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/*
* Win32 CryptoAPI EntropySource
* (C) 1999-2009,2016 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#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_Impl : public Win32_CAPI_EntropySource::CSP_Handle
{
public:
explicit CSP_Handle_Impl(u64bit capi_provider)
{
m_valid = ::CryptAcquireContext(&m_handle,
0,
0,
static_cast<DWORD>(capi_provider),
CRYPT_VERIFYCONTEXT);
}
~CSP_Handle_Impl()
{
if(m_valid)
::CryptReleaseContext(m_handle, 0);
}
size_t gen_random(byte out[], size_t n) const
{
if(m_valid && ::CryptGenRandom(m_handle, static_cast<DWORD>(n), out))
return n;
return 0;
}
private:
bool m_valid;
HCRYPTPROV m_handle;
};
}
/*
* Gather Entropy from Win32 CAPI
*/
size_t Win32_CAPI_EntropySource::poll(RandomNumberGenerator& rng)
{
secure_vector<uint8_t> buf(BOTAN_SYSTEM_RNG_POLL_REQUEST);
size_t bits = 0;
for(size_t i = 0; i != m_csp_provs.size(); ++i)
{
size_t got = m_csp_provs[i]->gen_random(buf.data(), buf.size());
if(got > 0)
{
rng.add_entropy(buf.data(), got);
bits += got * 8;
}
}
return bits;
}
/*
* Win32_Capi_Entropysource Constructor
*/
Win32_CAPI_EntropySource::Win32_CAPI_EntropySource(const std::string& provs)
{
for(std::string prov_name : split_on(provs, ':'))
{
DWORD prov_type;
if(prov_name == "RSA_FULL")
prov_type = PROV_RSA_FULL;
else if(prov_name == "INTEL_SEC")
prov_type = PROV_INTEL_SEC;
else if(prov_name == "RNG")
prov_type = PROV_RNG;
else
continue;
m_csp_provs.push_back(std::unique_ptr<CSP_Handle>(new CSP_Handle_Impl(prov_type)));
}
}
}
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