Programming

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Strings / Encrypt

Symmetric

Data is encoded and decoded with the same key. 
 
"""Symmetric key Ecryption

Fernet library
    pip install cryptography

Data is encoded and decoded with the same key
The receiver needs the key for decryption
Less secure, man in the middle attack
"""

from cryptography.fernet import Fernet

key = Fernet.generate_key()
obj = Fernet(key) # intance

msg = "password_123"
encrypted = obj.encrypt(msg.encode())
decrypted = obj.decrypt(encrypted).decode()

print(encrypted) # b'gAAAAABjiKtn9fwSOUqfduUbWn4sSW=='
print(decrypted) # password_123

Asymmetric

Two keys, a public key and a private key. 
 
"""Encryption with asymmetric key

Rsa library
    pip install rsa
    
Two keys, a public key and a private key
No one has your private key
"""

import rsa

publicKey, privateKey = rsa.newkeys(512)

msg = "password_123"
encrypted = rsa.encrypt(msg.encode(), publicKey)
decrypted = rsa.decrypt(encrypted, privateKey).decode()

print(encrypted) # b'\x07z\x110\xb4\x05\xcb\xb8\x0b[FN2\xeb'
print(decrypted) # password_123

Applications (2)

Encrypt / decrypt password using restricted private key .pem file. 
 
"""Generate keys

Two keys, a public key and a private key
/app/restricted/keys.py
"""

import rsa, os

publicKey, privateKey = rsa.newkeys(512)
DIR = os.path.dirname(os.path.realpath(__file__))

with open(DIR + '/../public.pem', 'wb') as p:
    p.write(publicKey.save_pkcs1('PEM'))
    
with open(DIR + '/private.pem', 'wb') as p:
    p.write(privateKey.save_pkcs1('PEM'))
    
print(publicKey)
print(privateKey)

 
"""Encrypt text

Use .pem asymmetric public key
/app/encrypt.py
"""

import rsa, os

msg = "password_123555"
DIR = os.path.dirname(os.path.realpath(__file__))

with open(DIR + '/public.pem', 'rb') as p:
    publicKey = rsa.PublicKey.load_pkcs1(p.read())
    with open(DIR + '/encrypted.txt', 'wb') as f:
        encrypted = rsa.encrypt(msg.encode(), publicKey)
        f.write(encrypted)

print(encrypted)

 
"""Decrypt text

Public encrypted.bin containing encrypted password
Use private.pem restricted private key
/app/restricted/decrypt.py
"""

import rsa, os

DIR = os.path.dirname(os.path.realpath(__file__))

with open(DIR + '/../encrypted.txt', "rb") as f:
    encrypted = f.read()
        
    with open(DIR + '/private.pem', "rb") as p:
        privateKey = rsa.PrivateKey.load_pkcs1(p.read())
        decrypted = rsa.decrypt(encrypted, privateKey).decode()
        
print(encrypted)
print(privateKey)
print(decrypted)
App with cmd arguments to encrypt / decrpyt password 
 
"""Encrypt App (cmd)
Using an asymmetric public key

$ cd encrypt/app2
$ python app2.py encrypt pass_123
$ python decrypt master_pass
"""

import sys, rsa

if len(sys.argv) < 2:
    sys.exit("Too few arguments")

action = sys.argv[1]

if action == 'encrypt':
    msg = sys.argv[2]
    with open('./public.pem', 'rb') as p:
        publicKey = rsa.PublicKey.load_pkcs1(p.read())
        with open('./password.bin', 'wb') as f:
            encrypted = rsa.encrypt(msg.encode(), publicKey)
            f.write(encrypted)
            print(encrypted)

if action == 'decrypt':
    master_pass = sys.argv[2]
    if master_pass != 'master_pass':
        sys.exit('Wrong master password')
    with open('./password.bin', "rb") as f:
        encrypted = f.read()
    with open('./restricted/private.pem', "rb") as p:
        privateKey = rsa.PrivateKey.load_pkcs1(p.read())
        decrypted = rsa.decrypt(encrypted, privateKey).decode()
        print(decrypted)




References


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