Rsa Encryption, probably bugged

internal/common/rsapacket.go

@@ -0,0 +1,63 @@
+package common
+
+import (
+	"crypto"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/sha256"
+	"encoding/binary"
+)
+
+type RsaPacket struct {
+	Sid          SessionID
+	DataLength   uint32
+	EncryptedKey []byte
+}
+
+func NewRsaPacket(pubKey *rsa.PublicKey, key [32]byte, sid SessionID) (*RsaPacket, error) {
+	enc, err := rsa.EncryptOAEP(sha256.New(), rand.Reader, pubKey, key[:], nil)
+	if err != nil {
+		return nil, err
+	}
+
+	pck := RsaPacket{
+		Sid:          sid,
+		DataLength:   uint32(len(enc)),
+		EncryptedKey: enc,
+	}
+
+	return &pck, nil
+}
+
+func (rsaPck *RsaPacket) ToBytes() []byte {
+	bytes := make([]byte, rsaPck.DataLength+8+4)
+	copy(bytes[0:8], rsaPck.Sid[:])
+	binary.LittleEndian.PutUint32(bytes[8:12], rsaPck.DataLength)
+	copy(bytes[12:], rsaPck.EncryptedKey[:])
+	return bytes
+}
+
+func RsaPacketFromBytes(bytes []byte) *RsaPacket {
+	sid := SessionID(bytes[0:8])
+	dLen := binary.LittleEndian.Uint32(bytes[8:12])
+	data := bytes[12 : 12+dLen]
+
+	return &RsaPacket{
+		Sid:          sid,
+		DataLength:   dLen,
+		EncryptedKey: data,
+	}
+}
+
+func (rsaPck *RsaPacket) ExtractKey(priv *rsa.PrivateKey) ([32]byte, error) {
+	// key, err := rsa.DecryptOAEP(sha256.New(), rand.Reader, priv, rsaPck.EncryptedKey, nil)
+	key, err := priv.Decrypt(
+		rand.Reader,
+		rsaPck.EncryptedKey,
+		&rsa.OAEPOptions{Hash: crypto.SHA256},
+	)
+	if err != nil {
+		return [32]byte{}, err
+	}
+	return [32]byte(key[0:32]), nil
+}