103 lines
4.2 KiB
C++
103 lines
4.2 KiB
C++
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/*
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Copyright (c) 2016, Arvid Norberg, Alden Torres
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in
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the documentation and/or other materials provided with the distribution.
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* Neither the name of the author nor the names of its
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contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef LIBTORRENT_ED25519_HPP
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#define LIBTORRENT_ED25519_HPP
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#include <libtorrent/config.hpp>
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#include <libtorrent/span.hpp>
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#include <libtorrent/kademlia/types.hpp>
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#include <array>
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#include <memory>
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namespace libtorrent {
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namespace dht
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{
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// See documentation of internal random_bytes
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TORRENT_EXPORT void ed25519_create_seed(std::array<char, 32>& seed);
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// Creates a new key pair from the given seed.
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//
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// It's important to clarify that the seed completely determines
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// the key pair. Then it's enough to save the seed and the
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// public key as the key-pair in a buffer of 64 bytes. The standard
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// is (32 bytes seed, 32 bytes public key).
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//
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// This function does work with a given seed, giving you a pair of
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// (64 bytes private key, 32 bytes public key). It's a trade-off between
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// space and CPU, saving in one format or another.
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//
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// The smaller format is not weaker by any means, in fact, it is only
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// the seed (32 bytes) that determines the point in the curve.
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TORRENT_EXPORT void ed25519_create_keypair(public_key& pk
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, secret_key& sk, std::array<char, 32> const& seed);
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// Creates a signature of the given message with the given key pair.
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TORRENT_EXPORT void ed25519_sign(signature& sig, span<char const> msg
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, public_key const& pk, secret_key const& sk);
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// Verifies the signature on the given message using ``pk``
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TORRENT_EXPORT bool ed25519_verify(signature const& sig
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, span<char const> msg, public_key const& pk);
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// Adds a scalar to the given key pair where scalar is a 32 byte buffer
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// (possibly generated with `ed25519_create_seed`), generating a new key pair.
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//
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// You can calculate the public key sum without knowing the private key and
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// vice versa by passing in null for the key you don't know. This is useful
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// when a third party (an authoritative server for example) needs to enforce
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// randomness on a key pair while only knowing the public key of the other
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// side.
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//
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// Warning: the last bit of the scalar is ignored - if comparing scalars make
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// sure to clear it with `scalar[31] &= 127`.
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//
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// see http://crypto.stackexchange.com/a/6215/4697
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// see test_ed25519 for a practical example
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TORRENT_EXPORT void ed25519_add_scalar(std::shared_ptr<public_key> pk
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, std::shared_ptr<secret_key> sk, std::array<char, 32> const& scalar);
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// Performs a key exchange on the given public key and private key, producing a
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// shared secret. It is recommended to hash the shared secret before using it.
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//
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// This is useful when two parties want to share a secret but both only knows
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// their respective public keys.
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// see test_ed25519 for a practical example
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TORRENT_EXPORT void ed25519_key_exchange(std::array<char, 32>& secret
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, public_key const& pk, secret_key const& sk);
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}}
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#endif // LIBTORRENT_ED25519_HPP
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