156 lines
3.7 KiB
C++
156 lines
3.7 KiB
C++
// rng.cpp - written and placed in the public domain by Wei Dai
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#include "pch.h"
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#include "rng.h"
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#include "fips140.h"
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#include <time.h>
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#include <math.h>
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NAMESPACE_BEGIN(CryptoPP)
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// linear congruential generator
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// originally by William S. England
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// do not use for cryptographic purposes
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/*
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** Original_numbers are the original published m and q in the
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** ACM article above. John Burton has furnished numbers for
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** a reportedly better generator. The new numbers are now
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** used in this program by default.
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*/
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#ifndef LCRNG_ORIGINAL_NUMBERS
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const word32 LC_RNG::m=2147483647L;
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const word32 LC_RNG::q=44488L;
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const word16 LC_RNG::a=(unsigned int)48271L;
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const word16 LC_RNG::r=3399;
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#else
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const word32 LC_RNG::m=2147483647L;
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const word32 LC_RNG::q=127773L;
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const word16 LC_RNG::a=16807;
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const word16 LC_RNG::r=2836;
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#endif
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void LC_RNG::GenerateBlock(byte *output, size_t size)
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{
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while (size--)
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{
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word32 hi = seed/q;
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word32 lo = seed%q;
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long test = a*lo - r*hi;
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if (test > 0)
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seed = test;
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else
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seed = test+ m;
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*output++ = (GETBYTE(seed, 0) ^ GETBYTE(seed, 1) ^ GETBYTE(seed, 2) ^ GETBYTE(seed, 3));
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}
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}
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// ********************************************************
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#ifndef CRYPTOPP_IMPORTS
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X917RNG::X917RNG(BlockTransformation *c, const byte *seed, const byte *deterministicTimeVector)
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: cipher(c),
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S(cipher->BlockSize()),
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dtbuf(S),
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randseed(seed, S),
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m_lastBlock(S),
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m_deterministicTimeVector(deterministicTimeVector, deterministicTimeVector ? S : 0)
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{
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if (!deterministicTimeVector)
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{
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time_t tstamp1 = time(0);
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xorbuf(dtbuf, (byte *)&tstamp1, UnsignedMin(sizeof(tstamp1), S));
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cipher->ProcessBlock(dtbuf);
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clock_t tstamp2 = clock();
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xorbuf(dtbuf, (byte *)&tstamp2, UnsignedMin(sizeof(tstamp2), S));
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cipher->ProcessBlock(dtbuf);
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}
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// for FIPS 140-2
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GenerateBlock(m_lastBlock, S);
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}
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void X917RNG::GenerateIntoBufferedTransformation(BufferedTransformation &target, const std::string &channel, lword size)
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{
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while (size > 0)
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{
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// calculate new enciphered timestamp
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if (m_deterministicTimeVector.size())
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{
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cipher->ProcessBlock(m_deterministicTimeVector, dtbuf);
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IncrementCounterByOne(m_deterministicTimeVector, S);
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}
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else
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{
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clock_t c = clock();
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xorbuf(dtbuf, (byte *)&c, UnsignedMin(sizeof(c), S));
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time_t t = time(NULL);
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xorbuf(dtbuf+S-UnsignedMin(sizeof(t), S), (byte *)&t, UnsignedMin(sizeof(t), S));
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cipher->ProcessBlock(dtbuf);
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}
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// combine enciphered timestamp with seed
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xorbuf(randseed, dtbuf, S);
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// generate a new block of random bytes
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cipher->ProcessBlock(randseed);
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if (memcmp(m_lastBlock, randseed, S) == 0)
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throw SelfTestFailure("X917RNG: Continuous random number generator test failed.");
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// output random bytes
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size_t len = UnsignedMin(S, size);
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target.ChannelPut(channel, randseed, len);
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size -= len;
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// compute new seed vector
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memcpy(m_lastBlock, randseed, S);
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xorbuf(randseed, dtbuf, S);
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cipher->ProcessBlock(randseed);
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}
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}
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#endif
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MaurerRandomnessTest::MaurerRandomnessTest()
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: sum(0.0), n(0)
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{
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for (unsigned i=0; i<V; i++)
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tab[i] = 0;
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}
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size_t MaurerRandomnessTest::Put2(const byte *inString, size_t length, int messageEnd, bool blocking)
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{
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while (length--)
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{
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byte inByte = *inString++;
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if (n >= Q)
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sum += log(double(n - tab[inByte]));
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tab[inByte] = n;
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n++;
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}
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return 0;
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}
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double MaurerRandomnessTest::GetTestValue() const
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{
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if (BytesNeeded() > 0)
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throw Exception(Exception::OTHER_ERROR, "MaurerRandomnessTest: " + IntToString(BytesNeeded()) + " more bytes of input needed");
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double fTu = (sum/(n-Q))/log(2.0); // this is the test value defined by Maurer
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double value = fTu * 0.1392; // arbitrarily normalize it to
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return value > 1.0 ? 1.0 : value; // a number between 0 and 1
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}
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NAMESPACE_END
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