Merge remote-tracking branch 'namada/murisi/smaller-signing' (#807) i…

…nto main

* namada/murisi/smaller-signing:
  proto/types: remove an & to placate 1.65 clippy
  changelog: add #807
  tx: sign hash of code rather than full code blob

.changelog/unreleased/improvements/807-smaller-signing.md

@@ -0,0 +1,2 @@
+- Sign over the hash of code rather than code in transaction signing.
+  ([#807](https://github.com/anoma/namada/pull/807))

shared/src/proto/types.rs

@@ -127,6 +127,100 @@ where
     }
 }
 
+/// A Tx with its code replaced by a hash salted with the Borsh
+/// serialized timestamp of the transaction. This structure will almost
+/// certainly be smaller than a Tx, yet in the usual cases it contains
+/// enough information to confirm that the Tx is as intended and make a
+/// non-malleable signature.
+#[derive(
+    Clone, Debug, PartialEq, BorshSerialize, BorshDeserialize, BorshSchema, Hash,
+)]
+pub struct SigningTx {
+    pub code_hash: [u8; 32],
+    pub data: Option<Vec<u8>>,
+    pub timestamp: DateTimeUtc,
+}
+
+impl SigningTx {
+    pub fn hash(&self) -> [u8; 32] {
+        let timestamp = Some(self.timestamp.into());
+        let mut bytes = vec![];
+        types::Tx {
+            code: self.code_hash.to_vec(),
+            data: self.data.clone(),
+            timestamp,
+        }
+        .encode(&mut bytes)
+        .expect("encoding a transaction failed");
+        hash_tx(&bytes).0
+    }
+
+    /// Sign a transaction using [`SignedTxData`].
+    pub fn sign(self, keypair: &common::SecretKey) -> Self {
+        let to_sign = self.hash();
+        let sig = common::SigScheme::sign(keypair, to_sign);
+        let signed = SignedTxData {
+            data: self.data,
+            sig,
+        }
+        .try_to_vec()
+        .expect("Encoding transaction data shouldn't fail");
+        SigningTx {
+            code_hash: self.code_hash,
+            data: Some(signed),
+            timestamp: self.timestamp,
+        }
+    }
+
+    /// Verify that the transaction has been signed by the secret key
+    /// counterpart of the given public key.
+    pub fn verify_sig(
+        &self,
+        pk: &common::PublicKey,
+        sig: &common::Signature,
+    ) -> std::result::Result<(), VerifySigError> {
+        // Try to get the transaction data from decoded `SignedTxData`
+        let tx_data = self.data.clone().ok_or(VerifySigError::MissingData)?;
+        let signed_tx_data = SignedTxData::try_from_slice(&tx_data[..])
+            .expect("Decoding transaction data shouldn't fail");
+        let data = signed_tx_data.data;
+        let tx = SigningTx {
+            code_hash: self.code_hash,
+            data,
+            timestamp: self.timestamp,
+        };
+        let signed_data = tx.hash();
+        common::SigScheme::verify_signature_raw(pk, &signed_data, sig)
+    }
+
+    /// Expand this reduced Tx using the supplied code only if the the code
+    /// hashes to the stored code hash
+    pub fn expand(self, code: Vec<u8>) -> Option<Tx> {
+        if hash_tx(&code).0 == self.code_hash {
+            Some(Tx {
+                code,
+                data: self.data,
+                timestamp: self.timestamp,
+            })
+        } else {
+            None
+        }
+    }
+}
+
+impl From<Tx> for SigningTx {
+    fn from(tx: Tx) -> SigningTx {
+        SigningTx {
+            code_hash: hash_tx(&tx.code).0,
+            data: tx.data,
+            timestamp: tx.timestamp,
+        }
+    }
+}
+
+/// A SigningTx but with the full code embedded. This structure will almost
+/// certainly be bigger than SigningTxs and contains enough information to
+/// execute the transaction.
 #[derive(
     Clone, Debug, PartialEq, BorshSerialize, BorshDeserialize, BorshSchema, Hash,
 )]
@@ -261,28 +355,20 @@ impl Tx {
     }
 
     pub fn hash(&self) -> [u8; 32] {
-        hash_tx(&self.to_bytes()).0
+        SigningTx::from(self.clone()).hash()
     }
 
     pub fn code_hash(&self) -> [u8; 32] {
-        hash_tx(&self.code).0
+        SigningTx::from(self.clone()).code_hash
     }
 
     /// Sign a transaction using [`SignedTxData`].
     pub fn sign(self, keypair: &common::SecretKey) -> Self {
-        let to_sign = self.hash();
-        let sig = common::SigScheme::sign(keypair, to_sign);
-        let signed = SignedTxData {
-            data: self.data,
-            sig,
-        }
-        .try_to_vec()
-        .expect("Encoding transaction data shouldn't fail");
-        Tx {
-            code: self.code,
-            data: Some(signed),
-            timestamp: self.timestamp,
-        }
+        let code = self.code.clone();
+        SigningTx::from(self)
+            .sign(keypair)
+            .expand(code)
+            .expect("code hashes to unexpected value")
     }
 
     /// Verify that the transaction has been signed by the secret key
@@ -292,18 +378,7 @@ impl Tx {
         pk: &common::PublicKey,
         sig: &common::Signature,
     ) -> std::result::Result<(), VerifySigError> {
-        // Try to get the transaction data from decoded `SignedTxData`
-        let tx_data = self.data.clone().ok_or(VerifySigError::MissingData)?;
-        let signed_tx_data = SignedTxData::try_from_slice(&tx_data[..])
-            .expect("Decoding transaction data shouldn't fail");
-        let data = signed_tx_data.data;
-        let tx = Tx {
-            code: self.code.clone(),
-            data,
-            timestamp: self.timestamp,
-        };
-        let signed_data = tx.hash();
-        common::SigScheme::verify_signature_raw(pk, &signed_data, sig)
+        SigningTx::from(self.clone()).verify_sig(pk, sig)
     }
 }
 

wasm/checksums.json

@@ -1,20 +1,20 @@
 {
-    "tx_bond.wasm": "tx_bond.27f2a447889b931c9ac5e175fbc19f124277cd677d83e1624a5467ac43f3551f.wasm",
-    "tx_change_validator_commission.wasm": "tx_change_validator_commission.df16d46f67c5fe02392f87cf3dbfabb728f4be506fb2461af051e2a17efff383.wasm",
-    "tx_ibc.wasm": "tx_ibc.494dda55184d02f1d0061e99f642683b916d6eada6ade291e3be26d0c1385be9.wasm",
-    "tx_init_account.wasm": "tx_init_account.67805cd6d6b9280d1b907d7a2eec3f3b740c9863aebf4ed655b387c455f44922.wasm",
-    "tx_init_proposal.wasm": "tx_init_proposal.1011afeb69c550014b4f8f989458af326258fc08b4ddb60067b7485b07eb2a55.wasm",
-    "tx_init_validator.wasm": "tx_init_validator.0df6c8985b40993b3ad62b2cde6a76aecaeb6282b6916a0c98e44deac38c5089.wasm",
-    "tx_reveal_pk.wasm": "tx_reveal_pk.c5d4ddb9a9ce2b5e1f2c3c063e36549a535d383a73e569476c218548392d5ccc.wasm",
-    "tx_transfer.wasm": "tx_transfer.52f882ed5abe72b456e490e035a09ad220141fc04dd8606e3300c7bc4971aea6.wasm",
-    "tx_unbond.wasm": "tx_unbond.6b1d54cf6978b55e2318deb1a2a37fd77d810dbabefc0a7422ca21c0ac3f6a61.wasm",
-    "tx_update_vp.wasm": "tx_update_vp.98cea95bd9191b65d90188c733514843333ae1c653c03c2a317fc641116ff01f.wasm",
-    "tx_vote_proposal.wasm": "tx_vote_proposal.d5da43dbe86aaa10ddd509cd451a762c52803af3e196b08cced3cee16feb63a7.wasm",
-    "tx_withdraw.wasm": "tx_withdraw.b6a713a643f6e5b7a4a8263881c4df7d50656990111ccd02e6596ca5575dbe8b.wasm",
-    "vp_implicit.wasm": "vp_implicit.5cfa9136bd218e9dcc44276265454a3dcebe81d0a11f2a090d354e3463098481.wasm",
-    "vp_masp.wasm": "vp_masp.00b2bfeb805847bc5f825b8ec632b6eae77cd64a9c5553b87599ba0756489fa4.wasm",
-    "vp_testnet_faucet.wasm": "vp_testnet_faucet.d4f1f3f54348630ee8d805ac44e6799da193f3a1353728fcafe7634cfc3ca0e4.wasm",
-    "vp_token.wasm": "vp_token.3f887a991f03a6c447a88307d8e04c569162e126e6016740dd884724bc7b3969.wasm",
-    "vp_user.wasm": "vp_user.2f63cc6f131760edd0975d41c081288921e76d82883699bbfcc8005980c98aca.wasm",
-    "vp_validator.wasm": "vp_validator.32701a8c9c331a3814e72bcd406b7ae9de3f250e820ac729145841e2ff802123.wasm"
+    "tx_bond.wasm": "tx_bond.fabf8f0daea4602ef589c993f14c0cc613be6d1fab64ee7bfeab2952d055bc17.wasm",
+    "tx_change_validator_commission.wasm": "tx_change_validator_commission.4a94b6517d06760c242b3f5f0d8be667c98a1271791f6480f53866b33176288e.wasm",
+    "tx_ibc.wasm": "tx_ibc.6d7783aa7610ed592cd7d38ebdc3a08ca0e1dac06114db739d150fd2db479a74.wasm",
+    "tx_init_account.wasm": "tx_init_account.e6a6999f85b08bec4fdad74e2cefb11a02c3a3ccfa22ac91c2bab675ebce78af.wasm",
+    "tx_init_proposal.wasm": "tx_init_proposal.57e8dbd77c0ed7126fe6a30c69b0776086f9500eddc6115f577bef33debfb2ae.wasm",
+    "tx_init_validator.wasm": "tx_init_validator.0c17686f4f5cb7914a917b93089c33415da261a9920458c3f527228b3cc7c0c5.wasm",
+    "tx_reveal_pk.wasm": "tx_reveal_pk.570e652620f16a5a3c77964cbe622dcf53235ff5954e4180530d3884421bda7d.wasm",
+    "tx_transfer.wasm": "tx_transfer.6db1b211f4896c914b55b01ee65cebcd982323729909e8567964bb862c2ccd0f.wasm",
+    "tx_unbond.wasm": "tx_unbond.3c1b61ca80181202dae3f64c007f3013232c2e415ab18e12138598a94ce4d6a0.wasm",
+    "tx_update_vp.wasm": "tx_update_vp.1c9559a300f2ebe16189467775c3c8fddd69c22a3a3ef6a09e658b5e769b3c03.wasm",
+    "tx_vote_proposal.wasm": "tx_vote_proposal.95cb4c6d8de9e46bbbf9c0176161047bb3c0e810d691ba06e28774dbdceaae70.wasm",
+    "tx_withdraw.wasm": "tx_withdraw.e7fc0142c2c02fff4524e502e2cc136e0691da3ff755b5e5c256ac09757da4ed.wasm",
+    "vp_implicit.wasm": "vp_implicit.ed1630c4850beff44553e79836acc14a2286e4255778f050c665f901881423fc.wasm",
+    "vp_masp.wasm": "vp_masp.3efc9e4795526a64a8b1c8a4de6470d6ac57dbaa40ef71f3bfe8107c4e7d6016.wasm",
+    "vp_testnet_faucet.wasm": "vp_testnet_faucet.94c8c0c0dba91aae890fa26e6b015b51c9ab8c1c44e01bb265438515a25ddbf8.wasm",
+    "vp_token.wasm": "vp_token.f4fc838a3007eacfecbf990992d0956c7ef5896b8a27bf54fd7283b26ab0fcc6.wasm",
+    "vp_user.wasm": "vp_user.7cc6e40deed64d39ed8b47a9ce067b3db6cf3d81d8f8003df75837b7554a1e4d.wasm",
+    "vp_validator.wasm": "vp_validator.34ffeca7c3e65782443ca6e0e18e06291cd537a888bf6fe70d50eb8121e66c4a.wasm"
 }