Introduction to python rsa encryption, decryption and base64 encoding and decoding

Recently, there is a need to study the security of RSA encryption and decryption; I looked at example articles on Baidu online, and there are few articles that describe how to save, transmit, and print encrypted text information, and they are all the same. Directly in a script, the encrypted text information is assigned to the variable , and then decryption is called immediately. After carefully thinking about the process of RSA encryption and decryption, I determined that there are two ends, one end is the encryption end, and the other end is the decryption end, which are generally not on the same machine. Here, I only simulated saving it in a file and then reading it out; the method of transmitting it through the network is similar.

The ciphertext encrypted with RSA cannot be directly displayed as text because there are some binary data that cannot be displayed using text information encoding. For saving, network transmission, and printing without garbled characters, base64 encoding is required for conversion; base64 encoding and decoding can convert some binary data that cannot be directly encoded with file information into regular binary data.

#/usr/bin/env python
# -*- coding: utf-8 -*-
import rsa
import sys
import base64

# 打印 python 版本 与 windows 系统编码
print("---- 1 ----")
print(sys.version)
print(sys.getdefaultencoding())
print(sys.getfilesystemencoding())

# 先生成一对密钥，然后保存.pem格式文件，当然也可以直接使用
print("---- 2 ----")
(pubkey, privkey) = rsa.newkeys(1024)
pub = pubkey.save_pkcs1()
print(type(pub))
pubfile = open('public.pem','w+')
pubfile.write(pub.decode('utf-8'))
pubfile.close()

print("---- 3 ----")
pri = privkey.save_pkcs1()
print(type(pri))
prifile = open('private.pem','w+')
prifile.write(pri.decode('utf-8'))
prifile.close()

# load公钥和密钥
print("---- 4 ----")
message = 'dPabdbGDpFTrwwgydVafdlsadlfsal%46645645s'
print('message:',type(message))
with open('public.pem') as publickfile:
    p = publickfile.read()
    print(type(p))
    pubkey = rsa.PublicKey.load_pkcs1(p.encode('utf-8'))
with open('private.pem') as privatefile:
    p = privatefile.read()
    print(type(p))
    privkey = rsa.PrivateKey.load_pkcs1(p.encode('utf-8'))

# 用公钥加密、再用私钥解密
crypto = rsa.encrypt(message.encode('utf-8'),pubkey)
print(crypto)

print("---- 5 ----")
print('crypto:',type(crypto))
print('cry_base64:',base64.encodestring(crypto))
print('cry_base64_utf8:',base64.encodestring(crypto).decode('utf-8'))
# 保存到本地文件
cry_file = open('cry_file.txt','w+')
cry_file.write(base64.encodestring(crypto).decode('utf-8'))
cry_file.close()

print("---- 6 ----")
# 从本地文件读取
cry_file = open('cry_file.txt','r')
cry_text = ''
for i in cry_file.readlines():
    cry_text += i

print('cry_text_type:',type(cry_text))
print('cry_text:',cry_text)
print('cry_base64:',cry_text.encode('utf-8'))
crypto_tra = base64.decodestring(cry_text.encode('utf-8'))

print("---- 7 ----")
assert crypto == crypto_tra
print(crypto)

print("---- 8 ----")
plaintext = rsa.decrypt(crypto,privkey)
assert  message == plaintext.decode('utf-8')
print(plaintext.decode('utf-8'))

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