74 lines
2.4 KiB
Elixir
74 lines
2.4 KiB
Elixir
# Amethyst - An experimental Minecraft server written in Elixir.
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# Copyright (C) 2024 KodiCraft
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Affero General Public License as
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# published by the Free Software Foundation, either version 3 of the
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# License, or (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Affero General Public License for more details.
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#
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# You should have received a copy of the GNU Affero General Public License
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# along with this program. If not, see <https://www.gnu.org/licenses/>.
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defmodule Amethyst.Keys do
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@moduledoc """
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This module generates and manages the keys used for encryption.
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Minecraft uses RSA encryption, keys are stored in ASN.1 format and should be
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generated at runtime. The vanilla server uses 1024-bit keys, but we can use
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a larger key size for added security.
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"""
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use GenServer
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require Logger
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def start_link(bits) do
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GenServer.start_link(__MODULE__, bits, name: __MODULE__)
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end
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def get_priv do
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GenServer.call(__MODULE__, :get_priv)
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end
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def get_pub do
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GenServer.call(__MODULE__, :get_pub)
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end
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def decrypt(encrypted) do
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GenServer.call(__MODULE__, {:decrypt, encrypted})
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end
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@impl true
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def init(bits) do
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Logger.info("Generating RSA keys with #{bits} bits")
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# https://elixirforum.com/t/how-to-generate-rsa-public-key-using-crypto-provided-exponent-and-modulus/38487
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{:RSAPrivateKey, _, modulus, public_exponent, _, _, _, _exponent1, _, _, _other_prime_infos} =
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rsa_private_key = :public_key.generate_key({:rsa, bits, 65_537})
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rsa_public_key = {:RSAPublicKey, modulus, public_exponent}
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Logger.info("Generated RSA keys")
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{:ok, {rsa_public_key, rsa_private_key}}
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end
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@impl true
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def handle_call(:get_priv, _from, {pubkey, privkey}) do
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{:reply, :public_key.der_encode(:RSAPrivateKey, privkey), {pubkey, privkey}}
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end
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@impl true
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def handle_call(:get_pub, _from, {pubkey, privkey}) do
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{:reply, :public_key.der_encode(:RSAPublicKey, pubkey), {pubkey, privkey}}
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end
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@impl true
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def handle_call({:decrypt, encrypted}, _from, {pubkey, privkey}) do
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plaintext = :public_key.decrypt_private(encrypted, privkey)
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{:reply, plaintext, {pubkey, privkey}}
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end
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end
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