diff --git a/src/main/java/com/sunyard/SydApiException.java b/src/main/java/com/sunyard/SydApiException.java
index 51cd224..1f95e2b 100644
--- a/src/main/java/com/sunyard/SydApiException.java
+++ b/src/main/java/com/sunyard/SydApiException.java
@@ -45,6 +45,9 @@ public class SydApiException extends RuntimeException{
             case 4:
                 msg = "DER 编码格式错误(公钥) ";
                 break;
+            case 31:
+                msg = "缓冲区索引错误";
+                break;
             case 0xd:
                 msg = "公钥加密错误";
                 break;
diff --git a/src/main/java/com/sunyard/util/BytesUtil.java b/src/main/java/com/sunyard/util/BytesUtil.java
new file mode 100644
index 0000000..06233b7
--- /dev/null
+++ b/src/main/java/com/sunyard/util/BytesUtil.java
@@ -0,0 +1,174 @@
+package com.sunyard.util;
+
+import java.nio.ByteOrder;
+
+/**
+ * 字节数组转换工具类，提供常见的基本类型与字节数组之间的互转功能。
+ * 默认采用大端字节序（高位在前），也支持通过参数指定字节序。
+ *
+ * @author YourName
+ */
+public final class BytesUtil {
+
+    private BytesUtil() {
+        // 私有构造方法，防止实例化
+    }
+
+    // ==================== 无符号 short 转字节数组 ====================
+
+    /**
+     * 将无符号 short 值（以 int 形式传入，范围 0 ~ 65535）转换为大端字节序的字节数组（2字节）。
+     *
+     * @param value 无符号 short 值（0 到 65535）
+     * @return 长度为 2 的字节数组，高位在前
+     * @throws IllegalArgumentException 如果 value 超出 0~65535 范围
+     */
+    public static byte[] unsignedShortToBytes(int value) {
+        if (value < 0 || value > 0xFFFF) {
+            throw new IllegalArgumentException("Value out of range for unsigned short: " + value);
+        }
+        return new byte[]{
+                (byte) ((value >> 8) & 0xFF),
+                (byte) (value & 0xFF)
+        };
+    }
+
+    /**
+     * 将无符号 short 值（以 short 类型传入，自动按无符号处理）转换为大端字节序的字节数组（2字节）。
+     * 例如，传入 (short) 0x8001 会得到 { (byte)0x80, (byte)0x01 }。
+     *
+     * @param value short 类型，将按其二进制补码表示直接作为无符号值处理
+     * @return 长度为 2 的字节数组，高位在前
+     */
+    public static byte[] unsignedShortToBytes(short value) {
+        // 将 short 转为无符号 int
+        int unsignedValue = value & 0xFFFF;
+        return unsignedShortToBytes(unsignedValue);
+    }
+
+    /**
+     * 将无符号 short 值（int 类型）转换为指定字节序的字节数组（2字节）。
+     *
+     * @param value     无符号 short 值（0 到 65535）
+     * @param byteOrder 字节序，ByteOrder.BIG_ENDIAN 或 ByteOrder.LITTLE_ENDIAN
+     * @return 长度为 2 的字节数组
+     * @throws IllegalArgumentException 如果 value 超出范围或 byteOrder 为 null
+     */
+    public static byte[] unsignedShortToBytes(int value, ByteOrder byteOrder) {
+        if (byteOrder == null) {
+            throw new IllegalArgumentException("ByteOrder must not be null");
+        }
+        byte[] bytes = unsignedShortToBytes(value);
+        if (byteOrder == ByteOrder.LITTLE_ENDIAN) {
+            // 交换高低位
+            byte tmp = bytes[0];
+            bytes[0] = bytes[1];
+            bytes[1] = tmp;
+        }
+        return bytes;
+    }
+
+    /**
+     * 将无符号 short 值（short 类型）转换为指定字节序的字节数组（2字节）。
+     *
+     * @param value     short 类型，按无符号处理
+     * @param byteOrder 字节序
+     * @return 长度为 2 的字节数组
+     */
+    public static byte[] unsignedShortToBytes(short value, ByteOrder byteOrder) {
+        return unsignedShortToBytes(value & 0xFFFF, byteOrder);
+    }
+
+    // ==================== 字节数组转无符号 short ====================
+
+    /**
+     * 从字节数组的起始位置读取 2 字节，按大端序转换为无符号 short 值（返回 int 类型）。
+     *
+     * @param bytes  字节数组
+     * @param offset 起始偏移量
+     * @return 无符号 short 值（0 ~ 65535）
+     * @throws IllegalArgumentException 如果 bytes 为 null 或长度不足
+     */
+    public static int bytesToUnsignedShort(byte[] bytes, int offset) {
+        if (bytes == null || offset + 2 > bytes.length) {
+            throw new IllegalArgumentException("Invalid byte array or offset");
+        }
+        return ((bytes[offset] & 0xFF) << 8) | (bytes[offset + 1] & 0xFF);
+    }
+
+    /**
+     * 从字节数组的起始位置读取 2 字节，按指定字节序转换为无符号 short 值。
+     *
+     * @param bytes     字节数组
+     * @param offset    起始偏移量
+     * @param byteOrder 字节序
+     * @return 无符号 short 值
+     */
+    public static int bytesToUnsignedShort(byte[] bytes, int offset, ByteOrder byteOrder) {
+        if (byteOrder == ByteOrder.LITTLE_ENDIAN) {
+            return ((bytes[offset + 1] & 0xFF) << 8) | (bytes[offset] & 0xFF);
+        } else {
+            return bytesToUnsignedShort(bytes, offset);
+        }
+    }
+
+    // ==================== 其他常见转换（扩展） ====================
+
+    /**
+     * 将 int 值转换为大端序的 4 字节数组。
+     */
+    public static byte[] intToBytes(int value) {
+        return new byte[]{
+                (byte) ((value >> 24) & 0xFF),
+                (byte) ((value >> 16) & 0xFF),
+                (byte) ((value >> 8) & 0xFF),
+                (byte) (value & 0xFF)
+        };
+    }
+
+    /**
+     * 将大端序的 4 字节数组转换为 int 值。
+     */
+    public static int bytesToInt(byte[] bytes, int offset) {
+        if (bytes == null || offset + 4 > bytes.length) {
+            throw new IllegalArgumentException("Invalid byte array or offset");
+        }
+        return ((bytes[offset] & 0xFF) << 24)
+                | ((bytes[offset + 1] & 0xFF) << 16)
+                | ((bytes[offset + 2] & 0xFF) << 8)
+                | (bytes[offset + 3] & 0xFF);
+    }
+
+    /**
+     * 将 long 值转换为大端序的 8 字节数组。
+     */
+    public static byte[] longToBytes(long value) {
+        return new byte[]{
+                (byte) ((value >> 56) & 0xFF),
+                (byte) ((value >> 48) & 0xFF),
+                (byte) ((value >> 40) & 0xFF),
+                (byte) ((value >> 32) & 0xFF),
+                (byte) ((value >> 24) & 0xFF),
+                (byte) ((value >> 16) & 0xFF),
+                (byte) ((value >> 8) & 0xFF),
+                (byte) (value & 0xFF)
+        };
+    }
+
+    /**
+     * 将大端序的 8 字节数组转换为 long 值。
+     */
+    public static long bytesToLong(byte[] bytes, int offset) {
+        if (bytes == null || offset + 8 > bytes.length) {
+            throw new IllegalArgumentException("Invalid byte array or offset");
+        }
+        return ((long) (bytes[offset] & 0xFF) << 56)
+                | ((long) (bytes[offset + 1] & 0xFF) << 48)
+                | ((long) (bytes[offset + 2] & 0xFF) << 40)
+                | ((long) (bytes[offset + 3] & 0xFF) << 32)
+                | ((long) (bytes[offset + 4] & 0xFF) << 24)
+                | ((long) (bytes[offset + 5] & 0xFF) << 16)
+                | ((long) (bytes[offset + 6] & 0xFF) << 8)
+                | ((long) (bytes[offset + 7] & 0xFF));
+    }
+}
diff --git a/src/main/java/racal/sunyard/main/SydApi4j.java b/src/main/java/racal/sunyard/main/SydApi4j.java
index d2d9dad..6ba343f 100644
--- a/src/main/java/racal/sunyard/main/SydApi4j.java
+++ b/src/main/java/racal/sunyard/main/SydApi4j.java
@@ -46,10 +46,7 @@ import racal.sunyard.main.proto.*;
 
 import javax.security.auth.x500.X500Principal;
 import java.io.*;
-import java.net.InetSocketAddress;
-import java.net.Socket;
-import java.net.SocketAddress;
-import java.net.SocketTimeoutException;
+import java.net.*;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.nio.charset.Charset;
@@ -6857,19 +6854,19 @@ public class SydApi4j implements SydApi {
         ParamChecker.checkNotNull(publicKey, "publicKey");
         ParamChecker.checkNotNull(pOrgData, "pOrgData");
 
-        final int CHUNK_SIZE = 63 * 1024; // 64 KB
+        final int CHUNK_SIZE = 62 * 1024; // 62 KB
         int dataLen = pOrgData.length;
         int offset = 0;
 
         while (offset < dataLen) {
             int len = Math.min(CHUNK_SIZE, dataLen - offset);
             // 调用底层支持偏移量的加密方法
-            SYD_SM2Encrypt(1, publicKey, ByteBuffer.wrap(pOrgData, offset, len), offset);
+            SYD_SM2Encrypt(1, publicKey, ByteBuffer.wrap(pOrgData, offset, len), offset, len, dataLen);
             offset += len;
         }
 
         // 计算
-        SYD_SM2Encrypt(2, publicKey, null, 0);
+        SYD_SM2Encrypt(2, publicKey, null, 0, 0, dataLen);
 
         // 取回
         int idx = 0;
@@ -6878,7 +6875,7 @@ public class SydApi4j implements SydApi {
         int isLast = 0;
 
         while (isLast != 1) {
-            MutiReturn7 ret = SYD_SM2Encrypt(3, null, null, idx);
+            MutiReturn7 ret = SYD_SM2Encrypt(3, null, null, idx, 0, 0);
             ByteBuffer bb = ret.getData();
             isLast = ret.getIsLast();
 
@@ -6905,7 +6902,7 @@ public class SydApi4j implements SydApi {
 
     //    @Override
     //  支持大包加解密
-    private MutiReturn7 SYD_SM2Encrypt(int dataType, byte[] publicKey, ByteBuffer pOrgData, int idx) {
+    private MutiReturn7 SYD_SM2Encrypt(int dataType, byte[] publicKey, ByteBuffer pOrgData, int idx, int inLen, int totalLen) {
         // 参数检查
         ParamChecker.checkInRange(dataType, "dataType", 1, 3);
 
@@ -6928,13 +6925,13 @@ public class SydApi4j implements SydApi {
             bb.put(publicKey);
         }
         if ( 1 == dataType ) { // 数据
-            bb.put(ByteUtil.shortToBytes((short) pOrgData.limit(), ByteOrder.BIG_ENDIAN));
+            bb.put(com.sunyard.util.BytesUtil.unsignedShortToBytes(inLen, ByteOrder.BIG_ENDIAN));
             bb.put(pOrgData);
-            bb.put(ByteUtil.intToBytes(idx));
+            bb.put(ByteUtil.intToBytes(idx, ByteOrder.BIG_ENDIAN));
         }
 
         if ( 3 == dataType) { // 仅数据长度
-            bb.put( ByteUtil.shortToBytes((short) (63*1024), ByteOrder.BIG_ENDIAN) );
+            bb.put( ByteUtil.shortToBytes((short) (62*1024), ByteOrder.BIG_ENDIAN) );
             bb.put( ByteUtil.intToBytes(idx, ByteOrder.BIG_ENDIAN));
         }
 
@@ -6947,8 +6944,41 @@ public class SydApi4j implements SydApi {
 
         // 通信
         synchronized (this) {
-            // 响应解析
-            bb = syncRead(syncSend(bb));
+            int originalTimeout = -1;
+            boolean timeoutModified = false;
+
+            try {
+                // 仅当 dataType == 2 时才执行超时时间调整逻辑
+                if (false && dataType == 2) {
+                    // 获取当前 Socket 超时时间（毫秒），可能为 -1（无限等待）或 0（立即超时）
+                    originalTimeout = this.socket.getSoTimeout();
+
+                    // 计算 totalLen 是 1MB 的多少倍（整数倍，如 2M→2，3M→3，4M→4）
+                    int rate = totalLen / (1024 * 1024);
+
+                    // 仅当倍数 >1 且原超时时间为正数时，才按比例放大超时时间
+                    if (rate > 1 && originalTimeout > 0) {
+                        int newTimeout = originalTimeout * rate;
+                        this.socket.setSoTimeout(newTimeout);
+                        timeoutModified = true;   // 标记已修改，以便 finally 中恢复
+                    }
+                }
+
+                // 响应解析（无论是否调整超时，都正常执行）
+                bb = syncRead(syncSend(bb));
+
+            } catch (SocketException e) {
+                throw new SydApiException("socket 状态错误", -5, e);
+            } finally {
+                // 仅当超时时间被实际修改过时才恢复原值
+                if (timeoutModified) {
+                    try {
+                        this.socket.setSoTimeout(originalTimeout);
+                    } catch (SocketException e) {
+                        // 恢复失败时可根据需要记录日志，此处忽略
+                    }
+                }
+            }
         }
 
         bb.flip();
@@ -6966,9 +6996,10 @@ public class SydApi4j implements SydApi {
             int isLast = bb.get();
             byte[] dataLenArr = new byte[2];
             bb.get(dataLenArr);
-            int dataLen = ByteUtil.bytesToShort(dataLenArr, ByteOrder.BIG_ENDIAN);
+            int dataLen = Short.toUnsignedInt(ByteUtil.bytesToShort(dataLenArr, ByteOrder.BIG_ENDIAN));
 //            byte[] data = new byte[dataLen];
 //            bb.get(data);
+            // 从返回数据中创建密文切片，此时不拷贝数据。
             ByteBuffer slice = ByteBufferUtil.sliceAndConsume(bb, dataLen);
             return new MutiReturn7(retCode, isLast, slice);
         } else {
@@ -6989,19 +7020,19 @@ public class SydApi4j implements SydApi {
         ParamChecker.checkNotNull(privateKey, "privateKey");
         ParamChecker.checkNotNull(pCipherData, "pCipherData");
 
-        final int CHUNK_SIZE = 63 * 1024; // 63 KB，与加密保持一致
+        final int CHUNK_SIZE = 62 * 1024; // 62 KB，与加密保持一致
         int dataLen = pCipherData.length;
         int offset = 0;
 
         // 1. 分块传入密文
         while (offset < dataLen) {
             int len = Math.min(CHUNK_SIZE, dataLen - offset);
-            SYD_SM2Decrypt(1, privateKey, ByteBuffer.wrap(pCipherData, offset, len), offset);
+            SYD_SM2Decrypt(1, privateKey, ByteBuffer.wrap(pCipherData, offset, len), offset, len, 0);
             offset += len;
         }
 
         // 2. 传入私钥，触发解密处理
-        SYD_SM2Decrypt(2, privateKey, null, 0);
+        SYD_SM2Decrypt(2, privateKey, null, 0, 0, dataLen);
 
         // 3. 分块取回明文
         int idx = 0;
@@ -7010,7 +7041,7 @@ public class SydApi4j implements SydApi {
         int isLast = 0;
 
         while (isLast != 1) {
-            MutiReturn7 ret = SYD_SM2Decrypt(3, null, null, idx);
+            MutiReturn7 ret = SYD_SM2Decrypt(3, null, null, idx, 0, 0);
             ByteBuffer bb = ret.getData();
             isLast = ret.getIsLast();
 
@@ -7042,7 +7073,7 @@ public class SydApi4j implements SydApi {
      * @param idx 偏移量索引
      * @return MutiReturn7 包含返回码、isLast标志及数据片
      */
-    private MutiReturn7 SYD_SM2Decrypt(int dataType, byte[] privateKey, ByteBuffer pCipherData, int idx) {
+    private MutiReturn7 SYD_SM2Decrypt(int dataType, byte[] privateKey, ByteBuffer pCipherData, int idx, int inLen, int totalLen) {
         ParamChecker.checkInRange(dataType, "dataType", 1, 3);
 
         // 估算缓存大小
@@ -7064,12 +7095,12 @@ public class SydApi4j implements SydApi {
             bb.put(privateKey);
         }
         if (dataType == 1) {                 // 密文块
-            bb.put(ByteUtil.shortToBytes((short) pCipherData.limit(), ByteOrder.BIG_ENDIAN));
+            bb.put( com.sunyard.util.BytesUtil.unsignedShortToBytes(inLen, ByteOrder.BIG_ENDIAN) );
             bb.put(pCipherData);
             bb.put(ByteUtil.intToBytes(idx, ByteOrder.BIG_ENDIAN));
         }
         if (dataType == 3) {                 // 请求明文块
-            bb.put(ByteUtil.shortToBytes((short) (63 * 1024), ByteOrder.BIG_ENDIAN));
+            bb.put(ByteUtil.shortToBytes((short) (62 * 1024), ByteOrder.BIG_ENDIAN));
             bb.put(ByteUtil.intToBytes(idx, ByteOrder.BIG_ENDIAN));
         }
 
@@ -7080,7 +7111,41 @@ public class SydApi4j implements SydApi {
 
         // 通信
         synchronized (this) {
-            bb = syncRead(syncSend(bb));
+            int originalTimeout = -1;
+            boolean timeoutModified = false;
+
+            try {
+                // 仅当 dataType == 2 时才执行超时时间调整逻辑
+                if (false && dataType == 2) {
+                    // 获取当前 Socket 超时时间（毫秒），可能为 -1（无限等待）或 0（立即超时）
+                    originalTimeout = this.socket.getSoTimeout();
+
+                    // 计算 totalLen 是 1MB 的多少倍（整数倍，如 2M→2，3M→3，4M→4）
+                    int rate = totalLen / (1024 * 1024);
+
+                    // 仅当倍数 >1 且原超时时间为正数时，才按比例放大超时时间
+                    if (rate > 1 && originalTimeout > 0) {
+                        int newTimeout = originalTimeout * rate;
+                        this.socket.setSoTimeout(newTimeout);
+                        timeoutModified = true;   // 标记已修改，以便 finally 中恢复
+                    }
+                }
+
+                // 响应解析（无论是否调整超时，都正常执行）
+                bb = syncRead(syncSend(bb));
+
+            } catch (SocketException e) {
+                throw new SydApiException("socket 状态错误", -5, e);
+            } finally {
+                // 仅当超时时间被实际修改过时才恢复原值
+                if (timeoutModified) {
+                    try {
+                        this.socket.setSoTimeout(originalTimeout);
+                    } catch (SocketException e) {
+                        // 恢复失败时可根据需要记录日志，此处忽略
+                    }
+                }
+            }
         }
 
         bb.flip();
@@ -7097,7 +7162,7 @@ public class SydApi4j implements SydApi {
             int isLast = bb.get();
             byte[] dataLenArr = new byte[2];
             bb.get(dataLenArr);
-            int dataLen = ByteUtil.bytesToShort(dataLenArr, ByteOrder.BIG_ENDIAN);
+            int dataLen = Short.toUnsignedInt(ByteUtil.bytesToShort(dataLenArr, ByteOrder.BIG_ENDIAN));
             ByteBuffer slice = ByteBufferUtil.sliceAndConsume(bb, dataLen);
             return new MutiReturn7(retCode, isLast, slice);
         } else {
diff --git a/src/test/java/cmbpoc/FunctionTest.java b/src/test/java/cmbpoc/FunctionTest.java
index 703be55..026024d 100644
--- a/src/test/java/cmbpoc/FunctionTest.java
+++ b/src/test/java/cmbpoc/FunctionTest.java
@@ -16,7 +16,10 @@ public class FunctionTest {
     private byte[] publicKey4Sign;
     private byte[] privateKey4Ende;
     private byte[] publicKey4Ende;
-    private byte[] orgData = new byte[15];
+    private byte[] orgData = new byte[1024];
+    private byte[] orgData2K = new byte[ 2 * 1024 ];
+    private byte[] orgData2M = new byte[ 2 * 1024 * 1024 ];
+    private byte[] orgData10M = new byte[ 4 * 1024 * 1024 - 1024];
     private String sign;
 
     @Before
@@ -26,7 +29,7 @@ public class FunctionTest {
         System.setProperty("com.sunyard.sydapi4j.debug", "true");
 
         // 建立链接（单台）
-        this.api = (SydApi4j) new SydApi4j().connect("192.168.100.145", 8889, null, 5000);
+        this.api = (SydApi4j) new SydApi4j().connect("192.168.100.145", 8889, null, 30000);
 
 //        RetWrap keypair = this.getPrivateKeyAndPublickKey(keypairIndex4Sign);
 //        this.publicKey4Sign = Util.hexString2Bytes( keypair.get("pk").toString() );
@@ -103,6 +106,33 @@ public class FunctionTest {
         byte[] deData = this.api.SYD_SM2Decrypt(privateKey4Ende, enData);
         Assert.assertArrayEquals(orgData, deData);
     }
+
+
+    @Test
+    public void SYD_SM2_Encrypt_2K(){
+        byte[] enData = this.api.SYD_SM2Encrypt(publicKey4Ende, orgData2K);
+        System.out.println("密文=" + Util.bytes2HexString(enData));
+        byte[] deData = this.api.SYD_SM2Decrypt(privateKey4Ende, enData);
+        Assert.assertArrayEquals(orgData2K, deData);
+    }
+
+
+    @Test
+    public void SYD_SM2_Encrypt_2M(){
+        byte[] enData = this.api.SYD_SM2Encrypt(publicKey4Ende, orgData2M);
+        System.out.println("密文=" + Util.bytes2HexString(enData));
+        byte[] deData = this.api.SYD_SM2Decrypt(privateKey4Ende, enData);
+        Assert.assertArrayEquals(orgData2M, deData);
+    }
+
+
+    @Test
+    public void SYD_SM2_Encrypt_10M(){
+        byte[] enData = this.api.SYD_SM2Encrypt(publicKey4Ende, orgData10M);
+        System.out.println("密文=" + Util.bytes2HexString(enData));
+        byte[] deData = this.api.SYD_SM2Decrypt(privateKey4Ende, enData);
+        Assert.assertArrayEquals(orgData10M, deData);
+    }
 }