Base64 encoding is a process of converting binary data to an ASCII string format by converting that binary data into a 6-bit character representation. The Base64 method of encoding is used when binary data, such as images or video, is transmitted over systems that are designed to transmit data in a plain-text [ASCII] format.
Follow this
link for further details about understanding and working of base64
encoding.
For those who want to implement base64
encoding from scratch for the sake of understanding, here's the code that encodes the string to base64
.
encoder.py
#!/usr/bin/env python3.10
class Base64Encoder:
#base64Encoding maps integer to the encoded text since its a list here the index act as the key
base64Encoding:list = None
#data must be type of str or bytes
def encode[data]->str:
#data = data.encode["UTF-8"]
if not isinstance[data, str] and not isinstance[data, bytes]:
raise AttributeError[f"Expected {type['']} or {type[b'']} but found {type[data]}"]
if isinstance[data, str]:
data = data.encode["ascii"]
if Base64Encoder.base64Encoding == None:
#construction base64Encoding
Base64Encoder.base64Encoding = list[]
#mapping A-Z
for key in range[0, 26]:
Base64Encoder.base64Encoding.append[chr[key + 65]]
#mapping a-z
for key in range[0, 26]:
Base64Encoder.base64Encoding.append[chr[key + 97]]
#mapping 0-9
for key in range[0, 10]:
Base64Encoder.base64Encoding.append[chr[key + 48]]
#mapping +
Base64Encoder.base64Encoding.append['+']
#mapping /
Base64Encoder.base64Encoding.append['/']
if len[data] == 0:
return ""
length=len[data]
bytes_to_append = -[length%3]+[3 if length%3 != 0 else 0]
#print[f"{bytes_to_append=}"]
binary_list = []
for s in data:
ascii_value = s
binary = f"{ascii_value:08b}"
#binary = bin[ascii_value][2:]
#print[s, binary, type[binary]]
for bit in binary:
binary_list.append[bit]
length=len[binary_list]
bits_to_append = -[length%6] + [6 if length%6 != 0 else 0]
binary_list.extend[[0]*bits_to_append]
#print[f"{binary_list=}"]
base64 = []
value = 0
for index, bit in enumerate[reversed[binary_list]]:
#print [f"{bit=}"]
#converting block of 6 bits to integer value
value += [ 2**[index%6] if bit=='1' else 0]
#print[f"{value=}"]
#print[bit, end = '']
if [index+1]%6 == 0:
base64.append[Base64Encoder.base64Encoding[value]]
#print[' ', end=""]
#resetting value
value = 0
pass
#print[]
#padding if there is less bytes and returning the result
return ''.join[reversed[base64]]+''.join[['=']*bytes_to_append]
testEncoder.py
#!/usr/bin/env python3.10
from encoder import Base64Encoder
if __name__ == "__main__":
print[Base64Encoder.encode["Hello"]]
print[Base64Encoder.encode["1 2 10 13 -7"]]
print[Base64Encoder.encode["A"]]
with open["image.jpg", "rb"] as file_data:
print[Base64Encoder.encode[file_data.read[]]]
Output:
$ ./testEncoder.py
SGVsbG8=
MSAyIDEwIDEzIC03
QQ==
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The Base64 encoding is used to convert bytes that have binary or text data into ASCII characters. Encoding prevents the data from getting corrupted when it is transferred or processed through a text-only system. In this article, we will discuss about Base64 encoding and decoding and its uses to encode and decode binary and text data.
Base64 encoding:
It is a type of conversion of bytes to ASCII characters. the list of available Base64 characters are mentioned below:
- 26 uppercase letters
- 26 lowercase letters
- 10 numbers
- + and / for new lines
Each Base64 character
represents 6 bits of data. it is also important to note that it is not meant for encryption for obvious reasons.
To convert a string into a Base64 character the following steps should be followed:
- Get the ASCII value of each character in the string.
- Compute the 8-bit binary equivalent of the ASCII values
- Convert the 8-bit characters chunk into chunks of 6 bits by re-grouping the digits
- Convert the 6-bit binary groups to their respective decimal values.
- Use the Base64 encoding table to align the respective Base64 values for each decimal value.
The below image provides us with a Base64 encoding table.
Image Source: Wikipedia
Using python to encode strings:
In Python the base64 module is used to encode and decode data. First, the
strings are converted into byte-like objects and then encoded using the base64 module. The below example shows the implementation of encoding strings isn’t base64 characters.
Example:
import
base64
sample_string
=
"GeeksForGeeks is the best"
sample_string_bytes
=
sample_string.encode[
"ascii"
]
base64_bytes
=
base64.b64encode[sample_string_bytes]
base64_string
=
base64_bytes.decode[
"ascii"
]
print
[f
"Encoded string: {base64_string}"
]
Output:
Encoded string: R2Vla3NGb3JHZWVrcyBpcyB0aGUgYmVzdA==
Using Python to decode strings:
Decoding Base64 string is exactly opposite to that of encoding. First we convert the Base64 strings into unencoded data bytes followed by conversion into bytes-like object into a string. The below example depicts the decoding of the above example encode string output.
Example:
import
base64
base64_string
=
" R2Vla3NGb3JHZWVrcyBpcyB0aGUgYmVzdA =="
base64_bytes
=
base64_string.encode[
"ascii"
]
sample_string_bytes
=
base64.b64decode[base64_bytes]
sample_string
=
sample_string_bytes.decode[
"ascii"
]
print
[f
"Decoded string: {sample_string}"
]
Output:
Decoded string: GeeksForGeeks is the best