mirror of
https://github.com/cbeuw/Cloak.git
synced 2024-10-23 15:46:25 +00:00
65 lines
1.5 KiB
Go
65 lines
1.5 KiB
Go
package server
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import (
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"bytes"
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"crypto"
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"crypto/sha256"
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"encoding/binary"
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"log"
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"github.com/cbeuw/Cloak/internal/util"
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ecdh "github.com/cbeuw/go-ecdh"
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)
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// input ticket, return SID
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func decryptSessionTicket(staticPv crypto.PrivateKey, ticket []byte) ([]byte, error) {
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ec := ecdh.NewCurve25519ECDH()
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ephPub, _ := ec.Unmarshal(ticket[0:32])
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key, err := ec.GenerateSharedSecret(staticPv, ephPub)
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if err != nil {
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return nil, err
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}
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SID := util.AESDecrypt(ticket[0:16], key, ticket[32:64])
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return SID, nil
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}
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func validateRandom(random []byte, SID []byte, time int64) bool {
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t := make([]byte, 8)
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binary.BigEndian.PutUint64(t, uint64(time/(12*60*60)))
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rdm := random[0:16]
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preHash := make([]byte, 56)
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copy(preHash[0:32], SID)
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copy(preHash[32:40], t)
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copy(preHash[40:56], rdm)
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h := sha256.New()
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h.Write(preHash)
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return bytes.Equal(h.Sum(nil)[0:16], random[16:32])
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}
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func TouchStone(ch *ClientHello, sta *State) (bool, []byte) {
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var random [32]byte
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copy(random[:], ch.random)
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used := sta.getUsedRandom(random)
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if used != 0 {
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log.Println("Replay! Duplicate random")
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return false, nil
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}
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sta.putUsedRandom(random)
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ticket := ch.extensions[[2]byte{0x00, 0x23}]
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if len(ticket) < 64 {
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return false, nil
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}
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SID, err := decryptSessionTicket(sta.staticPv, ticket)
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if err != nil {
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log.Printf("ts: %v\n", err)
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return false, nil
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}
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log.Printf("SID: %x\n", SID)
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isSS := validateRandom(ch.random, SID, sta.Now().Unix())
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if !isSS {
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return false, nil
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}
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return true, SID
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}
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