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rabin.cpp

00001 // rabin.cpp - written and placed in the public domain by Wei Dai
00002 
00003 #include "pch.h"
00004 #include "rabin.h"
00005 #include "nbtheory.h"
00006 #include "asn.h"
00007 #include "sha.h"
00008 
00009 NAMESPACE_BEGIN(CryptoPP)
00010 
00011 void RabinFunction::BERDecode(BufferedTransformation &bt)
00012 {
00013         BERSequenceDecoder seq(bt);
00014         m_n.BERDecode(seq);
00015         m_r.BERDecode(seq);
00016         m_s.BERDecode(seq);
00017         seq.MessageEnd();
00018 }
00019 
00020 void RabinFunction::DEREncode(BufferedTransformation &bt) const
00021 {
00022         DERSequenceEncoder seq(bt);
00023         m_n.DEREncode(seq);
00024         m_r.DEREncode(seq);
00025         m_s.DEREncode(seq);
00026         seq.MessageEnd();
00027 }
00028 
00029 Integer RabinFunction::ApplyFunction(const Integer &in) const
00030 {
00031         DoQuickSanityCheck();
00032 
00033         Integer out = in.Squared()%m_n;
00034         if (in.IsOdd())
00035                 out = out*m_r%m_n;
00036         if (Jacobi(in, m_n)==-1)
00037                 out = out*m_s%m_n;
00038         return out;
00039 }
00040 
00041 bool RabinFunction::Validate(RandomNumberGenerator &rng, unsigned int level) const
00042 {
00043         bool pass = true;
00044         pass = pass && m_n > Integer::One() && m_n%4 == 1;
00045         pass = pass && m_r > Integer::One() && m_r < m_n;
00046         pass = pass && m_s > Integer::One() && m_s < m_n;
00047         if (level >= 1)
00048                 pass = pass && Jacobi(m_r, m_n) == -1 && Jacobi(m_s, m_n) == -1;
00049         return pass;
00050 }
00051 
00052 bool RabinFunction::GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
00053 {
00054         return GetValueHelper(this, name, valueType, pValue).Assignable()
00055                 CRYPTOPP_GET_FUNCTION_ENTRY(Modulus)
00056                 CRYPTOPP_GET_FUNCTION_ENTRY(QuadraticResidueModPrime1)
00057                 CRYPTOPP_GET_FUNCTION_ENTRY(QuadraticResidueModPrime2)
00058                 ;
00059 }
00060 
00061 void RabinFunction::AssignFrom(const NameValuePairs &source)
00062 {
00063         AssignFromHelper(this, source)
00064                 CRYPTOPP_SET_FUNCTION_ENTRY(Modulus)
00065                 CRYPTOPP_SET_FUNCTION_ENTRY(QuadraticResidueModPrime1)
00066                 CRYPTOPP_SET_FUNCTION_ENTRY(QuadraticResidueModPrime2)
00067                 ;
00068 }
00069 
00070 // *****************************************************************************
00071 // private key operations:
00072 
00073 // generate a random private key
00074 void InvertibleRabinFunction::GenerateRandom(RandomNumberGenerator &rng, const NameValuePairs &alg)
00075 {
00076         int modulusSize = 2048;
00077         alg.GetIntValue("ModulusSize", modulusSize) || alg.GetIntValue("KeySize", modulusSize);
00078 
00079         if (modulusSize < 16)
00080                 throw InvalidArgument("InvertibleRabinFunction: specified modulus size is too small");
00081 
00082         // VC70 workaround: putting these after primeParam causes overlapped stack allocation
00083         bool rFound=false, sFound=false;
00084         Integer t=2;
00085 
00086         const NameValuePairs &primeParam = MakeParametersForTwoPrimesOfEqualSize(modulusSize)
00087                 ("EquivalentTo", 3)("Mod", 4);
00088         m_p.GenerateRandom(rng, primeParam);
00089         m_q.GenerateRandom(rng, primeParam);
00090 
00091         while (!(rFound && sFound))
00092         {
00093                 int jp = Jacobi(t, m_p);
00094                 int jq = Jacobi(t, m_q);
00095 
00096                 if (!rFound && jp==1 && jq==-1)
00097                 {
00098                         m_r = t;
00099                         rFound = true;
00100                 }
00101 
00102                 if (!sFound && jp==-1 && jq==1)
00103                 {
00104                         m_s = t;
00105                         sFound = true;
00106                 }
00107 
00108                 ++t;
00109         }
00110 
00111         m_n = m_p * m_q;
00112         m_u = m_q.InverseMod(m_p);
00113 }
00114 
00115 void InvertibleRabinFunction::BERDecode(BufferedTransformation &bt)
00116 {
00117         BERSequenceDecoder seq(bt);
00118         m_n.BERDecode(seq);
00119         m_r.BERDecode(seq);
00120         m_s.BERDecode(seq);
00121         m_p.BERDecode(seq);
00122         m_q.BERDecode(seq);
00123         m_u.BERDecode(seq);
00124         seq.MessageEnd();
00125 }
00126 
00127 void InvertibleRabinFunction::DEREncode(BufferedTransformation &bt) const
00128 {
00129         DERSequenceEncoder seq(bt);
00130         m_n.DEREncode(seq);
00131         m_r.DEREncode(seq);
00132         m_s.DEREncode(seq);
00133         m_p.DEREncode(seq);
00134         m_q.DEREncode(seq);
00135         m_u.DEREncode(seq);
00136         seq.MessageEnd();
00137 }
00138 
00139 Integer InvertibleRabinFunction::CalculateInverse(const Integer &in) const
00140 {
00141         DoQuickSanityCheck();
00142 
00143         Integer cp=in%m_p, cq=in%m_q;
00144 
00145         int jp = Jacobi(cp, m_p);
00146         int jq = Jacobi(cq, m_q);
00147 
00148         if (jq==-1)
00149         {
00150                 cp = cp*EuclideanMultiplicativeInverse(m_r, m_p)%m_p;
00151                 cq = cq*EuclideanMultiplicativeInverse(m_r, m_q)%m_q;
00152         }
00153 
00154         if (jp==-1)
00155         {
00156                 cp = cp*EuclideanMultiplicativeInverse(m_s, m_p)%m_p;
00157                 cq = cq*EuclideanMultiplicativeInverse(m_s, m_q)%m_q;
00158         }
00159 
00160         cp = ModularSquareRoot(cp, m_p);
00161         cq = ModularSquareRoot(cq, m_q);
00162 
00163         if (jp==-1)
00164                 cp = m_p-cp;
00165 
00166         Integer out = CRT(cq, m_q, cp, m_p, m_u);
00167 
00168         if ((jq==-1 && out.IsEven()) || (jq==1 && out.IsOdd()))
00169                 out = m_n-out;
00170 
00171         return out;
00172 }
00173 
00174 bool InvertibleRabinFunction::Validate(RandomNumberGenerator &rng, unsigned int level) const
00175 {
00176         bool pass = RabinFunction::Validate(rng, level);
00177         pass = pass && m_p > Integer::One() && m_p%4 == 3 && m_p < m_n;
00178         pass = pass && m_q > Integer::One() && m_q%4 == 3 && m_q < m_n;
00179         pass = pass && m_u.IsPositive() && m_u < m_p;
00180         if (level >= 1)
00181         {
00182                 pass = pass && m_p * m_q == m_n;
00183                 pass = pass && m_u * m_q % m_p == 1;
00184                 pass = pass && Jacobi(m_r, m_p) == 1;
00185                 pass = pass && Jacobi(m_r, m_q) == -1;
00186                 pass = pass && Jacobi(m_s, m_p) == -1;
00187                 pass = pass && Jacobi(m_s, m_q) == 1;
00188         }
00189         if (level >= 2)
00190                 pass = pass && VerifyPrime(rng, m_p, level-2) && VerifyPrime(rng, m_q, level-2);
00191         return pass;
00192 }
00193 
00194 bool InvertibleRabinFunction::GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
00195 {
00196         return GetValueHelper<RabinFunction>(this, name, valueType, pValue).Assignable()
00197                 CRYPTOPP_GET_FUNCTION_ENTRY(Prime1)
00198                 CRYPTOPP_GET_FUNCTION_ENTRY(Prime2)
00199                 CRYPTOPP_GET_FUNCTION_ENTRY(MultiplicativeInverseOfPrime2ModPrime1)
00200                 ;
00201 }
00202 
00203 void InvertibleRabinFunction::AssignFrom(const NameValuePairs &source)
00204 {
00205         AssignFromHelper<RabinFunction>(this, source)
00206                 CRYPTOPP_SET_FUNCTION_ENTRY(Prime1)
00207                 CRYPTOPP_SET_FUNCTION_ENTRY(Prime2)
00208                 CRYPTOPP_SET_FUNCTION_ENTRY(MultiplicativeInverseOfPrime2ModPrime1)
00209                 ;
00210 }
00211 
00212 NAMESPACE_END

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