summaryrefslogtreecommitdiffstats
path: root/lib/cryptopp/rw.cpp
blob: cdd9f2d22239a0f901fc5e16218728acd92eb369 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
// rw.cpp - written and placed in the public domain by Wei Dai

#include "pch.h"
#include "rw.h"
#include "nbtheory.h"
#include "asn.h"

#ifndef CRYPTOPP_IMPORTS

NAMESPACE_BEGIN(CryptoPP)

void RWFunction::BERDecode(BufferedTransformation &bt)
{
	BERSequenceDecoder seq(bt);
	m_n.BERDecode(seq);
	seq.MessageEnd();
}

void RWFunction::DEREncode(BufferedTransformation &bt) const
{
	DERSequenceEncoder seq(bt);
	m_n.DEREncode(seq);
	seq.MessageEnd();
}

Integer RWFunction::ApplyFunction(const Integer &in) const
{
	DoQuickSanityCheck();

	Integer out = in.Squared()%m_n;
	const word r = 12;
	// this code was written to handle both r = 6 and r = 12,
	// but now only r = 12 is used in P1363
	const word r2 = r/2;
	const word r3a = (16 + 5 - r) % 16;	// n%16 could be 5 or 13
	const word r3b = (16 + 13 - r) % 16;
	const word r4 = (8 + 5 - r/2) % 8;	// n%8 == 5
	switch (out % 16)
	{
	case r:
		break;
	case r2:
	case r2+8:
		out <<= 1;
		break;
	case r3a:
	case r3b:
		out.Negate();
		out += m_n;
		break;
	case r4:
	case r4+8:
		out.Negate();
		out += m_n;
		out <<= 1;
		break;
	default:
		out = Integer::Zero();
	}
	return out;
}

bool RWFunction::Validate(RandomNumberGenerator &rng, unsigned int level) const
{
	bool pass = true;
	pass = pass && m_n > Integer::One() && m_n%8 == 5;
	return pass;
}

bool RWFunction::GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
{
	return GetValueHelper(this, name, valueType, pValue).Assignable()
		CRYPTOPP_GET_FUNCTION_ENTRY(Modulus)
		;
}

void RWFunction::AssignFrom(const NameValuePairs &source)
{
	AssignFromHelper(this, source)
		CRYPTOPP_SET_FUNCTION_ENTRY(Modulus)
		;
}

// *****************************************************************************
// private key operations:

// generate a random private key
void InvertibleRWFunction::GenerateRandom(RandomNumberGenerator &rng, const NameValuePairs &alg)
{
	int modulusSize = 2048;
	alg.GetIntValue("ModulusSize", modulusSize) || alg.GetIntValue("KeySize", modulusSize);

	if (modulusSize < 16)
		throw InvalidArgument("InvertibleRWFunction: specified modulus length is too small");

	AlgorithmParameters primeParam = MakeParametersForTwoPrimesOfEqualSize(modulusSize);
	m_p.GenerateRandom(rng, CombinedNameValuePairs(primeParam, MakeParameters("EquivalentTo", 3)("Mod", 8)));
	m_q.GenerateRandom(rng, CombinedNameValuePairs(primeParam, MakeParameters("EquivalentTo", 7)("Mod", 8)));

	m_n = m_p * m_q;
	m_u = m_q.InverseMod(m_p);
}

void InvertibleRWFunction::BERDecode(BufferedTransformation &bt)
{
	BERSequenceDecoder seq(bt);
	m_n.BERDecode(seq);
	m_p.BERDecode(seq);
	m_q.BERDecode(seq);
	m_u.BERDecode(seq);
	seq.MessageEnd();
}

void InvertibleRWFunction::DEREncode(BufferedTransformation &bt) const
{
	DERSequenceEncoder seq(bt);
	m_n.DEREncode(seq);
	m_p.DEREncode(seq);
	m_q.DEREncode(seq);
	m_u.DEREncode(seq);
	seq.MessageEnd();
}

Integer InvertibleRWFunction::CalculateInverse(RandomNumberGenerator &rng, const Integer &x) const
{
	DoQuickSanityCheck();
	ModularArithmetic modn(m_n);
	Integer r, rInv;
	do {	// do this in a loop for people using small numbers for testing
		r.Randomize(rng, Integer::One(), m_n - Integer::One());
		rInv = modn.MultiplicativeInverse(r);
	} while (rInv.IsZero());
	Integer re = modn.Square(r);
	re = modn.Multiply(re, x);			// blind

	Integer cp=re%m_p, cq=re%m_q;
	if (Jacobi(cp, m_p) * Jacobi(cq, m_q) != 1)
	{
		cp = cp.IsOdd() ? (cp+m_p) >> 1 : cp >> 1;
		cq = cq.IsOdd() ? (cq+m_q) >> 1 : cq >> 1;
	}

	#pragma omp parallel
		#pragma omp sections
		{
			#pragma omp section
				cp = ModularSquareRoot(cp, m_p);
			#pragma omp section
				cq = ModularSquareRoot(cq, m_q);
		}

	Integer y = CRT(cq, m_q, cp, m_p, m_u);
	y = modn.Multiply(y, rInv);				// unblind
	y = STDMIN(y, m_n-y);
	if (ApplyFunction(y) != x)				// check
		throw Exception(Exception::OTHER_ERROR, "InvertibleRWFunction: computational error during private key operation");
	return y;
}

bool InvertibleRWFunction::Validate(RandomNumberGenerator &rng, unsigned int level) const
{
	bool pass = RWFunction::Validate(rng, level);
	pass = pass && m_p > Integer::One() && m_p%8 == 3 && m_p < m_n;
	pass = pass && m_q > Integer::One() && m_q%8 == 7 && m_q < m_n;
	pass = pass && m_u.IsPositive() && m_u < m_p;
	if (level >= 1)
	{
		pass = pass && m_p * m_q == m_n;
		pass = pass && m_u * m_q % m_p == 1;
	}
	if (level >= 2)
		pass = pass && VerifyPrime(rng, m_p, level-2) && VerifyPrime(rng, m_q, level-2);
	return pass;
}

bool InvertibleRWFunction::GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
{
	return GetValueHelper<RWFunction>(this, name, valueType, pValue).Assignable()
		CRYPTOPP_GET_FUNCTION_ENTRY(Prime1)
		CRYPTOPP_GET_FUNCTION_ENTRY(Prime2)
		CRYPTOPP_GET_FUNCTION_ENTRY(MultiplicativeInverseOfPrime2ModPrime1)
		;
}

void InvertibleRWFunction::AssignFrom(const NameValuePairs &source)
{
	AssignFromHelper<RWFunction>(this, source)
		CRYPTOPP_SET_FUNCTION_ENTRY(Prime1)
		CRYPTOPP_SET_FUNCTION_ENTRY(Prime2)
		CRYPTOPP_SET_FUNCTION_ENTRY(MultiplicativeInverseOfPrime2ModPrime1)
		;
}

NAMESPACE_END

#endif