200 lines
6.4 KiB
Markdown
200 lines
6.4 KiB
Markdown
# cox
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[](https://travis-ci.org/didactic-drunk/cox)
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[](https://didactic-drunk.github.io/cox/)
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Updated Crystal bindings for the [libsodium API](https://libsodium.gitbook.io/doc/)
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## Features
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- Public-Key Cryptography
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- [x] Crypto Box Easy
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- [ ] Sealed Box
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- [ ] Combined Signatures
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- [x] Detached Signatures
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- [Secret-Key Cryptography](https://libsodium.gitbook.io/doc/secret-key_cryptography)
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- Secret Box
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- [x] [Combined mode](https://libsodium.gitbook.io/doc/secret-key_cryptography/authenticated_encryption)
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- [ ] Detached mode
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- Streaming
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- [ ] XChaCha20 Poly1305
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- AEAD
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- [ ] [AES256-GCM (Requires hardware acceleration)](https://libsodium.gitbook.io/doc/secret-key_cryptography/aead)
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- [ ] XChaCha20-Poly1305-IETF
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- [ ] ChaCha20-Poly1305-IETF
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- [ ] ChaCha20-Poly1305
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- Hashing
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- [x] ☑ [Blake2b](https://libsodium.gitbook.io/doc/hashing/generic_hashing)
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- [ ] [SipHash](https://libsodium.gitbook.io/doc/hashing/short-input_hashing)
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- [Password Hashing](https://libsodium.gitbook.io/doc/password_hashing)
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- [x] [Argon2](https://libsodium.gitbook.io/doc/password_hashing/the_argon2i_function) (Use for new applications)
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- [ ] Scrypt (For compatibility with older applications)
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- Other
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- [x] [Key Derivation](https://libsodium.gitbook.io/doc/key_derivation)
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- [ ] [Key Exchange](https://libsodium.gitbook.io/doc/key_exchange)
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- Advanced
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- Stream Ciphers
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- [x] XSalsa20
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- [x] Salsa20
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- [x] XChaCha20
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- [x] ChaCha20 Ietf
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- [x] ChaCha20
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- [ ] One time auth
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- [ ] Padding
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- [?] Semi-automatic memory wiping.
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☑ Indicate specs are compared against test vectors from another source.
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Several features in libsodium are already provided by Crystal:
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* Random (Use [Random::Secure](https://crystal-lang.org/api/latest/Random/Secure.html))
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* SHA-2 (Use [OpenSSL::Digest](https://crystal-lang.org/api/latest/OpenSSL/Digest.html))
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* HMAC SHA-2 (Use [OpenSSL::HMAC](https://crystal-lang.org/api/latest/OpenSSL/HMAC.html))
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## Installation
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**[Optionally Install libsodium.](https://download.libsodium.org/doc/installation/)**
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A recent version of libsodium is automatically downloaded and compiled if you don't install your own version.
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Add this to your application's `shard.yml`:
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```yaml
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dependencies:
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cox:
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github: didactic-drunk/cox
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```
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## Usage
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### CryptoBox easy encryption
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```crystal
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require "cox"
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data = "Hello World!"
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# Alice is the sender
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alice = Cox::CryptoBox::SecretKey.new
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# Bob is the recipient
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bob = Cox::CryptoBox::SecretKey.new
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# Precompute a shared secret between alice and bob.
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pair = alice.pair bob.public_key
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# Encrypt a message for Bob using his public key, signing it with Alice's
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# secret key
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nonce, encrypted = pair.encrypt data
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# Precompute within a block. The shared secret is wiped when the block exits.
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bob.pair alice.public_key do |pair|
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# Decrypt the message using Bob's secret key, and verify its signature against
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# Alice's public key
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decrypted = Cox.decrypt(encrypted, nonce, alice.public, bob.secret)
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String.new(decrypted) # => "Hello World!"
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end
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```
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### Public key signing
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```crystal
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message = "Hello World!"
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secret_key = Cox::Sign::SecretKey.new
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# Sign the message
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signature = secret_key.sign_detached message
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# Send secret_key.public_key to the recipient
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public_key = Cox::Sign::PublicKey.new key_bytes
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# raises Cox::Error::VerificationFailed on failure.
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public_key.verify_detached message, signature
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```
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### Secret Key Encryption
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```crystal
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key = Cox::SecretKey.new
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message = "foobar"
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encrypted, nonce = key.encrypt_easy message
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# On the other side.
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key = Cox::SecretKey.new key
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message = key.decrypt_easy encrypted, nonce
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```
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### Blake2b
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```crystal
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key = Bytes.new Cox::Blake2B::KEY_SIZE
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salt = Bytes.new Cox::Blake2B::SALT_SIZE
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personal = Bytes.new Cox::Blake2B::PERSONAL_SIZE
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out_size = 64 # bytes between Cox::Blake2B::OUT_SIZE_MIN and Cox::Blake2B::OUT_SIZE_MAX
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data = "data".to_slice
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# output_size, key, salt, and personal are optional.
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digest = Cox::Blake2b.new out_size, key: key, salt: salt, personal: personal
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digest.update data
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output = d.hexdigest
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digest.reset # Reuse existing object to hash again.
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digest.update data
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output = d.hexdigest
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```
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### Key derivation
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```crystal
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kdf = Cox::Kdf.new
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# kdf.derive(8_byte_context, subkey_id, subkey_size)
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subkey1 = kdf.derive "context1", 0, 16
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subkey2 = kdf.derive "context1", 1, 16
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subkey3 = kdf.derive "context2", 0, 32
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subkey4 = kdf.derive "context2", 1, 64
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```
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### Password Hashing
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```crystal
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pwhash = Cox::Pwhash.new
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pwhash.memlimit = Cox::Pwhash::MEMLIMIT_MIN
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pwhash.opslimit = Cox::Pwhash::OPSLIMIT_MIN
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pass = "1234"
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hash = pwhash.hash_str pass
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pwhash.verify hash, pass
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```
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Use `examples/pwhash_selector.cr` to help choose ops/mem limits.
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Example output:
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Ops limit →
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| | 1 | 4 | 16 | 64 | 256 | 1024 | 4096 | 16384 | 65536 | 262144 | 1048576 |
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| -------- | ------- | ------- | ------- | ------- | ------- | ------- | ------- | ------- | ------- | ------- | ------- |
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| 8K | | | | | | | | | | 0.542s | 2.114s |
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| 32K | | | | | | | | | 0.513s | 2.069s |
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| 128K | | | | | | | | 0.530s | 2.121s |
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| 512K | | | | | | | 0.566s | 2.237s |
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| 2048K | | | | | | 0.567s | 2.290s |
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| 8192K | | | | | 0.670s | 2.542s |
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| 32768K | | | | 0.684s | 2.777s |
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| 131072K | | | 0.805s | 3.106s |
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| 524288K | 0.504s | 1.135s | 3.661s |
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| 2097152K | 2.119s |
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| Memory |
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## Contributing
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1. Fork it ( https://github.com/didactic-drunk/cox/fork )
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2. **Install a formatting check git hook (ln -sf ../../scripts/git/pre-commit .git/hooks)**
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3. Create your feature branch (git checkout -b my-new-feature)
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4. Commit your changes (git commit -am 'Add some feature')
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5. Push to the branch (git push origin my-new-feature)
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6. Create a new Pull Request
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## Contributors
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- [andrewhamon](https://github.com/andrewhamon) Andrew Hamon - creator, former maintainer
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- [dorkrawk](https://github.com/dorkrawk) Dave Schwantes - contributor
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- [didactic-drunk](https://github.com/didactic-drunk) - current maintainer
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