在golang中解码base64后一些字符消失

Question

我构建了简单的程序来生成 Json Web 令牌 (JWT)，一切正常运行直到我进行令牌验证以验证 JWT，问题出现在我解码 base64 字符串以检查header 标记。二进制文件的某些部分消失了，而字符串值来自编码的 base64。这是我的代码和结果

package auth

import "encoding/base64"
import "crypto/sha256"
import "encoding/json"
import "strings"
import "crypto/hmac"
import "encoding/hex"
import "fmt"


type Header struct{
    Alg string
    Typ string
}

type Payload struct{
    id          int
    name        string
    userType    bool
    keepLogin   bool
}

var key string = "12345678" //temporary
var payloadJson Payload

func GenerateToken(alg string, typ string, payload []byte)(string, error){
    var headerEncoded, payloadEncoded, signature, mergedEncoded string
    header := Header{Alg: alg,Typ: typ}
    hmacDeclare := hmac.New(sha256.New, []byte(key))


    headerJson, errHeader := json.Marshal(header)//struct -> byte
    if errHeader != nil{
        return "",errHeader
    }
    
    headerEncoded = encodeBase64(headerJson)//byte -> string
    payloadEncoded = encodeBase64(payload)//byte -> string
    mergedEncoded = headerEncoded+"."+payloadEncoded
    if alg=="SHA256"{
        hmacDeclare.Write([]byte(mergedEncoded))
        signature = hex.EncodeToString(hmacDeclare.Sum(nil))
    }

    finalToken := headerEncoded+"."+payloadEncoded+"."+signature
    
    //JUST SAMPLE TO TEST JWT RESULT
    fmt.Println("Before encode (byte) => ", headerJson)
    fmt.Println("Before encode (string) => ", string(headerJson))
    fmt.Println("After encode (base64/string) => ", headerEncoded)
    checkDecode,_ := decodeBase64(headerEncoded)//string -> byte
    fmt.Println("After decode (byte) => ", checkDecode)
    fmt.Println("After decode (string) => ", string(checkDecode))
    // _, _ = VerifyToken(finalToken)
    return finalToken, nil
}

func encodeBase64(data []byte) string {
    formatString := strings.TrimRight(base64.StdEncoding.EncodeToString(data),"=")
    return formatString
}

func decodeBase64(data string)([]byte, error){
    result, err := base64.StdEncoding.DecodeString(data)
    if err != nil{
        return result, err
    }
    return result, nil
}

这是结果

Before encode (byte) =>  [123 34 65 108 103 34 58 34 83 72 65 50 53 54 34 44 34 84 121 112 34 58 34 74 87 84 34 125]
Before encode (string) =>  {"Alg":"SHA256","Typ":"JWT"}
After encode (base64/string) =>  eyJBbGciOiJTSEEyNTYiLCJUeXAiOiJKV1QifQ
After decode (byte) =>  [123 34 65 108 103 34 58 34 83 72 65 50 53 54 34 44 34 84 121 112 34 58 34 74 87 84 34]
After decode (string) =>  {"Alg":"SHA256","Typ":"JWT"

有人遇到同样的问题吗？我试过浏览它但没有发现相同的问题

Answer 1

如果您不需要填充，请不要 trim，而是使用 WithPadding and pass in NoPadding。

func encodeBase64(data []byte) string {
    e := base64.StdEncoding.WithPadding(base64.NoPadding)
    return e.EncodeToString(data)
}

func decodeBase64(data string) ([]byte, error) {
    e := base64.StdEncoding.WithPadding(base64.NoPadding)
    result, err := e.DecodeString(data)
    if err != nil {
        return result, err
    }
    return result, nil
}

https://go.dev/play/p/bs6Wte-wHeD

在golang中解码base64后一些字符消失

Some character disappear after decode base64 in golang

base64

go

jwt