Merge pull request #2052 from blockstack/fix/1934

Fix 1934: mix burn block height into microblock pubkey

Author: Aaron Blankstein

src/vm/docs/mod.rs

@@ -545,7 +545,7 @@ const PRINT_API: SpecialAPI = SpecialAPI {
     input_type: "A",
     output_type: "A",
     signature: "(print expr)",
-    description: "The `print` function evaluates and returns its input expression. On Blockstack Core
+    description: "The `print` function evaluates and returns its input expression. On Stacks Core
 nodes configured for development (as opposed to production mining nodes), this function prints the resulting value to `STDOUT` (standard output).",
     example: "(print (+ 1 2 3)) ;; Returns 6",
 };

testnet/stacks-node/src/keychain.rs

@@ -7,7 +7,7 @@ use stacks::burnchains::{BurnchainSigner, PrivateKey};
 use stacks::chainstate::stacks::{
     StacksAddress, StacksPrivateKey, StacksPublicKey, StacksTransactionSigner, TransactionAuth,
 };
-use stacks::util::hash::Sha256Sum;
+use stacks::util::hash::{Hash160, Sha256Sum};
 use stacks::util::vrf::{VRFPrivateKey, VRFProof, VRFPublicKey, VRF};
 
 #[derive(Clone)]
@@ -97,14 +97,18 @@ impl Keychain {
         pk
     }
 
-    pub fn rotate_microblock_keypair(&mut self) -> StacksPrivateKey {
-        let mut seed = match self.microblocks_secret_keys.last() {
+    pub fn rotate_microblock_keypair(&mut self, burn_block_height: u64) -> StacksPrivateKey {
+        let mut secret_state = match self.microblocks_secret_keys.last() {
             // First key is the hash of the secret state
-            None => self.hashed_secret_state,
+            None => self.hashed_secret_state.to_bytes().to_vec(),
             // Next key is the hash of the last
-            Some(last_sk) => Sha256Sum::from_data(&last_sk.to_bytes()[..]),
+            Some(last_sk) => last_sk.to_bytes().to_vec(),
         };
 
+        secret_state.extend_from_slice(&burn_block_height.to_be_bytes());
+
+        let mut seed = Sha256Sum::from_data(&secret_state);
+
         // Not every 256-bit number is a valid secp256k1 secret key.
         // As such, we continuously generate seeds through re-hashing until one works.
         let mut sk = loop {
@@ -116,6 +120,10 @@ impl Keychain {
         sk.set_compress_public(true);
         self.microblocks_secret_keys.push(sk.clone());
 
+        debug!("Microblock keypair rotated";
+               "burn_block_height" => %burn_block_height,
+               "pubkey_hash" => %Hash160::from_node_public_key(&StacksPublicKey::from_private(&sk)).to_string(),);
+
         sk
     }
 

testnet/stacks-node/src/neon_node.rs

@@ -1033,7 +1033,20 @@ impl InitializedNeonNode {
 
         // Generates a new secret key for signing the trail of microblocks
         // of the upcoming tenure.
-        let microblock_secret_key = keychain.rotate_microblock_keypair();
+        let microblock_secret_key = if attempt > 1 {
+            match keychain.get_microblock_key() {
+                Some(k) => k,
+                None => {
+                    error!(
+                        "Failed to obtain microblock key for mining attempt";
+                        "attempt" => %attempt
+                    );
+                    return None;
+                }
+            }
+        } else {
+            keychain.rotate_microblock_keypair(burn_block.block_height)
+        };
         let mblock_pubkey_hash =
             Hash160::from_node_public_key(&StacksPublicKey::from_private(&microblock_secret_key));
 

testnet/stacks-node/src/node.rs

@@ -475,7 +475,9 @@ impl Node {
 
         // Generates a new secret key for signing the trail of microblocks
         // of the upcoming tenure.
-        let microblock_secret_key = self.keychain.rotate_microblock_keypair();
+        let microblock_secret_key = self
+            .keychain
+            .rotate_microblock_keypair(block_to_build_upon.block_snapshot.block_height);
 
         // Get the stack's chain tip
         let chain_tip = match self.bootstraping_chain {

testnet/stacks-node/src/tests/mempool.rs

@@ -637,8 +637,8 @@ fn mempool_setup_chainstate() {
                 conf.node.seed = vec![0x00];
 
                 let mut keychain = Keychain::default(conf.node.seed.clone());
-                for _i in 0..4 {
-                    let microblock_secret_key = keychain.rotate_microblock_keypair();
+                for i in 0..4 {
+                    let microblock_secret_key = keychain.rotate_microblock_keypair(1 + i);
                     let mut microblock_pubkey =
                         Secp256k1PublicKey::from_private(&microblock_secret_key);
                     microblock_pubkey.set_compressed(true);

testnet/stacks-node/src/tests/neon_integrations.rs

@@ -197,8 +197,9 @@ fn find_microblock_privkey(
     max_tries: u64,
 ) -> Option<StacksPrivateKey> {
     let mut keychain = Keychain::default(conf.node.seed.clone());
-    for _ in 0..max_tries {
-        let privk = keychain.rotate_microblock_keypair();
+    for ix in 0..max_tries {
+        // the first rotation occurs at 203.
+        let privk = keychain.rotate_microblock_keypair(203 + ix);
         let pubkh = Hash160::from_node_public_key(&StacksPublicKey::from_private(&privk));
         if pubkh == *pubkey_hash {
             return Some(privk);