diff options
Diffstat (limited to 'plugins/CryptoPP/crypto/ec2n.cpp')
| -rw-r--r-- | plugins/CryptoPP/crypto/ec2n.cpp | 288 |
1 files changed, 288 insertions, 0 deletions
diff --git a/plugins/CryptoPP/crypto/ec2n.cpp b/plugins/CryptoPP/crypto/ec2n.cpp new file mode 100644 index 0000000000..e2cf4ad0ed --- /dev/null +++ b/plugins/CryptoPP/crypto/ec2n.cpp @@ -0,0 +1,288 @@ +// ec2n.cpp - written and placed in the public domain by Wei Dai
+
+#include "pch.h"
+
+#ifndef CRYPTOPP_IMPORTS
+
+#include "ec2n.h"
+#include "asn.h"
+
+#include "algebra.cpp"
+#include "eprecomp.cpp"
+
+NAMESPACE_BEGIN(CryptoPP)
+
+EC2N::EC2N(BufferedTransformation &bt)
+ : m_field(BERDecodeGF2NP(bt))
+{
+ BERSequenceDecoder seq(bt);
+ m_field->BERDecodeElement(seq, m_a);
+ m_field->BERDecodeElement(seq, m_b);
+ // skip optional seed
+ if (!seq.EndReached())
+ BERDecodeOctetString(seq, TheBitBucket());
+ seq.MessageEnd();
+}
+
+void EC2N::DEREncode(BufferedTransformation &bt) const
+{
+ m_field->DEREncode(bt);
+ DERSequenceEncoder seq(bt);
+ m_field->DEREncodeElement(seq, m_a);
+ m_field->DEREncodeElement(seq, m_b);
+ seq.MessageEnd();
+}
+
+bool EC2N::DecodePoint(EC2N::Point &P, const byte *encodedPoint, size_t encodedPointLen) const
+{
+ StringStore store(encodedPoint, encodedPointLen);
+ return DecodePoint(P, store, encodedPointLen);
+}
+
+bool EC2N::DecodePoint(EC2N::Point &P, BufferedTransformation &bt, size_t encodedPointLen) const
+{
+ byte type;
+ if (encodedPointLen < 1 || !bt.Get(type))
+ return false;
+
+ switch (type)
+ {
+ case 0:
+ P.identity = true;
+ return true;
+ case 2:
+ case 3:
+ {
+ if (encodedPointLen != EncodedPointSize(true))
+ return false;
+
+ P.identity = false;
+ P.x.Decode(bt, m_field->MaxElementByteLength());
+
+ if (P.x.IsZero())
+ {
+ P.y = m_field->SquareRoot(m_b);
+ return true;
+ }
+
+ FieldElement z = m_field->Square(P.x);
+ assert(P.x == m_field->SquareRoot(z));
+ P.y = m_field->Divide(m_field->Add(m_field->Multiply(z, m_field->Add(P.x, m_a)), m_b), z);
+ assert(P.x == m_field->Subtract(m_field->Divide(m_field->Subtract(m_field->Multiply(P.y, z), m_b), z), m_a));
+ z = m_field->SolveQuadraticEquation(P.y);
+ assert(m_field->Add(m_field->Square(z), z) == P.y);
+ z.SetCoefficient(0, type & 1);
+
+ P.y = m_field->Multiply(z, P.x);
+ return true;
+ }
+ case 4:
+ {
+ if (encodedPointLen != EncodedPointSize(false))
+ return false;
+
+ unsigned int len = m_field->MaxElementByteLength();
+ P.identity = false;
+ P.x.Decode(bt, len);
+ P.y.Decode(bt, len);
+ return true;
+ }
+ default:
+ return false;
+ }
+}
+
+void EC2N::EncodePoint(BufferedTransformation &bt, const Point &P, bool compressed) const
+{
+ if (P.identity)
+ NullStore().TransferTo(bt, EncodedPointSize(compressed));
+ else if (compressed)
+ {
+ bt.Put(2 + (!P.x ? 0 : m_field->Divide(P.y, P.x).GetBit(0)));
+ P.x.Encode(bt, m_field->MaxElementByteLength());
+ }
+ else
+ {
+ unsigned int len = m_field->MaxElementByteLength();
+ bt.Put(4); // uncompressed
+ P.x.Encode(bt, len);
+ P.y.Encode(bt, len);
+ }
+}
+
+void EC2N::EncodePoint(byte *encodedPoint, const Point &P, bool compressed) const
+{
+ ArraySink sink(encodedPoint, EncodedPointSize(compressed));
+ EncodePoint(sink, P, compressed);
+ assert(sink.TotalPutLength() == EncodedPointSize(compressed));
+}
+
+EC2N::Point EC2N::BERDecodePoint(BufferedTransformation &bt) const
+{
+ SecByteBlock str;
+ BERDecodeOctetString(bt, str);
+ Point P;
+ if (!DecodePoint(P, str, str.size()))
+ BERDecodeError();
+ return P;
+}
+
+void EC2N::DEREncodePoint(BufferedTransformation &bt, const Point &P, bool compressed) const
+{
+ SecByteBlock str(EncodedPointSize(compressed));
+ EncodePoint(str, P, compressed);
+ DEREncodeOctetString(bt, str);
+}
+
+bool EC2N::ValidateParameters(RandomNumberGenerator &rng, unsigned int level) const
+{
+ bool pass = !!m_b;
+ pass = pass && m_a.CoefficientCount() <= m_field->MaxElementBitLength();
+ pass = pass && m_b.CoefficientCount() <= m_field->MaxElementBitLength();
+
+ if (level >= 1)
+ pass = pass && m_field->GetModulus().IsIrreducible();
+
+ return pass;
+}
+
+bool EC2N::VerifyPoint(const Point &P) const
+{
+ const FieldElement &x = P.x, &y = P.y;
+ return P.identity ||
+ (x.CoefficientCount() <= m_field->MaxElementBitLength()
+ && y.CoefficientCount() <= m_field->MaxElementBitLength()
+ && !(((x+m_a)*x*x+m_b-(x+y)*y)%m_field->GetModulus()));
+}
+
+bool EC2N::Equal(const Point &P, const Point &Q) const
+{
+ if (P.identity && Q.identity)
+ return true;
+
+ if (P.identity && !Q.identity)
+ return false;
+
+ if (!P.identity && Q.identity)
+ return false;
+
+ return (m_field->Equal(P.x,Q.x) && m_field->Equal(P.y,Q.y));
+}
+
+const EC2N::Point& EC2N::Identity() const
+{
+ return Singleton<Point>().Ref();
+}
+
+const EC2N::Point& EC2N::Inverse(const Point &P) const
+{
+ if (P.identity)
+ return P;
+ else
+ {
+ m_R.identity = false;
+ m_R.y = m_field->Add(P.x, P.y);
+ m_R.x = P.x;
+ return m_R;
+ }
+}
+
+const EC2N::Point& EC2N::Add(const Point &P, const Point &Q) const
+{
+ if (P.identity) return Q;
+ if (Q.identity) return P;
+ if (Equal(P, Q)) return Double(P);
+ if (m_field->Equal(P.x, Q.x) && m_field->Equal(P.y, m_field->Add(Q.x, Q.y))) return Identity();
+
+ FieldElement t = m_field->Add(P.y, Q.y);
+ t = m_field->Divide(t, m_field->Add(P.x, Q.x));
+ FieldElement x = m_field->Square(t);
+ m_field->Accumulate(x, t);
+ m_field->Accumulate(x, Q.x);
+ m_field->Accumulate(x, m_a);
+ m_R.y = m_field->Add(P.y, m_field->Multiply(t, x));
+ m_field->Accumulate(x, P.x);
+ m_field->Accumulate(m_R.y, x);
+
+ m_R.x.swap(x);
+ m_R.identity = false;
+ return m_R;
+}
+
+const EC2N::Point& EC2N::Double(const Point &P) const
+{
+ if (P.identity) return P;
+ if (!m_field->IsUnit(P.x)) return Identity();
+
+ FieldElement t = m_field->Divide(P.y, P.x);
+ m_field->Accumulate(t, P.x);
+ m_R.y = m_field->Square(P.x);
+ m_R.x = m_field->Square(t);
+ m_field->Accumulate(m_R.x, t);
+ m_field->Accumulate(m_R.x, m_a);
+ m_field->Accumulate(m_R.y, m_field->Multiply(t, m_R.x));
+ m_field->Accumulate(m_R.y, m_R.x);
+
+ m_R.identity = false;
+ return m_R;
+}
+
+// ********************************************************
+
+/*
+EcPrecomputation<EC2N>& EcPrecomputation<EC2N>::operator=(const EcPrecomputation<EC2N> &rhs)
+{
+ m_ec = rhs.m_ec;
+ m_ep = rhs.m_ep;
+ m_ep.m_group = m_ec.get();
+ return *this;
+}
+
+void EcPrecomputation<EC2N>::SetCurveAndBase(const EC2N &ec, const EC2N::Point &base)
+{
+ m_ec.reset(new EC2N(ec));
+ m_ep.SetGroupAndBase(*m_ec, base);
+}
+
+void EcPrecomputation<EC2N>::Precompute(unsigned int maxExpBits, unsigned int storage)
+{
+ m_ep.Precompute(maxExpBits, storage);
+}
+
+void EcPrecomputation<EC2N>::Load(BufferedTransformation &bt)
+{
+ BERSequenceDecoder seq(bt);
+ word32 version;
+ BERDecodeUnsigned<word32>(seq, version, INTEGER, 1, 1);
+ m_ep.m_exponentBase.BERDecode(seq);
+ m_ep.m_windowSize = m_ep.m_exponentBase.BitCount() - 1;
+ m_ep.m_bases.clear();
+ while (!seq.EndReached())
+ m_ep.m_bases.push_back(m_ec->BERDecodePoint(seq));
+ seq.MessageEnd();
+}
+
+void EcPrecomputation<EC2N>::Save(BufferedTransformation &bt) const
+{
+ DERSequenceEncoder seq(bt);
+ DEREncodeUnsigned<word32>(seq, 1); // version
+ m_ep.m_exponentBase.DEREncode(seq);
+ for (unsigned i=0; i<m_ep.m_bases.size(); i++)
+ m_ec->DEREncodePoint(seq, m_ep.m_bases[i]);
+ seq.MessageEnd();
+}
+
+EC2N::Point EcPrecomputation<EC2N>::Exponentiate(const Integer &exponent) const
+{
+ return m_ep.Exponentiate(exponent);
+}
+
+EC2N::Point EcPrecomputation<EC2N>::CascadeExponentiate(const Integer &exponent, const DL_FixedBasePrecomputation<Element> &pc2, const Integer &exponent2) const
+{
+ return m_ep.CascadeExponentiate(exponent, static_cast<const EcPrecomputation<EC2N> &>(pc2).m_ep, exponent2);
+}
+*/
+
+NAMESPACE_END
+
+#endif
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