package dhellman

import (
	"crypto/aes"
	"crypto/cipher"

	"git.ali33.ru/fcg-xvii/curve/v2/tools"
)

func aesEncode(data []byte, p *tools.Point) ([]byte, error) {
	rData := make([]byte, len(data))
	copy(rData, data)
	block, err := aes.NewCipher(tools.Bytes32(p.X()))
	if err != nil {
		return nil, err
	}
	iv := tools.Bytes32(p.Y())[:aes.BlockSize]
	stream := cipher.NewCFBEncrypter(block, iv)
	stream.XORKeyStream(rData, rData)
	return rData, nil
}

func aesDecode(encrypted []byte, p *tools.Point) ([]byte, error) {
	rData := make([]byte, len(encrypted))
	copy(rData, encrypted)
	block, err := aes.NewCipher(tools.Bytes32(p.X()))
	if err != nil {
		return nil, err
	}
	iv := tools.Bytes32(p.Y())[:aes.BlockSize]
	stream := cipher.NewCFBDecrypter(block, iv)
	stream.XORKeyStream(rData, rData)
	return rData, nil
}