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package handshake
import (
"crypto"
"crypto/cipher"
"crypto/rand"
"crypto/tls"
"testing"
"unsafe"
"github.com/stretchr/testify/require"
)
var tls13CipherSuites = []uint16{tls.TLS_AES_128_GCM_SHA256, tls.TLS_AES_256_GCM_SHA384, tls.TLS_CHACHA20_POLY1305_SHA256}
type cipherSuiteTLS13 struct {
ID uint16
KeyLen int
AEAD func(key, fixedNonce []byte) cipher.AEAD
Hash crypto.Hash
}
//go:linkname cipherSuitesTLS13 crypto/tls.cipherSuitesTLS13
var cipherSuitesTLS13 []unsafe.Pointer
func cipherSuiteTLS13ByID(id uint16) *cipherSuiteTLS13 {
for _, v := range cipherSuitesTLS13 {
cs := (*cipherSuiteTLS13)(v)
if cs.ID == id {
return cs
}
}
return nil
}
//go:linkname nextTrafficSecret crypto/tls.(*cipherSuiteTLS13).nextTrafficSecret
func nextTrafficSecret(cs *cipherSuiteTLS13, trafficSecret []byte) []byte
func TestHKDF(t *testing.T) {
for _, id := range tls13CipherSuites {
t.Run(tls.CipherSuiteName(id), func(t *testing.T) {
cs := cipherSuiteTLS13ByID(id)
expected := nextTrafficSecret(cs, []byte("foobar"))
expanded := hkdfExpandLabel(cs.Hash, []byte("foobar"), nil, "traffic upd", cs.Hash.Size())
require.Equal(t, expected, expanded)
})
}
}
// As of Go 1.24, the standard library and our implementation of hkdfExpandLabel should provide the same performance.
func BenchmarkHKDFExpandLabelStandardLibrary(b *testing.B) {
for _, id := range tls13CipherSuites {
b.Run(tls.CipherSuiteName(id), func(b *testing.B) { benchmarkHKDFExpandLabel(b, id, true) })
}
}
func BenchmarkHKDFExpandLabelOurs(b *testing.B) {
for _, id := range tls13CipherSuites {
b.Run(tls.CipherSuiteName(id), func(b *testing.B) { benchmarkHKDFExpandLabel(b, id, false) })
}
}
func benchmarkHKDFExpandLabel(b *testing.B, cipherSuite uint16, useStdLib bool) {
b.ReportAllocs()
cs := cipherSuiteTLS13ByID(cipherSuite)
secret := make([]byte, 32)
rand.Read(secret)
b.ResetTimer()
for i := 0; i < b.N; i++ {
if useStdLib {
nextTrafficSecret(cs, secret)
} else {
hkdfExpandLabel(cs.Hash, secret, nil, "traffic upd", cs.Hash.Size())
}
}
}
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