I want to encrypt the data with AES-256-CBC with block padding and data is segregated in multiple variables i.e. I want to call BCryptEncrypt multiple times and at the end I will combine all the ciphertext into one buffer.
#include <windows.h>
#include <stdio.h>
#include <bcrypt.h>
#pragma comment(lib, "bcrypt.lib")
#define NT_SUCCESS(Status) (((NTSTATUS)(Status)) >= 0)
#define STATUS_UNSUCCESSFUL ((NTSTATUS)0xC0000001L)
const PBYTE pbPlainText1="The quick brown ";
const PBYTE pbPlainText2="The quick brown fox jumps over t";
const PBYTE pbPlainText3="he lazy dog";
static const BYTE rgbIV[] = "1234567887654321";
static const BYTE rgbAES256Key[] = "0123456789abcdefghijklmnopqrstuv";
int ival_len = 16; //IV BUFF SIZE
int key_len = 32; //KEY LEN
void __cdecl wmain(
int argc,
__in_ecount(argc) LPWSTR *wargv)
{
BCRYPT_ALG_HANDLE hAesAlg = NULL;
BCRYPT_KEY_HANDLE hKey = NULL;
NTSTATUS status = STATUS_UNSUCCESSFUL;
DWORD cbCipherText = 0,
cbPlainText = 0,
cbData = 0,
cbKeyObject = 0,
cbBlockLen = 0,
cbBlob = 0;
PBYTE pbCipherText = NULL,
pbPlainText = NULL,
pbKeyObject = NULL,
pbIV = NULL,
pbBlob = NULL,
cipherText ;
DWORD cbKeyObject_d = 0,cbBlockLen_d = 0,cbData_d=0;
BCRYPT_ALG_HANDLE hAesAlg_d = NULL;
BCRYPT_KEY_HANDLE hKey_d = NULL;
PBYTE pbKeyObject_d = NULL, pbIV_d = NULL;
UNREFERENCED_PARAMETER(argc);
UNREFERENCED_PARAMETER(wargv);
// Open an algorithm handle.
if(!NT_SUCCESS(status = BCryptOpenAlgorithmProvider(
&hAesAlg,
BCRYPT_AES_ALGORITHM,
NULL,
0)))
{
wprintf(L"**** Error 0x%x returned by BCryptOpenAlgorithmProvider\n", status);
goto Cleanup;
}
// Calculate the size of the buffer to hold the KeyObject.
if(!NT_SUCCESS(status = BCryptGetProperty(
hAesAlg,
BCRYPT_OBJECT_LENGTH,
(PBYTE)&cbKeyObject,
sizeof(DWORD),
&cbData,
0)))
{
wprintf(L"**** Error 0x%x returned by BCryptGetProperty\n", status);
goto Cleanup;
}
// Allocate the key object on the heap.
pbKeyObject = (PBYTE)HeapAlloc (GetProcessHeap (), 0, cbKeyObject);
if(NULL == pbKeyObject)
{
wprintf(L"**** memory allocation failed\n");
goto Cleanup;
}
if (ival_len > sizeof (rgbIV))
{
wprintf (L"**** block length is longer than the provided IV length\n");
goto Cleanup;
}
// Allocate a buffer for the IV. The buffer is consumed during the
// encrypt/decrypt process.
if(ival_len > 0)
{
pbIV= (PBYTE) HeapAlloc (GetProcessHeap (), 0, ival_len + 1);
if(NULL == pbIV)
{
wprintf(L"**** memory allocation failed\n");
goto Cleanup;
}
strncpy(pbIV,rgbIV,ival_len);
pbIV[ival_len]='\0';
}
if(!NT_SUCCESS(status = BCryptSetProperty(
hAesAlg,
BCRYPT_CHAINING_MODE,
(PBYTE)BCRYPT_CHAIN_MODE_CBC,
sizeof(BCRYPT_CHAIN_MODE_CBC),
0)))
{
wprintf(L"**** Error 0x%x returned by BCryptSetProperty\n", status);
goto Cleanup;
}
if(!NT_SUCCESS(status = BCryptGetProperty(
hAesAlg,
BCRYPT_BLOCK_LENGTH,
(PBYTE)&cbBlockLen,
sizeof(DWORD),
&cbData,
0)))
{
wprintf(L"**** Error 0x%x returned by BCryptGetProperty\n", status);
goto Cleanup;
}
// Generate the key from supplied input key bytes.
if(!NT_SUCCESS(status = BCryptGenerateSymmetricKey(
hAesAlg,
&hKey,
pbKeyObject,
cbKeyObject,
(PBYTE)rgbAES256Key,
key_len,
0)))
{
wprintf(L"**** Error 0x%x returned by BCryptGenerateSymmetricKey\n ", status);
fprintf(stderr, "\nError number <%x>", GetLastError());
goto Cleanup;
}
cbPlainText = sizeof(rgbPlaintext);
pbPlainText = (PBYTE)HeapAlloc (GetProcessHeap (), 0, cbPlainText);
if(NULL == pbPlainText)
{
wprintf(L"**** memory allocation failed\n");
goto Cleanup;
}
strncpy(pbPlainText, rgbPlaintext,cbPlainText);
//Call BCryptEncrypt for pbPlainText1 and cipherText1
//Call BCryptEncrypt for pbPlainText2 and cipherText2
//Call BCryptEncrypt for pbPlainText2 and cipherText3
//Combine cipherText1, cipherText2 and cipherText3 to cipherText variable
//print cipherText in hex
printf("\nCipher Text is :");
for (DWORD i = 0; i < strlen(cipherText ); i++)
{
printf("%2.2X", cipherText[i]);
}
Cleanup:
if(hAesAlg)
{
BCryptCloseAlgorithmProvider(hAesAlg,0);
}
if (hKey)
{
BCryptDestroyKey(hKey);
}
if(pbCipherText)
{
HeapFree(GetProcessHeap(), 0, pbCipherText);
}
if(pbPlainText)
{
HeapFree(GetProcessHeap(), 0, pbPlainText);
}
if(pbKeyObject)
{
HeapFree(GetProcessHeap(), 0, pbKeyObject);
}
if(pbIV)
{
HeapFree(GetProcessHeap(), 0, pbIV);
}
}
I am expecting output "ABB7998EE4CE0699BD713AA9711E46F2EFCA1D16DABDA0291F1706B5F9F6B7B7E6705744981DB65EE6E14ECF896A90F8" for this code.
This is a sample program so I am using only 3 plain text buffers but in my real code the buffers can be multiple numbers.