mirror of
https://github.com/refraction-networking/uquic.git
synced 2025-04-03 20:27:35 +03:00
29 lines
896 B
Go
29 lines
896 B
Go
package handshake
|
|
|
|
import (
|
|
"crypto"
|
|
"encoding/binary"
|
|
|
|
"golang.org/x/crypto/hkdf"
|
|
)
|
|
|
|
// hkdfExpandLabel HKDF expands a label as defined in RFC 8446, section 7.1.
|
|
// Since this implementation avoids using a cryptobyte.Builder, it is about 15% faster than the
|
|
// hkdfExpandLabel in the standard library.
|
|
func hkdfExpandLabel(hash crypto.Hash, secret, context []byte, label string, length int) []byte {
|
|
b := make([]byte, 3, 3+6+len(label)+1+len(context))
|
|
binary.BigEndian.PutUint16(b, uint16(length))
|
|
b[2] = uint8(6 + len(label))
|
|
b = append(b, []byte("tls13 ")...)
|
|
b = append(b, []byte(label)...)
|
|
b = b[:3+6+len(label)+1]
|
|
b[3+6+len(label)] = uint8(len(context))
|
|
b = append(b, context...)
|
|
|
|
out := make([]byte, length)
|
|
n, err := hkdf.Expand(hash.New, secret, b).Read(out)
|
|
if err != nil || n != length {
|
|
panic("quic: HKDF-Expand-Label invocation failed unexpectedly")
|
|
}
|
|
return out
|
|
}
|