英文:
How to decode data stored in base64 with "type*:" prefix?
问题
如何解码以下示例的Base64编码字符串？（它存储在MySQL数据库中）
base64:type251:WXlnY2p0bFl5Z2NqdGxZeWdjanRsWXlnY2
我已经尝试使用普通的Base64解码它，但没有成功。前缀中的 "type251" 应该有特殊含义，但我在文档或搜索中没有找到任何信息。
是否有在线工具可用于解码它？
英文:
How do i decode the following example of base64 encoded string? (it is stored on MySQL DB)
base64:type251:WXlnY2p0bFl5Z2NqdGxZeWdjanRsWXlnY2
I have already tried to decode it using normal base64 to no avail. The "type251" prefix should mean something but I haven't found anyting on documentation/googling.
Is there any online tools available to decode it?
答案1
得分: 1
base64:type251:前缀除了对你的应用程序而言没有任何意义。我假设它是一些额外的注释，用于告诉客户端在解码结果后该如何处理。
你展示的字符串'WXlnY2p0bFl5Z2NqdGxZeWdjanRsWXlnY2'不是有效的 base64 字符串，因为它没有填充到八位组的倍数，使其成为24位的倍数。可以阅读维基百科关于 base64 填充的文章：https://en.wikipedia.org/wiki/Base64#Output_padding
尝试解码它将失败并且只会返回 NULL：
mysql> select from_base64('WXlnY2p0bFl5Z2NqdGxZeWdjanRsWXlnY2') as result;
+----------------+
| result |
+----------------+
| NULL |
+----------------+
如果添加了一对=填充字符，MySQL 的内置函数可以解码 base64 字符串，但需先去除前缀。
mysql> select from_base64('WXlnY2p0bFl5Z2NqdGxZeWdjanRsWXlnY2==') as result;
+------------------------------------------------------+
| result |
+------------------------------------------------------+
| 0x597967636A746C597967636A746C597967636A746C59796763 |
+------------------------------------------------------+
这是一串二进制字节的字符串，以十六进制数字表示，以便以人类可读的形式显示。
这意味着什么？我不知道。我猜想它是一个 "type251" 的序列化对象实例，这是保存数据的应用程序特有的内容。你并没有描述你的应用程序或者它使用的编程语言。
英文:
The prefix base64:type251: means nothing except to your application. I assume it is some extra annotation to tell the client what to do with the result once it is decoded.
The string you show, 'WXlnY2p0bFl5Z2NqdGxZeWdjanRsWXlnY2' is not a valid base64 string, because it's not padded to sets of octets to make an even multiple of 24 bits. Read the wikipedia article on base64 padding: https://en.wikipedia.org/wiki/Base64#Output_padding
Trying to decode it fails and only returns NULL:
mysql> select from_base64('WXlnY2p0bFl5Z2NqdGxZeWdjanRsWXlnY2') as result;
+----------------+
| result |
+----------------+
| NULL |
+----------------+
If a couple of = padding characters are added, MySQL's builtin function can decode the base64 string, after stripping the prefix.
mysql> select from_base64('WXlnY2p0bFl5Z2NqdGxZeWdjanRsWXlnY2==') as result;
+------------------------------------------------------+
| result |
+------------------------------------------------------+
| 0x597967636A746C597967636A746C597967636A746C59796763 |
+------------------------------------------------------+
That's a string of binary bytes, rendered as hex digits so it can be displayed in human-readable form.
What does it mean? I have no idea. I can guess that it's a serialized object instance of "type251" which is something specific to the application that saved that data. You haven't described anything about your application or even what language it's written in.
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