Go Base64
last modified April 11, 2024
In this artile we show how to encode and decode binary data to and from Base64 in Golang.
$ go version go version go1.22.2 linux/amd64
We use Go version 1.22.2.
Encoding is the process of converting data from one form to another. Decoding is the reverse process.
Base64 encoding schemes are commonly used when we need to store and transfer binary data over media that are designed to deal with text. For instance, Base64 encoding is used in email attachments.
In Go, we use the encoding/base64 package for base64 encoding and
decoding. It implements the base encoding specified by RFC 4648.
The following is the Base 64 Alphabet.
Value Encoding Value Encoding Value Encoding Value Encoding 0 A 17 R 34 i 51 z 1 B 18 S 35 j 52 0 2 C 19 T 36 k 53 1 3 D 20 U 37 l 54 2 4 E 21 V 38 m 55 3 5 F 22 W 39 n 56 4 6 G 23 X 40 o 57 5 7 H 24 Y 41 p 58 6 8 I 25 Z 42 q 59 7 9 J 26 a 43 r 60 8 10 K 27 b 44 s 61 9 11 L 28 c 45 t 62 + 12 M 29 d 46 u 63 / 13 N 30 e 47 v 14 O 31 f 48 w (pad) = 15 P 32 g 49 x 16 Q 33 h 50 y
Go base64.StdEncoding.Encode
The base64.StdEncoding.Encode function encodes the source slice of
bytes to the destination slice of bytes.
func (*base64.Encoding).Encode(dst []byte, src []byte)
This is the syntax of the function. The destination is the first parameter, the source is the second.
package main
import (
"encoding/base64"
"fmt"
)
func main() {
msg := "one 🐘 and three 🐋"
fmt.Println(msg)
data := make([]byte, base64.StdEncoding.EncodedLen(len(msg)))
base64.StdEncoding.Encode(data, []byte(msg))
fmt.Println(data)
encoded := string(data)
fmt.Println(encoded)
}
The program encodes a string to Base64 encoding
msg := "one 🐘 and three 🐋"
We have a string with two emojis.
data := make([]byte, base64.StdEncoding.EncodedLen(len(msg)))
With base64.StdEncoding.EncodedLen function returns the length in
bytes of the base64 encoding of an input buffer.
base64.StdEncoding.Encode(data, []byte(msg))
We encode the data with base64.StdEncoding.Encode.
$ go run main.go one 🐘 and three 🐋 [98 50 53 108 73 80 67 102 107 74 103 103 89 87 53 ... 115 61] b25lIPCfkJggYW5kIHRocmVlIPCfkIs=
Go base64.StdEncoding.Decode
The base64.StdEncoding.Decode function decodes the source slice of
bytes to the destination slice of bytes.
package main
import (
"encoding/base64"
"fmt"
"log"
)
func main() {
encoded := "b25lIPCfkJggYW5kIHRocmVlIPCfkIs="
fmt.Println(encoded)
data := make([]byte, base64.StdEncoding.DecodedLen(len(encoded)))
n, err := base64.StdEncoding.Decode(data, []byte(encoded))
fmt.Println(data)
if err != nil {
log.Fatal(err)
}
fmt.Println(string(data[:n]))
}
The program decodes a Base64 encoded string.
encoded := "b25lIPCfkJggYW5kIHRocmVlIPCfkIs="
This is the encoded string.
data := make([]byte, base64.StdEncoding.DecodedLen(len(encoded)))
We create a destination slice of bytes for a buffer.
n, err := base64.StdEncoding.Decode(data, []byte(encoded))
The data is decoded with base64.StdEncoding.Decode.
$ go run main.go b25lIPCfkJggYW5kIHRocmVlIPCfkIs= [111 110 101 32 240 159 144 152 32 97 110 100 ... 240 159 144 139 0] one 🐘 and three 🐋
Go Base64 encode/decode string
The base64.StdEncoding.EncodeToString function returns the base64
encoding of a string. The base64.StdEncoding.DecodeString returns
the bytes represented by the Base64 encoded string.
package main
import (
"encoding/base64"
"fmt"
"log"
)
func main() {
msg := "one 🐘 and three 🐋"
fmt.Println(msg)
str := base64.StdEncoding.EncodeToString([]byte(msg))
fmt.Println(str)
data, err := base64.StdEncoding.DecodeString(str)
if err != nil {
log.Fatal(err)
}
fmt.Println(data)
fmt.Println(string(data))
}
The program Base64 encodes and decodes a string.
$ go run main.go one 🐘 and three 🐋 b25lIPCfkJggYW5kIHRocmVlIPCfkIs= [111 110 101 32 240 159 144 152 32 ... 32 240 159 144 139] one 🐘 and three 🐋
Source
Go encoding/base64 package - reference
In this article have worked with Base64 encoding in Golang.
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