feat(service-party-app): 支持压缩公钥派生EVM地址并显示KAVA余额

- 实现secp256k1公钥解压缩算法 (y² = x³ + 7 mod p)
- 支持从TSS keygen的33字节压缩公钥派生EVM地址
- 在钱包主页显示KAVA代币余额 (通过Kava Testnet RPC获取)
- 添加余额加载状态和样式

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/mpc-system/services/service-party-app/src/pages/Home.module.css

@@ -373,3 +373,34 @@
   text-align: center;
   text-decoration: none;
 }
+
+/* Balance Section */
+.balanceSection {
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  padding: var(--spacing-md);
+  margin-bottom: var(--spacing-md);
+  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
+  border-radius: var(--radius-md);
+}
+
+.balanceLabel {
+  font-size: 12px;
+  color: rgba(255, 255, 255, 0.85);
+  font-weight: 500;
+}
+
+.balanceValue {
+  font-size: 18px;
+  font-weight: 700;
+  color: white;
+  font-family: monospace;
+}
+
+.balanceLoading {
+  font-size: 14px;
+  font-weight: 400;
+  color: rgba(255, 255, 255, 0.7);
+  font-style: italic;
+}

backend/mpc-system/services/service-party-app/src/pages/Home.tsx

@@ -16,6 +16,44 @@ interface ShareItem {
 
 interface ShareWithAddress extends ShareItem {
   evmAddress?: string;
+  kavaBalance?: string;
+  balanceLoading?: boolean;
+}
+
+// Kava Testnet EVM RPC endpoint
+const KAVA_TESTNET_RPC = 'https://evm.testnet.kava.io';
+
+/**
+ * 获取 KAVA 代币余额
+ * @param address EVM 地址
+ * @returns 余额字符串 (格式化后的 KAVA 数量)
+ */
+async function fetchKavaBalance(address: string): Promise<string> {
+  try {
+    const response = await fetch(KAVA_TESTNET_RPC, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({
+        jsonrpc: '2.0',
+        method: 'eth_getBalance',
+        params: [address, 'latest'],
+        id: 1,
+      }),
+    });
+
+    const data = await response.json();
+    if (data.result) {
+      // 将 wei 转换为 KAVA (18 位小数)
+      const balanceWei = BigInt(data.result);
+      const balanceKava = Number(balanceWei) / 1e18;
+      // 格式化显示，最多 6 位小数
+      return balanceKava.toFixed(balanceKava < 0.000001 && balanceKava > 0 ? 8 : 6).replace(/\.?0+$/, '') || '0';
+    }
+    return '0';
+  } catch (error) {
+    console.error('Failed to fetch KAVA balance:', error);
+    return '0';
+  }
 }
 
 export default function Home() {
@@ -30,7 +68,7 @@ export default function Home() {
     for (const share of shareList) {
       try {
         const evmAddress = await deriveEvmAddress(share.publicKey);
-        sharesWithAddresses.push({ ...share, evmAddress });
+        sharesWithAddresses.push({ ...share, evmAddress, balanceLoading: true });
       } catch (error) {
         console.warn(`Failed to derive address for share ${share.id}:`, error);
         sharesWithAddresses.push({ ...share });
@@ -39,6 +77,20 @@ export default function Home() {
     return sharesWithAddresses;
   }, []);
 
+  // 单独获取所有钱包的余额
+  const fetchAllBalances = useCallback(async (sharesWithAddrs: ShareWithAddress[]) => {
+    const updatedShares = await Promise.all(
+      sharesWithAddrs.map(async (share) => {
+        if (share.evmAddress) {
+          const kavaBalance = await fetchKavaBalance(share.evmAddress);
+          return { ...share, kavaBalance, balanceLoading: false };
+        }
+        return { ...share, balanceLoading: false };
+      })
+    );
+    setShares(updatedShares);
+  }, []);
+
   useEffect(() => {
     loadShares();
   }, []);
@@ -64,6 +116,9 @@ export default function Home() {
       // 为每个 share 派生 EVM 地址
       const sharesWithAddresses = await deriveAddresses(shareList);
       setShares(sharesWithAddresses);
+
+      // 异步获取所有余额 (不阻塞 UI)
+      fetchAllBalances(sharesWithAddresses);
     } catch (error) {
       console.error('Failed to load shares:', error);
     } finally {
@@ -215,6 +270,20 @@ export default function Home() {
                   </div>
                 )}
 
+                {/* KAVA 余额显示 */}
+                {share.evmAddress && (
+                  <div className={styles.balanceSection}>
+                    <span className={styles.balanceLabel}>KAVA 余额</span>
+                    <span className={styles.balanceValue}>
+                      {share.balanceLoading ? (
+                        <span className={styles.balanceLoading}>加载中...</span>
+                      ) : (
+                        <>{share.kavaBalance || '0'} KAVA</>
+                      )}
+                    </span>
+                  </div>
+                )}
+
                 <div className={styles.infoRow}>
                   <span className={styles.infoLabel}>参与方</span>
                   <span className={styles.infoValue}>

backend/mpc-system/services/service-party-app/src/utils/address.ts

@@ -3,6 +3,101 @@
  * 从 ECDSA 公钥派生 EVM 兼容地址
  */
 
+// secp256k1 曲线参数
+const SECP256K1_P = BigInt('0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFFC2F');
+const SECP256K1_B = 7n;
+
+/**
+ * 将 Uint8Array 转换为 BigInt
+ */
+function bytesToBigInt(bytes: Uint8Array): bigint {
+  let result = 0n;
+  for (let i = 0; i < bytes.length; i++) {
+    result = (result << 8n) | BigInt(bytes[i]);
+  }
+  return result;
+}
+
+/**
+ * 将 BigInt 转换为 32 字节的 Uint8Array
+ */
+function bigIntToBytes32(n: bigint): Uint8Array {
+  const bytes = new Uint8Array(32);
+  let temp = n;
+  for (let i = 31; i >= 0; i--) {
+    bytes[i] = Number(temp & 0xffn);
+    temp = temp >> 8n;
+  }
+  return bytes;
+}
+
+/**
+ * 模幂运算 (快速幂算法)
+ */
+function modPow(base: bigint, exp: bigint, mod: bigint): bigint {
+  let result = 1n;
+  base = ((base % mod) + mod) % mod;
+  while (exp > 0n) {
+    if (exp & 1n) {
+      result = (result * base) % mod;
+    }
+    exp = exp >> 1n;
+    base = (base * base) % mod;
+  }
+  return result;
+}
+
+/**
+ * 计算 secp256k1 曲线上给定 x 坐标的 y 坐标
+ * y² = x³ + 7 (mod p)
+ */
+function decompressY(x: bigint, isOdd: boolean): bigint {
+  // 计算 y² = x³ + 7 (mod p)
+  const x3 = modPow(x, 3n, SECP256K1_P);
+  const ySquared = (x3 + SECP256K1_B) % SECP256K1_P;
+
+  // 计算平方根: y = ySquared^((p+1)/4) mod p
+  // 这是因为 p ≡ 3 (mod 4) 对于 secp256k1
+  const exp = (SECP256K1_P + 1n) / 4n;
+  let y = modPow(ySquared, exp, SECP256K1_P);
+
+  // 根据奇偶性选择正确的 y 值
+  const yIsOdd = (y & 1n) === 1n;
+  if (yIsOdd !== isOdd) {
+    y = SECP256K1_P - y;
+  }
+
+  return y;
+}
+
+/**
+ * 解压缩 secp256k1 公钥
+ * 输入: 33 字节压缩公钥 (02/03 前缀 + 32 字节 x 坐标)
+ * 输出: 64 字节未压缩公钥 (32 字节 x + 32 字节 y，无前缀)
+ */
+function decompressPublicKey(compressedPubKey: Uint8Array): Uint8Array {
+  if (compressedPubKey.length !== 33) {
+    throw new Error('压缩公钥必须是 33 字节');
+  }
+
+  const prefix = compressedPubKey[0];
+  if (prefix !== 0x02 && prefix !== 0x03) {
+    throw new Error('无效的压缩公钥前缀');
+  }
+
+  const isOdd = prefix === 0x03;
+  const xBytes = compressedPubKey.slice(1);
+  const x = bytesToBigInt(xBytes);
+  const y = decompressY(x, isOdd);
+
+  // 组合 x 和 y 坐标
+  const result = new Uint8Array(64);
+  result.set(xBytes, 0);
+  result.set(bigIntToBytes32(y), 32);
+
+  return result;
+}
+
 /**
  * 将十六进制字符串转换为 Uint8Array
  */
@@ -155,9 +250,8 @@ export async function deriveEvmAddress(publicKey: string): Promise<string> {
     // 无前缀的未压缩格式
     uncompressedPubKey = pubKeyBytes;
   } else if (pubKeyBytes.length === 33 && (pubKeyBytes[0] === 0x02 || pubKeyBytes[0] === 0x03)) {
-    // 压缩格式，需要解压 - 这里简化处理，实际需要椭圆曲线计算
+    // 压缩格式，解压为 64 字节的 x,y 坐标
-    // 在真实场景中应该使用 elliptic 或 secp256k1 库
+    uncompressedPubKey = decompressPublicKey(pubKeyBytes);
-    throw new Error('压缩公钥暂不支持，请提供未压缩公钥');
   } else {
     throw new Error(`无效的公钥格式: length=${pubKeyBytes.length}`);
   }