Nacrypt

A simple and easy-to-use file encryption utility.

Installation

Nacrypt is available on the AUR To install it simply use your favorite AUR helper:

$ paru/yay -S nacrypt

Alternative installation methods:

(for all of the following methods you must have libsodium installed on your system)

You can install nacrypt as a binary crate with cargo:

$ cargo install nacrypt

Or alternatively build from source:

$ cargo build --release

Usage

Usage: nacrypt [OPTIONS] [INPUT]

Arguments:
  [INPUT]  The input file

Options:
  -o, --output <OUTPUT>                File to output to
  -e, --encrypt                        [optional] Specify encrypt mode
  -d, --decrypt                        [optional] Specify decrypt mode
  -g, --gen-key                        Generate a new keypair
  -R, --regen-public                   Regenerate your public key if it was lost
  -r, --recipient <RECIPIENTS>         Encrypt this file to recipient's public key
  -p, --private-key <SECRET_KEY_PATH>  Specify custom path to private key to use
  -v, --verbose                        Display verbose output
  -h, --help                           Print help
  -V, --version                        Print version

Symmetric example

$ nacrypt input.txt -o encrypted.txt.enc
Please create a password:
Please re-enter the password:
Deriving key.. done
$ nacrypt encrypted.txt.enc -o decrypted.txt
Please enter password for encrypted.txt.enc:
Deriving key.. done
$ md5sum input.txt decrypted.txt
# hashes match

# Encrypt this file to the recipients, multiple can be specified with -r
$ nacrypt input.txt -o encrypted.txt.enc -r nacrypt_pubkey_ljuqJBpGxwO0i8WL3hLaXjxCc3Eg1iR6EGGEfc5ln3c= -r nacrypt_pubkey_8OkScyA4nWI8odCBftmcwFyaU3SxtRrFFeFLlMyZ0x8=

# On the side of one of the recipients:
$ nacrypt encrypted.txt.enc -o decrypted.txt
Please enter password for ~/.nacrypt/private.key:
Deriving key.. done
# Recipient now has the same file

Security

File encryption is done using the xchacha20poly1305 AEAD cipher providing confidentiality and integrity. The file encryption key is generated using the Argon2ID 1.3 key derivation function with opslimit and memlimit set to SENSITIVE (high settings) In asymmetric mode, a random file key is generated and sealed inside a crypto_box for each recipient. Private keys are stored on disk using a crypto_secretbox with the same KDF parameters as normal file encryption.

Warning (post-quantum)

In asymmetric mode (no password), nacrypt currently uses libsodium's crypto_box which uses Curve25519. Curve25519 is susceptible to store-now-decrypt-later (SNDL) attacks from quantum computers, where an adversary stores encrypted files and waits until they have a suitably strong quantum computer to break the files in a couple of years/decades.

Warning (signatures)

Nacrypt, like age, does NOT use digital signatures when encrypting files to recipients. This means it CANNOT verify the identity of the sender. If you wish to do this, please use nacrypt on top of a tool like minisign to provide signatures to verify sender's identities.