I am encrypting the same plain text with AES-128-CFB but ciphertext generated by "Windows Cryptography API: Next Generation" and OpenSSL are different for the same IV, and key.
Plain Text: The quick brown fox jumps over the lazy dog
IV: 1234567887654321
Key: 1234567887654321
Cipher Text generated by Windows CNG in Hex: 279CB0C2FD67B37F33A861CDDAFBEDCEEAEFC68FD5B3478E67E4A936BA7CFE75DDBAD370A1E4D6CDC3455E2F4E188A9C
Cipher Text length generated by Windows CNG: 48 Bytes
Cipher Text generated by OpenSSL in Hex: 279CB0C2FD67B37F33A861CDDAFBEDCEEAEFC68FD5B3478E67E4A936BA7CFE75DDBAD370A1E4D6CDC3455E
Cipher Text length generated by Windows CNG: 43 Bytes
Windows CNG adding extra 5 bytes(2F4E188A9C) at the end, I thought it is due to padding and sent dwFlags value as 0 instead of BCRYPT_BLOCK_PADDING then BCryptEncrypt API call failing with error code 0xc0000206/STATUS_INVALID_BUFFER_SIZE.
Windows CNG code:
#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)
void
hexdump(const char *msg, const unsigned char *in, unsigned int len)
{
printf("%s [%d][", msg, len);
for (; len > 0; len--, in++) {
printf("%02X", *in);
}
printf("]\n");
}
const BYTE rgbPlaintext[] = "The quick brown fox jumps over the lazy dog";
static const BYTE rgbIV[] = "1234567887654321";
static const BYTE rgbAES128Key[] = "0123456789abcdefghijklmnopqrstuv";
const int ival_len = 16;
const int key_len = 16;
const DWORD block_len = 16;
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,
cbData = 0,
cbKeyObject = 0,
cbBlockLen = 0,
cbBlob = 0;
PBYTE pbCipherText = NULL,
pbKeyObject = NULL,
pbIV = NULL,
pbBlob = NULL;
UNREFERENCED_PARAMETER(argc);
UNREFERENCED_PARAMETER(wargv);
if(!NT_SUCCESS(status = BCryptOpenAlgorithmProvider(
&hAesAlg,
BCRYPT_AES_ALGORITHM,
NULL,
0)))
{
wprintf(L"**** Error 0x%x returned by BCryptOpenAlgorithmProvider\n", status);
goto Cleanup;
}
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;
}
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;
}
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_CFB,
sizeof(BCRYPT_CHAIN_MODE_CFB),
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;
}
if(!NT_SUCCESS(status = BCryptGenerateSymmetricKey(
hAesAlg,
&hKey,
pbKeyObject,
cbKeyObject,
(PBYTE)rgbAES128Key,
key_len,
0)))
{
wprintf(L"**** Error 0x%x returned by BCryptGenerateSymmetricKey\n ", status);
fprintf(stderr, "\nError number <%x>", GetLastError());
goto Cleanup;
}
if (!NT_SUCCESS(status = BCryptSetProperty(hKey,
BCRYPT_MESSAGE_BLOCK_LENGTH,
(PBYTE)&block_len,
sizeof(DWORD),
0))) {
wprintf(L"**** Error 0x%x returned by BCryptSetProperty\n ", status);
fprintf(stderr, "\nError number <%x>", GetLastError());
goto Cleanup;
}
printf("\nplan text is [%d][%s]\n", sizeof(rgbPlaintext) - 1, rgbPlaintext);
if(!NT_SUCCESS(status = BCryptEncrypt(
hKey,
rgbPlaintext,
sizeof(rgbPlaintext) - 1,
NULL,
pbIV,
ival_len,
NULL,
0,
&cbCipherText,
BCRYPT_BLOCK_PADDING)))
{
wprintf(L"\n**** Error 1 0x%x returned by BCryptEncrypt\n", status);
goto Cleanup;
}
pbCipherText = (PBYTE)HeapAlloc (GetProcessHeap (), 0, cbCipherText);
if(NULL == pbCipherText)
{
wprintf(L"**** memory allocation failed\n");
goto Cleanup;
}
// Use the key to encrypt the plaintext buffer.
// For block sized messages, block padding will add an extra block.
if(!NT_SUCCESS(status = BCryptEncrypt(
hKey,
rgbPlaintext,
sizeof(rgbPlaintext) - 1,
NULL,
pbIV,
ival_len,
pbCipherText,
cbCipherText,
&cbData,
BCRYPT_BLOCK_PADDING)))
{
wprintf(L"**** Error 2 0x%x returned by BCryptEncrypt\n", status);
goto Cleanup;
}
hexdump("cipher is", pbCipherText, cbCipherText);
Cleanup:
if(hAesAlg)
{
BCryptCloseAlgorithmProvider(hAesAlg,0);
}
if (hKey)
{
BCryptDestroyKey(hKey);
}
if(pbCipherText)
{
HeapFree(GetProcessHeap(), 0, pbCipherText);
}
if(pbKeyObject)
{
HeapFree(GetProcessHeap(), 0, pbKeyObject);
}
if(pbIV)
{
HeapFree(GetProcessHeap(), 0, pbIV);
}
}
OpenSSL Code:
#include <openssl/conf.h>
#include <openssl/evp.h>
#include <openssl/err.h>
#include <string.h>
void
hexdump(const char *msg, const unsigned char *in, unsigned int len)
{
printf("%s [%d][", msg, len);
for (; len > 0; len--, in++) {
printf("%02X", *in);
}
printf("]\n");
}
int main(void)
{
/* A 256 bit key */
unsigned char *key = (unsigned char *)"0123456789abcdefghijklmnopqrstuv";
/* A 128 bit IV */
unsigned char *iv = (unsigned char *)"1234567887654321";
/* Message to be encrypted */
unsigned char *plaintext =
(unsigned char *)"The quick brown fox jumps over the lazy dog12312";
unsigned char ciphertext[128];
int ciphertextLen = encrypt(plaintext, strlen ((char *)plaintext), key, iv, ciphertext);
hexdump("cipher value is:", ciphertext, ciphertextLen);
return 0;
}
void handleErrors(void)
{
ERR_print_errors_fp(stderr);
abort();
}
int encrypt(unsigned char *plaintext,
int plaintext_len,
unsigned char *key,
unsigned char *iv,
unsigned char *ciphertext)
{
EVP_CIPHER_CTX *ctx;
int len;
int ciphertextLen;
/* Create and initialise the context */
if(!(ctx = EVP_CIPHER_CTX_new()))
handleErrors();
if(1 != EVP_EncryptInit_ex(ctx, EVP_aes_128_cfb(), NULL, key, iv))
handleErrors();
if(1 != EVP_EncryptUpdate(ctx, ciphertext, &len, plaintext, plaintext_len))
handleErrors();
ciphertextLen = len;
if(1 != EVP_EncryptFinal_ex(ctx, ciphertext + len, &len))
handleErrors();
ciphertextLen += len;
EVP_CIPHER_CTX_free(ctx);
return ciphertextLen;
}