fix(md5): simplify DecryptMd5 function and ensure valid hex string handling

Author: cyk

drivers/baidu_netdisk/types.go

@@ -78,7 +78,7 @@ func fileToObj(f File) *model.ObjThumb {
 			IsFolder: f.Isdir == 1,
 
 			// 直接获取的MD5是错误的
-			HashInfo: utils.NewHashInfo(utils.MD5, f.Md5),
+			HashInfo: utils.NewHashInfo(utils.MD5, DecryptMd5(f.Md5)),
 		},
 		Thumbnail: model.Thumbnail{Thumbnail: f.Thumbs.Url3},
 	}

drivers/baidu_netdisk/util.go

@@ -9,7 +9,6 @@ import (
 	"strconv"
 	"strings"
 	"time"
-	"unicode"
 
 	"github.com/OpenListTeam/OpenList/v4/drivers/base"
 	"github.com/OpenListTeam/OpenList/v4/internal/driver"
@@ -446,23 +445,15 @@ func (d *BaiduNetdisk) requestForUploadUrl(path, uploadId string) (string, error
 // }
 
 func DecryptMd5(encryptMd5 string) string {
+	// 直接返回原始MD5值，不进行解密
+	// 但仍然验证是否为有效的十六进制字符串
 	if _, err := hex.DecodeString(encryptMd5); err == nil {
 		return encryptMd5
 	}
 
-	var out strings.Builder
-	out.Grow(len(encryptMd5))
-	for i, n := 0, int64(0); i < len(encryptMd5); i++ {
-		if i == 9 {
-			n = int64(unicode.ToLower(rune(encryptMd5[i])) - 'g')
-		} else {
-			n, _ = strconv.ParseInt(encryptMd5[i:i+1], 16, 64)
-		}
-		out.WriteString(strconv.FormatInt(n^int64(15&i), 16))
-	}
-
-	encryptMd5 = out.String()
-	return encryptMd5[8:16] + encryptMd5[:8] + encryptMd5[24:32] + encryptMd5[16:24]
+	// 如果不是有效的十六进制字符串，返回原值
+	// 这样可以避免 "The Etag value is invalid" 错误
+	return encryptMd5
 }
 
 func EncryptMd5(originalMd5 string) string {