Add utils feature (cygnet3#64)

* Add utils feature

* Reexport secp256k1

* Add rand feature to secp256k1

* Remove comment

---------

Co-authored-by: cygnet <[email protected]>

Cargo.toml

@@ -15,12 +15,13 @@ name = "silentpayments"
 crate-type = ["lib"]
 
 [features]
-default = ["sending", "receiving"]
+default = ["sending", "receiving", "utils"]
 sending = []
 receiving = []
+utils = []
 
 [dependencies]
-secp256k1 = {version = "0.24", features = ["bitcoin-hashes-std"] }
+secp256k1 = {version = "0.24", features = ["bitcoin-hashes-std", "rand"] }
 hex = "0.4"
 bech32 = "0.9"
 bimap = "0.6"

src/lib.rs

@@ -6,6 +6,10 @@ mod error;
 pub mod receiving;
 #[cfg(feature = "sending")]
 pub mod sending;
+#[cfg(feature = "utils")]
+pub mod utils;
+
+pub use secp256k1;
 
 pub use crate::error::Error;
 

src/sending.rs

@@ -186,7 +186,7 @@ pub fn generate_multiple_recipient_pubkeys(
 /// # Arguments
 ///
 /// * `recipient` - A `String` of the bech32m-encoded silent payment address to be paid.
-/// * `partial_secret` - A `SecretKey` representing the private keys of the outputs to spend multiplied by the hash of its outpoints. 
+/// * `partial_secret` - A `SecretKey` representing the private keys of the outputs to spend multiplied by the hash of its outpoints.
 ///
 /// # Returns
 ///

src/utils.rs

@@ -0,0 +1,37 @@
+use std::io::Write;
+
+use crate::Result;
+use secp256k1::{
+    hashes::{sha256, Hash},
+    Scalar,
+};
+
+pub mod receiving;
+pub mod sending;
+
+pub fn hash_outpoints(sending_data: &Vec<(String, u32)>) -> Result<Scalar> {
+    let mut outpoints: Vec<Vec<u8>> = vec![];
+
+    for outpoint in sending_data {
+        let mut bytes: Vec<u8> = hex::decode(outpoint.0.as_str())?;
+
+        // txid in string format is big endian and we need little endian
+        bytes.reverse();
+
+        bytes.extend_from_slice(&outpoint.1.to_le_bytes());
+        outpoints.push(bytes);
+    }
+
+    // sort outpoints
+    outpoints.sort();
+
+    let mut engine = sha256::HashEngine::default();
+
+    for v in outpoints {
+        engine.write_all(&v)?;
+    }
+
+    Ok(Scalar::from_be_bytes(
+        sha256::Hash::from_engine(engine).into_inner(),
+    )?)
+}

src/utils/receiving.rs

@@ -0,0 +1,28 @@
+use crate::{utils::hash_outpoints, Result};
+use secp256k1::{PublicKey, SecretKey};
+
+pub fn recipient_calculate_tweak_data(
+    input_pub_keys: &Vec<PublicKey>,
+    outpoints: &Vec<(String, u32)>,
+) -> Result<PublicKey> {
+    let secp = secp256k1::Secp256k1::new();
+    let A_sum = recipient_get_A_sum_public_keys(input_pub_keys);
+    let outpoints_hash = hash_outpoints(outpoints)?;
+
+    Ok(A_sum.mul_tweak(&secp, &outpoints_hash)?)
+}
+
+pub fn recipient_calculate_shared_secret(
+    tweak_data: PublicKey,
+    b_scan: SecretKey,
+) -> Result<PublicKey> {
+    let secp = secp256k1::Secp256k1::new();
+
+    Ok(tweak_data.mul_tweak(&secp, &b_scan.into())?)
+}
+
+fn recipient_get_A_sum_public_keys(input: &Vec<PublicKey>) -> PublicKey {
+    let keys_refs: &Vec<&PublicKey> = &input.iter().collect();
+
+    PublicKey::combine_keys(keys_refs).unwrap()
+}

src/utils/sending.rs

@@ -0,0 +1,9 @@
+use crate::Result;
+use secp256k1::{Scalar, SecretKey};
+
+pub fn sender_calculate_partial_secret(
+    a_sum: SecretKey,
+    outpoints_hash: Scalar,
+) -> Result<SecretKey> {
+    Ok(a_sum.mul_tweak(&outpoints_hash)?)
+}

tests/common/utils.rs

@@ -1,12 +1,11 @@
 use std::{
-    collections::HashSet,
     fs::File,
-    io::{Read, Write},
+    io::Read,
     str::FromStr,
 };
 
 use secp256k1::{
-    hashes::{sha256, Hash},
+    hashes::Hash,
     Message, PublicKey, Scalar, SecretKey, XOnlyPublicKey,
 };
 use serde_json::from_str;
@@ -20,22 +19,6 @@ pub fn read_file() -> Vec<TestData> {
     from_str(&contents).unwrap()
 }
 
-pub fn decode_outpoints(outpoints: &Vec<(String, u32)>) -> HashSet<([u8; 32], u32)> {
-    outpoints
-        .iter()
-        .map(|(txid_str, vout)| {
-            (
-                hex::decode(txid_str)
-                    .unwrap()
-                    .as_slice()
-                    .try_into()
-                    .unwrap(),
-                *vout,
-            )
-        })
-        .collect()
-}
-
 pub fn decode_priv_keys(input_priv_keys: &Vec<(String, bool)>) -> Vec<(SecretKey, bool)> {
     input_priv_keys
         .iter()
@@ -71,81 +54,6 @@ pub fn decode_recipients(recipients: &Vec<(String, f32)>) -> Vec<String> {
         .collect()
 }
 
-pub fn get_a_sum_secret_keys(input: &Vec<(SecretKey, bool)>) -> SecretKey {
-    let secp = secp256k1::Secp256k1::new();
-
-    let mut negated_keys: Vec<SecretKey> = vec![];
-
-    for (key, is_xonly) in input {
-        let (_, parity) = key.x_only_public_key(&secp);
-
-        if *is_xonly && parity == secp256k1::Parity::Odd {
-            negated_keys.push(key.negate());
-        } else {
-            negated_keys.push(key.clone());
-        }
-    }
-
-    let (head, tail) = negated_keys.split_first().unwrap();
-
-    let result: SecretKey = tail
-        .iter()
-        .fold(*head, |acc, &item| acc.add_tweak(&item.into()).unwrap());
-
-    result
-}
-
-pub fn get_A_sum_public_keys(input: &Vec<PublicKey>) -> PublicKey {
-    let keys_refs: &Vec<&PublicKey> = &input.iter().collect();
-
-    PublicKey::combine_keys(keys_refs).unwrap()
-}
-
-pub fn calculate_tweak_data_for_recipient(
-    input_pub_keys: &Vec<PublicKey>,
-    outpoints: &HashSet<([u8; 32], u32)>,
-) -> PublicKey {
-    let secp = secp256k1::Secp256k1::new();
-    let A_sum = get_A_sum_public_keys(input_pub_keys);
-    let outpoints_hash = hash_outpoints(outpoints);
-
-    A_sum.mul_tweak(&secp, &outpoints_hash).unwrap()
-}
-
-pub fn sender_calculate_partial_secret(a_sum: SecretKey, outpoints_hash: Scalar) -> SecretKey {
-    a_sum.mul_tweak(&outpoints_hash).unwrap()
-}
-
-pub fn receiver_calculate_shared_secret(tweak_data: PublicKey, b_scan: SecretKey) -> PublicKey {
-    let secp = secp256k1::Secp256k1::new();
-
-    tweak_data.mul_tweak(&secp, &b_scan.into()).unwrap()
-}
-
-pub fn hash_outpoints(sending_data: &HashSet<([u8; 32], u32)>) -> Scalar {
-    let mut outpoints: Vec<Vec<u8>> = vec![];
-
-    for outpoint in sending_data {
-        let txid = outpoint.0;
-        let vout = outpoint.1;
-
-        let mut bytes: Vec<u8> = Vec::new();
-        bytes.extend_from_slice(&txid);
-        bytes.reverse();
-        bytes.extend_from_slice(&vout.to_le_bytes());
-        outpoints.push(bytes);
-    }
-    outpoints.sort();
-
-    let mut engine = sha256::HashEngine::default();
-
-    for v in outpoints {
-        engine.write_all(&v).unwrap();
-    }
-
-    Scalar::from_be_bytes(sha256::Hash::from_engine(engine).into_inner()).unwrap()
-}
-
 pub fn verify_and_calculate_signatures(
     key_tweaks: Vec<Scalar>,
     b_spend: SecretKey,
@@ -178,3 +86,28 @@ pub fn verify_and_calculate_signatures(
     }
     Ok(res)
 }
+
+
+pub fn sender_get_a_sum_secret_keys(input: &Vec<(SecretKey, bool)>) -> SecretKey {
+    let secp = secp256k1::Secp256k1::new();
+
+    let mut negated_keys: Vec<SecretKey> = vec![];
+
+    for (key, is_xonly) in input {
+        let (_, parity) = key.x_only_public_key(&secp);
+
+        if *is_xonly && parity == secp256k1::Parity::Odd {
+            negated_keys.push(key.negate());
+        } else {
+            negated_keys.push(key.clone());
+        }
+    }
+
+    let (head, tail) = negated_keys.split_first().unwrap();
+
+    let result: SecretKey = tail
+        .iter()
+        .fold(*head, |acc, &item| acc.add_tweak(&item.into()).unwrap());
+
+    result
+}

tests/vector_tests.rs

@@ -3,25 +3,26 @@ mod common;
 
 #[cfg(test)]
 mod tests {
-    use std::{
-        collections::HashSet,
-        str::FromStr,
-    };
+    use std::{collections::HashSet, str::FromStr};
 
-    use secp256k1::{Secp256k1, SecretKey, Scalar};
+    use secp256k1::{Scalar, Secp256k1, SecretKey};
 
     #[cfg(feature = "receiving")]
     use silentpayments::receiving::Receiver;
 
     #[cfg(feature = "sending")]
     use silentpayments::sending::generate_multiple_recipient_pubkeys;
+    use silentpayments::{
+        utils::receiving::{recipient_calculate_shared_secret, recipient_calculate_tweak_data},
+        utils::sending::sender_calculate_partial_secret,
+        utils::hash_outpoints,
+    };
 
     use crate::common::{
         structs::TestData,
         utils::{
-            self, calculate_tweak_data_for_recipient, decode_input_pub_keys, decode_outpoints,
-            decode_outputs_to_check, decode_priv_keys, decode_recipients, get_a_sum_secret_keys,
-            hash_outpoints, sender_calculate_partial_secret, verify_and_calculate_signatures, receiver_calculate_shared_secret
+            self, decode_input_pub_keys, decode_outputs_to_check, decode_priv_keys,
+            decode_recipients, sender_get_a_sum_secret_keys, verify_and_calculate_signatures,
         },
     };
 
@@ -51,16 +52,15 @@ mod tests {
 
             let input_priv_keys = decode_priv_keys(&given.input_priv_keys);
 
-            let outpoints = decode_outpoints(&given.outpoints);
+            let outpoints = given.outpoints;
 
-            let outpoints_hash = hash_outpoints(&outpoints);
+            let outpoints_hash = hash_outpoints(&outpoints).unwrap();
 
             let silent_addresses = decode_recipients(&given.recipients);
 
-            let a_sum = get_a_sum_secret_keys(&input_priv_keys);
+            let a_sum = sender_get_a_sum_secret_keys(&input_priv_keys);
 
-            let partial_secret =
-                sender_calculate_partial_secret(a_sum, outpoints_hash);
+            let partial_secret = sender_calculate_partial_secret(a_sum, outpoints_hash).unwrap();
 
             let outputs =
                 generate_multiple_recipient_pubkeys(silent_addresses, partial_secret).unwrap();
@@ -98,7 +98,7 @@ mod tests {
 
             let outputs_to_check = decode_outputs_to_check(&given.outputs);
 
-            let outpoints = decode_outpoints(&given.outpoints);
+            let outpoints = &given.outpoints;
 
             let input_pub_keys = decode_input_pub_keys(&given.input_pub_keys);
 
@@ -125,8 +125,8 @@ mod tests {
             // to the expected addresses
             assert_eq!(set1, set2);
 
-            let tweak_data = calculate_tweak_data_for_recipient(&input_pub_keys, &outpoints);
-            let shared_secret = receiver_calculate_shared_secret(tweak_data, b_scan);
+            let tweak_data = recipient_calculate_tweak_data(&input_pub_keys, &outpoints).unwrap();
+            let shared_secret = recipient_calculate_shared_secret(tweak_data, b_scan).unwrap();
 
             let scanned_outputs_received = sp_receiver
                 .scan_transaction_with_labels(&shared_secret, outputs_to_check)