sing-box/common/tls/ech_shared.go
2025-07-23 11:26:06 +08:00

82 lines
2.4 KiB
Go

package tls
import (
"crypto/ecdh"
"crypto/rand"
"encoding/pem"
"golang.org/x/crypto/cryptobyte"
)
type ECHCapableConfig interface {
Config
ECHConfigList() []byte
SetECHConfigList([]byte)
}
func ECHKeygenDefault(publicName string) (configPem string, keyPem string, err error) {
echKey, err := ecdh.X25519().GenerateKey(rand.Reader)
if err != nil {
return
}
echConfig, err := marshalECHConfig(0, echKey.PublicKey().Bytes(), publicName, 0)
if err != nil {
return
}
configBuilder := cryptobyte.NewBuilder(nil)
configBuilder.AddUint16LengthPrefixed(func(builder *cryptobyte.Builder) {
builder.AddBytes(echConfig)
})
configBytes, err := configBuilder.Bytes()
if err != nil {
return
}
keyBuilder := cryptobyte.NewBuilder(nil)
keyBuilder.AddUint16LengthPrefixed(func(builder *cryptobyte.Builder) {
builder.AddBytes(echKey.Bytes())
})
keyBuilder.AddUint16LengthPrefixed(func(builder *cryptobyte.Builder) {
builder.AddBytes(echConfig)
})
keyBytes, err := keyBuilder.Bytes()
if err != nil {
return
}
configPem = string(pem.EncodeToMemory(&pem.Block{Type: "ECH CONFIGS", Bytes: configBytes}))
keyPem = string(pem.EncodeToMemory(&pem.Block{Type: "ECH KEYS", Bytes: keyBytes}))
return
}
func marshalECHConfig(id uint8, pubKey []byte, publicName string, maxNameLen uint8) ([]byte, error) {
const extensionEncryptedClientHello = 0xfe0d
const DHKEM_X25519_HKDF_SHA256 = 0x0020
const KDF_HKDF_SHA256 = 0x0001
builder := cryptobyte.NewBuilder(nil)
builder.AddUint16(extensionEncryptedClientHello)
builder.AddUint16LengthPrefixed(func(builder *cryptobyte.Builder) {
builder.AddUint8(id)
builder.AddUint16(DHKEM_X25519_HKDF_SHA256) // The only DHKEM we support
builder.AddUint16LengthPrefixed(func(builder *cryptobyte.Builder) {
builder.AddBytes(pubKey)
})
builder.AddUint16LengthPrefixed(func(builder *cryptobyte.Builder) {
const (
AEAD_AES_128_GCM = 0x0001
AEAD_AES_256_GCM = 0x0002
AEAD_ChaCha20Poly1305 = 0x0003
)
for _, aeadID := range []uint16{AEAD_AES_128_GCM, AEAD_AES_256_GCM, AEAD_ChaCha20Poly1305} {
builder.AddUint16(KDF_HKDF_SHA256) // The only KDF we support
builder.AddUint16(aeadID)
}
})
builder.AddUint8(maxNameLen)
builder.AddUint8LengthPrefixed(func(builder *cryptobyte.Builder) {
builder.AddBytes([]byte(publicName))
})
builder.AddUint16(0) // extensions
})
return builder.Bytes()
}