总是得到与CryptoAPI相同的加密字符串

Question

有没有办法从CryptoAPI获得非确定性输出？换句话说，加密字符串时会输出不同的字符串。

例如，获得与“密码”密码加密密钥和字符串加密的“A”在使用CALG_AES_256，它总是返回“SnÆwÞ¢大号\ X1E？6FÏLþw”

我有点的n00b使用CryptoAPI，所以任何帮助表示赞赏。

编辑： 下面是来自微软的示例代码密码系统的代码decrypte和encrypt这是相同的代码，只是缩短/压实。此代码作为Win32控制台应用程序在VS 2017中编译。 pszSource和pszDest是C：\ temp文件夹中的两个文件。 source.txt有我们试图加密的信件。

时遇到的问题是从的CryptoAPI 这隐窝/解密代码不允许某些字符串来进行加密，然后解密后的（即，n，T，L，P，AA，AB，AC，AD ，ae等）。如果有人能告诉我为什么，那会非常有帮助。

#include <windows.h> 
#include <tchar.h> 
#include <wincrypt.h> 

#define KEYLENGTH 0x00800000 
#define ENCRYPT_BLOCK_SIZE 8 

bool MyDecryptFile(LPTSTR szSource,LPTSTR szDestination,LPTSTR szPassword); 
bool MyEncryptFile(LPTSTR szSource,LPTSTR szDestination,LPTSTR szPassword); 

int _tmain(int argc, _TCHAR* argv[]) 
{ 

    LPTSTR pszSource = L"c:\\temp\\source.txt"; 
    LPTSTR pszDestination = L"c:\\temp\\dest.txt"; 
    LPTSTR pszPassword = L"t"; 

    if (MyEncryptFile(pszSource, pszDestination, pszPassword)) 
     { 
     _tprintf(TEXT("Encryption of the file %s was successful. \n"),pszSource); 
     _tprintf(TEXT("The encrypted data is in file %s.\n"),pszDestination); 
     } 

    if (MyDecryptFile(pszSource, pszDestination, pszPassword)) 
     { 
     _tprintf(TEXT("Encryption of the file %s was successful. \n"),pszSource); 
     _tprintf(TEXT("The encrypted data is in file %s.\n"),pszDestination); 
     } 

    return 0; 
} 

bool MyEncryptFile(LPTSTR pszSourceFile,LPTSTR pszDestinationFile,LPTSTR pszPassword) 
{ 
    bool fReturn = false; 
    HANDLE hSourceFile = INVALID_HANDLE_VALUE, hDestinationFile = INVALID_HANDLE_VALUE; 
    HCRYPTPROV hCryptProv = NULL; 
    HCRYPTKEY hKey = NULL, hXchgKey = NULL; 
    HCRYPTHASH hHash = NULL; 
    PBYTE pbBuffer = NULL; 
    DWORD dwBlockLen, dwBufferLen, dwCount; 

    hSourceFile = CreateFile(pszSourceFile,FILE_READ_DATA,FILE_SHARE_READ,NULL,OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL,NULL); 
    if (INVALID_HANDLE_VALUE == hSourceFile) 
     goto Exit_MyEncryptFile; 

    hDestinationFile = CreateFile(pszDestinationFile,FILE_WRITE_DATA,FILE_SHARE_READ,NULL,OPEN_ALWAYS,FILE_ATTRIBUTE_NORMAL,NULL); 
    if (INVALID_HANDLE_VALUE == hDestinationFile) 
     goto Exit_MyEncryptFile; 

    CryptAcquireContext(&hCryptProv,NULL,MS_ENH_RSA_AES_PROV,PROV_RSA_AES,0); 
    CryptCreateHash(hCryptProv,CALG_SHA_256,0,0,&hHash); 
    CryptHashData(hHash,(BYTE *)pszPassword,lstrlen(pszPassword),0); 
    CryptDeriveKey(hCryptProv,CALG_AES_256,hHash,CRYPT_EXPORTABLE,&hKey); 

    dwBlockLen = 1000 - 1000 % ENCRYPT_BLOCK_SIZE; 
    if (ENCRYPT_BLOCK_SIZE > 1) 
     dwBufferLen = dwBlockLen + ENCRYPT_BLOCK_SIZE; 
    else 
     dwBufferLen = dwBlockLen; 
    pbBuffer = (BYTE *)malloc(dwBufferLen); 

    bool fEOF = FALSE; 
    do 
    { 
     if (ReadFile(hSourceFile,pbBuffer,dwBlockLen,&dwCount,NULL)) 
      { 
      if (dwCount < dwBlockLen) 
       fEOF = TRUE; 
      if (CryptEncrypt(hKey,NULL,fEOF,0,pbBuffer,&dwCount,dwBufferLen)) 
       WriteFile(hDestinationFile,pbBuffer,dwCount,&dwCount,NULL); 
      } 
    } 
    while (!fEOF); 

    fReturn = true; 

Exit_MyEncryptFile: 
    if (hSourceFile) CloseHandle(hSourceFile); 
    if (hDestinationFile) CloseHandle(hDestinationFile); 
    if (pbBuffer) free(pbBuffer); 
    if (hHash) {CryptDestroyHash(hHash);hHash = NULL;} 
    if (hKey) CryptDestroyKey(hKey); 
    if (hCryptProv) CryptReleaseContext(hCryptProv, 0); 

    return fReturn; 
} 


bool MyDecryptFile(LPTSTR pszSourceFile,LPTSTR pszDestinationFile,LPTSTR pszPassword) 
{ 
    bool fReturn = false; 
    HANDLE hSourceFile = INVALID_HANDLE_VALUE, hDestinationFile = INVALID_HANDLE_VALUE; 
    HCRYPTKEY hKey = NULL; 
    HCRYPTHASH hHash = NULL; 
    HCRYPTPROV hCryptProv = NULL; 
    PBYTE pbBuffer = NULL; 
    DWORD dwCount, dwBlockLen, dwBufferLen; 

    hSourceFile = CreateFile(pszDestinationFile,FILE_READ_DATA,FILE_SHARE_READ,NULL,OPEN_ALWAYS,FILE_ATTRIBUTE_NORMAL,NULL); 
    if (INVALID_HANDLE_VALUE == hSourceFile) 
     goto Exit_MyDecryptFile; 

    hDestinationFile = CreateFile(pszSourceFile,FILE_WRITE_DATA,FILE_SHARE_READ,NULL,OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL,NULL); 
    if (INVALID_HANDLE_VALUE == hDestinationFile) 
     goto Exit_MyDecryptFile; 

    CryptAcquireContext(&hCryptProv,NULL,MS_ENH_RSA_AES_PROV,PROV_RSA_AES,0); 
    CryptCreateHash(hCryptProv,CALG_SHA_256,0,0,&hHash); 
    CryptHashData(hHash,(BYTE *)pszPassword,lstrlen(pszPassword),0); 
    CryptDeriveKey(hCryptProv,CALG_AES_256,hHash,CRYPT_EXPORTABLE,&hKey); 

    dwBlockLen = 1000 - 1000 % ENCRYPT_BLOCK_SIZE; 
    dwBufferLen = dwBlockLen; 

    pbBuffer = (PBYTE)malloc(dwBufferLen); 
    bool fEOF = false; 
    do 
    { 
     if (!ReadFile(hSourceFile,pbBuffer,dwBlockLen,&dwCount,NULL)) 
      goto Exit_MyDecryptFile; 

     if (dwCount <= dwBlockLen) 
      fEOF = TRUE; 

     LONG rv = CryptDecrypt(hKey,0,fEOF,0,pbBuffer,&dwCount); 
     if (rv==0) 
      { 
      DWORD dwErr = GetLastError();  // <--- fails if password and string are n, t, L, p, aa, ab, ac, ad , ae 
      goto Exit_MyDecryptFile; 
      } 

     if (!WriteFile(hDestinationFile,pbBuffer,dwCount,&dwCount,NULL)) 
      goto Exit_MyDecryptFile; 
    } 
    while (!fEOF); 

    fReturn = true; 

Exit_MyDecryptFile: 

    if (pbBuffer) free(pbBuffer); 
    if (hSourceFile) CloseHandle(hSourceFile); 
    if (hDestinationFile) CloseHandle(hDestinationFile); 
    if (hHash) {CryptDestroyHash(hHash);hHash = NULL;} 
    if (hKey) CryptDestroyKey(hKey); 
    if (hCryptProv) CryptReleaseContext(hCryptProv, 0); 

    return fReturn; 
} 

如何使用它来获得KP_IV选项？

BOOL bRV; 
bRV = CryptAcquireContextW(&hCryptProv, NULL, MS_ENH_RSA_AES_PROV, PROV_RSA_AES, 0); 
bRV = CryptGenKey(hCryptProv, CALG_AES_256,0,&hKey); 
DWORD dwMode = CRYPT_MODE_CBC; 
bRV = CryptSetKeyParam(hKey,KP_MODE,(BYTE*)&dwMode,0); 
BYTE pbData[16]; 
memcpy(pbData,"n",sizeof("n")); // <--- Hard coded password 
bRV = CryptSetKeyParam(hKey,KP_IV,pbData,0); 
enter code here 

Answer 1

如果你想用相同的密钥加密同一明文时获得不同的cypertext，你必须使用操作的CBC模式： https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation

为了与CBC正确加密，您需要每次生成不同的随机初始化向量（IV）。 为了解密，您需要知道加密过程中使用的IV。因此，IV必须与密文相关联（清楚地）。

关于你例如，调用CryptDeriveKey功能时，CBC是默认模式，但它使用的IV设置为零，并且该无效的CBC操作模式的效用： https://msdn.microsoft.com/en-us/library/windows/desktop/aa379916(v=vs.85).aspx

为了设置你需要调用CryptSetKeyParam功能，接受KP_IV PARAM随机IV： https://msdn.microsoft.com/en-us/library/windows/desktop/aa380272(v=vs.85).aspx

再见 乔瓦尼