ECB Encrypt&Decrypt

#include <cstring>
#include <iostream>
using namespace std;

#define ECB_CYCLE 7

void ecb_encrypt(const int* key, const char* msg, char*& enc)
{
    if (enc == nullptr) {
        enc = new char[strlen(msg) + 1];
    }

    for (int i = 0; msg[i] != '\0'; i++) {
        enc[i] = (msg[i] + key[i % ECB_CYCLE] - 32) % 91 + 32;
    }
}

void ecv_decrypt(const int* key, const char* enc, char*& dec)
{
    if (dec == nullptr) {
        dec = new char[strlen(enc) + 1];
    }

    for (int i = 0; enc[i] != '\0'; i++) {
        dec[i] = (enc[i] - key[i % ECB_CYCLE] + 59) % 91 + 32;
    }
}

int main()
{
    const int key[] = { 8, 7, 3, 4, 9, 6, 2 };

    cout << "Please input plain text:";
    char str[128];
    cin.getline(str, 100);

    char *enc = nullptr, *dec = nullptr;
    ecb_encrypt(key, str, enc);
    cout << "Encrypt: " << enc << endl;

    ecv_decrypt(key, enc, dec);
    cout << "Decrypt: " << dec << endl;

    delete[] enc;
    delete[] dec;

    return 0;
}