# Introduction

**Secure. Portable. Pure Kotlin.**

**Kodium** is a comprehensive, pure Kotlin Multiplatform (KMP) cryptography library. It acts as a faithful port of the renowned **TweetNaCl** C library, providing high-speed, high-security cryptographic primitives, advanced **Double Ratchet** session management, and **Post-Quantum Cryptography (PQC)** protocols without *any* native dependencies.

Write once, encrypt everywhere. Even in a post-quantum world.

## Why Kodium?

* **Pure Kotlin:** No JNI, no C interop headaches, no complex build scripts for native binaries. Just pure Kotlin code running everywhere.
* **TweetNaCl Core:** Built on the solid foundation of the TweetNaCl crypto suite, known for its security and simplicity.
* **Post-Quantum Ready:** Hybrid cryptographic primitives combining classical X25519 with FIPS 203 (ML-KEM) to protect against future quantum computers. Note that symmetric encryption (SecretBox) is naturally quantum-resistant.
* **Double Ratchet:** Includes a full implementation of the Double Ratchet Algorithm and X3DH for secure End-to-End Encryption (E2EE), featuring a built-in LRU policy for skipped message keys to prevent memory exhaustion.
* **Multiplatform Native:** First-class support for Android, iOS, JVM, JavaScript (Browser/Node), Wasm, Linux, macOS, and Windows.
* **Developer Friendly:** Simple, opinionated APIs for common tasks (Box, SecretBox, Signatures).

## Supported Platforms

| Platform                      | Support |
| ----------------------------- | :-----: |
| **Android**                   |    ✅    |
| **iOS** (Arm64, X64, Sim)     |    ✅    |
| **JVM** (Java 17+)            |    ✅    |
| **JavaScript** (Browser/Node) |    ✅    |
| **Wasm** (WebAssembly)        |    ✅    |
| **macOS** (Arm64, X64)        |    ✅    |
| **Linux** (X64)               |    ✅    |
| **Windows** (MinGW X64)       |    ✅    |

## Features

* **End-to-End Encryption:** Double Ratchet Algorithm & X3DH (Extended Triple Diffie-Hellman).
* **Post-Quantum Hybrid Encryption:** FIPS 203 (ML-KEM-768) + Curve25519 authenticated encryption.
* **Public-Key Cryptography (Box):** Authenticated encryption using Curve25519, XSalsa20, and Poly1305.
* **Secret-Key Cryptography (SecretBox):** Authenticated encryption using XSalsa20 and Poly1305.
* **Digital Signatures:** Ed25519 high-speed, high-security signatures.
* **Key Management:** Secure generation, import, and export of keys (Raw & Base58Check).
* **Utils:** Robust Base58Check encoding/decoding and HKDF (RFC 5869).


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