# kryptos
[](https://hex.pm/packages/kryptos)
[](https://hexdocs.pm/kryptos/)
A cryptography library for Gleam targeting both Erlang and JavaScript runtimes.
## Why kryptos?
<img src="https://github.com/jtdowney/kryptos/blob/main/assets/kryptos.png?raw=true" alt="kryptos logo" width="200" align="right">
- **Dual-runtime support** — Works on both Erlang and JavaScript (Node.js),
wrapping each platform's native crypto APIs for consistent behavior.
- **No custom cryptography** — All cryptographic operations delegate to the
runtime's battle-tested implementations (Erlang's `crypto` module,
Node.js `crypto` module). This library is a wrapper, not a reimplementation.
- **Misuse-resistant API** — Inspired by Go's crypto library, the API guides
you toward safe defaults and makes dangerous operations explicit.
- **Tested against Wycheproof** — Validated against Google's
[Wycheproof](https://github.com/C2SP/wycheproof) test vectors to catch
edge-case vulnerabilities.
## Installation
```sh
gleam add kryptos
```
## Features
| Module | Algorithms |
| -------------------------------------------------------- | ---------------------------------------------- |
| [hash](https://hexdocs.pm/kryptos/kryptos/hash.html) | SHA-1, SHA-2, SHA-3, BLAKE2 |
| [hmac](https://hexdocs.pm/kryptos/kryptos/hmac.html) | All hash algorithms |
| [aead](https://hexdocs.pm/kryptos/kryptos/aead.html) | AES-GCM, AES-CCM, ChaCha20-Poly1305 |
| [block](https://hexdocs.pm/kryptos/kryptos/block.html) | AES-128, AES-192, AES-256 |
| [ecdsa](https://hexdocs.pm/kryptos/kryptos/ecdsa.html) | P-256, P-384, P-521 |
| [eddsa](https://hexdocs.pm/kryptos/kryptos/eddsa.html) | Ed25519, Ed448 |
| [ecdh](https://hexdocs.pm/kryptos/kryptos/ecdh.html) | P-256, P-384, P-521 |
| [xdh](https://hexdocs.pm/kryptos/kryptos/xdh.html) | X25519, X448 |
| [rsa](https://hexdocs.pm/kryptos/kryptos/rsa.html) | OAEP, PKCS#1 v1.5, PSS, PKCS#1 v1.5 signatures |
| [crypto](https://hexdocs.pm/kryptos/kryptos/crypto.html) | HKDF, PBKDF2, random bytes |
## Getting Started
Encrypt and decrypt data using AES-GCM:
```gleam
import kryptos/aead
import kryptos/block
import kryptos/crypto
pub fn main() {
// Generate a random 256-bit key
let assert Ok(cipher) = block.aes_256(crypto.random_bytes(32))
let ctx = aead.gcm(cipher)
// Generate a random nonce (never reuse with the same key!)
let nonce = crypto.random_bytes(aead.nonce_size(ctx))
// Encrypt
let plaintext = <<"hello, world!":utf8>>
let assert Ok(#(ciphertext, tag)) = aead.seal(ctx, nonce:, plaintext:)
// Decrypt
let assert Ok(decrypted) = aead.open(ctx, nonce:, ciphertext:, tag:)
// decrypted == plaintext
}
```
## Security
For guidance on choosing cryptographic primitives, see
[Cryptographic Right Answers](https://latacora.micro.blog/2018/04/03/cryptographic-right-answers.html).
