1 // randpool.cpp - originally written and placed in the public domain by Wei Dai
2 // RandomPool used to follow the design of randpool in PGP 2.6.x,
3 // but as of version 5.5 it has been redesigned to reduce the risk
4 // of reusing random numbers after state rollback (which may occur
5 // when running in a virtual machine like VMware).
6
7 #include "pch.h"
8
9 #ifndef CRYPTOPP_IMPORTS
10
11 #include "randpool.h"
12 #include "aes.h"
13 #include "sha.h"
14 #include "hrtimer.h"
15 #include "trap.h"
16
17 // OldRandomPool
18 #include "mdc.h"
19 #include "modes.h"
20
21 #include <time.h>
22
NAMESPACE_BEGIN(CryptoPP)23 NAMESPACE_BEGIN(CryptoPP)
24
25 RandomPool::RandomPool()
26 : m_pCipher(new AES::Encryption), m_keySet(false)
27 {
28 std::memset(m_key, 0, m_key.SizeInBytes());
29 std::memset(m_seed, 0, m_seed.SizeInBytes());
30 }
31
IncorporateEntropy(const byte * input,size_t length)32 void RandomPool::IncorporateEntropy(const byte *input, size_t length)
33 {
34 SHA256 hash;
35 hash.Update(m_key, 32);
36 hash.Update(input, length);
37 hash.Final(m_key);
38 m_keySet = false;
39 }
40
GenerateIntoBufferedTransformation(BufferedTransformation & target,const std::string & channel,lword size)41 void RandomPool::GenerateIntoBufferedTransformation(BufferedTransformation &target, const std::string &channel, lword size)
42 {
43 if (size > 0)
44 {
45 if (!m_keySet)
46 m_pCipher->SetKey(m_key, 32);
47
48 CRYPTOPP_COMPILE_ASSERT(sizeof(TimerWord) <= 16);
49 CRYPTOPP_COMPILE_ASSERT(sizeof(time_t) <= 8);
50
51 Timer timer;
52 TimerWord tw = timer.GetCurrentTimerValue();
53
54 *(TimerWord *)(void*)m_seed.data() += tw;
55 time_t t = time(NULLPTR);
56
57 // UBsan finding: signed integer overflow: 1876017710 + 1446085457 cannot be represented in type 'long int'
58 // *(time_t *)(m_seed.data()+8) += t;
59 word64 tt1 = 0, tt2 = (word64)t;
60 std::memcpy(&tt1, m_seed.data()+8, 8);
61 std::memcpy(m_seed.data()+8, &(tt2 += tt1), 8);
62
63 // Wipe the intermediates
64 *((volatile TimerWord*)&tw) = 0;
65 *((volatile word64*)&tt1) = 0;
66 *((volatile word64*)&tt2) = 0;
67
68 do
69 {
70 m_pCipher->ProcessBlock(m_seed);
71 size_t len = UnsignedMin(16, size);
72 target.ChannelPut(channel, m_seed, len);
73 size -= len;
74 } while (size > 0);
75 }
76 }
77
78 // OldRandomPool is provided for backwards compatibility for a migration path
79 typedef MDC<SHA1> OldRandomPoolCipher;
80
OldRandomPool(unsigned int poolSize)81 OldRandomPool::OldRandomPool(unsigned int poolSize)
82 : pool(poolSize), key(OldRandomPoolCipher::DEFAULT_KEYLENGTH), addPos(0), getPos(poolSize)
83 {
84 CRYPTOPP_ASSERT(poolSize > key.size());
85 std::memset(pool, 0, poolSize);
86 std::memset(key, 0, key.size());
87 }
88
IncorporateEntropy(const byte * input,size_t length)89 void OldRandomPool::IncorporateEntropy(const byte *input, size_t length)
90 {
91 size_t t;
92 while (length > (t = pool.size() - addPos))
93 {
94 xorbuf(pool+addPos, input, t);
95 input += t;
96 length -= t;
97 Stir();
98 }
99
100 if (length)
101 {
102 xorbuf(pool+addPos, input, length);
103 addPos += length;
104 getPos = pool.size(); // Force stir on get
105 }
106 }
107
Stir()108 void OldRandomPool::Stir()
109 {
110 CFB_Mode<OldRandomPoolCipher>::Encryption cipher;
111
112 for (int i=0; i<2; i++)
113 {
114 cipher.SetKeyWithIV(key, key.size(), pool.end()-cipher.IVSize());
115 cipher.ProcessString(pool, pool.size());
116 std::memcpy(key, pool, key.size());
117 }
118
119 addPos = 0;
120 getPos = key.size();
121 }
122
GenerateIntoBufferedTransformation(BufferedTransformation & target,const std::string & channel,lword size)123 void OldRandomPool::GenerateIntoBufferedTransformation(BufferedTransformation &target, const std::string &channel, lword size)
124 {
125 while (size > 0)
126 {
127 if (getPos == pool.size())
128 Stir();
129 size_t t = UnsignedMin(pool.size() - getPos, size);
130 target.ChannelPut(channel, pool+getPos, t);
131 size -= t;
132 getPos += t;
133 }
134 }
135
GenerateByte()136 byte OldRandomPool::GenerateByte()
137 {
138 if (getPos == pool.size())
139 Stir();
140
141 return pool[getPos++];
142 }
143
GenerateBlock(byte * outString,size_t size)144 void OldRandomPool::GenerateBlock(byte *outString, size_t size)
145 {
146 ArraySink sink(outString, size);
147 GenerateIntoBufferedTransformation(sink, DEFAULT_CHANNEL, size);
148 }
149
150 NAMESPACE_END
151
152 #endif
153