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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                                 if (m_input == NULL)
00193                                         assert(m_output == NULL);
00194                                 else
00195                                 {
00196                                         WordType ct = *(const WordType *)m_input ^ registerWord;
00197                                         registerWord = ct;
00198                                         *(WordType*)m_output = ct;
00199                                         m_input += sizeof(WordType);
00200                                         m_output += sizeof(WordType);
00201                                 }
00202                         }
00203                         else
00204                         {
00205                                 WordType ct = *(const WordType *)m_input;
00206                                 *(WordType*)m_output = registerWord ^ ct;
00207                                 registerWord = ct;
00208                                 m_input += sizeof(WordType);
00209                                 m_output += sizeof(WordType);
00210                         }
00211 
00212                         // registerWord is left unreversed so it can be xor-ed with further input
00213 
00214                         return *this;
00215                 }
00216 
00217                 byte *m_output;
00218                 const byte *m_input;
00219                 CipherDir m_dir;
00220         };
00221 };
00222 
00223 template <class BASE>
00224 class CRYPTOPP_NO_VTABLE CFB_CipherTemplate : public BASE
00225 {
00226 public:
00227         void ProcessData(byte *outString, const byte *inString, unsigned int length);
00228         void Resynchronize(const byte *iv);
00229         unsigned int OptimalBlockSize() const {return this->GetPolicy().GetBytesPerIteration();}
00230         unsigned int GetOptimalNextBlockSize() const {return m_leftOver;}
00231         unsigned int OptimalDataAlignment() const {return this->GetPolicy().GetAlignment();}
00232         bool IsRandomAccess() const {return false;}
00233         bool IsSelfInverting() const {return false;}
00234 
00235         typedef typename BASE::PolicyInterface PolicyInterface;
00236 
00237 protected:
00238         virtual void CombineMessageAndShiftRegister(byte *output, byte *reg, const byte *message, unsigned int length) =0;
00239 
00240         void UncheckedSetKey(const NameValuePairs &params, const byte *key, unsigned int length, const byte *iv);
00241 
00242         unsigned int m_leftOver;
00243 };
00244 
00245 template <class BASE = AbstractPolicyHolder<CFB_CipherAbstractPolicy, SymmetricCipher> >
00246 class CRYPTOPP_NO_VTABLE CFB_EncryptionTemplate : public CFB_CipherTemplate<BASE>
00247 {
00248         bool IsForwardTransformation() const {return true;}
00249         void CombineMessageAndShiftRegister(byte *output, byte *reg, const byte *message, unsigned int length);
00250 };
00251 
00252 template <class BASE = AbstractPolicyHolder<CFB_CipherAbstractPolicy, SymmetricCipher> >
00253 class CRYPTOPP_NO_VTABLE CFB_DecryptionTemplate : public CFB_CipherTemplate<BASE>
00254 {
00255         bool IsForwardTransformation() const {return false;}
00256         void CombineMessageAndShiftRegister(byte *output, byte *reg, const byte *message, unsigned int length);
00257 };
00258 
00259 template <class BASE>
00260 class CFB_RequireFullDataBlocks : public BASE
00261 {
00262 public:
00263         unsigned int MandatoryBlockSize() const {return this->OptimalBlockSize();}
00264 };
00265 
00266 // for Darwin
00267 CRYPTOPP_DLL_TEMPLATE_CLASS CFB_CipherTemplate<AbstractPolicyHolder<CFB_CipherAbstractPolicy, SymmetricCipher> >;
00268 CRYPTOPP_DLL_TEMPLATE_CLASS CFB_EncryptionTemplate<>;
00269 CRYPTOPP_DLL_TEMPLATE_CLASS CFB_DecryptionTemplate<>;
00270 
00271 //! _
00272 template <class BASE, class INFO = BASE>
00273 class SymmetricCipherFinal : public AlgorithmImpl<SimpleKeyingInterfaceImpl<BASE, INFO>, INFO>
00274 {
00275 public:
00276         SymmetricCipherFinal() {}
00277         SymmetricCipherFinal(const byte *key)
00278                 {SetKey(key, this->DEFAULT_KEYLENGTH);}
00279         SymmetricCipherFinal(const byte *key, unsigned int length)
00280                 {SetKey(key, length);}
00281         SymmetricCipherFinal(const byte *key, unsigned int length, const byte *iv)
00282                 {this->SetKeyWithIV(key, length, iv);}
00283 
00284         void SetKey(const byte *key, unsigned int length, const NameValuePairs &params = g_nullNameValuePairs)
00285         {
00286                 this->ThrowIfInvalidKeyLength(length);
00287                 this->UncheckedSetKey(params, key, length, this->GetIVAndThrowIfInvalid(params));
00288         }
00289 
00290         Clonable * Clone() const {return static_cast<SymmetricCipher *>(new SymmetricCipherFinal<BASE, INFO>(*this));}
00291 };
00292 
00293 template <class S>
00294 void AdditiveCipherTemplate<S>::UncheckedSetKey(const NameValuePairs &params, const byte *key, unsigned int length, const byte *iv)
00295 {
00296         PolicyInterface &policy = this->AccessPolicy();
00297         policy.CipherSetKey(params, key, length);
00298         m_leftOver = 0;
00299         m_buffer.New(GetBufferByteSize(policy));
00300 
00301         if (this->IsResynchronizable())
00302                 policy.CipherResynchronize(m_buffer, iv);
00303 }
00304 
00305 template <class BASE>
00306 void CFB_CipherTemplate<BASE>::UncheckedSetKey(const NameValuePairs &params, const byte *key, unsigned int length, const byte *iv)
00307 {
00308         PolicyInterface &policy = this->AccessPolicy();
00309         policy.CipherSetKey(params, key, length);
00310 
00311         if (this->IsResynchronizable())
00312                 policy.CipherResynchronize(iv);
00313 
00314         m_leftOver = policy.GetBytesPerIteration();
00315 }
00316 
00317 NAMESPACE_END
00318 
00319 #endif

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