解码base64并将其编码为十六进制

Question

I have following code which decodes base64 and then encodes it to hex.

doc_id := "Can35qPeFkm9Xgmp9+aj3g=="
base64_decode, err := base64.StdEncoding.DecodeString(doc_id)
if err != nil {
log.Fatal("error:", err)
}
base64_decoded := fmt.Sprintf("%q", base64_decode)
fmt.Printf("base_decoded %v\n", base64_decoded)



src := []byte(base64_decoded)
fmt.Println(src)
hex_encode := make([]byte, hex.EncodedLen(len(src)))
hex.Encode(hex_encode, src)
hex_encoded := fmt.Sprintf("%s", hex_encode)
fmt.Printf("hex_encoded %v", hex_encoded)

where doc_id is base64 format. base64_decoded is its decoded value. I have to encode it to hex, so i pass it to src.

The problem is when i pass the identifier base64_decoded to src i get wrong when i pass in the value that base64_decoded is holding i get correct answer. for example: if i get base64_decoded value as "\\x11z\\xc0[d~\\xfcK\\xb1\\xf8\\x11z\\xc0[d~" if i pass its value which is "\\x11z\\xc0[d~\\xfcK\\xb1\\xf8\\x11z\\xc0[d~", i get correct answer 117ac05b647efc4bb1f8117ac05b647e

if i pass the variable holding "\\x11z\\xc0[d~\\xfcK\\xb1\\xf8\\x11z\\xc0[d~" i get wrong answer 225c7831317a5c7863305b647e5c7866634b5c7862315c7866385c7831317a5c7863305b647e22dn

Has it got something with this assignment base64_decoded := fmt.Sprintf("%q", base64_decode)

what am i doing wrong

Answer 1

Use the following code:

doc_id := "Can35qPeFkm9Xgmp9+aj3g=="
base64_decode, err := base64.StdEncoding.DecodeString(doc_id)
if err != nil {
    log.Fatal("error:", err)
}
fmt.Println(hex.EncodeToString(base64_decode))

Directly encode the bytes in base64_decode as hex.

The call to fmt.Sprintf("%q", base64_decode) returns a string with the bytes escaped per Go's string literal rules. In the general case, the bytes in the returned string are not equal to the bytes in base64_decode . For example, the input byte 0x11 is escaped to the four bytes \\x11 .

Answer 2

what happens is that the conversion that fmt.Sprintf("%q", base64_decode) makes to base64_decode, in this process to convert some bytes in the memory are lost.

here you below I leave an example: https://play.golang.org/p/pdQBp7NsvQM

doc_id := "Can35qPeFkm9Xgmp9+aj3g=="
var_encode := b64.StdEncoding.EncodeToString([]byte(doc_id))
fmt.Println(var_encode)
var_decode , _ := b64.StdEncoding.DecodeString(var_encode)
fmt.Println(string(var_decode))