libmc/docs/implement-encryption.md

• AES-128-CFB8 (NetworkCipher): Handles in-place network packet encryption and decryption.
• SHA-1 (Sha1Hasher): Computes the Minecraft server ID hash for online-mode authentication.
• RSA-1024 (RSA1024Encryptor): Encrypts the shared secret and verify token during the login handshake.
• Auth Join Request (AuthenticationProvider): Sends the HTTP POST request to Mojang's session server (https://sessionserver.mojang.com/session/minecraft/join).

Use libmc-protocol-encrypt

fun main() {
    val client = createMinecraftClient(
      // other parameter
      crypto = DefaultProtocolContext
    )
}