Add padding characters to base32 encoded data

base32-padding.go

package main

import (
	"encoding/base32"
	"fmt"
	"strings"
)

func main() {
	data := "2246b2egzcc3ktvvoklo5cvzh4"

	// add padding characters
	padding := ""
	switch len(data) % 8 {
	case 2:
		padding = "======"
	case 4:
		padding = "===="
	case 5:
		padding = "==="
	case 7:
		padding = "=="
	}
	data = data + padding

	data = strings.ToUpper(data)
	bytes, err := base32.StdEncoding.DecodeString(data)
	if err != nil {
		fmt.Printf("oops: %s\n", err)
	}
	fmt.Println(bytes)

	data = base32.StdEncoding.EncodeToString(bytes)
	fmt.Println(data)
}

Thank you past self. I searched for "base32 padding" and found my old Gist.

Hey, just ran across this. Are you sure the 7 case shouldn't be just one '='?

(8 - (len(data) % 8)) % 8 is more accurate/concise.

>>> from base64 import b32encode
>>> b32encode(b"A")
b'IE======'
>>> (8 - (len("IE") % 8)) % 8
6
>>> b32encode(b"AA")
b'IFAQ===='
>>> (8 - (len("IFAQ") % 8)) % 8
4
>>> b32encode(b"AAA")
b'IFAUC==='
>>> (8 - (len("IFAUC") % 8)) % 8
3
>>> b32encode(b"AAAA")
b'IFAUCQI='
>>> (8 - (len("IFAUCQI") % 8)) % 8
1
>>> b32encode(b"AAAAA")
b'IFAUCQKB'
>>> (8 - (len("IFAUCQKB") % 8)) % 8
0
>>> 

(8 - (len(data) % 8)) % 8 is more accurate/concise.

>>> from base64 import b32encode
>>> b32encode(b"A")
b'IE======'
>>> (8 - (len("IE") % 8)) % 8
6
>>> b32encode(b"AA")
b'IFAQ===='
>>> (8 - (len("IFAQ") % 8)) % 8
4
>>> b32encode(b"AAA")
b'IFAUC==='
>>> (8 - (len("IFAUC") % 8)) % 8
3
>>> b32encode(b"AAAA")
b'IFAUCQI='
>>> (8 - (len("IFAUCQI") % 8)) % 8
1
>>> b32encode(b"AAAAA")
b'IFAUCQKB'
>>> (8 - (len("IFAUCQKB") % 8)) % 8
0
>>> 

big thanks!!

TS version

/**
 * Add Base32 Padding
 *
 * @link https://gist.github.com/mndrix/b2494ebefd916c71ded5
 * @return {string}
 */
export const addBase32Padding = (data: string): string => {
  let padding = '';

  switch (data.length % 8) {
    case 2:
      padding = '======';
      break;
    case 4:
      padding = '====';
      break;
    case 5:
      padding = '===';
      break;
    case 7:
      padding = '=';
      break;
  }

  return data + padding;
};