単純異種暗号化

Dont’ use XOR encryption only when you encrypt data. It’s weak. Combine it with other methods/algorithms. You can for ex. xor a string and then encrypt it with AES 256.
Definitions and Includes

#include 
#include 
#include 
int XOR(WCHAR **dest, const WCHAR *src, int slen, const WCHAR *key, int klen);
XOR method

int XOR(WCHAR **dest, const WCHAR *src, int slen, const WCHAR *key, int klen){
    int kIndex = 0;
 
    *dest = (WCHAR*)HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, slen * sizeof(WCHAR));
    if (*dest == NULL) return 0;
 
    for (int i = 0; i < slen - 1; i++){
        *(*dest + i) = src[i] ^ key[kIndex++];
        if (kIndex == klen - 1) kIndex = 0;
    }
 
    *(*dest + (slen - 1)) = '\0';
 
    return slen;
}

Usage

int main(void){
    WCHAR *xored;
    const WCHAR plain[] = L"maldevel\0";
    const WCHAR xorkey[] = L"gt32fvbn678jkfdcvb34tgbn\0";
    int xoredChars = 0;
 
    wprintf(L"plain text: %s
", plain);
    xoredChars = XOR(&xored, plain, wcslen(plain) + 1, xorkey, wcslen(xorkey) + 1);
 
    if (xoredChars > 0)
        wprintf(L"xor result: %s
", xored);
 
    if (xored)HeapFree(GetProcessHeap(), 0, xored);
 
    return EXIT_SUCCESS;
}