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#include <qpdf/SecureRandomDataProvider.hh>
#include <qpdf/qpdf-config.h>
#include <qpdf/QUtil.hh>
#ifdef _WIN32
# include <Windows.h>
# include <direct.h>
# include <io.h>
# ifndef SKIP_OS_SECURE_RANDOM
# include <Wincrypt.h>
# endif
#endif
SecureRandomDataProvider::SecureRandomDataProvider()
{
}
SecureRandomDataProvider::~SecureRandomDataProvider()
{
}
#ifdef _WIN32
class WindowsCryptProvider
{
public:
WindowsCryptProvider()
{
if (! CryptAcquireContext(&crypt_prov, NULL, NULL, PROV_RSA_FULL, 0))
{
throw std::runtime_error("unable to acquire crypt context");
}
}
~WindowsCryptProvider()
{
// Ignore error
CryptReleaseContext(crypt_prov, 0);
}
HCRYPTPROV crypt_prov;
};
#endif
void
SecureRandomDataProvider::provideRandomData(unsigned char* data, size_t len)
{
#if defined(_WIN32)
// Optimization: make the WindowsCryptProvider static as long as
// it can be done in a thread-safe fashion.
WindowsCryptProvider c;
if (! CryptGenRandom(c.crypt_prov, len, reinterpret_cast<BYTE*>(data)))
{
throw std::runtime_error("unable to generate secure random data");
}
#elif defined(RANDOM_DEVICE)
// Optimization: wrap the file open and close in a class so that
// the file is closed in a destructor, then make this static to
// keep the file handle open. Only do this if it can be done in a
// thread-safe fashion.
FILE* f = QUtil::safe_fopen(RANDOM_DEVICE, "rb");
size_t fr = fread(data, 1, len, f);
fclose(f);
if (fr != len)
{
throw std::runtime_error(
"unable to read " +
QUtil::int_to_string(len) +
" bytes from " + std::string(RANDOM_DEVICE));
}
#else
# error "Don't know how to generate secure random numbers on this platform. See random number generation in the top-level README"
#endif
}
RandomDataProvider*
SecureRandomDataProvider::getInstance()
{
static SecureRandomDataProvider instance;
return &instance;
}
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