Initial revision

1 files changed, 108 insertions, 0 deletions

diff --git a/xtrcrypt.cpp b/xtrcrypt.cpp
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index 00000000..20e78e7c
--- /dev/null
+++ b/xtrcrypt.cpp
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+// xtrcrypt.cpp - written and placed in the public domain by Wei Dai
+
+#include "pch.h"
+#include "xtrcrypt.h"
+#include "nbtheory.h"
+#include "asn.h"
+#include "argnames.h"
+
+NAMESPACE_BEGIN(CryptoPP)
+
+XTR_DH::XTR_DH(const Integer &p, const Integer &q, const GFP2Element &g)
+	: m_p(p), m_q(q), m_g(g)
+{
+}
+
+XTR_DH::XTR_DH(RandomNumberGenerator &rng, unsigned int pbits, unsigned int qbits)
+{
+	XTR_FindPrimesAndGenerator(rng, m_p, m_q, m_g, pbits, qbits);
+}
+
+XTR_DH::XTR_DH(BufferedTransformation &bt)
+{
+	BERSequenceDecoder seq(bt);
+	m_p.BERDecode(seq);
+	m_q.BERDecode(seq);
+	m_g.c1.BERDecode(seq);
+	m_g.c2.BERDecode(seq);
+	seq.MessageEnd();
+}
+
+void XTR_DH::DEREncode(BufferedTransformation &bt) const
+{
+	DERSequenceEncoder seq(bt);
+	m_p.DEREncode(seq);
+	m_q.DEREncode(seq);
+	m_g.c1.DEREncode(seq);
+	m_g.c2.DEREncode(seq);
+	seq.MessageEnd();
+}
+
+bool XTR_DH::Validate(RandomNumberGenerator &rng, unsigned int level) const
+{
+	bool pass = true;
+	pass = pass && m_p > Integer::One() && m_p.IsOdd();
+	pass = pass && m_q > Integer::One() && m_q.IsOdd();
+	GFP2Element three = GFP2_ONB<ModularArithmetic>(m_p).ConvertIn(3);
+	pass = pass && !(m_g.c1.IsNegative() || m_g.c2.IsNegative() || m_g.c1 >= m_p || m_g.c2 >= m_p || m_g == three);
+	if (level >= 1)
+		pass = pass && ((m_p.Squared()-m_p+1)%m_q).IsZero();
+	if (level >= 2)
+	{
+		pass = pass && VerifyPrime(rng, m_p, level-2) && VerifyPrime(rng, m_q, level-2);
+		pass = pass && XTR_Exponentiate(m_g, (m_p.Squared()-m_p+1)/m_q, m_p) != three;
+		pass = pass && XTR_Exponentiate(m_g, m_q, m_p) == three;
+	}
+	return pass;
+}
+
+bool XTR_DH::GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
+{
+	return GetValueHelper(this, name, valueType, pValue).Assignable()
+		CRYPTOPP_GET_FUNCTION_ENTRY(Modulus)
+		CRYPTOPP_GET_FUNCTION_ENTRY(SubgroupOrder)
+		CRYPTOPP_GET_FUNCTION_ENTRY(SubgroupGenerator)
+		;
+}
+
+void XTR_DH::AssignFrom(const NameValuePairs &source)
+{
+	AssignFromHelper(this, source)
+		CRYPTOPP_SET_FUNCTION_ENTRY(Modulus)
+		CRYPTOPP_SET_FUNCTION_ENTRY(SubgroupOrder)
+		CRYPTOPP_SET_FUNCTION_ENTRY(SubgroupGenerator)
+		;
+}
+
+void XTR_DH::GeneratePrivateKey(RandomNumberGenerator &rng, byte *privateKey) const
+{
+	Integer x(rng, Integer::Zero(), m_q-1);
+	x.Encode(privateKey, PrivateKeyLength());
+}
+
+void XTR_DH::GeneratePublicKey(RandomNumberGenerator &rng, const byte *privateKey, byte *publicKey) const
+{
+	Integer x(privateKey, PrivateKeyLength());
+	GFP2Element y = XTR_Exponentiate(m_g, x, m_p);
+	y.Encode(publicKey, PublicKeyLength());
+}
+
+bool XTR_DH::Agree(byte *agreedValue, const byte *privateKey, const byte *otherPublicKey, bool validateOtherPublicKey) const
+{
+	GFP2Element w(otherPublicKey, PublicKeyLength());
+	if (validateOtherPublicKey)
+	{
+		GFP2_ONB<ModularArithmetic> gfp2(m_p);
+		GFP2Element three = gfp2.ConvertIn(3);
+		if (w.c1.IsNegative() || w.c2.IsNegative() || w.c1 >= m_p || w.c2 >= m_p || w == three)
+			return false;
+		if (XTR_Exponentiate(w, m_q, m_p) != three)
+			return false;
+	}
+	Integer s(privateKey, PrivateKeyLength());
+	GFP2Element z = XTR_Exponentiate(w, s, m_p);
+	z.Encode(agreedValue, AgreedValueLength());
+	return true;
+}
+
+NAMESPACE_END