i2pplus

I2P Core (`core/`)

The core module is the foundation of the I2P router. It provides the low-level APIs, data structures, cryptographic primitives, and native libraries that all other I2P components depend on.

Structure

Directory	Description
`java/src/net/i2p/client/`	I2P client API for applications connecting to the router
`java/src/net/i2p/crypto/`	Cryptographic engines (AES, ElGamal, EdDSA, ECDSA, HMAC, SHA)
`java/src/net/i2p/data/`	I2P data structures (Hash, Destination, LeaseSet, Keys, Certificates)
`java/src/net/i2p/internal/`	Internal router interfaces consumed by other modules
`java/src/net/i2p/kademlia/`	Kademlia DHT implementation used for network database lookups
`java/src/net/i2p/stat/`	Statistics and frequency tracking
`java/src/net/i2p/time/`	Clock and time offset management
`java/src/net/i2p/update/`	Update checking and installation
`java/src/net/i2p/util/`	General utilities (logging, crypto helpers, native BigInteger)
`java/src/net/i2p/socks/`	SOCKS proxy support
`java/test/`	JUnit and ScalaTest tests
`java/bench/`	JMH benchmarks
`c/jbigi/`	JBIGI native library (GMP wrapper for fast modular arithmetic)
`c/jcpuid/`	JCPUID native library (CPU feature detection)
`locale/`	Translation `.po` files (compiled to resource bundles at build time)

Key Packages

net.i2p.client - The public I2P client API (I2PClient, I2PSession) used by applications to send and receive data through the router.
net.i2p.crypto - All cryptographic operations: symmetric encryption (AES/ChaCha20), asymmetric (ElGamal/EdDSA/X25519), hashing (SHA-256/SHA-384/SHA-512), key management, and certificate handling.
net.i2p.data - Wire-format data structures serialized for I2CP, NTCP2, and SSU2 protocols.
net.i2p.internal - Interfaces bridging core to the router module (Floodfill, Tunnel Manager, etc.).

Building

# Gradle
./gradlew :core:jar

# Ant (from repo root)
ant buildCore

# Run tests
./gradlew :core:test

# Run benchmarks
./gradlew :core:jmh

Translations are compiled from .po files into Java resource bundles automatically during the build via java/bundle-messages.sh.

Native Libraries

The c/ directory contains JNI libraries that accelerate performance-critical operations:

JBIGI (c/jbigi/) - Wraps GMP for hardware-optimized modPow / modInverse. See c/jbigi/README.md for build instructions.
JCPUID (c/jcpuid/) - Detects CPU features (AES-NI, etc.) at runtime. See c/jcpuid/README.md for build instructions.

License

Public domain unless otherwise marked. Some components use BSD (DSA, ElGamal, SHA256 implementations), Cryptix (AES), or MIT licenses. See docs/LICENSES.md.