Hi, wrote a Qt-flavored version which might help you:
Using Qt 5.11.2 on my Ubuntu 18.04, I created a Qt console project.
I added LIBS += -lcrypto to my .pro file and clicked Build/Run qmake.
Then I changed main.cpp into this:
#include <QCoreApplication>
#include <stdio.h>
#include <stdlib.h>
#include <openssl/aes.h>
#include <openssl/evp.h>
int aes_init(unsigned char *key_data, int key_data_len, unsigned char *salt, EVP_CIPHER_CTX *e_ctx,EVP_CIPHER_CTX *d_ctx)
{
int i, nrounds = 5;
unsigned char key[32], iv[32];
i = EVP_BytesToKey(EVP_aes_256_cbc(), EVP_sha1(), salt, key_data, key_data_len, nrounds, key, iv);
if (i != 32)
{
printf("Key size is %d bits - should be 256 bits\n", i);
exit(-1);
}
EVP_CIPHER_CTX_init(e_ctx);
EVP_EncryptInit_ex(e_ctx, EVP_aes_256_cbc(), nullptr, key, iv);
EVP_CIPHER_CTX_init(d_ctx);
EVP_DecryptInit_ex(d_ctx, EVP_aes_256_cbc(), nullptr, key, iv);
return 0;
}
unsigned char *aes_encrypt(EVP_CIPHER_CTX *e, unsigned char *plaintext, int *len)
{
int c_len = *len + AES_BLOCK_SIZE, f_len = 0;
unsigned char *ciphertext = reinterpret_cast<unsigned char*>(malloc(static_cast<size_t>(c_len)));
EVP_EncryptInit_ex(e, nullptr, nullptr, nullptr, nullptr);
EVP_EncryptUpdate(e, ciphertext, &c_len, plaintext, *len);
EVP_EncryptFinal_ex(e, ciphertext+c_len, &f_len);
*len = c_len + f_len;
return ciphertext;
}
unsigned char *aes_decrypt(EVP_CIPHER_CTX *e, unsigned char *ciphertext, int *len)
{
int p_len = *len, f_len = 0;
unsigned char *plaintext = reinterpret_cast<unsigned char*>(malloc(static_cast<size_t>(p_len + AES_BLOCK_SIZE)));
EVP_DecryptInit_ex(e, nullptr, nullptr, nullptr, nullptr);
EVP_DecryptUpdate(e, plaintext, &p_len, ciphertext, *len);
EVP_DecryptFinal_ex(e, plaintext+p_len, &f_len);
*len = p_len + f_len;
return plaintext;
}
// modified main to use QString and QByteArray
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
EVP_CIPHER_CTX* en = EVP_CIPHER_CTX_new();
EVP_CIPHER_CTX* de = EVP_CIPHER_CTX_new();
unsigned int salt[] = {12345, 54321};
unsigned char key_data[] = "01234567890123456789012345678901";
int key_data_len = static_cast<int>(strlen(reinterpret_cast<char *>(key_data)));
// gen key and iv. init the cipher ctx object
if (aes_init(key_data, key_data_len, reinterpret_cast<unsigned char *>(&salt), en, de))
{
printf("Couldn't initialize AES cipher\n");
exit(1);
}
// encrypt or decrypt?
if (2 != argc)
{
// neither, print help text
printf("Usage:\n./untitled Plaintext\nPrints the ciphertext\n\n./untitled 0xXXXXX\nPrints the plaintext.\n");
exit(1);
}
QString arg = argv[1];
// is it decrypt?
if (arg.startsWith("0x") || arg.startsWith("0X"))
{
// yes, decrypt
auto ba = QByteArray::fromHex(arg.mid(2).toLatin1());
int len = ba.length();
const char* cipherText = ba;
printf("plainText = %s\n",aes_decrypt(de,reinterpret_cast<unsigned char*>(const_cast<char*>(cipherText)),&len));
}
else
{
// encrypt
int len = arg.length() + 1;
auto plainText = reinterpret_cast<unsigned char*>(const_cast<char*>(static_cast<const char*>(arg.toLatin1())));
unsigned char* cipherText = aes_encrypt(en,plainText,&len);
QByteArray ba(reinterpret_cast<char*>(cipherText),len);
printf("ciphertext = 0x%s\n",static_cast<const char*>(ba.toHex()));
}
}
If you specify a normal string it prints the encrypted string in hex, and if you specify the hex string (beginning with 0x) then it prints the original plaintext. Hope this helps!
