feat(slashing): double-sign fraud proof via nu_reportDoubleSign

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CHANGELOG.md

@@ -7,6 +7,13 @@ Format: [Keep a Changelog](https://keepachangelog.com/en/1.1.0/)
 
 ## [Unreleased]
 
+## [0.12.0] — 2026-04-25
+
+### Added
+- `nu-state/slash_evidence.rs` — `SlashEvidence` struct; DB key `slash_evidence:<validator>:<slot>`
+- `nu_reportDoubleSign` RPC handler — iki farklı block imzasını k256 ile doğrular, geçerliyse DB'ye yazar; idempotent (aynı kanıt tekrar kabul edilmez)
+- `block_loop::apply_pending_slashes` — her slot'ta uygulanmamış kanıtları işler: `slash_double_sign` çağırır, slashed stake'in %50'si BURN_WALLET'a, %50'si reporter'a akar
+
 ## [0.11.0] — 2026-04-25
 
 ### Added

Cargo.lock

@@ -154,12 +154,24 @@ dependencies = [
  "tracing",
 ]
 
+[[package]]
+name = "base16ct"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4c7f02d4ea65f2c1853089ffd8d2787bdbc63de2f0d29dedbcf8ccdfa0ccd4cf"
+
 [[package]]
 name = "base64"
 version = "0.22.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "72b3254f16251a8381aa12e40e3c4d2f0199f8c6508fbecb9d91f575e0fbb8c6"
 
+[[package]]
+name = "base64ct"
+version = "1.8.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2af50177e190e07a26ab74f8b1efbfe2ef87da2116221318cb1c2e82baf7de06"
+
 [[package]]
 name = "bindgen"
 version = "0.69.5"
@@ -333,6 +345,12 @@ version = "1.0.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1d07550c9036bf2ae0c684c4297d503f838287c83c53686d05370d0e139ae570"
 
+[[package]]
+name = "const-oid"
+version = "0.9.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c2459377285ad874054d797f3ccebf984978aa39129f6eafde5cdc8315b612f8"
+
 [[package]]
 name = "core-foundation"
 version = "0.9.4"
@@ -368,6 +386,18 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "crypto-bigint"
+version = "0.5.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0dc92fb57ca44df6db8059111ab3af99a63d5d0f8375d9972e319a379c6bab76"
+dependencies = [
+ "generic-array",
+ "rand_core",
+ "subtle",
+ "zeroize",
+]
+
 [[package]]
 name = "crypto-common"
 version = "0.1.7"
@@ -378,6 +408,16 @@ dependencies = [
  "typenum",
 ]
 
+[[package]]
+name = "der"
+version = "0.7.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e7c1832837b905bbfb5101e07cc24c8deddf52f93225eee6ead5f4d63d53ddcb"
+dependencies = [
+ "const-oid",
+ "zeroize",
+]
+
 [[package]]
 name = "digest"
 version = "0.10.7"
@@ -385,7 +425,9 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9ed9a281f7bc9b7576e61468ba615a66a5c8cfdff42420a70aa82701a3b1e292"
 dependencies = [
  "block-buffer",
+ "const-oid",
  "crypto-common",
+ "subtle",
 ]
 
 [[package]]
@@ -399,12 +441,45 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "ecdsa"
+version = "0.16.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ee27f32b5c5292967d2d4a9d7f1e0b0aed2c15daded5a60300e4abb9d8020bca"
+dependencies = [
+ "der",
+ "digest",
+ "elliptic-curve",
+ "rfc6979",
+ "signature",
+ "spki",
+]
+
 [[package]]
 name = "either"
 version = "1.15.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "48c757948c5ede0e46177b7add2e67155f70e33c07fea8284df6576da70b3719"
 
+[[package]]
+name = "elliptic-curve"
+version = "0.13.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b5e6043086bf7973472e0c7dff2142ea0b680d30e18d9cc40f267efbf222bd47"
+dependencies = [
+ "base16ct",
+ "crypto-bigint",
+ "digest",
+ "ff",
+ "generic-array",
+ "group",
+ "pkcs8",
+ "rand_core",
+ "sec1",
+ "subtle",
+ "zeroize",
+]
+
 [[package]]
 name = "encoding_rs"
 version = "0.8.35"
@@ -436,6 +511,16 @@ version = "2.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9f1f227452a390804cdb637b74a86990f2a7d7ba4b7d5693aac9b4dd6defd8d6"
 
+[[package]]
+name = "ff"
+version = "0.13.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c0b50bfb653653f9ca9095b427bed08ab8d75a137839d9ad64eb11810d5b6393"
+dependencies = [
+ "rand_core",
+ "subtle",
+]
+
 [[package]]
 name = "find-msvc-tools"
 version = "0.1.9"
@@ -519,6 +604,7 @@ checksum = "85649ca51fd72272d7821adaf274ad91c288277713d9c18820d8499a7ff69e9a"
 dependencies = [
  "typenum",
  "version_check",
+ "zeroize",
 ]
 
 [[package]]
@@ -550,6 +636,17 @@ version = "0.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0cc23270f6e1808e30a928bdc84dea0b9b4136a8bc82338574f23baf47bbd280"
 
+[[package]]
+name = "group"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f0f9ef7462f7c099f518d754361858f86d8a07af53ba9af0fe635bbccb151a63"
+dependencies = [
+ "ff",
+ "rand_core",
+ "subtle",
+]
+
 [[package]]
 name = "h2"
 version = "0.4.13"
@@ -587,6 +684,15 @@ version = "0.4.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"
 
+[[package]]
+name = "hmac"
+version = "0.12.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6c49c37c09c17a53d937dfbb742eb3a961d65a994e6bcdcf37e7399d0cc8ab5e"
+dependencies = [
+ "digest",
+]
+
 [[package]]
 name = "http"
 version = "1.4.0"
@@ -915,6 +1021,20 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "k256"
+version = "0.13.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f6e3919bbaa2945715f0bb6d3934a173d1e9a59ac23767fbaaef277265a7411b"
+dependencies = [
+ "cfg-if",
+ "ecdsa",
+ "elliptic-curve",
+ "once_cell",
+ "sha2",
+ "signature",
+]
+
 [[package]]
 name = "lazy_static"
 version = "1.5.0"
@@ -1157,6 +1277,8 @@ dependencies = [
  "anyhow",
  "axum",
  "chrono",
+ "hex",
+ "k256",
  "nu-block",
  "nu-mempool",
  "nu-state",
@@ -1293,6 +1415,16 @@ version = "0.2.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a89322df9ebe1c1578d689c92318e070967d1042b512afbe49518723f4e6d5cd"
 
+[[package]]
+name = "pkcs8"
+version = "0.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f950b2377845cebe5cf8b5165cb3cc1a5e0fa5cfa3e1f7f55707d8fd82e0a7b7"
+dependencies = [
+ "der",
+ "spki",
+]
+
 [[package]]
 name = "pkg-config"
 version = "0.3.33"
@@ -1332,6 +1464,15 @@ version = "5.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "69cdb34c158ceb288df11e18b4bd39de994f6657d83847bdffdbd7f346754b0f"
 
+[[package]]
+name = "rand_core"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+dependencies = [
+ "getrandom 0.2.17",
+]
+
 [[package]]
 name = "redox_syscall"
 version = "0.5.18"
@@ -1410,6 +1551,16 @@ dependencies = [
  "web-sys",
 ]
 
+[[package]]
+name = "rfc6979"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f8dd2a808d456c4a54e300a23e9f5a67e122c3024119acbfd73e3bf664491cb2"
+dependencies = [
+ "hmac",
+ "subtle",
+]
+
 [[package]]
 name = "ring"
 version = "0.17.14"
@@ -1519,6 +1670,20 @@ version = "1.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
 
+[[package]]
+name = "sec1"
+version = "0.7.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d3e97a565f76233a6003f9f5c54be1d9c5bdfa3eccfb189469f11ec4901c47dc"
+dependencies = [
+ "base16ct",
+ "der",
+ "generic-array",
+ "pkcs8",
+ "subtle",
+ "zeroize",
+]
+
 [[package]]
 name = "security-framework"
 version = "3.7.0"
@@ -1644,6 +1809,16 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "signature"
+version = "2.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "77549399552de45a898a580c1b41d445bf730df867cc44e6c0233bbc4b8329de"
+dependencies = [
+ "digest",
+ "rand_core",
+]
+
 [[package]]
 name = "slab"
 version = "0.4.12"
@@ -1666,6 +1841,16 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
+[[package]]
+name = "spki"
+version = "0.7.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d91ed6c858b01f942cd56b37a94b3e0a1798290327d1236e4d9cf4eaca44d29d"
+dependencies = [
+ "base64ct",
+ "der",
+]
+
 [[package]]
 name = "stable_deref_trait"
 version = "1.2.1"

crates/nu-rpc/Cargo.toml

@@ -11,6 +11,8 @@ anyhow.workspace     = true
 tracing.workspace    = true
 axum.workspace       = true
 chrono.workspace     = true
+k256                 = { version = "0.13", features = ["ecdsa"] }
+hex.workspace        = true
 nu-state             = { path = "../nu-state" }
 nu-mempool           = { path = "../nu-mempool" }
 nu-block             = { path = "../nu-block" }

crates/nu-rpc/src/handlers.rs

@@ -4,8 +4,9 @@ use crate::{
     server::AppState,
     types::{JsonRpcRequest, JsonRpcResponse},
 };
+use k256::ecdsa::{signature::Verifier, Signature, VerifyingKey};
 use nu_block::types::{Block, RawTransaction};
-use nu_state::{account::AccountState, ValidatorState};
+use nu_state::{account::AccountState, SlashEvidence, ValidatorState};
 
 pub async fn dispatch(req: JsonRpcRequest, state: &AppState) -> JsonRpcResponse {
     match req.method.as_str() {
@@ -15,6 +16,7 @@ pub async fn dispatch(req: JsonRpcRequest, state: &AppState) -> JsonRpcResponse
         "nu_getBlock"         => handle_get_block(&req, state).await,
         "nu_getValidator"     => handle_get_validator(&req, state).await,
         "nu_listValidators"   => handle_list_validators(&req, state).await,
+        "nu_reportDoubleSign" => handle_report_double_sign(&req, state).await,
         "nu_getTx"            => not_implemented(&req, "nu_getTx"),
         "nu_getStory"         => not_implemented(&req, "nu_getStory"),
         "nu_getNode"          => not_implemented(&req, "nu_getNode"),
@@ -137,6 +139,83 @@ async fn handle_list_validators(req: &JsonRpcRequest, state: &AppState) -> JsonR
     JsonRpcResponse::ok(req.id.clone(), serde_json::to_value(validators).unwrap())
 }
 
+async fn handle_report_double_sign(req: &JsonRpcRequest, state: &AppState) -> JsonRpcResponse {
+    // params: [validator, slot, block_hash_1, sig_1_hex, block_hash_2, sig_2_hex, reporter]
+    let get_str = |i: usize| req.params.get(i).and_then(|v| v.as_str()).map(String::from);
+    let get_u32 = |i: usize| req.params.get(i).and_then(|v| v.as_u64()).map(|n| n as u32);
+
+    let (Some(validator), Some(slot), Some(hash1), Some(sig1_hex), Some(hash2), Some(sig2_hex), Some(reporter)) = (
+        get_str(0), get_u32(1), get_str(2), get_str(3), get_str(4), get_str(5), get_str(6),
+    ) else {
+        return JsonRpcResponse::err(req.id.clone(), -32602, "Missing params".into());
+    };
+
+    if hash1 == hash2 {
+        return JsonRpcResponse::err(req.id.clone(), -32602, "Block hashes must differ".into());
+    }
+
+    // Verify both signatures are from the same validator key
+    let sig1_bytes = match hex::decode(&sig1_hex) {
+        Ok(b) => b,
+        Err(_) => return JsonRpcResponse::err(req.id.clone(), -32602, "Invalid sig_1 hex".into()),
+    };
+    let sig2_bytes = match hex::decode(&sig2_hex) {
+        Ok(b) => b,
+        Err(_) => return JsonRpcResponse::err(req.id.clone(), -32602, "Invalid sig_2 hex".into()),
+    };
+    let val_pubkey_bytes = match hex::decode(&validator) {
+        Ok(b) => b,
+        Err(_) => return JsonRpcResponse::err(req.id.clone(), -32602, "Invalid validator address".into()),
+    };
+    let verifying_key = match VerifyingKey::from_sec1_bytes(&val_pubkey_bytes) {
+        Ok(k) => k,
+        Err(_) => return JsonRpcResponse::err(req.id.clone(), -32602, "Invalid validator pubkey".into()),
+    };
+    let sig1 = match Signature::from_slice(&sig1_bytes) {
+        Ok(s) => s,
+        Err(_) => return JsonRpcResponse::err(req.id.clone(), -32602, "Invalid sig_1".into()),
+    };
+    let sig2 = match Signature::from_slice(&sig2_bytes) {
+        Ok(s) => s,
+        Err(_) => return JsonRpcResponse::err(req.id.clone(), -32602, "Invalid sig_2".into()),
+    };
+
+    if verifying_key.verify(hash1.as_bytes(), &sig1).is_err() {
+        return JsonRpcResponse::err(req.id.clone(), -32602, "sig_1 does not verify".into());
+    }
+    if verifying_key.verify(hash2.as_bytes(), &sig2).is_err() {
+        return JsonRpcResponse::err(req.id.clone(), -32602, "sig_2 does not verify".into());
+    }
+
+    let evidence = SlashEvidence {
+        validator:    validator.clone(),
+        slot,
+        block_hash_1: hash1,
+        sig_1:        sig1_bytes,
+        block_hash_2: hash2,
+        sig_2:        sig2_bytes,
+        reporter,
+        submitted_at: chrono::Utc::now().timestamp_millis(),
+        applied:      false,
+    };
+
+    let key = SlashEvidence::db_key(&validator, slot);
+    let db = state.db.lock().await;
+
+    // Idempotent — don't store duplicates
+    if let Ok(Some(_)) = db.get::<SlashEvidence>(&key) {
+        return JsonRpcResponse::ok(req.id.clone(), json!({ "status": "already_reported" }));
+    }
+
+    match db.put(&key, &evidence) {
+        Ok(_) => {
+            tracing::warn!(validator = %validator, slot, "double-sign evidence submitted");
+            JsonRpcResponse::ok(req.id.clone(), json!({ "status": "accepted", "key": key }))
+        }
+        Err(e) => JsonRpcResponse::err(req.id.clone(), -32000, e.to_string()),
+    }
+}
+
 fn not_implemented(req: &JsonRpcRequest, method: &str) -> JsonRpcResponse {
     JsonRpcResponse::err(req.id.clone(), -32000, format!("{method} not implemented yet"))
 }

crates/nu-state/src/lib.rs

@@ -2,11 +2,13 @@ pub mod accessor;
 pub mod account;
 pub mod db;
 pub mod nft;
+pub mod slash_evidence;
 pub mod story_node;
 pub mod validator;
 
 pub use accessor::StateAccessor;
 pub use db::StateDb;
 pub use nft::NftState;
+pub use slash_evidence::SlashEvidence;
 pub use story_node::{NodeStatus, StoryNodeState, WeightedVote};
 pub use validator::ValidatorState;

crates/nu-state/src/slash_evidence.rs

@@ -0,0 +1,22 @@
+use serde::{Deserialize, Serialize};
+
+/// Double-sign fraud proof submitted via nu_reportDoubleSign RPC.
+/// Stored as "slash_evidence:<validator_addr>:<slot>" in DB.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct SlashEvidence {
+    pub validator:    String,
+    pub slot:         u32,
+    pub block_hash_1: String,
+    pub sig_1:        Vec<u8>,
+    pub block_hash_2: String,
+    pub sig_2:        Vec<u8>,
+    pub reporter:     String,
+    pub submitted_at: i64,
+    pub applied:      bool,
+}
+
+impl SlashEvidence {
+    pub fn db_key(validator: &str, slot: u32) -> String {
+        format!("slash_evidence:{validator}:{slot:010}")
+    }
+}

src/block_loop.rs

@@ -9,12 +9,12 @@ use nu_block::{
 };
 use nu_consensus::{
     slot::current_slot,
-    slashing::record_skip,
+    slashing::{record_skip, slash_double_sign},
     types::ValidatorRecord,
     validator_set::ValidatorSet,
 };
 use nu_mempool::Mempool;
-use nu_state::{story_node::StoryNodeState, ValidatorState, StateDb};
+use nu_state::{account::AccountState, story_node::StoryNodeState, SlashEvidence, ValidatorState, StateDb};
 use nu_vm::execute_block;
 
 use crate::p2p::P2pSender;
@@ -86,6 +86,12 @@ pub async fn run(
             }
         }
 
+        // Apply any pending double-sign slash evidence
+        {
+            let db_guard = db.lock().await;
+            apply_pending_slashes(&db_guard, slot);
+        }
+
         // Scheduler: inject auto-txs for pending nodes
         {
             let db_guard = db.lock().await;
@@ -168,6 +174,70 @@ pub async fn run(
     }
 }
 
+fn apply_pending_slashes(db: &StateDb, current_slot: u32) {
+    let burn_wallet  = std::env::var("BURN_WALLET").unwrap_or_default();
+    let evidences: Vec<SlashEvidence> = db.scan_prefix("slash_evidence:");
+
+    for mut ev in evidences {
+        if ev.applied {
+            continue;
+        }
+        let vs_key = format!("validator:{}", ev.validator);
+        let mut vs = match db.get::<ValidatorState>(&vs_key).ok().flatten() {
+            Some(v) => v,
+            None    => continue,
+        };
+
+        let mut record = ValidatorRecord {
+            address:           vs.address.clone(),
+            stake:             vs.stake,
+            pon_score:         vs.pon_score,
+            is_active:         vs.is_active,
+            last_block:        vs.last_block,
+            slash_count:       vs.slash_count,
+            skip_count:        vs.skip_count,
+            consecutive_blocks: vs.consecutive_blocks,
+            ban_until_slot:    vs.ban_until_slot,
+        };
+
+        let result = slash_double_sign(&mut record, current_slot);
+
+        vs.stake          = record.stake;
+        vs.pon_score      = record.pon_score;
+        vs.is_active      = record.is_active;
+        vs.ban_until_slot = record.ban_until_slot;
+        vs.slash_count    = record.slash_count;
+
+        let _ = db.put(&vs_key, &vs);
+
+        // Burn half
+        if !burn_wallet.is_empty() {
+            if let Ok(Some(mut burn_acc)) = db.get::<AccountState>(&format!("account:{burn_wallet}")) {
+                burn_acc.balance = burn_acc.balance.saturating_add(result.burn_amount);
+                let _ = db.put(&format!("account:{burn_wallet}"), &burn_acc);
+            }
+        }
+
+        // Reporter reward
+        if !ev.reporter.is_empty() {
+            if let Ok(Some(mut reporter_acc)) = db.get::<AccountState>(&format!("account:{}", ev.reporter)) {
+                reporter_acc.balance = reporter_acc.balance.saturating_add(result.reporter_reward);
+                let _ = db.put(&format!("account:{}", ev.reporter), &reporter_acc);
+            }
+        }
+
+        ev.applied = true;
+        let _ = db.put(&SlashEvidence::db_key(&ev.validator, ev.slot), &ev);
+
+        tracing::warn!(
+            validator = %ev.validator,
+            slot      = ev.slot,
+            slashed   = result.slashed_amount,
+            "double-sign slash applied"
+        );
+    }
+}
+
 fn unban_expired_validators(db: &StateDb, current_slot: u32) {
     let records: Vec<ValidatorState> = db.scan_prefix("validator:");
     for mut vs in records {