diff --git a/xy_sh/crypto.go b/xy_sh/crypto.go
new file mode 100644
index 0000000..ff19ab1
--- /dev/null
+++ b/xy_sh/crypto.go
@@ -0,0 +1,134 @@
+package xy_sh
+
+import (
+	"bytes"
+	"crypto/cipher"
+	"crypto/hmac"
+	"crypto/rand"
+	"encoding/base64"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"time"
+
+	"github.com/tjfoc/gmsm/sm3"
+	"github.com/tjfoc/gmsm/sm4"
+)
+
+// ============================================================
+// 时间戳生成
+// ============================================================
+
+// GenerateTimestampMillis 生成毫秒级时间戳字符串
+func GenerateTimestampMillis() string {
+	return fmt.Sprintf("%d", time.Now().UnixMilli())
+}
+
+// ============================================================
+// SM3 哈希（含盐值）
+// ============================================================
+
+// SM3WithSalt 使用SM3算法结合盐值进行哈希
+// 对应Java Hutool的 SmUtil.sm3WithSalt(salt).digestHex(data)
+// 实现方式：将salt作为HMAC的key，对数据进行HMAC-SM3计算
+func SM3WithSalt(data []byte, salt []byte) string {
+	h := hmac.New(sm3.New, salt)
+	h.Write(data)
+	return hex.EncodeToString(h.Sum(nil))
+}
+
+// SM3WithSaltString 便捷方法：对字符串进行SM3加盐哈希
+func SM3WithSaltString(data string, salt string) string {
+	return SM3WithSalt([]byte(data), []byte(salt))
+}
+
+// ============================================================
+// SM4-CBC 加密/解密
+// ============================================================
+
+// SM4Encrypt SM4-CBC模式加密，返回base64编码字符串
+// 使用 github.com/tjfoc/gmsm/sm4 实现
+func SM4Encrypt(plaintext []byte, key []byte) (string, error) {
+	if len(key) != 16 {
+		return "", fmt.Errorf("SM4密钥长度必须为16字节")
+	}
+
+	block, err := sm4.NewCipher(key)
+	if err != nil {
+		return "", fmt.Errorf("创建SM4 cipher失败: %v", err)
+	}
+
+	padded := pkcs7Padding(plaintext, block.BlockSize())
+
+	iv := make([]byte, block.BlockSize())
+	if _, err := io.ReadFull(rand.Reader, iv); err != nil {
+		return "", fmt.Errorf("生成IV失败: %v", err)
+	}
+
+	mode := cipher.NewCBCEncrypter(block, iv)
+	ciphertext := make([]byte, len(padded))
+	mode.CryptBlocks(ciphertext, padded)
+
+	result := append(iv, ciphertext...)
+	return base64.StdEncoding.EncodeToString(result), nil
+}
+
+// SM4Decrypt SM4-CBC模式解密，输入base64编码字符串，返回明文
+func SM4Decrypt(encryptedData string, key []byte) ([]byte, error) {
+	if len(key) != 16 {
+		return nil, fmt.Errorf("SM4密钥长度必须为16字节")
+	}
+
+	data, err := base64.StdEncoding.DecodeString(encryptedData)
+	if err != nil {
+		return nil, fmt.Errorf("base64解码失败: %v", err)
+	}
+
+	block, err := sm4.NewCipher(key)
+	if err != nil {
+		return nil, fmt.Errorf("创建SM4 cipher失败: %v", err)
+	}
+
+	blockSize := block.BlockSize()
+	if len(data) < blockSize {
+		return nil, fmt.Errorf("数据长度不足")
+	}
+	iv := data[:blockSize]
+	ciphertext := data[blockSize:]
+
+	mode := cipher.NewCBCDecrypter(block, iv)
+	plaintext := make([]byte, len(ciphertext))
+	mode.CryptBlocks(plaintext, ciphertext)
+
+	plaintext, err = pkcs7UnPadding(plaintext)
+	if err != nil {
+		return nil, fmt.Errorf("去除填充失败: %v", err)
+	}
+
+	return plaintext, nil
+}
+
+// pkcs7Padding PKCS7填充
+func pkcs7Padding(data []byte, blockSize int) []byte {
+	padding := blockSize - len(data)%blockSize
+	padText := bytes.Repeat([]byte{byte(padding)}, padding)
+	return append(data, padText...)
+}
+
+// pkcs7UnPadding 去除PKCS7填充
+func pkcs7UnPadding(data []byte) ([]byte, error) {
+	length := len(data)
+	if length == 0 {
+		return nil, fmt.Errorf("数据为空")
+	}
+	padding := int(data[length-1])
+	if padding > length || padding == 0 {
+		return nil, fmt.Errorf("无效的填充")
+	}
+	for i := length - padding; i < length; i++ {
+		if data[i] != byte(padding) {
+			return nil, fmt.Errorf("无效的填充")
+		}
+	}
+	return data[:length-padding], nil
+}
\ No newline at end of file