# Overview

The `binascii` module in Python contains many functions that help convert data between binary and ASCII representations. `binascii` is necessary because the conversion of big data is slow in Python. 

The function `.a2b_base64` converts data of type `base64` to binary and returns bytes. 

# What is base64 data?

`base64` data is a way of representing data as shown in the table below: 


Base64 Representation

When a string is converted to `base64` data type, each character of the string is mapped to a number in `base64`, which is then represented as an 8-bit binary number.  

`base64` data is commonly used in mail servers, as it decreases the likelihood of data becoming corrupted during transmission; this is because `base64` data type allows us to convert both binary or text data type into ASCII characters.﻿

# Example

In the code below, we import the `binascii` and `base64` modules. First, we convert our string data to ASCII using the `encode()` method. The returned data is input into `base64.b64encode()` to convert our string completely into `base64` data type. Once the string has been converted, it can be input into `binascii.a2b_base64()` to convert to bytes.

The `binascii.a2b_base64()` method is used in cryptography to generate keys and authenticate credentials. 

import binascii
import base64

message = "Hello World!"
encode_string = message.encode('ascii')
b64_string = base64.b64encode(encode_string)

string = binascii.a2b_base64(b64_string)
print(string)

What is binascii.a2b_base64 in Python?

Converts base64 data to bytes, facilitating cryptographic tasks such as key generation and credential authentication.

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
15	P	32	g	49	x
16	Q	33	h	50	y