JSON module, hashlib, Base64

One 、JSON modular

1） brief introduction

json Official website ：https://www.json.org/

2） characteristic

Lightweight text data exchange format

Easy for human to read and write , At the same time, it is also easy for machine analysis and generation

Web The most ideal data exchange format in the world

Two 、 Front and back end data exchange

1） brief introduction

At present, the interactive use of end-to-end data before and after Internet development is basically json

3、 ... and 、JSON Rule of grammar

1） grammar

1. Data consists of key value pairs

2. Key value pairs are separated by commas

3. Save objects in braces

4. Save the array in square brackets

2） matters needing attention

1. String must be in double quotes （ namely ：””） To include

2. The value can be a string 、 Numbers 、true、false、null、 list , Or a dictionary

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3）JSON modular API

1.json.dumps(obj take python Data into json

Tips ： ndent Achieve indent ,ensure_ascii Whether to use ascii analysis

2.json.loads(s) take json Data to python The data of

3.json.dump(obj, fp) Convert to json And save it to a file

4.json.load(fp) Read from file json, And into python data

Four 、hashlib modular

1） Introduction to data security

2) Concept

1. Symmetric encryption ： Data encryption and decryption use the same key

2. Asymmetric encryption ： Two different keys are used for encryption and decryption , Public keys are used to encrypt data , The private key is used to decrypt data

3. One way encryption ： Only data can be encrypted , And not decrypt the data

3）HASH

4） characteristic

1. Irreversible ： The original data cannot be restored according to the hash value

2. Fixed length output ： No matter how long the original data is entered , The result is the same length

3. Resistance to change ： Small changes in input , Even if there is only one character , It's going to cause a huge change in the outcome

4. Strong collision ： It's hard to find two different pieces of data , Make them produce hash Value consistent , Next to impossible

5）hashlib modular API

1.Hashlib The module provides a number of hash Algorithm , There are mainly ：

1.md5

2.SHA series ：sha1, sha224, sha256, sha384, sha512

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import hashlib

res = hashlib.new('md5', ' Naughty bag '.encode())
print(res)  # <md5 HASH object @ 0x7fa67c687580>
print(res.digest())  # b'\x1f(\xa5\xb8v\xbf\x96\x10\x01\xc8a\xcb\x86=\xb9m'
print(res.hexdigest())  # 1f28a5b876bf961001c861cb863db96d

res = hashlib.sha256(' Naughty bag '.encode())
print(res)  # <sha256 HASH object @ 0x7fce6efe9508>
print(res.hexdigest())  # b38d80a1442acd6fc7e5254dbc610a84200c956ffff6d80d5f846ce3f8948b62

# update: Don't write the value first , When you need to update once , It can be used multiple times 
res = hashlib.sha1()

res.update(' spirit '.encode())
print(res.hexdigest())  # 6ff8f715acf0e19d02f416b34aa6cfb0fb521f70

res.update(' Que Linguo  '.encode())
print(res.hexdigest())  # ddd2186e6d3d6be4bf9d01c68280b74483ae3858

"""
 register ： Original account number + The original password ---->md5 encryption ----> Save the encrypted string 
 Sign in ： Original account number + The original password ---->md5 encryption ----> To the background , Verify whether the encrypted strings are equal 
"""

####  5、 ... and 、base64 modular 

##### 1） brief introduction 

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##### 2） characteristic 

1. Used to convert non ASCII The character data is converted to ASCII A method of characters 

2. Often used to correct URL The coding 

3. You can convert non printable binary data into printable strings 

##### 3）base64 modular API

1.Base64 The encoded data may contain  + /  Two symbols , If the encoded data is used for URL Or the system path of the file ,
 May lead to Bug, therefore base The module provides special coding url Methods 

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##### 4) Encode and decode strings 

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##### 5) Yes URL Encoding and decoding 

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import base64

data = ‘ Hello, Tanzhou ’ # 1 Chinese is three bytes ,base64 Is three bytes to 4 Bytes
res = base64.b64encode(data.encode())
print(res) # b’5L2g5aW95r2t5bee’

The number of bytes is not 3 Multiple , Less bytes are used = completion
data = ‘hello world’ # 11 Bytes
res = base64.b64encode(data.encode())
print(res) # b’aGVsbG8gd29ybGQ=’

data = ‘hello worl’ # 10 Bytes
res = base64.b64encode(data.encode())
print(res) # b’aGVsbG8gd29ybA==’

# If the encoded data is used for url Or the path of the file , choice base64.urlsafe_b64encode() Way code
data = ‘hello world Hello, Tanzhou I am me , Different fireworks ’
res = base64.b64encode(data.encode())
print(res)
res = base64.urlsafe_b64encode(data.encode())
print(res) # / become _,+ become -

# decode
data = ‘ Hello, Tanzhou ’ # 1 Chinese is three bytes ,base64 Is three bytes to 4 Bytes
res = base64.b64encode(data.encode())
print(res) # b’5L2g5aW95r2t5bee’
print(base64.b64decode(res).decode()) # b’\xe4\xbd\xa0\xe5\xa5\xbd\xe6\xbd\xad\xe5\xb7\x9e’