mirror of
https://github.com/v2fly/v2ray-core.git
synced 2024-11-17 18:06:15 -05:00
77 lines
1.7 KiB
Go
77 lines
1.7 KiB
Go
package kcp
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import (
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"crypto/cipher"
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"encoding/binary"
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"hash/fnv"
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"v2ray.com/core/common"
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)
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// SimpleAuthenticator is a legacy AEAD used for KCP encryption.
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type SimpleAuthenticator struct{}
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// NewSimpleAuthenticator creates a new SimpleAuthenticator
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func NewSimpleAuthenticator() cipher.AEAD {
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return &SimpleAuthenticator{}
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}
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// NonceSize implements cipher.AEAD.NonceSize().
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func (*SimpleAuthenticator) NonceSize() int {
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return 0
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}
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// Overhead implements cipher.AEAD.NonceSize().
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func (*SimpleAuthenticator) Overhead() int {
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return 6
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}
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// Seal implements cipher.AEAD.Seal().
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func (a *SimpleAuthenticator) Seal(dst, nonce, plain, extra []byte) []byte {
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dst = append(dst, 0, 0, 0, 0, 0, 0) // 4 bytes for hash, and then 2 bytes for length
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binary.BigEndian.PutUint16(dst[4:], uint16(len(plain)))
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dst = append(dst, plain...)
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fnvHash := fnv.New32a()
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common.Must2(fnvHash.Write(dst[4:]))
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fnvHash.Sum(dst[:0])
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dstLen := len(dst)
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xtra := 4 - dstLen%4
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if xtra != 4 {
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dst = append(dst, make([]byte, xtra)...)
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}
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xorfwd(dst)
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if xtra != 4 {
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dst = dst[:dstLen]
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}
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return dst
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}
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// Open implements cipher.AEAD.Open().
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func (a *SimpleAuthenticator) Open(dst, nonce, cipherText, extra []byte) ([]byte, error) {
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dst = append(dst, cipherText...)
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dstLen := len(dst)
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xtra := 4 - dstLen%4
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if xtra != 4 {
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dst = append(dst, make([]byte, xtra)...)
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}
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xorbkd(dst)
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if xtra != 4 {
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dst = dst[:dstLen]
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}
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fnvHash := fnv.New32a()
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common.Must2(fnvHash.Write(dst[4:]))
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if binary.BigEndian.Uint32(dst[:4]) != fnvHash.Sum32() {
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return nil, newError("invalid auth")
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}
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length := binary.BigEndian.Uint16(dst[4:6])
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if len(dst)-6 != int(length) {
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return nil, newError("invalid auth")
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}
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return dst[6:], nil
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}
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