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method_aes128gcm.go
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method_aes128gcm.go
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package shadowsocks2022
import (
"crypto/aes"
"crypto/cipher"
)
func newAES128GCMMethod() *AES128GCMMethod {
return &AES128GCMMethod{}
}
type AES128GCMMethod struct{}
func (a AES128GCMMethod) GetSessionSubKeyAndSaltLength() int {
return 16
}
func (a AES128GCMMethod) GetStreamAEAD(sessionSubKey []byte) (cipher.AEAD, error) {
aesCipher, err := aes.NewCipher(sessionSubKey)
if err != nil {
return nil, newError("failed to create AES cipher").Base(err)
}
aead, err := cipher.NewGCM(aesCipher)
if err != nil {
return nil, newError("failed to create AES-GCM AEAD").Base(err)
}
return aead, nil
}
func (a AES128GCMMethod) GenerateEIH(currentIdentitySubKey []byte, nextPskHash []byte, out []byte) error {
aesCipher, err := aes.NewCipher(currentIdentitySubKey)
if err != nil {
return newError("failed to create AES cipher").Base(err)
}
aesCipher.Encrypt(out, nextPskHash)
return nil
}
func (a AES128GCMMethod) GetUDPClientProcessor(ipsk [][]byte, psk []byte, derivation KeyDerivation) (UDPClientPacketProcessor, error) {
reqSeparateHeaderPsk := psk
if ipsk != nil {
reqSeparateHeaderPsk = ipsk[0]
}
reqSeparateHeaderCipher, err := aes.NewCipher(reqSeparateHeaderPsk)
if err != nil {
return nil, newError("failed to create AES cipher").Base(err)
}
respSeparateHeaderCipher, err := aes.NewCipher(psk)
if err != nil {
return nil, newError("failed to create AES cipher").Base(err)
}
getPacketAEAD := func(sessionID []byte) cipher.AEAD {
sessionKey := make([]byte, a.GetSessionSubKeyAndSaltLength())
derivation.GetSessionSubKey(psk, sessionID, sessionKey)
block, err := aes.NewCipher(sessionKey)
if err != nil {
panic(err)
}
aead, err := cipher.NewGCM(block)
if err != nil {
panic(err)
}
return aead
}
eihGenerator := newAESEIHGeneratorContainer(len(ipsk), psk, ipsk)
getEIH := func(mask []byte) ExtensibleIdentityHeaders {
eih, err := eihGenerator.GenerateEIHUDP(derivation, a, mask)
if err != nil {
newError("failed to generate EIH").Base(err).WriteToLog()
}
return eih
}
return NewAESUDPClientPacketProcessor(reqSeparateHeaderCipher, respSeparateHeaderCipher, getPacketAEAD, getEIH), nil
}