gfpcrypt.h

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#ifndef CRYPTOPP_GFPCRYPT_H
#define CRYPTOPP_GFPCRYPT_H

/** \file
        Implementation of schemes based on DL over GF(p)
*/

#include "pubkey.h"
#include "modexppc.h"
#include "sha.h"
#include "algparam.h"
#include "asn.h"
#include "smartptr.h"
#include "hmac.h"

#include <limits.h>

NAMESPACE_BEGIN(CryptoPP)

CRYPTOPP_DLL_TEMPLATE_CLASS DL_GroupParameters<Integer>;

//! _
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE DL_GroupParameters_IntegerBased : public ASN1CryptoMaterial<DL_GroupParameters<Integer> >
{
        typedef DL_GroupParameters_IntegerBased ThisClass;
        
public:
        void Initialize(const DL_GroupParameters_IntegerBased &params)
                {Initialize(params.GetModulus(), params.GetSubgroupOrder(), params.GetSubgroupGenerator());}
        void Initialize(RandomNumberGenerator &rng, unsigned int pbits)
                {GenerateRandom(rng, MakeParameters("ModulusSize", (int)pbits));}
        void Initialize(const Integer &p, const Integer &g)
                {SetModulusAndSubgroupGenerator(p, g); SetSubgroupOrder(ComputeGroupOrder(p)/2);}
        void Initialize(const Integer &p, const Integer &q, const Integer &g)
                {SetModulusAndSubgroupGenerator(p, g); SetSubgroupOrder(q);}

        // ASN1Object interface
        void BERDecode(BufferedTransformation &bt);
        void DEREncode(BufferedTransformation &bt) const;

        // GeneratibleCryptoMaterial interface
        /*! parameters: (ModulusSize, SubgroupOrderSize (optional)) */
        void GenerateRandom(RandomNumberGenerator &rng, const NameValuePairs &alg);
        bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const;
        void AssignFrom(const NameValuePairs &source);
        
        // DL_GroupParameters
        const Integer & GetSubgroupOrder() const {return m_q;}
        Integer GetGroupOrder() const {return GetFieldType() == 1 ? GetModulus()-Integer::One() : GetModulus()+Integer::One();}
        bool ValidateGroup(RandomNumberGenerator &rng, unsigned int level) const;
        bool ValidateElement(unsigned int level, const Integer &element, const DL_FixedBasePrecomputation<Integer> *precomp) const;
        bool FastSubgroupCheckAvailable() const {return GetCofactor() == 2;}
        void EncodeElement(bool reversible, const Element &element, byte *encoded) const
                {element.Encode(encoded, GetModulus().ByteCount());}
        unsigned int GetEncodedElementSize(bool reversible) const {return GetModulus().ByteCount();}
        Integer DecodeElement(const byte *encoded, bool checkForGroupMembership) const;
        Integer ConvertElementToInteger(const Element &element) const
                {return element;}
        Integer GetMaxExponent() const;
        static std::string CRYPTOPP_API StaticAlgorithmNamePrefix() {return "";}

        OID GetAlgorithmID() const;

        virtual const Integer & GetModulus() const =0;
        virtual void SetModulusAndSubgroupGenerator(const Integer &p, const Integer &g) =0;

        void SetSubgroupOrder(const Integer &q)
                {m_q = q; ParametersChanged();}

protected:
        Integer ComputeGroupOrder(const Integer &modulus) const
                {return modulus-(GetFieldType() == 1 ? 1 : -1);}

        // GF(p) = 1, GF(p^2) = 2
        virtual int GetFieldType() const =0;
        virtual unsigned int GetDefaultSubgroupOrderSize(unsigned int modulusSize) const;

private:
        Integer m_q;
};

//! _
template <class GROUP_PRECOMP, class BASE_PRECOMP = DL_FixedBasePrecomputationImpl<CPP_TYPENAME GROUP_PRECOMP::Element> >
class CRYPTOPP_NO_VTABLE DL_GroupParameters_IntegerBasedImpl : public DL_GroupParametersImpl<GROUP_PRECOMP, BASE_PRECOMP, DL_GroupParameters_IntegerBased>
{
        typedef DL_GroupParameters_IntegerBasedImpl<GROUP_PRECOMP, BASE_PRECOMP> ThisClass;

public:
        typedef typename GROUP_PRECOMP::Element Element;

        // GeneratibleCryptoMaterial interface
        bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
                {return GetValueHelper<DL_GroupParameters_IntegerBased>(this, name, valueType, pValue).Assignable();}

        void AssignFrom(const NameValuePairs &source)
                {AssignFromHelper<DL_GroupParameters_IntegerBased>(this, source);}

        // DL_GroupParameters
        const DL_FixedBasePrecomputation<Element> & GetBasePrecomputation() const {return this->m_gpc;}
        DL_FixedBasePrecomputation<Element> & AccessBasePrecomputation() {return this->m_gpc;}

        // IntegerGroupParameters
        const Integer & GetModulus() const {return this->m_groupPrecomputation.GetModulus();}
    const Integer & GetGenerator() const {return this->m_gpc.GetBase(this->GetGroupPrecomputation());}

        void SetModulusAndSubgroupGenerator(const Integer &p, const Integer &g)         // these have to be set together
                {this->m_groupPrecomputation.SetModulus(p); this->m_gpc.SetBase(this->GetGroupPrecomputation(), g); this->ParametersChanged();}

        // non-inherited
        bool operator==(const DL_GroupParameters_IntegerBasedImpl<GROUP_PRECOMP, BASE_PRECOMP> &rhs) const
                {return GetModulus() == rhs.GetModulus() && GetGenerator() == rhs.GetGenerator() && this->GetSubgroupOrder() == rhs.GetSubgroupOrder();}
        bool operator!=(const DL_GroupParameters_IntegerBasedImpl<GROUP_PRECOMP, BASE_PRECOMP> &rhs) const
                {return !operator==(rhs);}
};

CRYPTOPP_DLL_TEMPLATE_CLASS DL_GroupParameters_IntegerBasedImpl<ModExpPrecomputation>;

//! GF(p) group parameters
class CRYPTOPP_DLL DL_GroupParameters_GFP : public DL_GroupParameters_IntegerBasedImpl<ModExpPrecomputation>
{
public:
        // DL_GroupParameters
        bool IsIdentity(const Integer &element) const {return element == Integer::One();}
        void SimultaneousExponentiate(Element *results, const Element &base, const Integer *exponents, unsigned int exponentsCount) const;

        // NameValuePairs interface
        bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
        {
                return GetValueHelper<DL_GroupParameters_IntegerBased>(this, name, valueType, pValue).Assignable();
        }

        // used by MQV
        Element MultiplyElements(const Element &a, const Element &b) const;
        Element CascadeExponentiate(const Element &element1, const Integer &exponent1, const Element &element2, const Integer &exponent2) const;

protected:
        int GetFieldType() const {return 1;}
};

//! GF(p) group parameters that default to same primes
class CRYPTOPP_DLL DL_GroupParameters_GFP_DefaultSafePrime : public DL_GroupParameters_GFP
{
public:
        typedef NoCofactorMultiplication DefaultCofactorOption;

protected:
        unsigned int GetDefaultSubgroupOrderSize(unsigned int modulusSize) const {return modulusSize-1;}
};

//! GDSA algorithm
template <class T>
class DL_Algorithm_GDSA : public DL_ElgamalLikeSignatureAlgorithm<T>
{
public:
        static const char * CRYPTOPP_API StaticAlgorithmName() {return "DSA-1363";}

        void Sign(const DL_GroupParameters<T> &params, const Integer &x, const Integer &k, const Integer &e, Integer &r, Integer &s) const
        {
                const Integer &q = params.GetSubgroupOrder();
                r %= q;
                Integer kInv = k.InverseMod(q);
                s = (kInv * (x*r + e)) % q;
                assert(!!r && !!s);
        }

        bool Verify(const DL_GroupParameters<T> &params, const DL_PublicKey<T> &publicKey, const Integer &e, const Integer &r, const Integer &s) const
        {
                const Integer &q = params.GetSubgroupOrder();
                if (r>=q || r<1 || s>=q || s<1)
                        return false;

                Integer w = s.InverseMod(q);
                Integer u1 = (e * w) % q;
                Integer u2 = (r * w) % q;
                // verify r == (g^u1 * y^u2 mod p) mod q
                return r == params.ConvertElementToInteger(publicKey.CascadeExponentiateBaseAndPublicElement(u1, u2)) % q;
        }
};

CRYPTOPP_DLL_TEMPLATE_CLASS DL_Algorithm_GDSA<Integer>;

//! NR algorithm
template <class T>
class DL_Algorithm_NR : public DL_ElgamalLikeSignatureAlgorithm<T>
{
public:
        static const char * CRYPTOPP_API StaticAlgorithmName() {return "NR";}

        void Sign(const DL_GroupParameters<T> &params, const Integer &x, const Integer &k, const Integer &e, Integer &r, Integer &s) const
        {
                const Integer &q = params.GetSubgroupOrder();
                r = (r + e) % q;
                s = (k - x*r) % q;
                assert(!!r);
        }

        bool Verify(const DL_GroupParameters<T> &params, const DL_PublicKey<T> &publicKey, const Integer &e, const Integer &r, const Integer &s) const
        {
                const Integer &q = params.GetSubgroupOrder();
                if (r>=q || r<1 || s>=q)
                        return false;

                // check r == (m_g^s * m_y^r + m) mod m_q
                return r == (params.ConvertElementToInteger(publicKey.CascadeExponentiateBaseAndPublicElement(s, r)) + e) % q;
        }
};

/*! DSA public key format is defined in 7.3.3 of RFC 2459. The
        private key format is defined in 12.9 of PKCS #11 v2.10. */
template <class GP>
class DL_PublicKey_GFP : public DL_PublicKeyImpl<GP>
{
public:
        void Initialize(const DL_GroupParameters_IntegerBased &params, const Integer &y)
                {this->AccessGroupParameters().Initialize(params); this->SetPublicElement(y);}
        void Initialize(const Integer &p, const Integer &g, const Integer &y)
                {this->AccessGroupParameters().Initialize(p, g); this->SetPublicElement(y);}
        void Initialize(const Integer &p, const Integer &q, const Integer &g, const Integer &y)
                {this->AccessGroupParameters().Initialize(p, q, g); this->SetPublicElement(y);}

        // X509PublicKey
        void BERDecodePublicKey(BufferedTransformation &bt, bool, size_t)
                {this->SetPublicElement(Integer(bt));}
        void DEREncodePublicKey(BufferedTransformation &bt) const
                {this->GetPublicElement().DEREncode(bt);}
};

//! DL private key (in GF(p) groups)
template <class GP>
class DL_PrivateKey_GFP : public DL_PrivateKeyImpl<GP>
{
public:
        void Initialize(RandomNumberGenerator &rng, unsigned int modulusBits)
                {this->GenerateRandomWithKeySize(rng, modulusBits);}
        void Initialize(RandomNumberGenerator &rng, const Integer &p, const Integer &g)
                {this->GenerateRandom(rng, MakeParameters("Modulus", p)("SubgroupGenerator", g));}
        void Initialize(RandomNumberGenerator &rng, const Integer &p, const Integer &q, const Integer &g)
                {this->GenerateRandom(rng, MakeParameters("Modulus", p)("SubgroupOrder", q)("SubgroupGenerator", g));}
        void Initialize(const DL_GroupParameters_IntegerBased &params, const Integer &x)
                {this->AccessGroupParameters().Initialize(params); this->SetPrivateExponent(x);}
        void Initialize(const Integer &p, const Integer &g, const Integer &x)
                {this->AccessGroupParameters().Initialize(p, g); this->SetPrivateExponent(x);}
        void Initialize(const Integer &p, const Integer &q, const Integer &g, const Integer &x)
                {this->AccessGroupParameters().Initialize(p, q, g); this->SetPrivateExponent(x);}
};

//! DL signing/verification keys (in GF(p) groups)
struct DL_SignatureKeys_GFP
{
        typedef DL_GroupParameters_GFP GroupParameters;
        typedef DL_PublicKey_GFP<GroupParameters> PublicKey;
        typedef DL_PrivateKey_GFP<GroupParameters> PrivateKey;
};

//! DL encryption/decryption keys (in GF(p) groups)
struct DL_CryptoKeys_GFP
{
        typedef DL_GroupParameters_GFP_DefaultSafePrime GroupParameters;
        typedef DL_PublicKey_GFP<GroupParameters> PublicKey;
        typedef DL_PrivateKey_GFP<GroupParameters> PrivateKey;
};

//! provided for backwards compatibility, this class uses the old non-standard Crypto++ key format
template <class BASE>
class DL_PublicKey_GFP_OldFormat : public BASE
{
public:
        void BERDecode(BufferedTransformation &bt)
        {
                BERSequenceDecoder seq(bt);
                        Integer v1(seq);
                        Integer v2(seq);
                        Integer v3(seq);

                        if (seq.EndReached())
                        {
                                this->AccessGroupParameters().Initialize(v1, v1/2, v2);
                                this->SetPublicElement(v3);
                        }
                        else
                        {
                                Integer v4(seq);
                                this->AccessGroupParameters().Initialize(v1, v2, v3);
                                this->SetPublicElement(v4);
                        }

                seq.MessageEnd();
        }

        void DEREncode(BufferedTransformation &bt) const
        {
                DERSequenceEncoder seq(bt);
                        this->GetGroupParameters().GetModulus().DEREncode(seq);
                        if (this->GetGroupParameters().GetCofactor() != 2)
                                this->GetGroupParameters().GetSubgroupOrder().DEREncode(seq);
                        this->GetGroupParameters().GetGenerator().DEREncode(seq);
                        this->GetPublicElement().DEREncode(seq);
                seq.MessageEnd();
        }
};

//! provided for backwards compatibility, this class uses the old non-standard Crypto++ key format
template <class BASE>
class DL_PrivateKey_GFP_OldFormat : public BASE
{
public:
        void BERDecode(BufferedTransformation &bt)
        {
                BERSequenceDecoder seq(bt);
                        Integer v1(seq);
                        Integer v2(seq);
                        Integer v3(seq);
                        Integer v4(seq);

                        if (seq.EndReached())
                        {
                                this->AccessGroupParameters().Initialize(v1, v1/2, v2);
                                this->SetPrivateExponent(v4 % (v1/2));  // some old keys may have x >= q
                        }
                        else
                        {
                                Integer v5(seq);
                                this->AccessGroupParameters().Initialize(v1, v2, v3);
                                this->SetPrivateExponent(v5);
                        }

                seq.MessageEnd();
        }

        void DEREncode(BufferedTransformation &bt) const
        {
                DERSequenceEncoder seq(bt);
                        this->GetGroupParameters().GetModulus().DEREncode(seq);
                        if (this->GetGroupParameters().GetCofactor() != 2)
                                this->GetGroupParameters().GetSubgroupOrder().DEREncode(seq);
                        this->GetGroupParameters().GetGenerator().DEREncode(seq);
                        this->GetGroupParameters().ExponentiateBase(this->GetPrivateExponent()).DEREncode(seq);
                        this->GetPrivateExponent().DEREncode(seq);
                seq.MessageEnd();
        }
};

//! <a href="http://www.weidai.com/scan-mirror/sig.html#DSA-1363">DSA-1363</a>
template <class H>
struct GDSA : public DL_SS<
        DL_SignatureKeys_GFP, 
        DL_Algorithm_GDSA<Integer>, 
        DL_SignatureMessageEncodingMethod_DSA,
        H>
{
};

//! <a href="http://www.weidai.com/scan-mirror/sig.html#NR">NR</a>
template <class H>
struct NR : public DL_SS<
        DL_SignatureKeys_GFP, 
        DL_Algorithm_NR<Integer>, 
        DL_SignatureMessageEncodingMethod_NR,
        H>
{
};

//! DSA group parameters, these are GF(p) group parameters that are allowed by the DSA standard
class CRYPTOPP_DLL DL_GroupParameters_DSA : public DL_GroupParameters_GFP
{
public:
        /*! also checks that the lengths of p and q are allowed by the DSA standard */
        bool ValidateGroup(RandomNumberGenerator &rng, unsigned int level) const;
        /*! parameters: (ModulusSize), or (Modulus, SubgroupOrder, SubgroupGenerator) */
        /*! ModulusSize must be between DSA::MIN_PRIME_LENGTH and DSA::MAX_PRIME_LENGTH, and divisible by DSA::PRIME_LENGTH_MULTIPLE */
        void GenerateRandom(RandomNumberGenerator &rng, const NameValuePairs &alg);
};

struct DSA;

//! DSA keys
struct DL_Keys_DSA
{
        typedef DL_PublicKey_GFP<DL_GroupParameters_DSA> PublicKey;
        typedef DL_PrivateKey_WithSignaturePairwiseConsistencyTest<DL_PrivateKey_GFP<DL_GroupParameters_DSA>, DSA> PrivateKey;
};

//! <a href="http://www.weidai.com/scan-mirror/sig.html#DSA">DSA</a>
struct CRYPTOPP_DLL DSA : public DL_SS<
        DL_Keys_DSA, 
        DL_Algorithm_GDSA<Integer>, 
        DL_SignatureMessageEncodingMethod_DSA,
        SHA, 
        DSA>
{
        static const char * CRYPTOPP_API StaticAlgorithmName() {return "DSA";}

        //! Generate DSA primes according to NIST standard
        /*! Both seedLength and primeLength are in bits, but seedLength should
                be a multiple of 8.
                If useInputCounterValue == true, the counter parameter is taken as input, otherwise it's used for output
        */
        static bool CRYPTOPP_API GeneratePrimes(const byte *seed, unsigned int seedLength, int &counter,
                                                                Integer &p, unsigned int primeLength, Integer &q, bool useInputCounterValue = false);

        static bool CRYPTOPP_API IsValidPrimeLength(unsigned int pbits)
                {return pbits >= MIN_PRIME_LENGTH && pbits <= MAX_PRIME_LENGTH && pbits % PRIME_LENGTH_MULTIPLE == 0;}

        //! FIPS 186-2 Change Notice 1 changed the minimum modulus length to 1024
        enum {
#if (DSA_1024_BIT_MODULUS_ONLY)
                MIN_PRIME_LENGTH = 1024,
#else
                MIN_PRIME_LENGTH = 512,
#endif
                MAX_PRIME_LENGTH = 1024, PRIME_LENGTH_MULTIPLE = 64};
};

CRYPTOPP_DLL_TEMPLATE_CLASS DL_PublicKey_GFP<DL_GroupParameters_DSA>;
CRYPTOPP_DLL_TEMPLATE_CLASS DL_PrivateKey_GFP<DL_GroupParameters_DSA>;
CRYPTOPP_DLL_TEMPLATE_CLASS DL_PrivateKey_WithSignaturePairwiseConsistencyTest<DL_PrivateKey_GFP<DL_GroupParameters_DSA>, DSA>;

//! the XOR encryption method, for use with DL-based cryptosystems
template <class MAC, bool DHAES_MODE>
class DL_EncryptionAlgorithm_Xor : public DL_SymmetricEncryptionAlgorithm
{
public:
        bool ParameterSupported(const char *name) const {return strcmp(name, Name::EncodingParameters()) == 0;}
        size_t GetSymmetricKeyLength(size_t plaintextLength) const
                {return plaintextLength + MAC::DEFAULT_KEYLENGTH;}
        size_t GetSymmetricCiphertextLength(size_t plaintextLength) const
                {return plaintextLength + MAC::DIGESTSIZE;}
        size_t GetMaxSymmetricPlaintextLength(size_t ciphertextLength) const
                {return (unsigned int)SaturatingSubtract(ciphertextLength, (unsigned int)MAC::DIGESTSIZE);}
        void SymmetricEncrypt(RandomNumberGenerator &rng, const byte *key, const byte *plaintext, size_t plaintextLength, byte *ciphertext, const NameValuePairs &parameters) const
        {
                const byte *cipherKey, *macKey;
                if (DHAES_MODE)
                {
                        macKey = key;
                        cipherKey = key + MAC::DEFAULT_KEYLENGTH;
                }
                else
                {
                        cipherKey = key;
                        macKey = key + plaintextLength;
                }

                ConstByteArrayParameter encodingParameters;
                parameters.GetValue(Name::EncodingParameters(), encodingParameters);

                xorbuf(ciphertext, plaintext, cipherKey, plaintextLength);
                MAC mac(macKey);
                mac.Update(ciphertext, plaintextLength);
                mac.Update(encodingParameters.begin(), encodingParameters.size());
                if (DHAES_MODE)
                {
                        byte L[8] = {0,0,0,0};
                        UnalignedPutWord(BIG_ENDIAN_ORDER, L+4, word32(encodingParameters.size()));
                        mac.Update(L, 8);
                }
                mac.Final(ciphertext + plaintextLength);
        }
        DecodingResult SymmetricDecrypt(const byte *key, const byte *ciphertext, size_t ciphertextLength, byte *plaintext, const NameValuePairs &parameters) const
        {
                size_t plaintextLength = GetMaxSymmetricPlaintextLength(ciphertextLength);
                const byte *cipherKey, *macKey;
                if (DHAES_MODE)
                {
                        macKey = key;
                        cipherKey = key + MAC::DEFAULT_KEYLENGTH;
                }
                else
                {
                        cipherKey = key;
                        macKey = key + plaintextLength;
                }

                ConstByteArrayParameter encodingParameters;
                parameters.GetValue(Name::EncodingParameters(), encodingParameters);

                MAC mac(macKey);
                mac.Update(ciphertext, plaintextLength);
                mac.Update(encodingParameters.begin(), encodingParameters.size());
                if (DHAES_MODE)
                {
                        byte L[8] = {0,0,0,0};
                        UnalignedPutWord(BIG_ENDIAN_ORDER, L+4, word32(encodingParameters.size()));
                        mac.Update(L, 8);
                }
                if (!mac.Verify(ciphertext + plaintextLength))
                        return DecodingResult();

                xorbuf(plaintext, ciphertext, cipherKey, plaintextLength);
                return DecodingResult(plaintextLength);
        }
};

//! _
template <class T, bool DHAES_MODE, class KDF>
class DL_KeyDerivationAlgorithm_P1363 : public DL_KeyDerivationAlgorithm<T>
{
public:
        bool ParameterSupported(const char *name) const {return strcmp(name, Name::KeyDerivationParameters()) == 0;}
        void Derive(const DL_GroupParameters<T> &params, byte *derivedKey, size_t derivedLength, const T &agreedElement, const T &ephemeralPublicKey, const NameValuePairs &parameters) const
        {
                SecByteBlock agreedSecret;
                if (DHAES_MODE)
                {
                        agreedSecret.New(params.GetEncodedElementSize(true) + params.GetEncodedElementSize(false));
                        params.EncodeElement(true, ephemeralPublicKey, agreedSecret);
                        params.EncodeElement(false, agreedElement, agreedSecret + params.GetEncodedElementSize(true));
                }
                else
                {
                        agreedSecret.New(params.GetEncodedElementSize(false));
                        params.EncodeElement(false, agreedElement, agreedSecret);
                }

                ConstByteArrayParameter derivationParameters;
                parameters.GetValue(Name::KeyDerivationParameters(), derivationParameters);
                KDF::DeriveKey(derivedKey, derivedLength, agreedSecret, agreedSecret.size(), derivationParameters.begin(), derivationParameters.size());
        }
};

//! Discrete Log Integrated Encryption Scheme, AKA <a href="http://www.weidai.com/scan-mirror/ca.html#DLIES">DLIES</a>
template <class COFACTOR_OPTION = NoCofactorMultiplication, bool DHAES_MODE = true>
struct DLIES
        : public DL_ES<
                DL_CryptoKeys_GFP,
                DL_KeyAgreementAlgorithm_DH<Integer, COFACTOR_OPTION>,
                DL_KeyDerivationAlgorithm_P1363<Integer, DHAES_MODE, P1363_KDF2<SHA1> >,
                DL_EncryptionAlgorithm_Xor<HMAC<SHA1>, DHAES_MODE>,
                DLIES<> >
{
        static std::string CRYPTOPP_API StaticAlgorithmName() {return "DLIES";} // TODO: fix this after name is standardized
};

NAMESPACE_END

#endif

---