mirror of
https://github.com/xtaci/kcp-go.git
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77 lines
2.2 KiB
Go
77 lines
2.2 KiB
Go
// The MIT License (MIT)
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//
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// Copyright (c) 2015 xtaci
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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package kcp
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import (
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"crypto/aes"
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"crypto/cipher"
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"crypto/md5"
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"crypto/rand"
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"io"
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)
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// Entropy defines a entropy source
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//
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// Entropy in this file generate random bits for the first 16-bytes of each packets.
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type Entropy interface {
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Init()
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Fill(nonce []byte)
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}
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// nonceMD5 nonce generator for packet header
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type nonceMD5 struct {
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seed [md5.Size]byte
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}
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func (n *nonceMD5) Init() { /*nothing required*/ }
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func (n *nonceMD5) Fill(nonce []byte) {
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if n.seed[0] == 0 { // entropy update
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io.ReadFull(rand.Reader, n.seed[:])
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}
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n.seed = md5.Sum(n.seed[:])
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copy(nonce, n.seed[:])
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}
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// nonceAES128 nonce generator for packet headers
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type nonceAES128 struct {
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seed [aes.BlockSize]byte
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block cipher.Block
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}
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func (n *nonceAES128) Init() {
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var key [16]byte //aes-128
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io.ReadFull(rand.Reader, key[:])
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io.ReadFull(rand.Reader, n.seed[:])
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block, _ := aes.NewCipher(key[:])
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n.block = block
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}
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func (n *nonceAES128) Fill(nonce []byte) {
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if n.seed[0] == 0 { // entropy update
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io.ReadFull(rand.Reader, n.seed[:])
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}
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n.block.Encrypt(n.seed[:], n.seed[:])
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copy(nonce, n.seed[:])
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}
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