrap();
+        assert_eq!(sig, decoded);
+    }
+
+    #[test]
+    fn serde_monero_private_key() {
+        let key = MoneroPrivateKey(monero::PrivateKey::from_scalar(Scalar::random(&mut OsRng)));
+        let encoded = serde_cbor::to_vec(&key).unwrap();
+        let decoded: MoneroPrivateKey = serde_cbor::from_slice(&encoded).unwrap();
+        assert_eq!(key, decoded);
+    }
+    #[test]
+    fn serde_bitcoin_amount() {
+        let amount = BitcoinAmount(::bitcoin::Amount::from_sat(100));
+        let encoded = serde_cbor::to_vec(&amount).unwrap();
+        let decoded: BitcoinAmount = serde_cbor::from_slice(&encoded).unwrap();
+        assert_eq!(amount, decoded);
+    }
+}

xmr-btc/tests/e2e.rs

@@ -18,6 +18,8 @@ use xmr_btc::{alice, bitcoin, bob, monero};
 const TEN_XMR: u64 = 10_000_000_000_000;
 const RELATIVE_REFUND_TIMELOCK: u32 = 1;
 const RELATIVE_PUNISH_TIMELOCK: u32 = 1;
+const ALICE_TEST_DB_FOLDER: &str = "../target/e2e-test-alice-recover";
+const BOB_TEST_DB_FOLDER: &str = "../target/e2e-test-bob-recover";
 
 pub async fn init_bitcoind(tc_client: &Cli) -> Bitcoind<'_> {
     let bitcoind = Bitcoind::new(tc_client, "0.19.1").expect("failed to create bitcoind");
@@ -59,9 +61,9 @@ pub fn init_alice_and_bob_transports() -> (
     (a_transport, b_transport)
 }
 
-pub async fn init_test(
+pub async fn init_test<'a>(
-    monero: &Monero,
+    monero: &'a Monero<'a>,
-    bitcoind: &Bitcoind<'_>,
+    bitcoind: &Bitcoind<'a>,
 ) -> (
     alice::State0,
     bob::State0,
@@ -142,15 +144,21 @@ pub async fn init_test(
 }
 
 mod tests {
+    // NOTE: For some reason running these tests overflows the stack. In order to
+    // mitigate this run them with:
+    //
+    //     RUST_MIN_STACK=100000000 cargo test
+
     use crate::{
         harness,
         harness::node::{run_alice_until, run_bob_until},
-        init_bitcoind, init_test,
+        init_bitcoind, init_test, ALICE_TEST_DB_FOLDER, BOB_TEST_DB_FOLDER,
     };
     use futures::future;
     use monero_harness::Monero;
     use rand::rngs::OsRng;
-    use std::convert::TryInto;
+
+    use std::{convert::TryInto, path::Path};
     use testcontainers::clients::Cli;
     use tracing_subscriber::util::SubscriberInitExt;
     use xmr_btc::{
@@ -375,4 +383,126 @@ mod tests {
             initial_balances.bob_btc - swap_amounts.btc - lock_tx_bitcoin_fee
         );
     }
+
+    #[tokio::test]
+    async fn recover_protocol_state_from_db() {
+        let _guard = tracing_subscriber::fmt()
+            .with_env_filter("info")
+            .set_default();
+
+        let cli = Cli::default();
+        let monero = Monero::new(&cli);
+        let bitcoind = init_bitcoind(&cli).await;
+        let alice_db = harness::storage::Database::open(Path::new(ALICE_TEST_DB_FOLDER)).unwrap();
+        let bob_db = harness::storage::Database::open(Path::new(BOB_TEST_DB_FOLDER)).unwrap();
+
+        let (
+            alice_state0,
+            bob_state0,
+            mut alice_node,
+            mut bob_node,
+            initial_balances,
+            swap_amounts,
+        ) = init_test(&monero, &bitcoind).await;
+
+        {
+            let (alice_state, bob_state) = future::try_join(
+                run_alice_until(
+                    &mut alice_node,
+                    alice_state0.into(),
+                    harness::alice::is_state5,
+                    &mut OsRng,
+                ),
+                run_bob_until(
+                    &mut bob_node,
+                    bob_state0.into(),
+                    harness::bob::is_state3,
+                    &mut OsRng,
+                ),
+            )
+            .await
+            .unwrap();
+
+            let alice_state5: alice::State5 = alice_state.try_into().unwrap();
+            let bob_state3: bob::State3 = bob_state.try_into().unwrap();
+
+            // save state to db
+            alice_db.insert_latest_state(&alice_state5).await.unwrap();
+            bob_db.insert_latest_state(&bob_state3).await.unwrap();
+        };
+
+        let (alice_state6, bob_state5) = {
+            // recover state from db
+            let alice_state5: alice::State5 = alice_db.get_latest_state().unwrap();
+            let bob_state3: bob::State3 = bob_db.get_latest_state().unwrap();
+
+            let (alice_state, bob_state) = future::try_join(
+                run_alice_until(
+                    &mut alice_node,
+                    alice_state5.into(),
+                    harness::alice::is_state6,
+                    &mut OsRng,
+                ),
+                run_bob_until(
+                    &mut bob_node,
+                    bob_state3.into(),
+                    harness::bob::is_state5,
+                    &mut OsRng,
+                ),
+            )
+            .await
+            .unwrap();
+
+            let alice_state: alice::State6 = alice_state.try_into().unwrap();
+            let bob_state: bob::State5 = bob_state.try_into().unwrap();
+
+            (alice_state, bob_state)
+        };
+
+        let alice_final_btc_balance = alice_node.bitcoin_wallet.balance().await.unwrap();
+        let bob_final_btc_balance = bob_node.bitcoin_wallet.balance().await.unwrap();
+
+        let lock_tx_bitcoin_fee = bob_node
+            .bitcoin_wallet
+            .transaction_fee(bob_state5.tx_lock_id())
+            .await
+            .unwrap();
+
+        let alice_final_xmr_balance = alice_node
+            .monero_wallet
+            .0
+            .get_balance_alice()
+            .await
+            .unwrap();
+
+        bob_node
+            .monero_wallet
+            .0
+            .wait_for_bob_wallet_block_height()
+            .await
+            .unwrap();
+
+        let bob_final_xmr_balance = bob_node.monero_wallet.0.get_balance_bob().await.unwrap();
+
+        assert_eq!(
+            alice_final_btc_balance,
+            initial_balances.alice_btc + swap_amounts.btc
+                - bitcoin::Amount::from_sat(bitcoin::TX_FEE)
+        );
+        assert_eq!(
+            bob_final_btc_balance,
+            initial_balances.bob_btc - swap_amounts.btc - lock_tx_bitcoin_fee
+        );
+
+        assert_eq!(
+            alice_final_xmr_balance,
+            initial_balances.alice_xmr
+                - u64::from(swap_amounts.xmr)
+                - u64::from(alice_state6.lock_xmr_fee())
+        );
+        assert_eq!(
+            bob_final_xmr_balance,
+            initial_balances.bob_xmr + u64::from(swap_amounts.xmr)
+        );
+    }
 }

xmr-btc/tests/harness/mod.rs

@@ -1,4 +1,5 @@
 pub mod node;
+pub mod storage;
 pub mod transport;
 pub mod wallet;
 

xmr-btc/tests/harness/storage.rs

@@ -0,0 +1,159 @@
+use anyhow::{anyhow, Context, Result};
+use serde::{de::DeserializeOwned, Deserialize, Serialize};
+use std::path::Path;
+
+pub struct Database {
+    db: sled::Db,
+}
+
+impl Database {
+    const LAST_STATE_KEY: &'static str = "latest_state";
+
+    pub fn open(path: &Path) -> Result<Self> {
+        let path = path
+            .to_str()
+            .ok_or_else(|| anyhow!("The path is not utf-8 valid: {:?}", path))?;
+        let db = sled::open(path).with_context(|| format!("Could not open the DB at {}", path))?;
+
+        Ok(Database { db })
+    }
+
+    pub async fn insert_latest_state<T>(&self, state: &T) -> Result<()>
+    where
+        T: Serialize + DeserializeOwned,
+    {
+        let key = serialize(&Self::LAST_STATE_KEY)?;
+        let new_value = serialize(&state).context("Could not serialize new state value")?;
+
+        let old_value = self.db.get(&key)?;
+
+        self.db
+            .compare_and_swap(key, old_value, Some(new_value))
+            .context("Could not write in the DB")?
+            .context("Stored swap somehow changed, aborting saving")?; // let _ =
+
+        self.db
+            .flush_async()
+            .await
+            .map(|_| ())
+            .context("Could not flush db")
+    }
+
+    pub fn get_latest_state<T>(&self) -> anyhow::Result<T>
+    where
+        T: DeserializeOwned,
+    {
+        let key = serialize(&Self::LAST_STATE_KEY)?;
+
+        let encoded = self
+            .db
+            .get(&key)?
+            .ok_or_else(|| anyhow!("State does not exist {:?}", key))?;
+
+        let state = deserialize(&encoded).context("Could not deserialize state")?;
+        Ok(state)
+    }
+}
+
+pub fn serialize<T>(t: &T) -> anyhow::Result<Vec<u8>>
+where
+    T: Serialize,
+{
+    Ok(serde_cbor::to_vec(t)?)
+}
+
+pub fn deserialize<T>(v: &[u8]) -> anyhow::Result<T>
+where
+    T: DeserializeOwned,
+{
+    Ok(serde_cbor::from_slice(&v)?)
+}
+
+#[cfg(test)]
+mod tests {
+    #![allow(non_snake_case)]
+    use super::*;
+    use bitcoin::SigHash;
+    use curve25519_dalek::scalar::Scalar;
+    use ecdsa_fun::fun::rand_core::OsRng;
+    use std::str::FromStr;
+    use xmr_btc::serde::{
+        bitcoin_amount, cross_curve_dleq_scalar, ecdsa_fun_signature, monero_private_key,
+    };
+
+    #[derive(Debug, Serialize, Deserialize, PartialEq)]
+    pub struct TestState {
+        A: xmr_btc::bitcoin::PublicKey,
+        a: xmr_btc::bitcoin::SecretKey,
+        #[serde(with = "cross_curve_dleq_scalar")]
+        s_a: ::cross_curve_dleq::Scalar,
+        #[serde(with = "monero_private_key")]
+        s_b: monero::PrivateKey,
+        S_a_monero: ::monero::PublicKey,
+        S_a_bitcoin: xmr_btc::bitcoin::PublicKey,
+        v: xmr_btc::monero::PrivateViewKey,
+        #[serde(with = "bitcoin_amount")]
+        btc: ::bitcoin::Amount,
+        xmr: xmr_btc::monero::Amount,
+        refund_timelock: u32,
+        refund_address: ::bitcoin::Address,
+        transaction: ::bitcoin::Transaction,
+        #[serde(with = "ecdsa_fun_signature")]
+        tx_punish_sig: xmr_btc::bitcoin::Signature,
+    }
+
+    #[tokio::test]
+    async fn recover_state_from_db() {
+        let db = Database::open(Path::new("../target/test_recover.db")).unwrap();
+
+        let a = crate::bitcoin::SecretKey::new_random(&mut OsRng);
+        let s_a = cross_curve_dleq::Scalar::random(&mut OsRng);
+        let s_b = monero::PrivateKey::from_scalar(Scalar::random(&mut OsRng));
+        let v_a = xmr_btc::monero::PrivateViewKey::new_random(&mut OsRng);
+        let S_a_monero = monero::PublicKey::from_private_key(&monero::PrivateKey {
+            scalar: s_a.into_ed25519(),
+        });
+        let S_a_bitcoin = s_a.into_secp256k1().into();
+        let tx_punish_sig = a.sign(SigHash::default());
+
+        let state = TestState {
+            A: a.public(),
+            a,
+            s_b,
+            s_a,
+            S_a_monero,
+            S_a_bitcoin,
+            v: v_a,
+            btc: ::bitcoin::Amount::from_sat(100),
+            xmr: crate::monero::Amount::from_piconero(1000),
+            refund_timelock: 0,
+            refund_address: ::bitcoin::Address::from_str("1L5wSMgerhHg8GZGcsNmAx5EXMRXSKR3He")
+                .unwrap(),
+            transaction: ::bitcoin::Transaction {
+                version: 0,
+                lock_time: 0,
+                input: vec![::bitcoin::TxIn::default()],
+                output: vec![::bitcoin::TxOut::default()],
+            },
+            tx_punish_sig,
+        };
+
+        db.insert_latest_state(&state)
+            .await
+            .expect("Failed to save state the first time");
+        let recovered: TestState = db
+            .get_latest_state()
+            .expect("Failed to recover state the first time");
+
+        // We insert and recover twice to ensure database implementation allows the
+        // caller to write to an existing key
+        db.insert_latest_state(&recovered)
+            .await
+            .expect("Failed to save state the second time");
+        let recovered: TestState = db
+            .get_latest_state()
+            .expect("Failed to recover state the second time");
+
+        assert_eq!(state, recovered);
+    }
+}