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# randpool.cpp

    00001 // randpool.cpp - written and placed in the public domain by Wei Dai
    00002 // RandomPool used to follow the design of randpool in PGP 2.6.x,
    00003 // but as of version 5.5 it has been redesigned to reduce the risk
    00004 // of reusing random numbers after state rollback (which may occur
    00005 // when running in a virtual machine like VMware).
    00006
    00007 #include "pch.h"
    00008
    00009 #ifndef CRYPTOPP_IMPORTS
    00010
    00011 #include "randpool.h"
    00012 #include "aes.h"
    00013 #include "sha.h"
    00014 #include "hrtimer.h"
    00015 #include <time.h>
    00016
    00017 NAMESPACE_BEGIN(CryptoPP)
    00018
    00019 RandomPool::RandomPool()
    00020         : m_pCipher(new AES::Encryption), m_keySet(false)
    00021 {
    00022 }
    00023
    00024 void RandomPool::IncorporateEntropy(const byte *input, size_t length)
    00025 {
    00026         SHA256 hash;
    00027         hash.Update(m_key, 32);
    00028         hash.Update(input, length);
    00029         hash.Final(m_key);
    00030         m_keySet = false;
    00031 }
    00032
    00033 void RandomPool::GenerateIntoBufferedTransformation(BufferedTransformation &target, const std::string &channel, lword size)
    00034 {
    00035         if (size > 0)
    00036         {
    00037                 if (!m_keySet)
    00038                         m_pCipher->SetKey(m_key, 32);
    00039
    00040                 Timer timer;
    00041                 TimerWord tw = timer.GetCurrentTimerValue();
    00042                 CRYPTOPP_COMPILE_ASSERT(sizeof(tw) <= 16);
    00043                 *(TimerWord *)m_seed.data() += tw;
    00044
    00045                 time_t t = time(NULL);
    00046                 CRYPTOPP_COMPILE_ASSERT(sizeof(t) <= 8);
    00047                 *(time_t *)(m_seed.data()+8) += t;
    00048
    00049                 do
    00050                 {
    00051                         m_pCipher->ProcessBlock(m_seed);
    00052                         size_t len = UnsignedMin(16, size);
    00053                         target.ChannelPut(channel, m_seed, len);
    00054                         size -= len;
    00055                 } while (size > 0);
    00056         }
    00057 }
    00058
    00059 NAMESPACE_END
    00060
    00061 #endif