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This article mainly introduces how to code Base64, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let the editor take you to understand it.

Base64 coding solution of self-defined character Table by Python

When it comes to decoding Base64 with custom character tables (Alphabet Table), we first need to know how Base64 encodes. Next, let's introduce how Base64 is encoded.

First of all, let's introduce the ASCII code table: 2. A byte is 8 bits. First, find the corresponding ASCII code, and then convert it into 8-bit binary, as follows:

The corresponding code value of H is 72, and its corresponding binary is 01001000.

E corresponds to a code value of 101, and its corresponding binary is: 01100101

L corresponds to a code value of 108, and its corresponding binary is: 01101100

L corresponds to a code value of 108, and its corresponding binary is: 01101100

O the corresponding code value is 111and its corresponding binary is: 01101111

The code value of Base64 is 0-63, so the code value of Base64 can be fully represented by 6-bit binary (for example, 000000 corresponding to decimal 0 ~ 111111 corresponding to 63). Change the above 8-bit binary into 6-bit binary. Since the above is 5-8-40 binary, it cannot be divisible by 6, so add a set of zeros to change it into 48 binary numbers (if it is still not divisible, continue to add 8 zeros It is actually a multiple of the least common multiple.

Original: 01001000 01100101 01101100 01101100 01101111 00000000

Now: 010010 000110 010101 101100 011011 000110 111100000000

3. Then calculate the decimal system from a set of 6 bits, compare it with the coding table of Base64, and then change the 0 of the last complement into =, and you can get the Base64 character.

010010 corresponding binary is: 18pr 18 corresponding Base64 characters are: s

000110 corresponding binary is: 6, 6 corresponds to Base64 character: G

010101 corresponds to binary: 21, 21 corresponds to Base64 character: v

101100 corresponding binary is: 44, 44 corresponding to Base64 character is: s

011011 corresponding binary is: 27, 27 corresponds to Base64 character: B

000110 corresponding binary is: 6, 6 corresponds to Base64 character: G

111100 corresponds to binary: 18, 18 corresponds to Base64 character: 8

The 0 of 000000 complement becomes =

So the corresponding Base64 code for Hello is: SGVsbG8=

In the above process, how many numbers correspond to how many Base64 characters. This is the Alphab Table of the Base64 standard. The standard Table is as follows:

What should we do when we use Python to solve the Base64 encoding of custom tables?

Let's move on to our main topic:

In fact, it is very simple, we can replace his original Table in our own Base64 with the maketrans class in str. Why?

We can analyze through the above coding process, we only use the table at the end of the coding process, but in fact, our original data information corresponding to the table is unchanged, so we can get normal Base64 coding by replacing the encoded content characters, and we can decode it.

So we get the following code:

Import base64import string str1 = "NhFpbUihxvB=" string1 = "ZYXABCDEFGHIJKLMNOPQRSTUVWzyxabcdefghijklmnopqrstuvw0123456789+/" string2 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" print (base64.b64decode (str1.translate (str.maketrans (string1,string2)

The above code is a replacement of the table with:

Code for "ZYXABCDEFGHIJKLMNOPQRSTUVWzyxabcdefghijklmnopqrstuvw0123456789+/".

Let's take a look at how to code.

Print (str (base64.b64encode (str2)). Translate (str.maketrans (string2,string1)

The above is the encryption code that uses the replacement character table.

Thank you for reading this article carefully. I hope the article "how to encode Base64" shared by the editor will be helpful to everyone. At the same time, I also hope you will support us and pay attention to the industry information channel. More related knowledge is waiting for you to learn!

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