mirror of
https://github.com/v2fly/v2ray-core.git
synced 2024-09-14 07:58:16 -04:00
59 lines
1.5 KiB
Go
59 lines
1.5 KiB
Go
package crypto
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import (
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"crypto"
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"crypto/hmac"
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"encoding/binary"
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)
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// copied from https://v2ray.com/core/external/github.com/cloudflare/tls-tris/blob/master/hkdf.go
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func hkdfExtract(hash crypto.Hash, secret, salt []byte) []byte {
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if salt == nil {
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salt = make([]byte, hash.Size())
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}
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if secret == nil {
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secret = make([]byte, hash.Size())
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}
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extractor := hmac.New(hash.New, salt)
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extractor.Write(secret)
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return extractor.Sum(nil)
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}
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// copied from https://v2ray.com/core/external/github.com/cloudflare/tls-tris/blob/master/hkdf.go
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func hkdfExpand(hash crypto.Hash, prk, info []byte, l int) []byte {
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var (
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expander = hmac.New(hash.New, prk)
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res = make([]byte, l)
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counter = byte(1)
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prev []byte
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)
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if l > 255*expander.Size() {
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panic("hkdf: requested too much output")
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}
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p := res
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for len(p) > 0 {
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expander.Reset()
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expander.Write(prev)
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expander.Write(info)
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expander.Write([]byte{counter})
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prev = expander.Sum(prev[:0])
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counter++
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n := copy(p, prev)
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p = p[n:]
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}
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return res
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}
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// hkdfExpandLabel HKDF expands a label
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func HkdfExpandLabel(hash crypto.Hash, secret []byte, label string, length int) []byte {
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const prefix = "quic "
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qlabel := make([]byte, 2 /* length */ +1 /* length of label */ +len(prefix)+len(label)+1 /* length of context (empty) */)
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binary.BigEndian.PutUint16(qlabel[0:2], uint16(length))
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qlabel[2] = uint8(len(prefix) + len(label))
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copy(qlabel[3:], []byte(prefix+label))
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return hkdfExpand(hash, secret, qlabel, length)
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}
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