Question

Alejandro Magencio的以下代码生成密钥对，使用Microsoft CryptoAPI加密和解密文件效果很好，但仅适用于小于密钥的文件： http://blogs.msdn.com/b/alejacma/archive/2008/01/28/how-to-generate-key-pairs-encrypt-and-decrypt-data-with-cryptoapi.aspx

我正在尝试扩展此代码以加密和解密更大的文件。

就我而言，这是完整的清单。它加密但在解密循环中第二次出现错误数据错误。

我们将非常感谢任何帮助，并保证发布完整的工作代码。

提前致谢！

/*
    EncryptDecrypt.c

    This program was compiled on Windows 7 64-bit with Visual Studio 2013 Desktop Express. To run:

    EncryptDecrypt.exe k C:\temp\myprivate.key C:\temp\mypublic.key

    EncryptDecrypt.exe e C:\temp\myprivate.key C:\temp\todo.txt C:\temp\done.txt

    EncryptDecrypt.exe d C:\temp\mypublic.key C:\temp\done.txt C:\temp\redone.txt  
*/
#include "stdio.h"
#include "conio.h"
#include "windows.h"
#include "wincrypt.h"
#include "tchar.h"

#define ENCRYPTEDLENGTH (128)
#define MAXSIZE (128 - 11) // size of chunk we can use for this program

// FUNCTIONS
int Keys(_TCHAR* strPublicKeyFile, _TCHAR* strPrivateKeyFile);
int Encrypt(_TCHAR* strPublicKeyFile, _TCHAR* strPlainFile, _TCHAR* strEncryptedFile);
int Decrypt(_TCHAR* strPrivateKeyFile, _TCHAR* strEncryptedFile, _TCHAR* strPlainFile);

// Main
int _tmain(int argc, _TCHAR* argv[])
{
    int iResult = 0;

    if ((argc == 4) && (_tcscmp(argv[1], _T("k")) == 0))
    {
        // Generate a new key pair
        iResult = Keys(argv[2], argv[3]);
    }
    else if ((argc == 5) && (_tcscmp(argv[1], _T("e")) == 0))
    {
        // Encrypt
        iResult = Encrypt(argv[2], argv[3], argv[4]);
    }
    else if ((argc == 5) && (_tcscmp(argv[1], _T("d")) == 0))
    {
        // Decrypt
        iResult = Decrypt(argv[2], argv[3], argv[4]);
    }
else
 {
        // Show usage
        _tprintf(_T("Usage:\n"));
        _tprintf(_T("   - New key pair: EncryptDecrypt k public_key_file private_key_file\n"));
        _tprintf(_T("   - Encrypt:      EncryptDecrypt e public_key_file plain_file encrypted_file\n"));
        _tprintf(_T("   - Decrypt:      EncryptDecrypt d private_key_file encrypted_file plain_file\n"));
        iResult = 1;
    }

    _tprintf(_T("\n<< Press any key to continue >>\n"));
    _getch();

    return iResult;
}
// End of Main

// Keys
int Keys(_TCHAR* strPublicKeyFile, _TCHAR* strPrivateKeyFile)
 {
    HCRYPTPROV hCryptProv = NULL;
    HCRYPTKEY hKey = NULL;
    DWORD dwPublicKeyLen = 0;
    DWORD dwPrivateKeyLen = 0;
    BYTE* pbPublicKey = NULL;
    BYTE* pbPrivateKey = NULL;
    HANDLE hPublicKeyFile = NULL;
    HANDLE hPrivateKeyFile = NULL;
    DWORD lpNumberOfBytesWritten = 0;

    __try
    {
        // Acquire access to key container
        _tprintf(_T("CryptAcquireContext...\n"));
        if (!CryptAcquireContext(&hCryptProv, _T("ACMEENCRYPT.EncryptDecrypt"), NULL, PROV_RSA_FULL, 0))
        {
            // Error
            _tprintf(_T("(ref 12) CryptAcquireContext error 0x%x\n"), GetLastError());

            // Try to create a new key container
            if (!CryptAcquireContext(&hCryptProv, _T("ACMEENCRYPT.EncryptDecrypt"), NULL, PROV_RSA_FULL, CRYPT_NEWKEYSET))
            {
                // Error
                _tprintf(_T("(ref 13) CryptAcquireContext error 0x%x\n"), GetLastError());
                return 1;
            }
        }

        // Generate new key pair
        _tprintf(_T("CryptGenKey...\n"));
        if (!CryptGenKey(hCryptProv, AT_KEYEXCHANGE, CRYPT_ARCHIVABLE, &hKey))
        {
            // Error
            _tprintf(_T("CryptGenKey error 0x%x\n"), GetLastError());
            return 1;
        }

        // Get public key size
        _tprintf(_T("CryptExportKey...\n"));
        if (!CryptExportKey(hKey, NULL, PUBLICKEYBLOB, 0, NULL, &dwPublicKeyLen))
        {
            // Error
            _tprintf(_T("CryptExportKey error 0x%x\n"), GetLastError());
            return 1;
        }

        // Create a buffer for the public key
        _tprintf(_T("malloc...\n"));
        if (!(pbPublicKey = (BYTE *)malloc(dwPublicKeyLen)))
        {
            // Error
            _tprintf(_T("(ref 29) malloc error 0x%x\n"), GetLastError());
            return 1;
        }

        // Get public key
        _tprintf(_T("CryptExportKey...\n"));
        if (!CryptExportKey(hKey, NULL, PUBLICKEYBLOB, 0, pbPublicKey, &dwPublicKeyLen))
        {
            // Error
            _tprintf(_T("CryptExportKey error 0x%x\n"), GetLastError());
            return 1;
        }

        // Get private key size
        _tprintf(_T("CryptExportKey...\n"));
        if (!CryptExportKey(hKey, NULL, PRIVATEKEYBLOB, 0, NULL, &dwPrivateKeyLen))
        {
            // Error
            _tprintf(_T("CryptExportKey error 0x%x\n"), GetLastError());
            return 1;
        }

        // Create a buffer for the private key
        _tprintf(_T("malloc...\n"));
        if (!(pbPrivateKey = (BYTE *)malloc(dwPrivateKeyLen)))
    {
            // Error
        _tprintf(_T("(ref 30) malloc error 0x%x\n"), GetLastError());
        return 1;
    }

        // Get private key
        _tprintf(_T("CryptExportKey...\n"));
        if (!CryptExportKey(hKey, NULL, PRIVATEKEYBLOB, 0, pbPrivateKey, &dwPrivateKeyLen))
        {
            // Error
            _tprintf(_T("CryptExportKey error 0x%x\n"), GetLastError());
            return 1;
        }

        // Create a file to save the public key
        _tprintf(_T("CreateFile...\n"));
        if ((hPublicKeyFile = CreateFile(
            strPublicKeyFile,
            GENERIC_WRITE,
            0,
            NULL,
            CREATE_ALWAYS,
            FILE_ATTRIBUTE_NORMAL,
            NULL
            )) == INVALID_HANDLE_VALUE)
        {
            // Error
            _tprintf(_T("(ref 21) CreateFile error 0x%x\n"), GetLastError());
            return 1;
        }

        // Write the public key to the file
        _tprintf(_T("WriteFile...\n"));
        if (!WriteFile(
            hPublicKeyFile,
            (LPCVOID)pbPublicKey,
            dwPublicKeyLen,
            &lpNumberOfBytesWritten,
            NULL
            ))
        {
            // Error
            _tprintf(_T("(ref 51) WriteFile error 0x%x\n"), GetLastError());
            return 1;
        }

        // Create a file to save the private key
        _tprintf(_T("CreateFile...\n"));
        if ((hPrivateKeyFile = CreateFile(
            strPrivateKeyFile,
            GENERIC_WRITE,
            0,
            NULL,
            CREATE_ALWAYS,
            FILE_ATTRIBUTE_NORMAL,
            NULL
            )) == INVALID_HANDLE_VALUE)
        {
            // Error
            _tprintf(_T("(ref 22) CreateFile error 0x%x\n"), GetLastError());
            return 1;
        }

        // Write the private key to the file
        _tprintf(_T("WriteFile...\n"));
        if (!WriteFile(
            hPrivateKeyFile,
            (LPCVOID)pbPrivateKey,
            dwPrivateKeyLen,
            &lpNumberOfBytesWritten,
            NULL
            ))
        {
            // Error
            _tprintf(_T("(ref 52) WriteFile error 0x%x\n"), GetLastError());
            return 1;
        }

        return 0;
    }
    __finally
    {
        // Clean up       
        if (!pbPublicKey) {
            _tprintf(_T("free...\n"));
            free(pbPublicKey);
        }
        if (!pbPrivateKey) {
            _tprintf(_T("free...\n"));
            free(pbPrivateKey);
        }
        if (hPublicKeyFile) {
            _tprintf(_T("CloseHandle...\n"));
            CloseHandle(hPublicKeyFile);
        }
        if (hPrivateKeyFile) {
            _tprintf(_T("CloseHandle...\n"));
            CloseHandle(hPrivateKeyFile);
        }
        if (hKey) {
            _tprintf(_T("CryptDestroyKey...\n"));
            CryptDestroyKey(hKey);
        }
        if (hCryptProv) {
            _tprintf(_T("CryptReleaseContext...\n"));
            CryptReleaseContext(hCryptProv, 0);
        }
    }
}
// End of Keys

// Encrypt
int Encrypt(_TCHAR* strPublicKeyFile, _TCHAR* strPlainFile, _TCHAR* strEncryptedFile)
{
    HCRYPTPROV hCryptProv = NULL;
    HCRYPTKEY hKey = NULL;
    DWORD dwPublicKeyLen = 0;
    DWORD dwDataLen = 0;
    DWORD dwEncryptedLen = 0;
    DWORD myloopcount = 0;
    DWORD mymodulus = 0;
    DWORD i = 0;
    DWORD myencryptedlength = 0;
    DWORD mymaxsize = MAXSIZE;
    BYTE* pbPublicKey = NULL;
    BYTE* pbData = NULL;
    BYTE* pbEncData = NULL;
    HANDLE hPublicKeyFile = NULL;
    HANDLE hEncryptedFile = NULL;
    HANDLE hPlainFile = NULL;
    DWORD lpNumberOfBytesWritten = 0;

    __try
    {
        // Acquire access to key container
        _tprintf(_T("CryptAcquireContext...\n"));
        if (!CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
        {
            // Error
            _tprintf(_T("(ref 9) CryptAcquireContext error 0x%x\n"), GetLastError());
            return 1;
        }

        // Open public key file
        _tprintf(_T("CreateFile...\n"));
        if ((hPublicKeyFile = CreateFile(
            strPublicKeyFile,
            GENERIC_READ,
            FILE_SHARE_READ,
            NULL,
            OPEN_EXISTING,
            FILE_FLAG_SEQUENTIAL_SCAN,
            NULL
            )) == INVALID_HANDLE_VALUE)
        {
            // Error
            _tprintf(_T("(ref 14) CreateFile error 0x%x\n"), GetLastError());
            return 1;
        }

        // Get file size
        _tprintf(_T("GetFileSize...\n"));
        if ((dwPublicKeyLen = GetFileSize(hPublicKeyFile, NULL)) == INVALID_FILE_SIZE)
        {
            // Error
            _tprintf(_T("(ref 43) GetFileSize error 0x%x\n"), GetLastError());
            return 1;
        }

        // Create a buffer for the public key
        _tprintf(_T("malloc...\n"));
        if (!(pbPublicKey = (BYTE *)malloc(dwPublicKeyLen)))
        {
            // Error
            _tprintf(_T("(ref 22) malloc error 0x%x\n"), GetLastError());
            return 1;
        }

        // Read public key
        _tprintf(_T("ReadFile...\n"));
        if (!ReadFile(hPublicKeyFile, pbPublicKey, dwPublicKeyLen, &dwPublicKeyLen, NULL))
        {
            // Error
            _tprintf(_T("(ref 31) ReadFile error 0x%x\n"), GetLastError());
            return 1;
        }

        // Import public key
        _tprintf(_T("CryptImportKey...\n"));
        if (!CryptImportKey(hCryptProv, pbPublicKey, dwPublicKeyLen, 0, 0, &hKey))
        {
            // Error
            _tprintf(_T("(ref 38) CryptImportKey error 0x%x\n"), GetLastError());
            return 1;
        }

        // Open plain text file
        _tprintf(_T("CreateFile...\n"));
        if ((hPlainFile = CreateFile(
            strPlainFile,
            GENERIC_READ,
            FILE_SHARE_READ,
            NULL,
            OPEN_EXISTING,
            FILE_FLAG_SEQUENTIAL_SCAN,
            NULL
            )) == INVALID_HANDLE_VALUE)
        {
            // Error
            _tprintf(_T("(ref 15) CreateFile error 0x%x\n"), GetLastError());
            return 1;
        }

        // Get file size
        _tprintf(_T("GetFileSize...\n"));
        if ((dwDataLen = GetFileSize(hPlainFile, NULL)) == INVALID_FILE_SIZE)
        {
            // Error
            _tprintf(_T("(ref 40) GetFileSize error 0x%x\n"), GetLastError());
            return 1;
        }

        _tprintf(_T("my data length is %d\n"), dwDataLen);
        _tprintf(_T("my max size is %d\n"), MAXSIZE);

        // Get length for encrypted data
        if (!CryptEncrypt(hKey, NULL, TRUE, 0, NULL, &dwEncryptedLen, 0))
        {
            // Error
            _tprintf(_T("(ref 1) CryptEncrypt error 0x%x\n"), GetLastError());
            return 1;
        }

        if (dwDataLen < MAXSIZE)
        {
            // as before... Just one run through.

            // BEGIN OLD BLOCK
            // Create a buffer for the plain text
            _tprintf(_T("malloc...\n"));
            if (!(pbData = (BYTE *)malloc(dwDataLen)))
            {
                // Error
                _tprintf(_T("(ref 23) malloc error 0x%x\n"), GetLastError());
                return 1;
            }

            // Read plain text
            _tprintf(_T("ReadFile...\n"));
            if (!ReadFile(hPlainFile, pbData, dwDataLen, &dwDataLen, NULL))
            {
                // Error
                _tprintf(_T("(ref 32) ReadFile error 0x%x\n"), GetLastError());
                return 1;
            }

            // Next line: dwEncryptedLen is the length of key! Ergo, when decrypting
            //  use 128 instead of MAXSIZE:
            _tprintf(_T("My encrypted length is %d\n"), dwEncryptedLen); 

            // Create a buffer for encrypted data
            _tprintf(_T("realloc...\n"));
            if (!(pbData = (BYTE *)realloc(pbData, dwEncryptedLen)))
            {
                // Error
                _tprintf(_T("(ref 24) malloc error 0x%x\n"), GetLastError());
                return 1;
            }

            // Encrypt data
            if (!CryptEncrypt(hKey, NULL, TRUE, 0, pbData, &dwDataLen, dwEncryptedLen))
            {
                // Error
                _tprintf(_T("(ref 2) CryptEncrypt error 0x%x\n"), GetLastError());
                return 1;
            }

            // Create a file to save the encrypted data
            _tprintf(_T("CreateFile...\n"));
            if ((hEncryptedFile = CreateFile(
                strEncryptedFile,
                GENERIC_WRITE,
                0,
                NULL,
                CREATE_ALWAYS,          // will truncate if already existing
                FILE_ATTRIBUTE_NORMAL,
                NULL
                )) == INVALID_HANDLE_VALUE)
            {
                // Error
                _tprintf(_T("(ref 16) CreateFile error 0x%x\n"), GetLastError());
                return 1;
            }

            // Write the public key to the file
            _tprintf(_T("WriteFile...\n"));
            if (!WriteFile(
                hEncryptedFile,
                (LPCVOID)pbData,
                dwDataLen,
                &lpNumberOfBytesWritten,
                NULL
                ))
            {
                // Error
                _tprintf(_T("(ref 47) WriteFile error 0x%x\n"), GetLastError());
                return 1;
            }
            // END OLD BLOCK
            return 0;
        }
        else
        {
            // File is bigger than key.

            // Figure out how many times we will need to loop.
            myloopcount = (DWORD)(dwDataLen / MAXSIZE);
            _tprintf(_T("Loop counter is %d\n"), myloopcount);

            mymodulus = dwDataLen % MAXSIZE;
            _tprintf(_T("Remainder is %d\n"), mymodulus);

            if (mymodulus == 0) // no remainder
            {
                myloopcount -= 1; // decrement by one
            }

            // Create a file to save the encrypted data with append flag.
            // The parameter for appending data to a file is FILE_APPEND_DATA in the CreateFile function. 
            // Ref: http://msdn.microsoft.com/en-us/library/windows/desktop/aa363778(v=vs.85).aspx
            _tprintf(_T("CreateFile...\n"));
            if ((hEncryptedFile = CreateFile(
                strEncryptedFile,  // if you hardcode a filename here, use syntax: _T("C:\\temp\\append.txt"),
                GENERIC_WRITE,
                0,
                NULL,
                CREATE_ALWAYS,
                FILE_APPEND_DATA,
                NULL
                )) == INVALID_HANDLE_VALUE)
            {
                // Error
                _tprintf(_T("(ref 17) CreateFile error saving the encrypted data 0x%x\n"), GetLastError());
                return 1;
            }

            // Create a buffer for the plain text
            _tprintf(_T("malloc...\n"));
            pbData = NULL;
            if (!(pbData = (BYTE *)malloc(MAXSIZE)))
            {
                // Error
                _tprintf(_T("(ref 25) malloc error 0x%x\n"), GetLastError());
                return 1;
            }

            _tprintf(_T("malloc...\n"));
            pbEncData = NULL;
            if (!(pbEncData = (BYTE *)malloc(ENCRYPTEDLENGTH)))
            {
                // Error
                _tprintf(_T("(ref 53) malloc error 0x%x\n"), GetLastError());
                return 1;
            }

            for (i = 0; i < myloopcount; i++)
            {
                // ref https://msdn.microsoft.com/en-us/library/windows/desktop/aa365541(v=vs.85).aspx
                if (i > 0)
                {
                    SetFilePointer(
                        hPlainFile,     //     HANDLE hFile,
                        MAXSIZE,        //    LONG lDistanceToMove,
                        NULL,           //  PLONG lpDistanceToMoveHigh,
                        FILE_CURRENT
                        );
                }

                mymaxsize = MAXSIZE;

                // Read plain text
                _tprintf(_T("ReadFile...\n"));
                if (!ReadFile(hPlainFile, pbData, mymaxsize, &mymaxsize, NULL))
                {
                    // Error
                    _tprintf(_T("(ref 33) ReadFile error 0x%x\n"), GetLastError());
                    return 1;
                }

                // Encrypt data
                if (!CryptEncrypt(hKey, NULL, FALSE, 0, pbEncData, &mymaxsize, dwEncryptedLen))
                {
                    // Error
                    _tprintf(_T("(ref 4) CryptEncrypt error in loop number %i 0x%x\n"),i, GetLastError());
                    return 1;
                }

                _tprintf(_T("WriteFile...\n"));
                if (!WriteFile(
                    hEncryptedFile,
                    (LPCVOID)pbEncData,
                    dwDataLen,
                    &lpNumberOfBytesWritten,
                    NULL
                    ))
                {
                    // Error
                    _tprintf(_T("(ref 48) WriteFile error, i is %d 0x%x\n"), i, GetLastError());
                    return 1;
                }
            } // end for loop

            SetFilePointer(
                hPlainFile,     //     HANDLE hFile,
                MAXSIZE,        //     LONG lDistanceToMove,
                NULL,           //     PLONG lpDistanceToMoveHigh,
                FILE_CURRENT    
                );

            mymaxsize = MAXSIZE;

            if (mymodulus == 0)
            {
                _tprintf(_T("ReadFile...\n"));
                if (!ReadFile(hPlainFile, pbData, mymaxsize, &mymaxsize, NULL))
                {
                    // Error
                    _tprintf(_T("(ref 34) ReadFile error 0x%x\n"), GetLastError());
                    return 1;
                }

                // Encrypt data; last chunk must have TRUE flag when encrypting.
                if (!CryptEncrypt(hKey, NULL, TRUE, 0, pbEncData, &dwDataLen, dwEncryptedLen))
                {
                    // Error
                    _tprintf(_T("(ref 6) CryptEncrypt error 0x%x\n"), GetLastError());
                    return 1;
                }
            }
            else
            {
                _tprintf(_T("ReadFile...\n"));
                if (!ReadFile(hPlainFile, pbData, mymodulus, &mymodulus, NULL))
                {
                    // Error
                    _tprintf(_T("(ref 35) ReadFile error 0x%x\n"), GetLastError());
                    return 1;
                }

                // Encrypt data
                if (!CryptEncrypt(hKey, NULL, TRUE, 0, pbEncData, &mymodulus, dwEncryptedLen))
                {
                    // Error
                    _tprintf(_T("(ref 8) CryptEncrypt error 0x%x\n"), GetLastError());
                    return 1;
                }
            }

            // Finish writing.
            _tprintf(_T("WriteFile...\n"));
            if (!WriteFile(
                hEncryptedFile,
                (LPCVOID)pbEncData,
                dwDataLen,
                &lpNumberOfBytesWritten,
                NULL
                ))
            {
                // Error
                _tprintf(_T("(ref 49) WriteFile error 0x%x\n"), GetLastError());
                return 1;
            }
        }
        return 0;
    }
    __finally
    {
        // Clean up
        if (!pbPublicKey) {
            _tprintf(_T("free...\n"));
            free(pbPublicKey);
        }
        if (!pbData) {
            _tprintf(_T("free...\n"));
            free(pbData);
        }
        if (hPublicKeyFile) {
            _tprintf(_T("CloseHandle...\n"));
            CloseHandle(hPublicKeyFile);
        }
        if (hPlainFile) {
            _tprintf(_T("CloseHandle...\n"));
            CloseHandle(hPlainFile);
        }
        if (hEncryptedFile) {
            _tprintf(_T("CloseHandle...\n"));
            CloseHandle(hEncryptedFile);
        }
        if (hKey) {
            _tprintf(_T("CryptDestroyKey...\n"));
        CryptDestroyKey(hKey);
        }
        if (hCryptProv) {
            _tprintf(_T("CryptReleaseContext...\n"));
            CryptReleaseContext(hCryptProv, 0);
        }
    }
}
// End of Encrypt

// Decrypt
int Decrypt(_TCHAR* strPrivateKeyFile, _TCHAR* strEncryptedFile, _TCHAR* strPlainFile)
{
    HCRYPTPROV hCryptProv = NULL;
    HCRYPTKEY hKey = NULL;
    DWORD dwPrivateKeyLen = 0;
    DWORD dwDataLen = 0;
    DWORD myloopcount = 0;
    DWORD mymodulus = 0;
    DWORD i = 0;
    DWORD mysize = 0;
    BYTE* pbPrivateKey = NULL;
    BYTE* pbData = NULL;
    BYTE* pbEncData = NULL;
    HANDLE hPrivateKeyFile = NULL;
    HANDLE hEncryptedFile = NULL;
    HANDLE hPlainFile = NULL;
    DWORD lpNumberOfBytesWritten = 0;

    __try
    {
        // Acquire access to key container
        _tprintf(_T("CryptAcquireContext...\n"));
        if (!CryptAcquireContext(&hCryptProv, _T("ACMEENCRYPT.EncryptDecrypt"), NULL, PROV_RSA_FULL, 0))
        {
            // Error
            _tprintf(_T("(ref 10) CryptAcquireContext error 0x%x\n"), GetLastError());

            // Try to create a new key container
            if (!CryptAcquireContext(&hCryptProv, _T("ACMEENCRYPT.EncryptDecrypt"), NULL, PROV_RSA_FULL, CRYPT_NEWKEYSET))
            {
                // Error
                _tprintf(_T("(ref 11) CryptAcquireContext error 0x%x\n"), GetLastError());
                return 1;
            }
        }

        // Open private key file
        _tprintf(_T("CreateFile...\n"));
        if ((hPrivateKeyFile = CreateFile(
            strPrivateKeyFile,
            GENERIC_READ,
            FILE_SHARE_READ,
            NULL,
            OPEN_EXISTING,
            FILE_FLAG_SEQUENTIAL_SCAN,
            NULL
            )) == INVALID_HANDLE_VALUE)
        {
            // Error
            _tprintf(_T("(ref 18) CreateFile error 0x%x\n"), GetLastError());
            return 1;
        }

        // Get file size
        _tprintf(_T("GetFileSize...\n"));
        if ((dwPrivateKeyLen = GetFileSize(hPrivateKeyFile, NULL)) == INVALID_FILE_SIZE)
        {
            // Error
            _tprintf(_T("(ref 41) GetFileSize error 0x%x\n"), GetLastError());
            return 1;
        }

        // Create a buffer for the private key
        _tprintf(_T("malloc...\n"));
        if (!(pbPrivateKey = (BYTE *)malloc(dwPrivateKeyLen)))
        {
            // Error
            _tprintf(_T("(ref 27) malloc error 0x%x\n"), GetLastError());
            return 1;
        }

        // Read private key
        _tprintf(_T("ReadFile...\n"));
        if (!ReadFile(hPrivateKeyFile, pbPrivateKey, dwPrivateKeyLen, &dwPrivateKeyLen, NULL))
        {
            // Error
            _tprintf(_T("(ref 36) ReadFile error 0x%x\n"), GetLastError());
            return 1;
        }

        // Import private key
        _tprintf(_T("CryptImportKey...\n"));
        if (!CryptImportKey(hCryptProv, pbPrivateKey, dwPrivateKeyLen, 0, 0, &hKey))
        {
            // Error
            _tprintf(_T("(ref 39) CryptImportKey error 0x%x\n"), GetLastError());
            return 1;
        }

        // Open encrypted file
        _tprintf(_T("CreateFile...\n"));
        if ((hEncryptedFile = CreateFile(
            strEncryptedFile,
            GENERIC_READ,
            FILE_SHARE_READ,
            NULL,
            OPEN_EXISTING,
            FILE_FLAG_SEQUENTIAL_SCAN,
            NULL
            )) == INVALID_HANDLE_VALUE)
        {
            // Error
            _tprintf(_T("(ref 19) CreateFile error 0x%x\n"), GetLastError());
            return 1;
        }

        // Get file size
        _tprintf(_T("GetFileSize...\n"));
        if ((dwDataLen = GetFileSize(hEncryptedFile, NULL)) == INVALID_FILE_SIZE)
        {
            // Error
            _tprintf(_T("(ref 42) GetFileSize error 0x%x\n"), GetLastError());
            return 1;
        }

        if (dwDataLen == ENCRYPTEDLENGTH)
        {
            // Create a buffer for the encrypted data
            _tprintf(_T("malloc...\n"));
            if (!(pbData = (BYTE *)malloc(dwDataLen)))
            {
                // Error
                _tprintf(_T("(ref 28) malloc error 0x%x\n"), GetLastError());
                return 1;
            }

            // Read encrypted data
            _tprintf(_T("ReadFile...\n"));
            if (!ReadFile(hEncryptedFile, pbData, dwDataLen, &dwDataLen, NULL))
            {
                // Error
                _tprintf(_T("(ref 37) ReadFile error 0x%x\n"), GetLastError());
                return 1;
            }

            if (!CryptDecrypt(hKey, NULL, TRUE, 0, pbData, &dwDataLen))
            {
                // Error
                _tprintf(_T("(ref 54) CryptDecrypt error 0x%x\n"), GetLastError());
                return 1;
            }

            // Create a file to save the plain text
            _tprintf(_T("CreateFile...\n"));
            if ((hPlainFile = CreateFile(
                strPlainFile,
                GENERIC_WRITE,
                0,
                NULL,
                CREATE_ALWAYS,
                FILE_ATTRIBUTE_NORMAL,
                NULL
                )) == INVALID_HANDLE_VALUE)
            {
                // Error
                _tprintf(_T("(ref 20) CreateFile error 0x%x\n"), GetLastError());
                return 1;
            }

            // Write the plain text the file
            _tprintf(_T("WriteFile...\n"));
            if (!WriteFile(
                hPlainFile,
                (LPCVOID)pbData,
                dwDataLen,
                &lpNumberOfBytesWritten,
                NULL
                ))
            {
                // Error
                _tprintf(_T("(ref 50) WriteFile error 0x%x\n"), GetLastError());
                return 1;
            }
        }
        else
        {
            // encrypted file is bigger than 128 bytes
            // Figure out how many times we will need to loop.
            myloopcount = (DWORD)(dwDataLen / ENCRYPTEDLENGTH);
            _tprintf(_T("Loop counter is %d\n"), myloopcount);

            mymodulus = dwDataLen % ENCRYPTEDLENGTH;
            _tprintf(_T("Remainder is %d\n"), mymodulus);

            if (mymodulus == 0) // no remainder
            {
                myloopcount -= 1; // decrement by one
            }

            // Create a file to save the plain text
            _tprintf(_T("CreateFile...\n"));
            if ((hPlainFile = CreateFile(
                strPlainFile,
                GENERIC_WRITE,
                0,
                NULL,
                CREATE_ALWAYS,
                FILE_APPEND_DATA,
                NULL
                )) == INVALID_HANDLE_VALUE)
            {
                // Error
                _tprintf(_T("(ref 55) CreateFile error 0x%x\n"), GetLastError());
                return 1;
            }

            // Create a buffer for the encrypted data
            _tprintf(_T("malloc...\n"));
            if (!(pbData = (BYTE *)malloc(ENCRYPTEDLENGTH)))
            {
                // Error
                _tprintf(_T("(ref 56) malloc error 0x%x\n"), GetLastError());
                return 1;
            }

            for (i = 0; i < myloopcount; i++)
            {
                // ref https://msdn.microsoft.com/en-us/library/windows/desktop/aa365541(v=vs.85).aspx
                if (i > 0)
                {
                    SetFilePointer(
                        hEncryptedFile,     //  HANDLE hFile,
                        ENCRYPTEDLENGTH,    //  LONG lDistanceToMove,
                        NULL,               //  PLONG lpDistanceToMoveHigh,
                        FILE_CURRENT
                        );
                }

                mysize = ENCRYPTEDLENGTH;

                // Read encrypted data
                _tprintf(_T("ReadFile...\n"));
                if (!ReadFile(hEncryptedFile, pbData, mysize, &mysize, NULL))
                {
                    // Error
                    _tprintf(_T("(ref 37) ReadFile error 0x%x\n"), GetLastError());
                    return 1;
                }

                if (!CryptDecrypt(hKey, NULL, FALSE, 0, pbData, &mysize))
                {
                    // Error
                    _tprintf(_T("(ref 54) CryptDecrypt error in loop number %d 0x%x\n"),i, GetLastError());
                    return 1;
                }

                // Write the plain text the file
                _tprintf(_T("WriteFile...\n"));
                if (!WriteFile(
                    hPlainFile,
                    (LPCVOID)pbData,
                    dwDataLen,
                    &lpNumberOfBytesWritten,
                    NULL
                    ))
                {
                    // Error
                    _tprintf(_T("(ref 50) WriteFile error 0x%x\n"), GetLastError());
                    return 1;
                }
            } // end for loop

            SetFilePointer(
                hEncryptedFile,     //     HANDLE hFile,
                ENCRYPTEDLENGTH,        //     LONG lDistanceToMove,
                NULL,           //     PLONG lpDistanceToMoveHigh,
                FILE_CURRENT    //  DWORD dwMoveMethod, with FILE_CURRENT it's more efficient, not forced 
                //  to do (i * MAXSIZE) for second parameter size
                );

            mysize = ENCRYPTEDLENGTH;

            // Read encrypted data
            _tprintf(_T("ReadFile...\n"));
            if (!ReadFile(hEncryptedFile, pbData, mysize, &mysize, NULL))
            {
                // Error
                _tprintf(_T("(ref 37) ReadFile error 0x%x\n"), GetLastError());
                return 1;
            }

            if (!CryptDecrypt(hKey, NULL, TRUE, 0, pbData, &mysize))
            {
                // Error
                _tprintf(_T("(ref 54) CryptDecrypt error 0x%x\n"), GetLastError());
                return 1;
            }

            // Write the plain text the file
            _tprintf(_T("WriteFile...\n"));
            if (!WriteFile(
                hPlainFile,
                (LPCVOID)pbData,
                dwDataLen,
                &lpNumberOfBytesWritten,
                NULL
                ))
            {
                // Error
                _tprintf(_T("(ref 50) WriteFile error 0x%x\n"), GetLastError());
                return 1;
            }
        }

        return 0;
    }
    __finally
    {
        // Clean up       
        if (!pbPrivateKey) {
            _tprintf(_T("free...\n"));
            free(pbPrivateKey);
        }
        if (!pbData) {
            _tprintf(_T("free...\n"));
            free(pbData);
        }
        if (hPrivateKeyFile) {
            _tprintf(_T("CloseHandle...\n"));
            CloseHandle(hPrivateKeyFile);
        }
        if (hEncryptedFile) {
            _tprintf(_T("CloseHandle...\n"));
            CloseHandle(hEncryptedFile);
        }
        if (hPlainFile) {
            _tprintf(_T("CloseHandle...\n"));
            CloseHandle(hPlainFile);
        }
        if (hKey) {
            _tprintf(_T("CryptDestroyKey...\n"));
            CryptDestroyKey(hKey);
        }
        if (hCryptProv) {
            _tprintf(_T("CryptReleaseContext...\n"));
            CryptReleaseContext(hCryptProv, 0);
        }
    }
}
// End of Decrypt

Answer 1

是;一般情况下，您不能使用RSA在一次通过中加密大于密钥大小的数据，这个限制实际上比密钥大小略短，具体取决于填充。

要加密大量数据，您通常会使用混合方法生成对称密钥（例如AES）并使用它来加密数据。

然后，您可以使用RSA公钥加密AES密钥，将其与密文结合使用，并且您有一个需要私钥解密的Blob。

CryptDecrypt失败，NT_BAD_DATA（0x80090005）

1 个答案: