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# seckey.h

    00001 // seckey.h - written and placed in the public domain by Wei Dai
    00002
    00003 // This file contains helper classes/functions for implementing secret key algorithms.
    00004
    00005 #ifndef CRYPTOPP_SECKEY_H
    00006 #define CRYPTOPP_SECKEY_H
    00007
    00008 #include "cryptlib.h"
    00009 #include "misc.h"
    00010 #include "simple.h"
    00011
    00012 NAMESPACE_BEGIN(CryptoPP)
    00013
    00014 inline CipherDir ReverseCipherDir(CipherDir dir)
    00015 {
    00016         return (dir == ENCRYPTION) ? DECRYPTION : ENCRYPTION;
    00017 }
    00018
    00019 //! to be inherited by block ciphers with fixed block size
    00020 template <unsigned int N>
    00021 class FixedBlockSize
    00022 {
    00023 public:
    00024         enum {BLOCKSIZE = N};
    00025 };
    00026
    00027 // ************** rounds ***************
    00028
    00029 //! to be inherited by ciphers with fixed number of rounds
    00030 template <unsigned int R>
    00031 class FixedRounds
    00032 {
    00033 public:
    00034         enum {ROUNDS = R};
    00035
    00036 protected:
    00037         template <class T>
    00038         static inline void CheckedSetKey(T *obj, CipherDir dir, const byte *key, size_t length, const NameValuePairs &param)
    00039         {
    00040                 obj->ThrowIfInvalidKeyLength(length);
    00041                 int rounds = param.GetIntValueWithDefault("Rounds", ROUNDS);
    00042                 if (rounds != ROUNDS)
    00043                         throw InvalidRounds(obj->StaticAlgorithmName(), rounds);
    00044                 obj->UncheckedSetKey(dir, key, (unsigned int)length);
    00045         }
    00046 };
    00047
    00048 //! to be inherited by ciphers with variable number of rounds
    00049 template <unsigned int D, unsigned int N=1, unsigned int M=INT_MAX>             // use INT_MAX here because enums are treated as signed ints
    00050 class VariableRounds
    00051 {
    00052 public:
    00053         enum {DEFAULT_ROUNDS = D, MIN_ROUNDS = N, MAX_ROUNDS = M};
    00054         static unsigned int StaticGetDefaultRounds(size_t keylength) {return DEFAULT_ROUNDS;}
    00055
    00056 protected:
    00057         static inline void AssertValidRounds(unsigned int rounds)
    00058         {
    00059                 assert(rounds >= (unsigned int)MIN_ROUNDS && rounds <= (unsigned int)MAX_ROUNDS);
    00060         }
    00061
    00062         template <class T>
    00063         static inline void CheckedSetKey(T *obj, CipherDir dir, const byte *key, size_t length, const NameValuePairs &param)
    00064         {
    00065                 obj->ThrowIfInvalidKeyLength(length);
    00066                 int rounds = param.GetIntValueWithDefault("Rounds", obj->StaticGetDefaultRounds(length));
    00067                 if (rounds < (int)MIN_ROUNDS || rounds > (int)MAX_ROUNDS)
    00068                         throw InvalidRounds(obj->AlgorithmName(), rounds);
    00069                 obj->UncheckedSetKey(dir, key, (unsigned int)length, rounds);
    00070         }
    00071 };
    00072
    00073 // ************** key length ***************
    00074
    00075 //! to be inherited by keyed algorithms with fixed key length
    00076 template <unsigned int N, unsigned int IV_REQ = SimpleKeyingInterface::NOT_RESYNCHRONIZABLE>
    00077 class FixedKeyLength
    00078 {
    00079 public:
    00080         enum {KEYLENGTH=N, MIN_KEYLENGTH=N, MAX_KEYLENGTH=N, DEFAULT_KEYLENGTH=N};
    00081         enum {IV_REQUIREMENT = IV_REQ};
    00082         static size_t CRYPTOPP_API StaticGetValidKeyLength(size_t) {return KEYLENGTH;}
    00083 };
    00084
    00085 /// support query of variable key length, template parameters are default, min, max, multiple (default multiple 1)
    00086 template <unsigned int D, unsigned int N, unsigned int M, unsigned int Q = 1, unsigned int IV_REQ = SimpleKeyingInterface::NOT_RESYNCHRONIZABLE>
    00087 class VariableKeyLength
    00088 {
    00089         // make these private to avoid Doxygen documenting them in all derived classes
    00090         CRYPTOPP_COMPILE_ASSERT(Q > 0);
    00091         CRYPTOPP_COMPILE_ASSERT(N % Q == 0);
    00092         CRYPTOPP_COMPILE_ASSERT(M % Q == 0);
    00093         CRYPTOPP_COMPILE_ASSERT(N < M);
    00094         CRYPTOPP_COMPILE_ASSERT(D >= N && M >= D);
    00095
    00096 public:
    00097         enum {MIN_KEYLENGTH=N, MAX_KEYLENGTH=M, DEFAULT_KEYLENGTH=D, KEYLENGTH_MULTIPLE=Q};
    00098         enum {IV_REQUIREMENT = IV_REQ};
    00099         static size_t CRYPTOPP_API StaticGetValidKeyLength(size_t n)
    00100         {
    00101                 if (n < (size_t)MIN_KEYLENGTH)
    00102                         return MIN_KEYLENGTH;
    00103                 else if (n > (size_t)MAX_KEYLENGTH)
    00104                         return (size_t)MAX_KEYLENGTH;
    00105                 else
    00106                 {
    00107                         n += KEYLENGTH_MULTIPLE-1;
    00108                         return n - n%KEYLENGTH_MULTIPLE;
    00109                 }
    00110         }
    00111 };
    00112
    00113 /// support query of key length that's the same as another class
    00114 template <class T>
    00115 class SameKeyLengthAs
    00116 {
    00117 public:
    00118         enum {MIN_KEYLENGTH=T::MIN_KEYLENGTH, MAX_KEYLENGTH=T::MAX_KEYLENGTH, DEFAULT_KEYLENGTH=T::DEFAULT_KEYLENGTH};
    00119         enum {IV_REQUIREMENT = T::IV_REQUIREMENT};
    00120         static size_t CRYPTOPP_API StaticGetValidKeyLength(size_t keylength)
    00121                 {return T::StaticGetValidKeyLength(keylength);}
    00122 };
    00123
    00124 // ************** implementation helper for SimpledKeyed ***************
    00125
    00126 template <class T>
    00127 static inline void CheckedSetKey(T *obj, Empty empty, const byte *key, size_t length, const NameValuePairs &param)
    00128 {
    00129         obj->ThrowIfInvalidKeyLength(length);
    00130         obj->UncheckedSetKey(key, (unsigned int)length);
    00131 }
    00132
    00133 template <class T>
    00134 static inline void CheckedSetKey(T *obj, CipherDir dir, const byte *key, size_t length, const NameValuePairs &param)
    00135 {
    00136         obj->ThrowIfInvalidKeyLength(length);
    00137         obj->UncheckedSetKey(dir, key, (unsigned int)length);
    00138 }
    00139
    00140 //! _
    00141 template <class BASE, class INFO = BASE>
    00142 class CRYPTOPP_NO_VTABLE SimpleKeyingInterfaceImpl : public BASE
    00143 {
    00144 public:
    00145         size_t MinKeyLength() const {return INFO::MIN_KEYLENGTH;}
    00146         size_t MaxKeyLength() const {return (size_t)INFO::MAX_KEYLENGTH;}
    00147         size_t DefaultKeyLength() const {return INFO::DEFAULT_KEYLENGTH;}
    00148         size_t GetValidKeyLength(size_t n) const {return INFO::StaticGetValidKeyLength(n);}
    00149         typename BASE::IV_Requirement IVRequirement() const {return (typename BASE::IV_Requirement)INFO::IV_REQUIREMENT;}
    00150
    00151 protected:
    00152         void AssertValidKeyLength(size_t length) {assert(GetValidKeyLength(length) == length);}
    00153 };
    00154
    00155 template <class INFO, class BASE = BlockCipher>
    00156 class CRYPTOPP_NO_VTABLE BlockCipherImpl : public AlgorithmImpl<SimpleKeyingInterfaceImpl<TwoBases<BASE, INFO> > >
    00157 {
    00158 public:
    00159         unsigned int BlockSize() const {return this->BLOCKSIZE;}
    00160 };
    00161
    00162 //! _
    00163 template <CipherDir DIR, class BASE>
    00164 class BlockCipherFinal : public ClonableImpl<BlockCipherFinal<DIR, BASE>, BASE>
    00165 {
    00166 public:
    00167         BlockCipherFinal() {}
    00168         BlockCipherFinal(const byte *key)
    00169                 {SetKey(key, this->DEFAULT_KEYLENGTH);}
    00170         BlockCipherFinal(const byte *key, size_t length)
    00171                 {SetKey(key, length);}
    00172         BlockCipherFinal(const byte *key, size_t length, unsigned int rounds)
    00173                 {this->SetKeyWithRounds(key, length, rounds);}
    00174
    00175         bool IsForwardTransformation() const {return DIR == ENCRYPTION;}
    00176
    00177         void SetKey(const byte *key, size_t length, const NameValuePairs &param = g_nullNameValuePairs)
    00178         {
    00179                 CheckedSetKey(this, DIR, key, length, param);
    00180         }
    00181 };
    00182
    00183 //! _
    00184 template <class BASE, class INFO = BASE>
    00185 class MessageAuthenticationCodeImpl : public AlgorithmImpl<SimpleKeyingInterfaceImpl<BASE, INFO>, INFO>
    00186 {
    00187 public:
    00188         void SetKey(const byte *key, size_t length, const NameValuePairs &params = g_nullNameValuePairs)
    00189         {
    00190                 CheckedSetKey(this, Empty(), key, length, params);
    00191         }
    00192 };
    00193
    00194 //! _
    00195 template <class BASE>
    00196 class MessageAuthenticationCodeFinal : public ClonableImpl<MessageAuthenticationCodeFinal<BASE>, MessageAuthenticationCodeImpl<BASE> >
    00197 {
    00198 public:
    00199         MessageAuthenticationCodeFinal() {}
    00200         MessageAuthenticationCodeFinal(const byte *key)
    00201                 {SetKey(key, this->DEFAULT_KEYLENGTH);}
    00202         MessageAuthenticationCodeFinal(const byte *key, size_t length)
    00203                 {this->SetKey(key, length);}
    00204 };
    00205
    00206 // ************** documentation ***************
    00207
    00208 //! These objects usually should not be used directly. See CipherModeDocumentation instead.
    00209 /*! Each class derived from this one defines two types, Encryption and Decryption,
    00210         both of which implement the BlockCipher interface. */
    00211 struct BlockCipherDocumentation
    00212 {
    00213         //! implements the BlockCipher interface
    00214         typedef BlockCipher Encryption;
    00215         //! implements the BlockCipher interface
    00216         typedef BlockCipher Decryption;
    00217 };
    00218
    00219 /*! \brief Each class derived from this one defines two types, Encryption and Decryption,
    00220         both of which implement the SymmetricCipher interface. Two types of classes derive
    00221         from this class: stream ciphers and block cipher modes. Stream ciphers can be used
    00222         alone, cipher mode classes need to be used with a block cipher. See CipherModeDocumentation
    00223         for more for information about using cipher modes and block ciphers. */
    00224 struct SymmetricCipherDocumentation
    00225 {
    00226         //! implements the SymmetricCipher interface
    00227         typedef SymmetricCipher Encryption;
    00228         //! implements the SymmetricCipher interface
    00229         typedef SymmetricCipher Decryption;
    00230 };
    00231
    00232 NAMESPACE_END
    00233
    00234 #endif