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package handshake
import (
"crypto"
"crypto/tls"
"golang.org/x/crypto/hkdf"
"github.com/quic-go/quic-go/internal/protocol"
)
var (
quicSaltV1 = []byte{0x38, 0x76, 0x2c, 0xf7, 0xf5, 0x59, 0x34, 0xb3, 0x4d, 0x17, 0x9a, 0xe6, 0xa4, 0xc8, 0x0c, 0xad, 0xcc, 0xbb, 0x7f, 0x0a}
quicSaltV2 = []byte{0x0d, 0xed, 0xe3, 0xde, 0xf7, 0x00, 0xa6, 0xdb, 0x81, 0x93, 0x81, 0xbe, 0x6e, 0x26, 0x9d, 0xcb, 0xf9, 0xbd, 0x2e, 0xd9}
)
const (
hkdfLabelKeyV1 = "quic key"
hkdfLabelKeyV2 = "quicv2 key"
hkdfLabelIVV1 = "quic iv"
hkdfLabelIVV2 = "quicv2 iv"
)
func getSalt(v protocol.Version) []byte {
if v == protocol.Version2 {
return quicSaltV2
}
return quicSaltV1
}
var initialSuite = getCipherSuite(tls.TLS_AES_128_GCM_SHA256)
// NewInitialAEAD creates a new AEAD for Initial encryption / decryption.
func NewInitialAEAD(connID protocol.ConnectionID, pers protocol.Perspective, v protocol.Version) (LongHeaderSealer, LongHeaderOpener) {
clientSecret, serverSecret := computeSecrets(connID, v)
var mySecret, otherSecret []byte
if pers == protocol.PerspectiveClient {
mySecret = clientSecret
otherSecret = serverSecret
} else {
mySecret = serverSecret
otherSecret = clientSecret
}
myKey, myIV := computeInitialKeyAndIV(mySecret, v)
otherKey, otherIV := computeInitialKeyAndIV(otherSecret, v)
encrypter := initialSuite.AEAD(myKey, myIV)
decrypter := initialSuite.AEAD(otherKey, otherIV)
return newLongHeaderSealer(encrypter, newHeaderProtector(initialSuite, mySecret, true, v)),
newLongHeaderOpener(decrypter, newAESHeaderProtector(initialSuite, otherSecret, true, hkdfHeaderProtectionLabel(v)))
}
func computeSecrets(connID protocol.ConnectionID, v protocol.Version) (clientSecret, serverSecret []byte) {
initialSecret := hkdf.Extract(crypto.SHA256.New, connID.Bytes(), getSalt(v))
clientSecret = hkdfExpandLabel(crypto.SHA256, initialSecret, []byte{}, "client in", crypto.SHA256.Size())
serverSecret = hkdfExpandLabel(crypto.SHA256, initialSecret, []byte{}, "server in", crypto.SHA256.Size())
return
}
func computeInitialKeyAndIV(secret []byte, v protocol.Version) (key, iv []byte) {
keyLabel := hkdfLabelKeyV1
ivLabel := hkdfLabelIVV1
if v == protocol.Version2 {
keyLabel = hkdfLabelKeyV2
ivLabel = hkdfLabelIVV2
}
key = hkdfExpandLabel(crypto.SHA256, secret, []byte{}, keyLabel, 16)
iv = hkdfExpandLabel(crypto.SHA256, secret, []byte{}, ivLabel, 12)
return
}
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