//cipher.h  额外添加的文件，用来放置相关算法，此文件独立于MFC外，可直接移植到支持CString的项目中

int* CStringToInt(CString str){

    //将CString转换为zero_based整数

    int size=str.GetLength();

    int *asc_space=new int[size];//使用new为了返回时不被消除

    for (int i=;i<size;i++)

    {

        asc_space[i]=int(str.GetAt(i));

        if(asc_space[i]>&&asc_space[i]<)        //A-Z转化

            asc_space[i]-=;

        else if(asc_space[i]>&&asc_space[i]<)    //a-z转化

            asc_space[i]-=;

    }

    return asc_space;

}

void Encode(CString key,CString plain,CString &cipher){

    //维吉尼亚加密算法

    int *keycode=CStringToInt(key);

    int *plaincode=CStringToInt(plain);

    int *ciphercode=CStringToInt(plain);

    int keysize=key.GetLength();

    int plainsize=plain.GetLength();

    int flag=;

    CString blank(' ',plainsize+);    //预留一个字节放\0

    cipher=blank;                    //生成空白的密文

    for (int i=;i<plainsize;i++)

    {

        if(flag>=keysize)            //轮换钥匙

            flag=;

        ciphercode[i]=(plaincode[i]+keycode[flag])%;    //求密文的数字码

        cipher.SetAt(i,'A'+ciphercode[i]);                //生成密文

        ++flag;

    }

    cipher.SetAt(i,'\0');                //在末尾放入\0

    delete keycode,plaincode,ciphercode;//释放CStringToInt()申请的空间

}

void Decode(CString key,CString &plain,CString cipher){

    //加密稍作修改就是解密算法

    int *keycode=CStringToInt(key);

    int *plaincode=CStringToInt(cipher);

    int *ciphercode=CStringToInt(cipher);

    int keysize=key.GetLength();

    int ciphersize=cipher.GetLength();

    int flag=;

    CString blank(' ',ciphersize+);

    plain=blank;

    for (int i=;i<ciphersize;i++)

    {

        if(flag>=keysize)

            flag=;

        //+26是为了对密文数字码小于密钥数字码的情况进行矫正

        plaincode[i]=(ciphercode[i]-keycode[flag]+)%;

        plain.SetAt(i,'a'+plaincode[i]);

        ++flag;

    }

    plain.SetAt(i,'\0');

    delete keycode,plaincode,ciphercode;

}

//MFC OnButton()响应
void CVigenereCipherDlg::OnEncrypt() //加密按钮

{

    UpdateData();

    if(m_key.IsEmpty()||m_plain.IsEmpty())

        MessageBox("密钥及明文不能为空！");

    else{

        Encode(m_key,m_plain,m_cipher);//调用加密函数

        UpdateData(false);

        m_ctrEDIT1.SetReadOnly(TRUE);//防止修改密钥

        m_ctrEDIT2.SetReadOnly(TRUE);//防止修改明文

        m_ctrEDIT3.SetReadOnly(TRUE);//防止修改密文

        m_ctrEDIT4.SetReadOnly(FALSE);

    }

}

void CVigenereCipherDlg::OnDecrypt() //解密按钮

{

    UpdateData();

    if(m_key.IsEmpty()||m_cipher.IsEmpty())

        MessageBox("密钥及密文不能为空！");

    else{

        Decode(m_key,m_explainted,m_cipher);

        UpdateData(false);

        m_explainted="";

        m_ctrEDIT1.SetReadOnly(FALSE);

        m_ctrEDIT2.SetReadOnly(FALSE);

        m_ctrEDIT3.SetReadOnly(FALSE);

        m_ctrEDIT4.SetReadOnly(TRUE);

    }

}