encrypt-decrypt-file

Simple file encryption and decryption using AES-256-GCM with password-based key derivation (scrypt).

Features

• Strong Encryption: Uses AES-256-GCM for authenticated encryption
• Secure Key Derivation: Implements scrypt for password-based key derivation
• Simple API: Easy-to-use functions for encrypting and decrypting files
• CLI Support: Can be used as a command-line tool
• Node.js Native: Built with Node.js crypto module (Node 18+)

Installation

npm install @codegeekdevs/encrypt-decrypt-file

Usage

As a Module

const { encryptFile, decryptFile } = require('encrypt-decrypt-file');

// Encrypt a file
encryptFile('./myfile.txt', 'my-secret-password', './myfile.txt.enc');

// Decrypt a file
decryptFile('./myfile.txt.enc', 'my-secret-password', './myfile-decrypted.txt');

As a CLI Tool

# Encrypt a file
node encrypt-decrypt-file.js encrypt ./myfile.txt "my-secret-password"

# Decrypt a file
node encrypt-decrypt-file.js decrypt ./myfile.txt.enc "my-secret-password"

# Specify custom output path
node encrypt-decrypt-file.js encrypt ./myfile.txt "my-secret-password" ./custom-output.enc

API

encryptFile(inputPath, password, outputPath)

Encrypts a file using AES-256-GCM.

Parameters:

• inputPath (string): Path to the file to encrypt
• password (string): Password for encryption
• outputPath (string, optional): Output path for encrypted file. Defaults to ${inputPath}.enc

Returns: String - Path to the encrypted file

Example:

const outputPath = encryptFile('./document.pdf', 'super-secret-password');
console.log(`File encrypted at: ${outputPath}`);

decryptFile(inputPath, password, outputPath)

Decrypts a file that was encrypted with encryptFile.

Parameters:

• inputPath (string): Path to the encrypted file
• password (string): Password used for encryption
• outputPath (string, optional): Output path for decrypted file. Auto-generated if not provided

Returns: String - Path to the decrypted file

Example:

const outputPath = decryptFile('./document.pdf.enc', 'super-secret-password');
console.log(`File decrypted at: ${outputPath}`);

Technical Details

Encryption Algorithm

• Algorithm: AES-256-GCM (Galois/Counter Mode)
• Key Length: 256 bits (32 bytes)
• IV Length: 96 bits (12 bytes)
• Auth Tag: 128 bits (16 bytes)

Key Derivation

• Function: scrypt
• Parameters:
  • N: 16384
  • r: 8
  • p: 1
  • Salt: 128 bits (16 bytes, randomly generated)

File Format

Encrypted files have the following structure:

[ "ENC1" (4 bytes) | SALT (16 bytes) | IV (12 bytes) | CIPHERTEXT | AUTH TAG (16 bytes) ]

The "ENC1" magic bytes allow for format versioning.

Requirements

• Node.js 18.0.0 or higher

Security Considerations

• Always use strong, unique passwords
• Keep your passwords secure and never commit them to version control
• The security of the encrypted data depends entirely on the strength of your password
• Use environment variables or secure vaults for password management in production

License

MIT

Contributing

Issues and pull requests are welcome!

Author

David Faltermier, CodeGeek