package minsecurity.crypto;

import minsecurity.Common;
import minsecurity.crypto.sm2.SM2PrivateKey;
import minsecurity.crypto.sm2.SM2PublicKey;

/*
 * @Author: hongyu guo
 * @Description:
 * @Version: 1.0.0
 * @Date: 16:02 2021/03/06
 * @Copyright: MIN-Group；国家重大科技基础设施——未来网络北大实验室；深圳市信息论与未来网络重点实验室
 */
public class KeyUtils {
    /**
     * 可以理解为公钥的"构造函数"
     * 返回的数据类型为PublicKeyInterface接口, 必要时调用者需要手动将类型强制转化为需要的类型
     * @param bytesOfPublicKey 公钥的bytes数组
	 * @param algorithm 公钥类型
     * @return minsecurity.crypto.PublicKeyInterface
     * @author ghy
     * @date 2021/3/7
    **/
    public static PublicKeyInterface unMarshalPublicKey(byte[] bytesOfPublicKey, int algorithm) {
        if (bytesOfPublicKey == null || bytesOfPublicKey.length == 0) {
            return null;
        }
        switch (algorithm) {
            case Common.SM2:
                SM2PublicKey sm2PublicKey = new SM2PublicKey();
                sm2PublicKey.setBytes(bytesOfPublicKey);
                return sm2PublicKey;
            default:
                return null;
        }
    }
    /**
     * 可以理解为私钥的"构造函数"
     * 返回的数据类型为PrivateKeyInterface接口, 必要时调用者需要手动将类型强制转化为需要的类型
     * @param bytesOfPrivateKey 私钥的bytes数组
	 * @param algorithm 私钥类型
     * @return minsecurity.crypto.PrivateKeyInterface
     * @throws
     * @author hongyu guo
     * @date 2021/3/15
    **/
    public static PrivateKeyInterface unMarshalPrivateKey(byte[] bytesOfPrivateKey, int algorithm){
        if(bytesOfPrivateKey == null || bytesOfPrivateKey.length == 0){
            return null;
        }
        switch (algorithm) {
            case Common.SM2:
                SM2PrivateKey sm2PrivateKey = new SM2PrivateKey();
                sm2PrivateKey.setBytes(bytesOfPrivateKey);
                return sm2PrivateKey;
            default:
                return null;
        }
    }

    /**
     * 获取一个16字节的byte数组, 可用作sm4的key
     * @param passwd 密码
     * @return byte[]
     * @throws
     * @author hongyu guo
     * @date 2021/3/15
    **/
    public static byte[] get16bytePasswd(byte[] passwd) {
        byte[] hashPasswd = HashAlgo.sm3(passwd);
        if( hashPasswd.length == 32){
            for(int i = 0; i < 16; i++){
                hashPasswd[i] += hashPasswd[i + 16];
            }
        }
        byte[] sm4Key = new byte[16];
        System.arraycopy(hashPasswd,0,sm4Key,0,16);
        return sm4Key;
    }
}