使用空格解码base64

Question

我有一个base64编码的字符串,我试图用go解密.该字符串包含应忽略的空格.我正在尝试的示例代码:

s := "eyJ0aHJlZURTU2VydmVyVHJhbnNJRCI6IjEzZmU3MWQ0LWQxMGQtNDIyMC1hMjE2LTIwMDZkMWRkNGNiOCIsImFjc1RyY++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++W5zSUQiOiJkN2M0NWY5OS05NDc4LTQ0YTYtYjFmMi0xMDAwMDAwMDMzNjYiLCJtZXNzYWdlVHlwZSI6IkNSZXEiLCJtZXNzYWdlVmVyc2lvbiI6IjIuMS4wIiwiY2hhbGxlbmdlV2luZG93U2l6ZSI6IjAyIn0%3D"

out, err := base64.URLEncoding.DecodeString(s)
if err != nil {
    fmt.Println(err)
    return
}
fmt.Println(string(out))

此代码返回:

输入字节93处的非法base64数据

---

更改字符串填充后,使用StdEncoding而不是URLEncoding:

s= strings.Replace(s, "%3D", "=", -1)
out, err := base64.StdEncoding.DecodeString(s)
if err != nil {
    fmt.Println(err)
    return
}
fmt.Println(string(out))

输出将是:

{ "threeDSServerTransID": "13fe71d4-D10D-4220-a216-2006d1dd4cb8","acsTrc NSID ":" d7c45f99- 9478-44a6-b1f2-100000003366" , "为messageType": "CREQ", "messageVersion": "2.1.0", "challengeWindowSize": "02"}

---

如何正确解密字符串？

Answer 1

您拥有的内容最有可能从URL"切断",并且采用URL编码形式.因此,要获得Base64字符串,您必须首先解码它,您可以使用url.PathUnescape()它.

获得未转义的字符串后,您可以使用base64.StdEncoding编码器对其进行解码.请注意,仅仅因为它是/是URL的一部分,它不会使它成为使用URL安全版Base64的字母表的base64字符串.

+中间的标志实际上只是"垃圾".他们不应该在那里,所以仔细检查你如何得到你的意见,但现在他们在那里,你必须删除它们.为此,您可以使用strings.Replace().

解码无效输入的最终代码:

s := "eyJ0aHJlZURTU2VydmVyVHJhbnNJRCI6IjEzZmU3MWQ0LWQxMGQtNDIyMC1hMjE2LTIwMDZkMWRkNGNiOCIsImFjc1RyY++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++W5zSUQiOiJkN2M0NWY5OS05NDc4LTQ0YTYtYjFmMi0xMDAwMDAwMDMzNjYiLCJtZXNzYWdlVHlwZSI6IkNSZXEiLCJtZXNzYWdlVmVyc2lvbiI6IjIuMS4wIiwiY2hhbGxlbmdlV2luZG93U2l6ZSI6IjAyIn0%3D"
s = strings.Replace(s, "+", "", -1)
var err error
if s, err = url.PathUnescape(s); err != nil {
    panic(err)
}

out, err := base64.StdEncoding.DecodeString(s)
if err != nil {
    panic(err)
}
fmt.Println(string(out))

完成输出(在Go Playground上试试):

{"threeDSServerTransID":"13fe71d4-d10d-4220-a216-2006d1dd4cb8",
   "acsTransID":"d7c45f99-9478-44a6-b1f2-100000003366","messageType":"CReq",
    "messageVersion":"2.1.0","challengeWindowSize":"02"}

请注意,+符号是标准Base64字母表中的有效符号,您甚至可以在不删除+符号的情况下解码Base64 ,但随后您会在结果中获得JSON键中的垃圾数据.