Encryption-and-Decryption-using-Python

I recently learned about cryptography and several encryption and decryption algorithms using Python. Here is the code for the simplest "Encryption Decryption" little project. The main goal of this project is to learn how to implement various algorithms in Python; nevertheless, there are many better and stronger techniques than this code.

Outline

• Cryptography
• Terminologies in Cryptography
  • Plain Text
  • Cipher Text
  • Encryption
    • Symmetric Encryption
    • Asymmetric Encryption
    • Hashing
  • Decryption
• Installation
• Encryption Python Code
• Decryption Python Code
• Conclusion
• Contribution

Cryptography

Cryptography is defined as the art and science of concealing the message to introduce privacy and secrecy as recognized in information security.

Cryptography is traditionally used to hide messages from the eyes of certain users. Today, this use has an even greater advantage since communications via the Internet circulate in infrastructures whose reliability and confidentiality cannot be guaranteed. Cryptography is now used not only to protect the confidentiality of data but also to guarantee its integrity and authenticity.

Terminologies in Cryptography

Plain Text

The plain text message is the text which is readable and can be understood by all users. The plain text is the message which undergoes cryptography.

Cipher Text

Cipher text is the message obtained after applying cryptography on plain text.

Encryption

Encryption is the process of encoding the data. i.e converting plain text into ciphertext. This conversion is done with a key called an encryption key.

There are several data encryption approaches available to choose from.

Symmetric Encryption

Also called private-key cryptography or a secret key algorithm, this method requires the sender and the receiver to have access to the same key. So, the recipient needs to have the key before the message is decrypted. This method works best for closed systems, which have less risk of a third-party intrusion.

Asymmetric Encryption

Also called public-key cryptography, this method uses two keys for the encryption process, a public and a private key, which are mathematically linked. The user employs one key for encryption and the other for decryption, though it doesn’t matter which you choose first.

Hashing

Hashing generates a unique signature of fixed length for a data set or message. Each specific message has its unique hash, making minor changes to the information easily trackable. Data encrypted with hashing cannot be deciphered or reversed back into its original form. That’s why hashing is used only as a method of verifying data.

Decryption

Decryption is a process of decoding the encoded data. Converting the ciphertext into plain text. This process requires a key that we used for encryption.

Installation

You require python IDE on your laptop/PC.

Encryption Python Code

The plain text character is traversed one at a time. Each letter of plain text is replaced by a letter with some fixed number of positions down with alphabet. After the steps is followed, a new string is generated which is referred as cipher text. This algorithm is known as "Caeser Cipher".

# Create a function for Encryption algorithm
def encrpyt_message(text, key):
    encrypted_msg = "" # initially empty string is created
    for char in text:
    
        if char.isupper(): # check character is uppercase
            encrypted_msg += chr((((ord(char) + key) -65) % 26) + 65)

        elif char.islower(): # checks character is  lowercase
            encrypted_msg += chr((((ord(char) + key) -97) % 26) + 97)
            
        else:
            encrypted_msg += char # Number, spaces and special charcters are added as it is.

    return encrypted_msg
    
text = input("Please Enter your message: ") 
key = int(input("Enter key value: "))

print("Your message: ", text)

encrpyted_message = encrpyt_message(text, key)

print("The Encrypted message is: ", encrpyted_message)

Decryption Python Code

This code can only be used when we know key else we have try brute force method by trying for every key value. In this method we undo the previous code to get original message.

#Create a function for Decryption algorithm
def decrpyt_message(text, key):

    decrypted_msg = "" # initially empty string is created

    for char in text:    

        if char.isupper(): # check character is uppercase
            decrypted_msg += chr((((ord(char) - key) - 65) % 26) + 65)

        elif char.islower(): # checks character is  lowercase
            decrypted_msg += chr((((ord(char) -key) - 97) % 26) + 97)

        else:
            decrypted_msg += char # Number, spaces and special charcters are added as it is.

    return decrypted_msg

text = input("Please Enter your message: ") 
key = int(input("Enter key value: "))

print("Your message: ", text)

decrpyted_message = decrpyt_message(text, key)
print("The Decrypted message is: ", decrpyted_message)

Conclusion

In a world where cybercrimes are on the rise, it’s comforting to know that there are as many methods available to protect network security as there are ways of trying to penetrate it. Here I have shown one of the method using its algorithm. There is already different packages available in python which can be used for this. The main objective of this project is to learn how to implement various algorithms in Python.

Contribution

Pull requests are welcome. For major changes, please open and issue first to discuss what you would like to change.

Please make sure to update tests as appropriate.