在 Swift 中解码 JSON Web 令牌 [英] Decoding JSON Web Tokens in Swift

问题描述

尝试在 Swift 中解码 JWT 有效负载并且遇到了非常困难的时间

trying to decode a JWT payload in Swift and having a really difficult time

static func decodePayload(tokenstr: String) {

    //splitting JWT to extract payload
    let arr = split(tokenstr) {$0 == "."}

    //base64 encoded string i want to decode
    let base64String = arr[1] as String
    println(base64String) //eyJleHAiOjE0MjY4MjIxNjMsImlkIjoiNTUwYjA3NzM4ODk1NjAwZTk5MDAwMDAxIn0

    //attempting to convert base64 string to nsdata 
    let nsdata: NSData = NSData(base64EncodedString: base64String, options: NSDataBase64DecodingOptions(rawValue: 0))

    //decoding fails because nsdata unwraps as nil
    let base64Decoded: NSString = NSString(data: nsdata!, encoding: NSUTF8StringEncoding)!


}

推荐答案

eyJleHAiOjE0MjY4MjIxNjMsImlkIjoiNTUwYjA3NzM4ODk1NjAwZTk5MDAwMDAxIn0

不是有效的 Base64 编码字符串，因为它的长度不是 4 的倍数.一些 Base64 解码器可以容忍这个错误，但是NSData 方法没有.

is not a valid Base64 encoded string because its length is not a multiple of 4. Some Base64 decoder tolerate this error, but the NSData methods don't.

所以这实际上是服务器端创建的错误Base64 编码的字符串.如有必要，您可以在您的应用程序中修复它通过使用 = 字符添加所需的填充(针对 Swift 2 更新的代码):

So this is actually an error on the server side creating the Base64 encoded string. If necessary, you can fix it in your app by adding the required padding with = characters (code updated for Swift 2):

var base64String = arr[1] as String
if base64String.characters.count % 4 != 0 {
    let padlen = 4 - base64String.characters.count % 4
    base64String += String(count: padlen, repeatedValue: Character("="))
}

现在解码按预期工作:

if let data = NSData(base64EncodedString: base64String, options: []),
    let str = String(data: data, encoding: NSUTF8StringEncoding) {
    print(str) // {"exp":1426822163,"id":"550b07738895600e99000001"}
}

<小时>

斯威夫特 4:

var base64String = "eyJleHAiOjE0MjY4MjIxNjMsImlkIjoiNTUwYjA3NzM4ODk1NjAwZTk5MDAwMDAxIn0"

if base64String.count % 4 != 0 {
    let padlen = 4 - base64String.count % 4
    base64String.append(contentsOf: repeatElement("=", count: padlen))
}

if let data = Data(base64Encoded: base64String) ,
    let str = String(data: data, encoding: .utf8) {
    print(str) // {"exp":1426822163,"id":"550b07738895600e99000001"}
}

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