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/*
* Win32 CryptoAPI EntropySource
* (C) 1999-2009 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/internal/es_capi.h>
#include <botan/parsing.h>
#include <windows.h>
#include <wincrypt.h>
#undef min
#undef max
namespace Botan {
namespace {
class CSP_Handle
{
public:
CSP_Handle(u64bit capi_provider)
{
valid = false;
DWORD prov_type = (DWORD)capi_provider;
if(CryptAcquireContext(&handle, 0, 0,
prov_type, CRYPT_VERIFYCONTEXT))
valid = true;
}
~CSP_Handle()
{
if(is_valid())
CryptReleaseContext(handle, 0);
}
size_t gen_random(byte out[], size_t n) const
{
if(is_valid() && CryptGenRandom(handle, static_cast<DWORD>(n), out))
return n;
return 0;
}
bool is_valid() const { return valid; }
HCRYPTPROV get_handle() const { return handle; }
private:
HCRYPTPROV handle;
bool valid;
};
}
/*
* Gather Entropy from Win32 CAPI
*/
void Win32_CAPI_EntropySource::poll(Entropy_Accumulator& accum)
{
secure_vector<byte>& io_buffer = accum.get_io_buffer(32);
for(size_t i = 0; i != prov_types.size(); ++i)
{
CSP_Handle csp(prov_types[i]);
size_t got = csp.gen_random(&io_buffer[0], io_buffer.size());
if(got)
{
accum.add(&io_buffer[0], io_buffer.size(), 6);
break;
}
}
}
/*
* Win32_Capi_Entropysource Constructor
*/
Win32_CAPI_EntropySource::Win32_CAPI_EntropySource(const std::string& provs)
{
std::vector<std::string> capi_provs = split_on(provs, ':');
for(size_t i = 0; i != capi_provs.size(); ++i)
{
if(capi_provs[i] == "RSA_FULL") prov_types.push_back(PROV_RSA_FULL);
if(capi_provs[i] == "INTEL_SEC") prov_types.push_back(PROV_INTEL_SEC);
if(capi_provs[i] == "FORTEZZA") prov_types.push_back(PROV_FORTEZZA);
if(capi_provs[i] == "RNG") prov_types.push_back(PROV_RNG);
}
if(prov_types.size() == 0)
prov_types.push_back(PROV_RSA_FULL);
}
}
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