CryptEncrypt AES-CBC demo for Stack Overflow, C++ (vc++)

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// CryptEncrypt() AES-CBC demo for https://stackoverflow.com/questions/57850242/how-to-use-cryptoapi-in-order-to-encrypt-more-then-one-block-size-of-buffer-with

#include <iostream>
#include <stdio.h>
#include <windows.h>
#include <wincrypt.h>

#pragma comment (lib, "advapi32")

using std::string;

char *key = "swordfish";

HCRYPTPROV hCryptProv = NULL; 
HCRYPTKEY hKey = NULL;

#define AES_BLOCK_SIZE 16

BOOL AesInitialization()
{
    char *stage = "n/a";
    BOOL success = TRUE;

HCRYPTHASH hHash = NULL;

if (success) {
        stage = "CryptAcquireContext";
        success = CryptAcquireContext(&hCryptProv, NULL, MS_ENH_RSA_AES_PROV, PROV_RSA_AES, NULL);
    }
    if (success) {
        stage = "CryptCreateHash";
        success = CryptCreateHash(hCryptProv, CALG_SHA_256, 0, 0, &hHash);
    }
    if (success) {
        stage = "CryptHashData";
        success = CryptHashData(hHash, (BYTE*)key, strlen(key), 0);
    }
    if (success) {
        stage = "CryptDeriveKey";
        success = CryptDeriveKey(hCryptProv, CALG_AES_256, hHash, 0, &hKey);
    }
    if (success) {
        stage = "CryptSetKeyParam";
        DWORD dwMode = CRYPT_MODE_CBC;
        success = CryptSetKeyParam(hKey, KP_MODE, (BYTE *)&dwMode, 0);
    }

if (!success) printf("AES initialization - %s failed: 0x%08x\n", stage, GetLastError());
    if (hHash != NULL) CryptDestroyHash(hHash);
    return success;
}

BOOL AesEncrypt(string &data, string &iv)
{
    char *stage = "n/a";
    BOOL success = TRUE;
    
    if (success) {
        stage = "CryptGenRandom";
        iv.resize(AES_BLOCK_SIZE);  // allocate space for random IV
        success = CryptGenRandom(hCryptProv, AES_BLOCK_SIZE, (BYTE *)&iv[0]);
    }
    if (success) {
        stage = "CryptSetKeyParam";
        success = CryptSetKeyParam(hKey, KP_IV, (BYTE *)&iv[0], 0);
    }
    if (success) {
        stage = "CryptEncrypt";
        DWORD dwDataLen = data.length();
        data.resize(dwDataLen + AES_BLOCK_SIZE); // give enough space for padding
        success = CryptEncrypt(hKey, NULL, TRUE, 0, (BYTE *)&data[0], &dwDataLen, data.length());
        data.resize(dwDataLen);  // resize to actual ciphertext length
    }

if (!success) printf("AES encryption - %s failed: 0x%08x\n", stage, GetLastError());
    return success;
}

BOOL AesDecrypt(string &data, string &iv)
{
    char *stage = "n/a";
    BOOL success = TRUE;
    
    if (success) {
        stage = "CryptSetKeyParam";
        iv.resize(AES_BLOCK_SIZE);  // ensure IV has the correct size
        success = CryptSetKeyParam(hKey, KP_IV, (BYTE *)&iv[0], 0);
    }
    if (success) {
        stage = "CryptDecrypt";
        DWORD dwDataLen = data.length();
        success = CryptDecrypt(hKey, NULL, TRUE, 0, (BYTE *)&data[0], &dwDataLen);
        data.resize(dwDataLen);  // resize to actual ciphertext length
    }

if (!success) printf("AES encryption - %s failed: 0x%08x\n", stage, GetLastError());
    return success;
}

int main()
{
    if (!AesInitialization()) return 1;

string message = "Hello, World! This is a test of AES-CBC encryption.";
    printf("Plaintext: %s\n\n", message.data());
    
    string iv;
    if (!AesEncrypt(message, iv)) return 1;

printf("CBC IV (hex):");
    for (unsigned char c : iv) printf(" %02X", c);
    printf("\n");

printf("Ciphertext (hex):");
    for (unsigned char c : message) printf(" %02X", c);
    printf("\n\n");
    
    if (!AesDecrypt(message, iv)) return 1;

printf("Decrypted (hex):");
    for (unsigned char c : message) printf(" %02X", c);
    printf("\n");
    printf("Decrypted (text): %s\n", message.data());

return 0;
}

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Compilation time: 2,43 sec, absolute running time: 0,24 sec, absolute service time: 2,68 sec