Crypto++  8.2
Free C++ class library of cryptographic schemes
rng.cpp
1 // rng.cpp - originally written and placed in the public domain by Wei Dai
2 
3 #include "pch.h"
4 
5 #include "rng.h"
6 #include "fips140.h"
7 
8 #include <time.h>
9 #include <math.h>
10 
11 NAMESPACE_BEGIN(CryptoPP)
12 
13 // linear congruential generator
14 // originally by William S. England
15 
16 // do not use for cryptographic purposes
17 
18 /*
19 ** Original_numbers are the original published m and q in the
20 ** ACM article above. John Burton has furnished numbers for
21 ** a reportedly better generator. The new numbers are now
22 ** used in this program by default.
23 */
24 
25 #ifndef LCRNG_ORIGINAL_NUMBERS
26 const word32 LC_RNG::m=2147483647L;
27 const word32 LC_RNG::q=44488L;
28 
29 const word16 LC_RNG::a=(unsigned int)48271L;
30 const word16 LC_RNG::r=3399;
31 #else
32 const word32 LC_RNG::m=2147483647L;
33 const word32 LC_RNG::q=127773L;
34 
35 const word16 LC_RNG::a=16807;
36 const word16 LC_RNG::r=2836;
37 #endif
38 
39 void LC_RNG::GenerateBlock(byte *output, size_t size)
40 {
41  while (size--)
42  {
43  const word32 hi = seed/q;
44  const word32 lo = seed%q;
45  const sword64 test = a*lo - r*hi;
46 
47  if (test > 0)
48  seed = static_cast<word32>(test);
49  else
50  seed = static_cast<word32>(test + m);
51 
52  *output++ = byte((GETBYTE(seed, 0) ^ GETBYTE(seed, 1) ^ GETBYTE(seed, 2) ^ GETBYTE(seed, 3)));
53  }
54 }
55 
56 // ********************************************************
57 
58 #ifndef CRYPTOPP_IMPORTS
59 
60 X917RNG::X917RNG(BlockTransformation *c, const byte *seed, const byte *deterministicTimeVector)
61  : m_cipher(c),
62  m_size(m_cipher->BlockSize()),
63  m_datetime(m_size),
64  m_randseed(seed, m_size),
65  m_lastBlock(m_size),
66  m_deterministicTimeVector(deterministicTimeVector, deterministicTimeVector ? m_size : 0)
67 {
68  // Valgrind finding, http://github.com/weidai11/cryptopp/issues/105
69  // Garbage in the tail creates a non-conforming X9.17 or X9.31 generator.
70  if (m_size > 8)
71  {
72  memset(m_datetime, 0x00, m_size);
73  memset(m_lastBlock, 0x00, m_size);
74  }
75 
76  if (!deterministicTimeVector)
77  {
78  time_t tstamp1 = ::time(NULLPTR);
79  xorbuf(m_datetime, (byte *)&tstamp1, UnsignedMin(sizeof(tstamp1), m_size));
80  m_cipher->ProcessBlock(m_datetime);
81  clock_t tstamp2 = clock();
82  xorbuf(m_datetime, (byte *)&tstamp2, UnsignedMin(sizeof(tstamp2), m_size));
83  m_cipher->ProcessBlock(m_datetime);
84  }
85 
86  // for FIPS 140-2
87  // GenerateBlock(m_lastBlock, m_size);
88 
89  // Make explicit call to avoid virtual-dispatch findings in ctor
90  ArraySink target(m_lastBlock, m_size);
92 }
93 
94 void X917RNG::GenerateIntoBufferedTransformation(BufferedTransformation &target, const std::string &channel, lword size)
95 {
96  while (size > 0)
97  {
98  // calculate new enciphered timestamp
99  if (m_deterministicTimeVector.size())
100  {
101  m_cipher->ProcessBlock(m_deterministicTimeVector, m_datetime);
102  IncrementCounterByOne(m_deterministicTimeVector, m_size);
103  }
104  else
105  {
106  clock_t c = clock();
107  xorbuf(m_datetime, (byte *)&c, UnsignedMin(sizeof(c), m_size));
108  time_t t = ::time(NULLPTR);
109  xorbuf(m_datetime+m_size-UnsignedMin(sizeof(t), m_size), (byte *)&t, UnsignedMin(sizeof(t), m_size));
110  m_cipher->ProcessBlock(m_datetime);
111  }
112 
113  // combine enciphered timestamp with seed
114  xorbuf(m_randseed, m_datetime, m_size);
115 
116  // generate a new block of random bytes
117  m_cipher->ProcessBlock(m_randseed);
118  if (memcmp(m_lastBlock, m_randseed, m_size) == 0)
119  throw SelfTestFailure("X917RNG: Continuous random number generator test failed.");
120 
121  // output random bytes
122  size_t len = UnsignedMin(m_size, size);
123  target.ChannelPut(channel, m_randseed, len);
124  size -= len;
125 
126  // compute new seed vector
127  memcpy(m_lastBlock, m_randseed, m_size);
128  xorbuf(m_randseed, m_datetime, m_size);
129  m_cipher->ProcessBlock(m_randseed);
130  }
131 }
132 
133 #endif
134 
136  : sum(0.0), n(0)
137 {
138  for (unsigned i=0; i<V; i++)
139  tab[i] = 0;
140 }
141 
142 size_t MaurerRandomnessTest::Put2(const byte *inString, size_t length, int /*messageEnd*/, bool /*blocking*/)
143 {
144  while (length--)
145  {
146  byte inByte = *inString++;
147  if (n >= Q)
148  sum += ::log(double(n - tab[inByte]));
149  tab[inByte] = n;
150  n++;
151  }
152  return 0;
153 }
154 
155 double MaurerRandomnessTest::GetTestValue() const
156 {
157  if (BytesNeeded() > 0)
158  throw Exception(Exception::OTHER_ERROR, "MaurerRandomnessTest: " + IntToString(BytesNeeded()) + " more bytes of input needed");
159 
160  double fTu = (sum/(n-Q))/::log(2.0); // this is the test value defined by Maurer
161 
162  double value = fTu * 0.1392; // arbitrarily normalize it to
163  return value > 1.0 ? 1.0 : value; // a number between 0 and 1
164 }
165 
166 NAMESPACE_END
Base class for all exceptions thrown by the library.
Definition: cryptlib.h:158
void IncrementCounterByOne(byte *inout, unsigned int size)
Performs an addition with carry on a block of bytes.
Definition: misc.h:1268
size_t ChannelPut(const std::string &channel, byte inByte, bool blocking=true)
Input a byte for processing on a channel.
Definition: cryptlib.h:2165
Some other error occurred not belonging to other categories.
Definition: cryptlib.h:177
X917RNG(BlockTransformation *cipher, const byte *seed, const byte *deterministicTimeVector=NULL)
Construct a X917RNG.
Definition: rng.cpp:60
Interface for buffered transformations.
Definition: cryptlib.h:1627
Copy input to a memory buffer.
Definition: filters.h:1137
size_t Put2(const byte *inString, size_t length, int messageEnd, bool blocking)
Input multiple bytes for processing.
Definition: rng.cpp:142
const std::string DEFAULT_CHANNEL
Default channel for BufferedTransformation.
Definition: cryptlib.h:511
Exception thrown when a crypto algorithm is used after a self test fails.
Definition: fips140.h:22
Precompiled header file.
void ProcessBlock(const byte *inBlock, byte *outBlock) const
Encrypt or decrypt a block.
Definition: cryptlib.h:880
const T1 UnsignedMin(const T1 &a, const T2 &b)
Safe comparison of values that could be neagtive and incorrectly promoted.
Definition: misc.h:647
void GenerateBlock(byte *output, size_t size)
Generate random array of bytes.
Definition: rng.cpp:39
Miscellaneous classes for RNGs.
void GenerateIntoBufferedTransformation(BufferedTransformation &target, const std::string &channel, lword size)
Generate random bytes into a BufferedTransformation.
Definition: rng.cpp:94
const char * BlockSize()
int, in bytes
Definition: argnames.h:27
unsigned int BytesNeeded() const
Provides the number of bytes of input is needed by the test.
Definition: rng.h:94
Classes and functions for the FIPS 140-2 validated library.
std::string IntToString(T value, unsigned int base=10)
Converts a value to a string.
Definition: misc.h:677
CRYPTOPP_DLL void CRYPTOPP_API xorbuf(byte *buf, const byte *mask, size_t count)
Performs an XOR of a buffer with a mask.
Definition: misc.cpp:32
Crypto++ library namespace.
Interface for the data processing part of block ciphers.
Definition: cryptlib.h:856
MaurerRandomnessTest()
Construct a MaurerRandomnessTest.
Definition: rng.cpp:135
size_type size() const
Provides the count of elements in the SecBlock.
Definition: secblock.h:797