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5e3bad2f86
Add new RandomDataProvider object and implement existing random number generation in terms of that. This enables end users to supply their own random data providers.
87 lines
2.0 KiB
C++
87 lines
2.0 KiB
C++
#include <qpdf/SecureRandomDataProvider.hh>
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#include <qpdf/qpdf-config.h>
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#include <qpdf/QUtil.hh>
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#ifdef _WIN32
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# include <Windows.h>
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# include <direct.h>
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# include <io.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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SecureRandomDataProvider::SecureRandomDataProvider()
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{
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}
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SecureRandomDataProvider::~SecureRandomDataProvider()
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{
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}
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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 (! CryptAcquireContext(&crypt_prov, NULL, NULL, PROV_RSA_FULL, 0))
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{
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throw std::runtime_error("unable to acquire crypt context");
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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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};
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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(c.crypt_prov, len, reinterpret_cast<BYTE*>(data)))
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{
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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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{
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throw std::runtime_error(
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"unable to read " +
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QUtil::int_to_string(len) +
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" bytes from " + std::string(RANDOM_DEVICE));
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}
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#else
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# error "Don't know how to generate secure random numbers on this platform. See random number generation in the top-level README"
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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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