NaCl

Full Crystal binidings to libsodium. Very much a work in progress, but the lib bindings are there.

Installation

1. Make sure you have libsodium installed on your system.

# Debian
sudo apt install libsodium23

# Arch
sudo pacman -S libsodium

# Fedora
sudo yum install libsodium

2. Add the dependency to your shard.yml:

   dependencies:
     nacl:
       github: watzon/nacl
   

3. Run shards install

Usage

require "nacl"

Secret Key Encryption

XChaCha20Poly1305

# Generate a random secret key
key = NaCl::AEAD::XChaCha20Poly1305.keygen

# Initialize a XChaCha20Poly1305 cipher object
cipher = NaCl::AEAD::XChaCha20Poly1305.new(key)

# Generate a random nonce: a single-use value never repeated under the same key.
# The nonce isn't secret, and can be sent with the ciphertext.
# The cipher instance has a nonce_bytes method for determining how many bytes should be in a nonce.
nonce = NaCl::Random.random_bytes(cipher.nonce_bytes)

# Encrypt a message with XChaCha20Poly1305
message = "Crystal is amazing" # Message to be encrypted
ad = "" # Additional data sent *in the clear* to be authenticated. This can be `nil`.
ciphertext = cipher.encrypt_string(nonce, message, ad)
# => "..." string of random bytes, 16 bytes longer than the message.
# The extra 16 bytes are the authenticator.

# Decrypt a message, passing in the same additional data we used to encrypt.
decrypted_message = cipher.decrypt_string(nonce, ciphertext, ad)
# => "Crystal is amazing"

# But if the cipher has been tampered with:
cipher.decrypt_string(nonce, corrupted_ciphertext, ad)
# => NaCl::CryptoError

# For encrypting bytes you can use:
ciphertext = cipher.encrypt(nonce, message.bytes, ad)

# And to decrypt back to bytes
decrypted_bytes = cipher.decrypt(nonce, ciphertext, ad)
# => Bytes[...]

Digital Signatures

Signer's Perspective

# Generate a new random signing key
signing_key = NaCl::SigningKey.generate

# Message to be signed
message = "Crystal is amazing

# Sign a message with the signing key
signature = signing_key.sign(message)

# Obtain the verify key for a given signing key
verify_key = signing_key.verify_key

# Convert the verify key to a string to send it to a third party
verify_key.to_s

Verifier's Perspective

# Create a VerifyKey object from a public key
verify_key = NaCl::VerifyKey.new(verify_key.bytes)

# Check the validity of a message's signature
# Will raise NaCl::BadSignatureError if the signature check fails
verify_key.verify(signature, message)

Supported

• SimpleBox (simplified cryptography)
• Secret-key Encryption
  • NaCl::SecretBox
  • NaCl::AEAD::XChaCha20Poly1305
  • NaCl::AEAD::ChaCha20Poly1305IETF
  • NaCl::AEAD::ChaCha20Poly1305Legacy
• Public-key Encryption
  • NaCl::Box
  • NaCl::PrivateKey
  • NaCl::PublicKey
• Digital Signatures
  • NaCl::SigningKey
  • NaCl::VerifyKey
• HMAC
  • NaCl::HMAC::SHA256
  • NaCl::HMAC::SHA512256
• Hash Functions
  • NaCl::Hash::Blake2b
• Password Hashing
  • NaCl::PasswordHash
• Scalar Manipulation
  • NaCl::GroupElement
• One-time Authentication
• Random Number Generation
• Utilities

Contributing

1. Fork it (https://github.com/watzon/nacl/fork)
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

Contributors

• Chris Watson - creator and maintainer