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56 lines
1.2 KiB
Go
56 lines
1.2 KiB
Go
6 years ago
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package server
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import (
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"bytes"
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"crypto/sha256"
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"encoding/binary"
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"github.com/cbeuw/ecies"
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"log"
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)
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// input ticket, return SID
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func decryptSessionTicket(pv *ecies.PrivateKey, ticket []byte) ([]byte, error) {
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ciphertext := make([]byte, 153)
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ciphertext[0] = 0x04
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copy(ciphertext[1:], ticket)
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plaintext, err := pv.Decrypt(ciphertext, nil, nil)
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if err != nil {
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return nil, err
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}
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return plaintext[0:32], 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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rand := 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], rand)
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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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SID, err := decryptSessionTicket(sta.pv, ch.extensions[[2]byte{0x00, 0x23}])
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if err != nil {
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return false, nil
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}
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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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