Combine Stored Key and Password-Based Key Derivation Methods into a Single Encryption Script

[Vikranth3140]

This pull request merges the two separate encryption methods—stored key encryption and password-based key derivation—into a single, unified script. Users can now choose their preferred key management method via command-line options, enhancing flexibility and usability.

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Key Changes:

• Unified Encryption Script:

  • Combined the functionalities of both the stored key and password-based key derivation scripts into one file (script.py).
  • Users can select the encryption/decryption method at runtime using command-line options.

• Command-Line Interface Enhancements:

  • New Options Added:
  • -k for stored key method.
  • -p for password-based key derivation method.
  • Usage Instructions Updated:
  • Generate a Key:
    • python script.py -g
  • Encrypt a File:
    • Using stored key: python script.py -e -k <filename>
    • Using password: python script.py -e -p <filename>
  • Decrypt a File:
    • Using stored key: python script.py -d -k <filename>.encrypted
    • Using password: python script.py -d -p <filename>.encrypted

• Modified Functions:

  • encrypt_file(file_name, key_method):
  • Now accepts key_method parameter to determine the encryption approach.
  • Handles both key methods within a single function.
  • decrypt_file(encrypted_file_name, key_method):
  • Similarly updated to handle decryption for both methods.
  • main():
  • Adjusted to parse the new command-line arguments and direct the flow accordingly.

• Password-Based Key Derivation Improvements:

  • Dynamic Salt Generation:
  • Generates a unique, random 16-byte salt for each encryption operation.
  • Enhances security by ensuring different keys even with the same password.
  • Salt Storage:
  • The salt is prepended to the encrypted file, making it available during decryption.
  • Password Confirmation:
  • Added a password confirmation prompt during encryption to prevent typos.

• Error Handling and User Feedback:

  • Improved error messages for better user guidance.
  • Added checks for common errors like missing files, incorrect passwords, or corrupted data.
  • Ensured that invalid options prompt the user with correct usage instructions.

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Benefits:

• Flexibility:

  • Users can choose the encryption method that best suits their needs—either the convenience of a stored key or the security of a password-derived key.

• Simplified Maintenance:

  • Consolidating both methods into a single script reduces redundancy and simplifies updates.

• Enhanced Security:

  • Password-based encryption now uses unique salts, strengthening resistance against certain cryptographic attacks.

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Usage Instructions:

Generate a Fernet Key (for Stored Key Method):

python script.py -g

• Generates a new Fernet key and saves it to secret.key.
• Necessary for encryption/decryption using the stored key method.

Encrypt a File:

• Using Stored Key Method:

  python script.py -e -k <filename>

• Using Password-Based Key Derivation:

  python script.py -e -p <filename>

• Process:

  • For password-based encryption, the script prompts for a password and confirmation.
  • Encrypted files are saved with a .encrypted extension.

Decrypt a File:

• Using Stored Key Method:

  python script.py -d -k <filename>.encrypted

• Using Password-Based Key Derivation:

  python script.py -d -p <filename>.encrypted

• Process:

  • For password-based decryption, the script prompts for the password used during encryption.
  • Decrypted files are saved with a .decrypted extension or by removing .encrypted.

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Important Considerations:

• Security Recommendations:

  • Stored Key Method:
  • Keep secret.key secure; unauthorized access can compromise encrypted data.
  • Password-Based Method:
  • Encourage users to use strong, unique passwords.
  • Passwords are not stored; if forgotten, data cannot be recovered.

• Salt Handling:

  • Salts are 16 bytes in size and are prepended to encrypted files.
  • During decryption, the salt is extracted from the file.

• Compatibility:

  • The script maintains compatibility with files encrypted using the previous separate scripts, as long as the same method is used.

• Error Messages:

  • Informative messages help users troubleshoot issues like incorrect passwords or missing files.