Some problem with Crypto API

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Windows

VisualC++

I used the crypto API to encrypt/decrypt a file, but have a problem.
On some computer, decrypt fails, especially when the system just start up。
I find the call CryptImportKey fails, and the error code is NTE_BAD_DATA。

Could someone give me a help?

Here is my code.

BOOL CUserCrypt::Crypt(unsigned char *pIn, long *plSize, unsigned char **ppOut)
{
    HCRYPTPROV hProv = 0;
    HCRYPTKEY hKey = 0;
    HCRYPTKEY hXchgKey = 0;
 
    DWORD dwCount, dwNewBufLen;
 
    BYTE *pbKeyBlob = NULL;
    DWORD dwBlobLen;
 
    // 获得默认provider句柄.
    if(!CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_FULL, 0))
    {
        // 如果发生错误，则创建默认密钥容器
        if (!CryptAcquireContext( &hProv, 
            NULL, 
            NULL, 
            PROV_RSA_FULL,
            CRYPT_NEWKEYSET))
        {
            // 创建密钥容器发生错误
			DWORD dwLastErr = ::GetLastError();
 
			if(0x8009000F == dwLastErr) //  Object already exists.
			{
				if(!CryptAcquireContext(&hProv,
							NULL,
							NULL,
							PROV_RSA_FULL,
							CRYPT_DELETEKEYSET))
				{
					return FALSE;
				}
				else
				{
					if(!CryptAcquireContext(&hProv,
								NULL,
								NULL,
								PROV_RSA_FULL,
								CRYPT_NEWKEYSET))
					{
						
						return FALSE;
					}
				}
			}
		}
	}
 
    // 获得密钥交换密钥句柄
    if (!CryptGetUserKey(hProv, AT_KEYEXCHANGE, &hXchgKey))
    {
        if (NTE_NO_KEY==GetLastError())
        {
            // 创建密钥交换密钥对.
            if (!CryptGenKey(hProv,AT_KEYEXCHANGE,0,&hKey))
            {
                // CryptGenKey发生错误!
                CryptReleaseContext(hProv, 0);
                return FALSE;
            }
            else
            {
                CryptDestroyKey(hKey);
                CryptGetUserKey(hProv, AT_KEYEXCHANGE, &hXchgKey);
            }
        }
        else
            return FALSE;
    }
 

    // 创建随机块加密会话密钥.
    if (!CryptGenKey(hProv, CALG_RC2, CRYPT_EXPORTABLE, &hKey))
        return FALSE; 
 
    // 获取默认密钥blob大小, 并分配内存.
    if (!CryptExportKey( hKey, hXchgKey, SIMPLEBLOB, 0, NULL, &dwBlobLen))
    {
        if( hProv != NULL){
            CryptReleaseContext(hProv, 0);
        }
        return FALSE;
    }
 
    if (NULL == (pbKeyBlob = (unsigned char *)malloc(dwBlobLen)) ){
        if( hProv != NULL){
            CryptReleaseContext(hProv, 0);
        }
        if( hKey != NULL ){
            CryptDestroyKey( hKey );
        }
        return FALSE;
    }
 

 
    // 将密钥导出到简单密钥blob.
    if (!CryptExportKey(hKey, hXchgKey, SIMPLEBLOB, 0, pbKeyBlob, &dwBlobLen))
    {
        if( hProv != NULL){
            CryptReleaseContext(hProv, 0);
        }
        if( hKey != NULL ){
            CryptDestroyKey( hKey );
        }
        free(pbKeyBlob);
        return FALSE;
    }
 
    // 加密数据需要多少内存?
    dwCount = *plSize;
    if (!CryptEncrypt(hKey, 0, TRUE, 0, NULL, &dwCount, 0)){
        if( hProv != NULL){
            CryptReleaseContext(hProv, 0);
        }
        if( hKey != NULL ){
            CryptDestroyKey( hKey );
        }
        if(hXchgKey != NULL ){
            CryptDestroyKey(hXchgKey);
        }
        free(pbKeyBlob);
        return FALSE;
    }
 
    // 输出长度、密钥blob、分配内存
    *ppOut = (unsigned char *)malloc(sizeof(dwBlobLen) + dwBlobLen + dwCount);
    if (!*ppOut)
    {
        if( hProv != NULL){
            CryptReleaseContext(hProv, 0);
        }
        if( hKey != NULL ){
            CryptDestroyKey( hKey );
        }
        if(hXchgKey != NULL ){
            CryptDestroyKey(hXchgKey);
        }
        free(pbKeyBlob);
        return FALSE;
    }
    memcpy(*ppOut, &dwBlobLen, sizeof(dwBlobLen));
    memcpy(&(*ppOut)[sizeof(dwBlobLen)], pbKeyBlob, dwBlobLen);
 
    // 释放内存.
    free(pbKeyBlob);
    pbKeyBlob = NULL;
 
    // 最终的加密过程!
    memcpy(&(*ppOut)[sizeof(dwBlobLen)+dwBlobLen], pIn, *plSize);
    dwNewBufLen = dwCount;
    dwCount = *plSize;
    BOOL bSuccess = FALSE;
    if ( CryptEncrypt(hKey, 
        0, 
        TRUE, 
        0, 
        &(*ppOut)[sizeof(dwBlobLen)+dwBlobLen], 
        &dwCount, 
        dwNewBufLen)){
            bSuccess = TRUE;
    }
 
    // 更新输出长度
    *plSize = sizeof(dwBlobLen) + dwBlobLen + dwCount;
 
    // 销毁会话密钥.
    if(hKey != 0) CryptDestroyKey(hKey);
 
    // 销毁密钥交换密钥.
    if(hXchgKey != 0) CryptDestroyKey(hXchgKey);
 
    // 释放provider句柄.
    if(hProv != 0) CryptReleaseContext(hProv, 0);
 
    return bSuccess;
}
 
BOOL CUserCrypt::Decrypt(unsigned char *pIn, long *plSize)
{
    HCRYPTPROV hProv = 0;
    HCRYPTKEY hKey = 0;
    HCRYPTKEY hXchgKey = 0;
    DWORD dwCount;
 
    BYTE *pbKeyBlob = NULL;
    DWORD dwBlobLen;
 
    //unsigned char* buffer = new unsigned char[256];
    //unsigned int iLen = 0;
    //CryptCString( _T("t"), buffer, iLen);

    // 获得默认provider句柄.
    if (!CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_FULL, 0))
    {
        LOG_DEBUG(_T("CryptAcquireContext failed, errorcode = %d, Function: %s"), GetLastError(), __FUNCTIONW__ );
        if( GetLastError() == NTE_BAD_KEYSET)
        {
            if( !CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_FULL, CRYPT_NEWKEYSET) )
            {
                LOG_DEBUG(_T("CryptAcquireContext failed again, errorcode = %d, Function: %s"), GetLastError(), __FUNCTIONW__ );
                return FALSE;
            }
        }
        else
        {
            return FALSE;
        }
    }
 
    if( !CryptGetUserKey(hProv, AT_KEYEXCHANGE, &hKey) )
    {
        LOG_DEBUG(_T("CryptGetUserKey failed, errorcode = %d, Function: %s"), GetLastError(), __FUNCTIONW__ );
        if( GetLastError() == NTE_NO_KEY )
        {		
            // There is a container but no key - Create an encryption key pair
            if( !CryptGenKey( hProv, AT_KEYEXCHANGE, 0, &hKey ) )
            {
                LOG_DEBUG(_T("CryptGenKey failed, errorcode = %d, Function: %s"), GetLastError(), __FUNCTIONW__ );
                return FALSE;
            }
        }
    }
 
    if( hKey )
    {
        CryptDestroyKey( hKey );
        hKey = NULL;
    }
 
    // 从源数据中取得密钥blob长度
    // 并初始化指针
    memcpy(&dwBlobLen, pIn, sizeof(DWORD));
    pbKeyBlob = (BYTE *)&pIn[sizeof(DWORD)];
 
    // 将密钥blob导入CSP.
    if (!CryptImportKey(hProv, pbKeyBlob, dwBlobLen, 0, 0, &hKey))
    {
        LOG_DEBUG(_T("CryptImportKey failed, errorcode = %d, Function: %s"), GetLastError(), __FUNCTIONW__ );
        CryptReleaseContext(hProv, 0);
        return FALSE;
    }
 
    // 解密
    dwCount =*plSize - (sizeof(DWORD)+dwBlobLen);
    if (!CryptDecrypt(hKey, 0, TRUE, 0, &pIn[sizeof(DWORD)+dwBlobLen], &dwCount))
    {
        LOG_DEBUG(_T("CryptDecrypt failed, errorcode = %d, Function: %s"), GetLastError(), __FUNCTIONW__ );
        return FALSE;
    }
 
    // 提示用户解密数据的长度
    memmove(pIn, &pIn[sizeof(DWORD)+dwBlobLen], dwCount);
    *plSize = dwCount;
 
    // 销毁会话密钥.
    if(hKey != 0) CryptDestroyKey(hKey);
 
    // 释放provider句柄.
    if(hProv != 0) CryptReleaseContext(hProv, 0);
 
    return TRUE;
}