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# strciphr.h

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    00001 /*! \file
    00002         This file contains helper classes for implementing stream ciphers.
    00003
    00004         All this infrastructure may look very complex compared to what's in Crypto++ 4.x,
    00005         but stream ciphers implementations now support a lot of new functionality,
    00006         including better performance (minimizing copying), resetting of keys and IVs, and methods to
    00007         query which features are supported by a cipher.
    00008
    00009         Here's an explanation of these classes. The word "policy" is used here to mean a class with a
    00010         set of methods that must be implemented by individual stream cipher implementations.
    00011         This is usually much simpler than the full stream cipher API, which is implemented by
    00012         either AdditiveCipherTemplate or CFB_CipherTemplate using the policy. So for example, an
    00013         implementation of SEAL only needs to implement the AdditiveCipherAbstractPolicy interface
    00014         (since it's an additive cipher, i.e., it xors a keystream into the plaintext).
    00015         See this line in seal.h:
    00016
    00017         typedef SymmetricCipherFinal<ConcretePolicyHolder<SEAL_Policy<B>, AdditiveCipherTemplate<> > > Encryption;
    00018
    00019         AdditiveCipherTemplate and CFB_CipherTemplate are designed so that they don't need
    00020         to take a policy class as a template parameter (although this is allowed), so that
    00021         their code is not duplicated for each new cipher. Instead they each
    00022         get a reference to an abstract policy interface by calling AccessPolicy() on itself, so
    00023         AccessPolicy() must be overriden to return the actual policy reference. This is done
    00024         by the ConceretePolicyHolder class. Finally, SymmetricCipherFinal implements the constructors and
    00025         other functions that must be implemented by the most derived class.
    00026 */
    00027
    00028 #ifndef CRYPTOPP_STRCIPHR_H
    00029 #define CRYPTOPP_STRCIPHR_H
    00030
    00031 #include "seckey.h"
    00032 #include "secblock.h"
    00033 #include "argnames.h"
    00034
    00035 NAMESPACE_BEGIN(CryptoPP)
    00036
    00037 template <class POLICY_INTERFACE, class BASE = Empty>
    00038 class CRYPTOPP_NO_VTABLE AbstractPolicyHolder : public BASE
    00039 {
    00040 public:
    00041         typedef POLICY_INTERFACE PolicyInterface;
    00042
    00043 protected:
    00044         virtual const POLICY_INTERFACE & GetPolicy() const =0;
    00045         virtual POLICY_INTERFACE & AccessPolicy() =0;
    00046 };
    00047
    00048 template <class POLICY, class BASE, class POLICY_INTERFACE = CPP_TYPENAME BASE::PolicyInterface>
    00049 class ConcretePolicyHolder : public BASE, protected POLICY
    00050 {
    00051 protected:
    00052         const POLICY_INTERFACE & GetPolicy() const {return *this;}
    00053         POLICY_INTERFACE & AccessPolicy() {return *this;}
    00054 };
    00055
    00056 enum KeystreamOperation {WRITE_KEYSTREAM, XOR_KEYSTREAM, XOR_KEYSTREAM_INPLACE};
    00057
    00058 struct CRYPTOPP_DLL CRYPTOPP_NO_VTABLE AdditiveCipherAbstractPolicy
    00059 {
    00060         virtual unsigned int GetAlignment() const =0;
    00061         virtual unsigned int GetBytesPerIteration() const =0;
    00062         virtual unsigned int GetIterationsToBuffer() const =0;
    00063         virtual void WriteKeystream(byte *keystreamBuffer, unsigned int iterationCount) =0;
    00064         virtual bool CanOperateKeystream() const {return false;}
    00065         virtual void OperateKeystream(KeystreamOperation operation, byte *output, const byte *input, unsigned int iterationCount) {assert(false);}
    00066         virtual void CipherSetKey(const NameValuePairs &params, const byte *key, unsigned int length) =0;
    00067         virtual void CipherResynchronize(byte *keystreamBuffer, const byte *iv) {throw NotImplemented("StreamTransformation: this object doesn't support resynchronization");}
    00068         virtual bool IsRandomAccess() const =0;
    00069         virtual void SeekToIteration(lword iterationCount) {assert(!IsRandomAccess()); throw NotImplemented("StreamTransformation: this object doesn't support random access");}
    00070 };
    00071
    00072 template <typename WT, unsigned int W, unsigned int X = 1, class BASE = AdditiveCipherAbstractPolicy>
    00073 struct CRYPTOPP_NO_VTABLE AdditiveCipherConcretePolicy : public BASE
    00074 {
    00075         typedef WT WordType;
    00076
    00077         unsigned int GetAlignment() const {return sizeof(WordType);}
    00078         unsigned int GetBytesPerIteration() const {return sizeof(WordType) * W;}
    00079         unsigned int GetIterationsToBuffer() const {return X;}
    00080         void WriteKeystream(byte *buffer, unsigned int iterationCount)
    00081                 {OperateKeystream(WRITE_KEYSTREAM, buffer, NULL, iterationCount);}
    00082         bool CanOperateKeystream() const {return true;}
    00083         virtual void OperateKeystream(KeystreamOperation operation, byte *output, const byte *input, unsigned int iterationCount) =0;
    00084
    00085         template <class B>
    00086         struct KeystreamOutput
    00087         {
    00088                 KeystreamOutput(KeystreamOperation operation, byte *output, const byte *input)
    00089                         : m_operation(operation), m_output(output), m_input(input) {}
    00090
    00091                 inline KeystreamOutput & operator()(WordType keystreamWord)
    00092                 {
    00093                         assert(IsAligned<WordType>(m_input));
    00094                         assert(IsAligned<WordType>(m_output));
    00095
    00096                         if (!NativeByteOrderIs(B::ToEnum()))
    00097                                 keystreamWord = ByteReverse(keystreamWord);
    00098
    00099                         if (m_operation == WRITE_KEYSTREAM)
    00100                                 *(WordType*)m_output = keystreamWord;
    00101                         else if (m_operation == XOR_KEYSTREAM)
    00102                         {
    00103                                 *(WordType*)m_output = keystreamWord ^ *(WordType*)m_input;
    00104                                 m_input += sizeof(WordType);
    00105                         }
    00106                         else if (m_operation == XOR_KEYSTREAM_INPLACE)
    00107                                 *(WordType*)m_output ^= keystreamWord;
    00108
    00109                         m_output += sizeof(WordType);
    00110
    00111                         return *this;
    00112                 }
    00113
    00114                 KeystreamOperation m_operation;
    00115                 byte *m_output;
    00116                 const byte *m_input;
    00117         };
    00118 };
    00119
    00120 template <class BASE = AbstractPolicyHolder<AdditiveCipherAbstractPolicy, TwoBases<SymmetricCipher, RandomNumberGenerator> > >
    00121 class CRYPTOPP_NO_VTABLE AdditiveCipherTemplate : public BASE
    00122 {
    00123 public:
    00124     byte GenerateByte();
    00125     void ProcessData(byte *outString, const byte *inString, unsigned int length);
    00126         void Resynchronize(const byte *iv);
    00127         unsigned int OptimalBlockSize() const {return this->GetPolicy().GetBytesPerIteration();}
    00128         unsigned int GetOptimalNextBlockSize() const {return this->m_leftOver;}
    00129         unsigned int OptimalDataAlignment() const {return this->GetPolicy().GetAlignment();}
    00130         bool IsSelfInverting() const {return true;}
    00131         bool IsForwardTransformation() const {return true;}
    00132         bool IsRandomAccess() const {return this->GetPolicy().IsRandomAccess();}
    00133         void Seek(lword position);
    00134
    00135         typedef typename BASE::PolicyInterface PolicyInterface;
    00136
    00137 protected:
    00138         void UncheckedSetKey(const NameValuePairs &params, const byte *key, unsigned int length, const byte *iv);
    00139
    00140         unsigned int GetBufferByteSize(const PolicyInterface &policy) const {return policy.GetBytesPerIteration() * policy.GetIterationsToBuffer();}
    00141
    00142         inline byte * KeystreamBufferBegin() {return this->m_buffer.data();}
    00143         inline byte * KeystreamBufferEnd() {return (this->m_buffer.data() + this->m_buffer.size());}
    00144
    00145         SecByteBlock m_buffer;
    00146         unsigned int m_leftOver;
    00147 };
    00148
    00149 CRYPTOPP_DLL_TEMPLATE_CLASS TwoBases<SymmetricCipher, RandomNumberGenerator>;
    00150 CRYPTOPP_DLL_TEMPLATE_CLASS AbstractPolicyHolder<AdditiveCipherAbstractPolicy, TwoBases<SymmetricCipher, RandomNumberGenerator> >;
    00151 CRYPTOPP_DLL_TEMPLATE_CLASS AdditiveCipherTemplate<>;
    00152
    00153 class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE CFB_CipherAbstractPolicy
    00154 {
    00155 public:
    00156         virtual unsigned int GetAlignment() const =0;
    00157         virtual unsigned int GetBytesPerIteration() const =0;
    00158         virtual byte * GetRegisterBegin() =0;
    00159         virtual void TransformRegister() =0;
    00160         virtual bool CanIterate() const {return false;}
    00161         virtual void Iterate(byte *output, const byte *input, CipherDir dir, unsigned int iterationCount) {assert(false);}
    00162         virtual void CipherSetKey(const NameValuePairs &params, const byte *key, unsigned int length) =0;
    00163         virtual void CipherResynchronize(const byte *iv) {throw NotImplemented("StreamTransformation: this object doesn't support resynchronization");}
    00164 };
    00165
    00166 template <typename WT, unsigned int W, class BASE = CFB_CipherAbstractPolicy>
    00167 struct CRYPTOPP_NO_VTABLE CFB_CipherConcretePolicy : public BASE
    00168 {
    00169         typedef WT WordType;
    00170
    00171         unsigned int GetAlignment() const {return sizeof(WordType);}
    00172         unsigned int GetBytesPerIteration() const {return sizeof(WordType) * W;}
    00173         bool CanIterate() const {return true;}
    00174         void TransformRegister() {this->Iterate(NULL, NULL, ENCRYPTION, 1);}
    00175
    00176         template <class B>
    00177         struct RegisterOutput
    00178         {
    00179                 RegisterOutput(byte *output, const byte *input, CipherDir dir)
    00180                         : m_output(output), m_input(input), m_dir(dir) {}
    00181
    00182                 inline RegisterOutput& operator()(WordType &registerWord)
    00183                 {
    00184                         assert(IsAligned<WordType>(m_output));
    00185                         assert(IsAligned<WordType>(m_input));
    00186
    00187                         if (!NativeByteOrderIs(B::ToEnum()))
    00188                                 registerWord = ByteReverse(registerWord);
    00189
    00190                         if (m_dir == ENCRYPTION)
    00191                         {
    00192                                 WordType ct = *(const WordType *)m_input ^ registerWord;
    00193                                 registerWord = ct;
    00194                                 *(WordType*)m_output = ct;
    00195                                 m_input += sizeof(WordType);
    00196                                 m_output += sizeof(WordType);
    00197                         }
    00198                         else
    00199                         {
    00200                                 WordType ct = *(const WordType *)m_input;
    00201                                 *(WordType*)m_output = registerWord ^ ct;
    00202                                 registerWord = ct;
    00203                                 m_input += sizeof(WordType);
    00204                                 m_output += sizeof(WordType);
    00205                         }
    00206
    00207                         // registerWord is left unreversed so it can be xor-ed with further input
    00208
    00209                         return *this;
    00210                 }
    00211
    00212                 byte *m_output;
    00213                 const byte *m_input;
    00214                 CipherDir m_dir;
    00215         };
    00216 };
    00217
    00218 template <class BASE>
    00219 class CRYPTOPP_NO_VTABLE CFB_CipherTemplate : public BASE
    00220 {
    00221 public:
    00222         void ProcessData(byte *outString, const byte *inString, unsigned int length);
    00223         void Resynchronize(const byte *iv);
    00224         unsigned int OptimalBlockSize() const {return this->GetPolicy().GetBytesPerIteration();}
    00225         unsigned int GetOptimalNextBlockSize() const {return m_leftOver;}
    00226         unsigned int OptimalDataAlignment() const {return this->GetPolicy().GetAlignment();}
    00227         bool IsRandomAccess() const {return false;}
    00228         bool IsSelfInverting() const {return false;}
    00229
    00230         typedef typename BASE::PolicyInterface PolicyInterface;
    00231
    00232 protected:
    00233         virtual void CombineMessageAndShiftRegister(byte *output, byte *reg, const byte *message, unsigned int length) =0;
    00234
    00235         void UncheckedSetKey(const NameValuePairs &params, const byte *key, unsigned int length, const byte *iv);
    00236
    00237         unsigned int m_leftOver;
    00238 };
    00239
    00240 template <class BASE = AbstractPolicyHolder<CFB_CipherAbstractPolicy, SymmetricCipher> >
    00241 class CRYPTOPP_NO_VTABLE CFB_EncryptionTemplate : public CFB_CipherTemplate<BASE>
    00242 {
    00243         bool IsForwardTransformation() const {return true;}
    00244         void CombineMessageAndShiftRegister(byte *output, byte *reg, const byte *message, unsigned int length);
    00245 };
    00246
    00247 template <class BASE = AbstractPolicyHolder<CFB_CipherAbstractPolicy, SymmetricCipher> >
    00248 class CRYPTOPP_NO_VTABLE CFB_DecryptionTemplate : public CFB_CipherTemplate<BASE>
    00249 {
    00250         bool IsForwardTransformation() const {return false;}
    00251         void CombineMessageAndShiftRegister(byte *output, byte *reg, const byte *message, unsigned int length);
    00252 };
    00253
    00254 template <class BASE>
    00255 class CFB_RequireFullDataBlocks : public BASE
    00256 {
    00257 public:
    00258         unsigned int MandatoryBlockSize() const {return this->OptimalBlockSize();}
    00259 };
    00260
    00261 // for Darwin
    00262 CRYPTOPP_DLL_TEMPLATE_CLASS CFB_CipherTemplate<AbstractPolicyHolder<CFB_CipherAbstractPolicy, SymmetricCipher> >;
    00263 CRYPTOPP_DLL_TEMPLATE_CLASS CFB_EncryptionTemplate<>;
    00264 CRYPTOPP_DLL_TEMPLATE_CLASS CFB_DecryptionTemplate<>;
    00265
    00266 //! _
    00267 template <class BASE, class INFO = BASE>
    00268 class SymmetricCipherFinal : public AlgorithmImpl<SimpleKeyingInterfaceImpl<BASE, INFO>, INFO>
    00269 {
    00270 public:
    00271         SymmetricCipherFinal() {}
    00272         SymmetricCipherFinal(const byte *key)
    00273                 {SetKey(key, this->DEFAULT_KEYLENGTH);}
    00274         SymmetricCipherFinal(const byte *key, unsigned int length)
    00275                 {SetKey(key, length);}
    00276         SymmetricCipherFinal(const byte *key, unsigned int length, const byte *iv)
    00277                 {this->SetKeyWithIV(key, length, iv);}
    00278
    00279         void SetKey(const byte *key, unsigned int length, const NameValuePairs &params = g_nullNameValuePairs)
    00280         {
    00281                 this->ThrowIfInvalidKeyLength(length);
    00282                 this->UncheckedSetKey(params, key, length, this->GetIVAndThrowIfInvalid(params));
    00283         }
    00284
    00285         Clonable * Clone() const {return static_cast<SymmetricCipher *>(new SymmetricCipherFinal<BASE, INFO>(*this));}
    00286 };
    00287
    00288 template <class S>
    00289 void AdditiveCipherTemplate<S>::UncheckedSetKey(const NameValuePairs &params, const byte *key, unsigned int length, const byte *iv)
    00290 {
    00291         PolicyInterface &policy = this->AccessPolicy();
    00292         policy.CipherSetKey(params, key, length);
    00293         m_leftOver = 0;
    00294         m_buffer.New(GetBufferByteSize(policy));
    00295
    00296         if (this->IsResynchronizable())
    00297                 policy.CipherResynchronize(m_buffer, iv);
    00298 }
    00299
    00300 template <class BASE>
    00301 void CFB_CipherTemplate<BASE>::UncheckedSetKey(const NameValuePairs &params, const byte *key, unsigned int length, const byte *iv)
    00302 {
    00303         PolicyInterface &policy = this->AccessPolicy();
    00304         policy.CipherSetKey(params, key, length);
    00305
    00306         if (this->IsResynchronizable())
    00307                 policy.CipherResynchronize(iv);
    00308
    00309         m_leftOver = policy.GetBytesPerIteration();
    00310 }
    00311
    00312 NAMESPACE_END
    00313
    00314 #endif