LlamaCrypt

A secure file encryption tool using AES-256-GCM with Argon2id key derivation.

Features

• Password-based encryption: Encrypt files with a password you choose
• Key-based encryption: Encrypt files with an auto-generated key (safer for sensitive data)
• Secure by default: AES-256-GCM encryption with Argon2id key derivation (64 MiB memory)
• Streaming: Handles large files efficiently without loading entire file into memory
• Plain-language errors: Clear error messages, no technical jargon

Installation

Prerequisites

• Java 17 or later
• Gradle 8.x (or use the included wrapper)

Build from source

./gradlew shadowJar

This creates build/libs/lcrypt.jar

Or download release

Download the latest lcrypt.jar from the releases page.

Usage

lcrypt <command> <filename> [password]

Commands

Command	Description
encrypt	Encrypt a file with a password
encrypt-key	Encrypt a file with an auto-generated key
decrypt	Decrypt an encrypted file

Examples

Encrypt with password:

java -jar lcrypt.jar encrypt myfile.txt mypassword

Encrypt with auto-generated key:

java -jar lcrypt.jar encrypt-key secret.docx

This generates a key that you must save securely. If you lose it, your data cannot be recovered.

Decrypt a file:

java -jar lcrypt.jar decrypt myfile.txt.lcrypt mypassword

Interactive mode

If you omit the password, LlamaCrypt will prompt you:

java -jar lcrypt.jar encrypt myfile.txt
Enter password: ********

Security Notes

• Files are encrypted with AES-256-GCM (authenticated encryption)
• Passwords are derived using Argon2id (memory-hard, GPU-resistant)
• Sensitive data is cleared from memory after use
• Original files are never modified or deleted
• Encrypted files have .lcrypt extension

File Format

Encrypted files (.lcrypt) contain:

• Magic bytes: LCRY
• Argon2id parameters (memory: 64 MiB, iterations: 3)
• Salt and IV (unique per encryption)
• Encrypted content with authentication tag

Troubleshooting

"File not found"

• Check the file path is correct
• Use absolute paths if relative paths don't work

"Incorrect password or the file is corrupted"

• Verify you used the correct password
• Check the file wasn't modified after encryption

"Not a valid encrypted file"

• Make sure you're decrypting a .lcrypt file
• File may be corrupted or not a LlamaCrypt file

License

MIT License