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123 lines
3.1 KiB
C++
123 lines
3.1 KiB
C++
#include <qpdf/SecureRandomDataProvider.hh>
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#include <qpdf/QUtil.hh>
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#include <qpdf/qpdf-config.h>
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#ifdef _WIN32
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# define WIN32_LEAN_AND_MEAN
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# include <direct.h>
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# include <io.h>
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# include <windows.h>
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# ifndef SKIP_OS_SECURE_RANDOM
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# include <wincrypt.h>
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# endif
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#endif
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#ifdef SKIP_OS_SECURE_RANDOM
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void
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SecureRandomDataProvider::provideRandomData(unsigned char* data, size_t len)
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{
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throw std::logic_error("SecureRandomDataProvider::provideRandomData called "
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"when support was not compiled in");
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}
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RandomDataProvider*
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SecureRandomDataProvider::getInstance()
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{
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return 0;
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}
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#else
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# ifdef _WIN32
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class WindowsCryptProvider
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{
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public:
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WindowsCryptProvider()
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{
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if (!CryptAcquireContextW(
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&crypt_prov, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT)) {
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throw std::runtime_error(
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"unable to acquire crypt context: " + getErrorMessage());
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}
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}
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~WindowsCryptProvider()
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{
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// Ignore error
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CryptReleaseContext(crypt_prov, 0);
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}
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HCRYPTPROV crypt_prov;
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private:
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std::string
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getErrorMessage()
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{
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DWORD errorMessageID = ::GetLastError();
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LPSTR messageBuffer = nullptr;
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size_t size = FormatMessageA(
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FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM |
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FORMAT_MESSAGE_IGNORE_INSERTS,
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NULL,
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errorMessageID,
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MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
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reinterpret_cast<LPSTR>(&messageBuffer),
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0,
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NULL);
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std::string message(messageBuffer, size);
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LocalFree(messageBuffer);
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return (
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"error number " + QUtil::int_to_string_base(errorMessageID, 16) +
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": " + message);
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}
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};
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# endif
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void
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SecureRandomDataProvider::provideRandomData(unsigned char* data, size_t len)
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{
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# if defined(_WIN32)
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// Optimization: make the WindowsCryptProvider static as long as
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// it can be done in a thread-safe fashion.
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WindowsCryptProvider c;
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if (!CryptGenRandom(
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c.crypt_prov,
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static_cast<DWORD>(len),
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reinterpret_cast<BYTE*>(data))) {
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throw std::runtime_error("unable to generate secure random data");
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}
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# elif defined(RANDOM_DEVICE)
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// Optimization: wrap the file open and close in a class so that
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// the file is closed in a destructor, then make this static to
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// keep the file handle open. Only do this if it can be done in a
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// thread-safe fashion.
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FILE* f = QUtil::safe_fopen(RANDOM_DEVICE, "rb");
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size_t fr = fread(data, 1, len, f);
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fclose(f);
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if (fr != len) {
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throw std::runtime_error(
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"unable to read " + QUtil::uint_to_string(len) + " bytes from " +
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std::string(RANDOM_DEVICE));
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}
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# else
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# error \
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"Don't know how to generate secure random numbers on this platform. See random number generation in the top-level README.md"
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# endif
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}
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RandomDataProvider*
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SecureRandomDataProvider::getInstance()
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{
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static SecureRandomDataProvider instance;
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return &instance;
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}
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#endif
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