diff options
Diffstat (limited to 'plugins/CryptoPP/crypto/src/eprecomp.cpp')
| -rw-r--r-- | plugins/CryptoPP/crypto/src/eprecomp.cpp | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/plugins/CryptoPP/crypto/src/eprecomp.cpp b/plugins/CryptoPP/crypto/src/eprecomp.cpp new file mode 100644 index 0000000000..67a4ab6105 --- /dev/null +++ b/plugins/CryptoPP/crypto/src/eprecomp.cpp @@ -0,0 +1,117 @@ +// eprecomp.cpp - written and placed in the public domain by Wei Dai
+
+#include "pch.h"
+
+// prevent Sun's CC compiler from including this file automatically
+#if !defined(__SUNPRO_CC) || defined(CRYPTOPP_MANUALLY_INSTANTIATE_TEMPLATES)
+
+#ifndef CRYPTOPP_IMPORTS
+
+#include "eprecomp.h"
+#include "asn.h"
+
+NAMESPACE_BEGIN(CryptoPP)
+
+template <class T> void DL_FixedBasePrecomputationImpl<T>::SetBase(const DL_GroupPrecomputation<Element> &group, const Element &i_base)
+{
+ m_base = group.NeedConversions() ? group.ConvertIn(i_base) : i_base;
+
+ if (m_bases.empty() || !(m_base == m_bases[0]))
+ {
+ m_bases.resize(1);
+ m_bases[0] = m_base;
+ }
+
+ if (group.NeedConversions())
+ m_base = i_base;
+}
+
+template <class T> void DL_FixedBasePrecomputationImpl<T>::Precompute(const DL_GroupPrecomputation<Element> &group, unsigned int maxExpBits, unsigned int storage)
+{
+ assert(m_bases.size() > 0);
+ assert(storage <= maxExpBits);
+
+ if (storage > 1)
+ {
+ m_windowSize = (maxExpBits+storage-1)/storage;
+ m_exponentBase = Integer::Power2(m_windowSize);
+ }
+
+ m_bases.resize(storage);
+ for (unsigned i=1; i<storage; i++)
+ m_bases[i] = group.GetGroup().ScalarMultiply(m_bases[i-1], m_exponentBase);
+}
+
+template <class T> void DL_FixedBasePrecomputationImpl<T>::Load(const DL_GroupPrecomputation<Element> &group, BufferedTransformation &bt)
+{
+ BERSequenceDecoder seq(bt);
+ word32 version;
+ BERDecodeUnsigned<word32>(seq, version, INTEGER, 1, 1);
+ m_exponentBase.BERDecode(seq);
+ m_windowSize = m_exponentBase.BitCount() - 1;
+ m_bases.clear();
+ while (!seq.EndReached())
+ m_bases.push_back(group.BERDecodeElement(seq));
+ if (!m_bases.empty() && group.NeedConversions())
+ m_base = group.ConvertOut(m_bases[0]);
+ seq.MessageEnd();
+}
+
+template <class T> void DL_FixedBasePrecomputationImpl<T>::Save(const DL_GroupPrecomputation<Element> &group, BufferedTransformation &bt) const
+{
+ DERSequenceEncoder seq(bt);
+ DEREncodeUnsigned<word32>(seq, 1); // version
+ m_exponentBase.DEREncode(seq);
+ for (unsigned i=0; i<m_bases.size(); i++)
+ group.DEREncodeElement(seq, m_bases[i]);
+ seq.MessageEnd();
+}
+
+template <class T> void DL_FixedBasePrecomputationImpl<T>::PrepareCascade(const DL_GroupPrecomputation<Element> &i_group, std::vector<BaseAndExponent<Element> > &eb, const Integer &exponent) const
+{
+ const AbstractGroup<T> &group = i_group.GetGroup();
+
+ Integer r, q, e = exponent;
+ bool fastNegate = group.InversionIsFast() && m_windowSize > 1;
+ unsigned int i;
+
+ for (i=0; i+1<m_bases.size(); i++)
+ {
+ Integer::DivideByPowerOf2(r, q, e, m_windowSize);
+ std::swap(q, e);
+ if (fastNegate && r.GetBit(m_windowSize-1))
+ {
+ ++e;
+ eb.push_back(BaseAndExponent<Element>(group.Inverse(m_bases[i]), m_exponentBase - r));
+ }
+ else
+ eb.push_back(BaseAndExponent<Element>(m_bases[i], r));
+ }
+ eb.push_back(BaseAndExponent<Element>(m_bases[i], e));
+}
+
+template <class T> T DL_FixedBasePrecomputationImpl<T>::Exponentiate(const DL_GroupPrecomputation<Element> &group, const Integer &exponent) const
+{
+ std::vector<BaseAndExponent<Element> > eb; // array of segments of the exponent and precalculated bases
+ eb.reserve(m_bases.size());
+ PrepareCascade(group, eb, exponent);
+ return group.ConvertOut(GeneralCascadeMultiplication<Element>(group.GetGroup(), eb.begin(), eb.end()));
+}
+
+template <class T> T
+ DL_FixedBasePrecomputationImpl<T>::CascadeExponentiate(const DL_GroupPrecomputation<Element> &group, const Integer &exponent,
+ const DL_FixedBasePrecomputation<T> &i_pc2, const Integer &exponent2) const
+{
+ std::vector<BaseAndExponent<Element> > eb; // array of segments of the exponent and precalculated bases
+ const DL_FixedBasePrecomputationImpl<T> &pc2 = static_cast<const DL_FixedBasePrecomputationImpl<T> &>(i_pc2);
+ eb.reserve(m_bases.size() + pc2.m_bases.size());
+ PrepareCascade(group, eb, exponent);
+ pc2.PrepareCascade(group, eb, exponent2);
+ return group.ConvertOut(GeneralCascadeMultiplication<Element>(group.GetGroup(), eb.begin(), eb.end()));
+}
+
+NAMESPACE_END
+
+#endif
+
+#endif
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