How to do Text Encryption?

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Hi everyone.

How to do text encryption? Instead of the file itself to be encrypted, I’m trying to find out on how to encrypt only specific text inside the file.

It would be great if someone can explain briefly or point me to a guide about this.

Thank you.

2

At a very high level?

  1. Open file
  2. Scan for text to be encrypted.
  3. Encrypt it, and replace that instance of the plain-text with the encrypted text.
  4. Repeat for all other instances of target text.
  5. Repeat for all other target texts to be encrypted.
  6. Save.
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How to Encrypt a Word in a Text File

Lets say you have a text file, and want to encrypt the word “Secret”.

Steps

  1. Generate an encryption key
  2. open the file
  3. Search through each word
  4. If word equals target than encrypt word with key
  5. Save changes to file

Project Requirements

  • cryptography - This package provides cryptographic recipes and primitives to Python developers.

Directory Structure

encryption/
├── app/
│   ├── cryptKey.key
│   ├── decrypt_me.py
│   ├── encrypted_text.txt
│   ├── encrypt_me.py
│   ├── generate_key.py
│   ├── original_text.txt

Project Files

  • cryptKey - this is your secret key which is used for encryption
  • decrypt_me.py - this file decrypts a word in a file
  • encrypted.txt - This will be the output file of the encrypted text
  • encrypt_me.py - This file encrypts a word in a file
  • generate_key.py - This file generates the secret key (cryptKey.key)
  • original_text.txt - This file is the original plain text file.

original_text.txt

This file contains a word that you want to encrypt; “Secret .”

image

generate_key.py

First, lets generate a secret key, and save it to file.

# generate_key.py

from cryptography.fernet import Fernet

# generate encryption key:
key = Fernet.generate_key()

# Write key to file:
with open('crypt_key.key', 'wb') as filekey:
    filekey.write(key)

Your key should look something like the screen shot below:

image

encrypt_me.py

Now, lets open the original_text file, and encrypt the word Secret :

# encrypt_me.py
from cryptography.fernet import Fernet


# Open cryptKey from file:
with open('cryptKey.key', 'rb') as filekey:
    crypt_key = filekey.read()


# Using the encryption key
fernet = Fernet(crypt_key)

# Open File:
with open('original_text.txt', 'r') as file:
    pageFile = file.read().split(' ')
    
    # Print original file
    print(pageFile)

    # Iterate through file:
    for i, word in enumerate(pageFile):
        if word == 'Secret':
             pageFile[i] = fernet.encrypt(word.encode())
    
    # show encrypted word
    print(pageFile)

    result = ' '.join([word.decode() if isinstance(word, bytes) else word for word in pageFile])

    # Save results as
    with open('encrypted_text.txt', 'w') as file:
        file.write(result)

Screen Shot

image
image1290×63 10.6 KB

decrypt_me.py

Now lets decrypt the word in the file:

# decrypt_me.py
from cryptography.fernet import Fernet

# Write key to file:
with open('cryptKey.key', 'rb') as filekey:
    crypt_key = filekey.read()

# Using the generated key
fernet = Fernet(crypt_key)

# Open File:
with open('encrypted_text.txt','r') as file:    
    pageFile = file.read().split(' ')
    
    # Show encrypted file
    print(pageFile)    
    
    # Decrypt secret word   
    secretWord = fernet.decrypt(bytes(pageFile[-1], 'utf8')).decode()
    pageFile[-1] = secretWord
    
    # Show results
    print(pageFile)

Screen Shot

image
image1286×69 11 KB

Conclusion

I hope this helps answer your question on “how to encrypt only specific text inside the file”. If you have any questions or concerns, please don’t hesitate to ask. If anyone catches any bugs or errors please let me know!

Best regards,

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