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1 /* |
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2 * Copyright (c) 2006-2009 Nokia Corporation and/or its subsidiary(-ies). |
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3 * All rights reserved. |
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4 * This component and the accompanying materials are made available |
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5 * under the terms of the License "Eclipse Public License v1.0" |
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6 * which accompanies this distribution, and is available |
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7 * at the URL "http://www.eclipse.org/legal/epl-v10.html". |
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8 * |
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9 * Initial Contributors: |
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10 * Nokia Corporation - initial contribution. |
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11 * |
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12 * Contributors: |
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13 * |
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14 * Description: |
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15 * |
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16 */ |
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17 |
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18 |
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19 #ifndef __SYMMETRICCIPHERIMPL_H__ |
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20 #define __SYMMETRICCIPHERIMPL_H__ |
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21 |
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22 /** |
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23 @file |
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24 @internalComponent |
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25 @released |
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26 */ |
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27 |
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28 #include <e32base.h> |
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29 #include <e32cmn.h> |
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30 #include <cryptospi/cryptospidef.h> |
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31 #include <padding.h> |
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32 #include "symmetriccipherplugin.h" |
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33 |
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34 /** The maximum block size supported (in bytes) */ |
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35 const TUint KMaxBlockSizeSupported = 32; |
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36 |
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37 /** |
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38 Abstract base class for symmetric cipher plug-ins. |
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39 */ |
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40 namespace SoftwareCrypto |
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41 { |
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42 using namespace CryptoSpi; |
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43 |
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44 NONSHARABLE_CLASS(CSymmetricCipherImpl) : public CBase, public MSymmetricCipher |
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45 { |
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46 public: |
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47 /** |
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48 Implemented by each cipher subclass to determine whether the |
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49 specified key length is valid for that cipher. |
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50 This is called by ConstructL and SetKeyL |
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51 @param aKeyLength The key length in bytes to verify. |
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52 */ |
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53 virtual TBool IsValidKeyLength(TInt aKeyBytes) const = 0; |
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54 |
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55 /** |
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56 Helper function implemented by concrete cipher sub-class that |
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57 allows GetCharacteristicsL to return the correct characteristics object. |
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58 @return The implemention uid |
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59 */ |
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60 virtual TUid ImplementationUid() const = 0; |
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61 |
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62 /** |
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63 Gets the strength of the current key, needed to check whether the cipher |
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64 may operate if strong cryptography is not enabled. |
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65 @return The strength of the current key |
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66 */ |
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67 virtual TInt GetKeyStrength() const; |
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68 |
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69 |
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70 // Override MPlugin virtual functions |
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71 void Close(); |
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72 TAny* GetExtension(TUid aExtensionId); |
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73 void GetCharacteristicsL(const TCharacteristics*& aPluginCharacteristics); |
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74 // End of MPlugin |
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75 |
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76 // Override MSymmetricCipherBase virtual functions |
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77 TInt KeySize() const; |
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78 |
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79 /// Destructor |
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80 ~CSymmetricCipherImpl(); |
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81 |
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82 protected: |
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83 |
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84 //Constructor |
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85 CSymmetricCipherImpl(); |
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86 |
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87 /** |
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88 Second phase of construction. Always call ConstructL in the super-class |
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89 if your override this method. |
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90 |
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91 @param aKey The key to initialise the cipher with. |
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92 */ |
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93 virtual void ConstructL(const CKey& aKey); |
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94 |
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95 /** |
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96 Extracts the raw symmetric key from a generic key object. The buffer |
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97 is placed on the cleanup stack. |
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98 |
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99 @param aKey The key object |
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100 @return A buffer containing the raw key value |
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101 */ |
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102 HBufC8* ExtractKeyDataLC(const CKey& aKey) const; |
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103 |
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104 /** |
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105 Zeros a buffer before deleting it to ensure that |
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106 the contents will not be visible to another process if the page |
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107 is re-used. |
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108 @param aBuffer The pointer (possibly null) to the buffer to delete. This |
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109 is set to null after deletion. |
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110 */ |
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111 void SecureDelete(HBufC8*& aBuffer); |
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112 |
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113 /** |
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114 Extracts the raw key from aKey and sets iKey and iKeyBytes |
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115 The key length is also checked to meet export restrictions and |
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116 to ensure that it is appropriate for the cipher. |
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117 @param aKey The key |
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118 */ |
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119 virtual void DoSetKeyL(const CKey& aKey); |
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120 |
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121 |
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122 protected: |
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123 /// the key, extracted from a CKey object |
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124 HBufC8* iKey; |
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125 |
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126 /// key size in bytes |
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127 TUint iKeyBytes; |
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128 |
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129 }; |
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130 |
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131 NONSHARABLE_CLASS(CSymmetricStreamCipherImpl) : public CSymmetricCipherImpl |
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132 { |
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133 public: |
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134 // Destructor |
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135 ~CSymmetricStreamCipherImpl(); |
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136 |
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137 // Override MSymmetricCipherBase virtual functions |
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138 TInt BlockSize() const; |
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139 void SetKeyL(const CKey& aKey); // override DoSetKeyL instead |
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140 void SetCryptoModeL(TUid aCryptoMode); |
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141 void SetOperationModeL(TUid aOperationMode); |
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142 void SetPaddingModeL(TUid aPaddingMode); |
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143 void SetIvL(const TDesC8& aIv); |
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144 TInt MaxOutputLength(TInt aInputLength) const; |
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145 TInt MaxFinalOutputLength(TInt aInputLength) const; |
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146 // End of MSymmetricCipherBase |
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147 |
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148 // Override MSymmetricCipher virtual functions |
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149 void ProcessL(const TDesC8& aInput, TDes8& aOutput); |
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150 void ProcessFinalL(const TDesC8& aInput, TDes8& aOutput); |
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151 // End of MSymmetricCipher |
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152 |
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153 protected: |
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154 // Constructor |
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155 CSymmetricStreamCipherImpl(); |
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156 |
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157 // Override CSymmetricCipherImpl virtual functions |
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158 virtual void ConstructL(const CKey& aKey); |
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159 |
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160 /** |
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161 Performs an encryption or decryption on supplied data. |
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162 @param aData On input, data to be transformed; |
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163 on return, transformed data. |
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164 */ |
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165 virtual void DoProcess(TDes8& aData) = 0; |
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166 }; |
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167 |
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168 NONSHARABLE_CLASS(CSymmetricBlockCipherImpl) : public CSymmetricCipherImpl |
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169 { |
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170 public: |
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171 |
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172 |
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173 /** |
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174 This function is invoked by SetKey and SetCryptoMode |
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175 allowing the cipher sub-class to rebuild it's key schedule. |
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176 N.B. It is assumed that the key schedule is NOT modified |
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177 by TransformEncrypt or TransformDecrypt |
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178 */ |
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179 virtual void SetKeySchedule() = 0; |
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180 |
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181 // Override MPlugin virtual functions |
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182 void Reset(); // Always call reset in super-class if you override this |
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183 // End of MPlugin virtual functions |
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184 |
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185 // Override MSymmetricCipherBase virtual functions |
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186 TInt BlockSize() const; |
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187 void SetKeyL(const CKey& aKey); // override DoSetKeyL instead |
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188 void SetCryptoModeL(TUid aCryptoMode); // override DoSetCryptoModeL instead |
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189 void SetOperationModeL(TUid aOperationMode); // override DoSetOperationMode instead |
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190 void SetPaddingModeL(TUid aPaddingMode); // override DoSetPaddingModeL instead |
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191 void SetIvL(const TDesC8& aIv); |
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192 |
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193 TInt MaxOutputLength(TInt aInputLength) const; |
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194 TInt MaxFinalOutputLength(TInt aInputLength) const; |
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195 // End of MSymmetricCipherBase |
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196 |
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197 // Override MSymmetricCipher virtual functions |
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198 void ProcessL(const TDesC8& aInput, TDes8& aOutput); |
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199 void ProcessFinalL(const TDesC8& aInput, TDes8& aOutput); |
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200 // End of MSymmetricCipher |
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201 |
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202 /// Destructor |
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203 ~CSymmetricBlockCipherImpl(); |
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204 protected: |
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205 /** |
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206 Constructor |
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207 @param aBlockBytes The block size in bytes |
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208 @param aOperationMode The mode of operation e.g. CBC |
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209 @param aCryptoMode Whether to encrypt or decrypt |
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210 */ |
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211 CSymmetricBlockCipherImpl( |
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212 TUint8 aBlockBytes, |
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213 TUid aOperationMode, |
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214 TUid aCryptoMode, |
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215 TUid aPaddingMode); |
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216 |
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217 // Override CSymmetricCipherImpl virtual functions |
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218 virtual void ConstructL(const CKey& aKey); |
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219 |
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220 /** |
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221 Validates and sets the crypto mode (iCryptoMode) |
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222 @param aCryptoMode The crypto mode |
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223 */ |
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224 virtual void DoSetCryptoModeL(TUid aCryptoMode); |
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225 |
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226 /** |
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227 Validates and sets the operation mode (iOperationMode) |
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228 @param aOperationMode The operation mode |
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229 */ |
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230 virtual void DoSetOperationModeL(TUid aOperationMode); |
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231 |
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232 /** |
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233 Validates and sets the padding mode (iPaddingMode & iPadding) |
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234 @param aPadding The desired padding mode |
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235 */ |
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236 virtual void DoSetPaddingModeL(TUid aPadding); |
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237 |
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238 void DoSetIvL(const TDesC8& aIv); |
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239 |
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240 inline void ModeEncryptStart(TUint8* aBuffer); |
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241 inline void ModeEncryptEnd(TUint8* aBuffer); |
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242 inline void ModeDecryptStart(TUint8* aBuffer); |
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243 inline void ModeDecryptEnd(TUint8* aBuffer); |
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244 |
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245 private: |
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246 |
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247 /** |
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248 Encrypts a number of blocks of data |
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249 |
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250 @param aBuffer The buffer containing exactly aNumBlocks of data to destructively encrypt |
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251 @param aNumBlocks The number of blocks of data to encrypt |
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252 */ |
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253 virtual void TransformEncrypt(TUint8* aBuffer, TUint aNumBlocks) = 0; |
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254 |
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255 /** |
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256 Decrypts a number of blocks of data |
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257 |
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258 @param aBuffer The buffer containing exactly aNumBlocks of data to destructively decrypt |
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259 @param aNumBlocks The number of blocks of data to decrypt |
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260 */ |
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261 virtual void TransformDecrypt(TUint8* aBuffer, TUint aNumBlocks) = 0; |
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262 |
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263 /// Pad the last block and encrypt |
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264 void DoProcessFinalEncryptL(const TDesC8& aInput, TDes8& aOutput); |
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265 |
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266 /// Decrypt and unpad the last block |
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267 void DoProcessFinalDecryptL(const TDesC8& aInput, TDes8& aOutput); |
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268 |
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269 inline void Transform(TUint8* aBuffer, TUint aNumBlocks); |
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270 |
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271 void ProcessCtrL(const TDesC8& aInput, TDes8& aOutput); |
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272 |
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273 protected: |
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274 |
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275 /// block size in bytes, current largest block size is 16 bytes (AES) |
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276 TUint8 iBlockBytes; |
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277 /// encryption or decryption |
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278 TUid iCryptoMode; |
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279 /// The block cipher mode e.g. ECB, CBC |
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280 TUid iOperationMode; |
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281 /// the current padding scheme |
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282 TUid iPaddingMode; |
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283 |
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284 /// the initialisation vector |
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285 RBuf8 iIv; |
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286 |
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287 /// current padding scheme implementation |
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288 CPadding* iPadding; |
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289 /// buffer to store blocks |
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290 RBuf8 iInputStore; |
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291 /// buffer to store input / output of padding |
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292 RBuf8 iPaddingBlock; |
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293 |
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294 /// The current block of cipher text - for CBC |
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295 TUint32* iCurrentCipherText; |
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296 /// A pointer to the current block of cipher text |
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297 TUint8* iCurrentCipherTextPtr; |
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298 |
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299 /** Used in both CBC and CTR mode. In CBC mode it stores the result of the last transform. In CTR mode |
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300 it stores the counter.*/ |
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301 TUint32* iRegister; |
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302 /** A pointer to iRegister.*/ |
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303 TUint8* iRegisterPtr; |
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304 |
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305 /** Used in CTR mode to buffer plaintext during encryption.*/ |
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306 HBufC8* iBufferedPlaintext; |
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307 /** Pointer to manipulate iBufferedPlaintext.*/ |
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308 TPtr8 iBufferedPlaintextPtr; |
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309 |
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310 /** CTR mode behaves like a stream cipher allowing arbitrary sized inputs to the encryption/decryption functions. |
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311 When handling an input whose length is not a multiple of the blocksize iCtrUnusedKeystream is used to buffer |
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312 the unused portions of keystream for use in the next call. Cleared in Reset().*/ |
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313 HBufC8* iCtrUnusedKeystream; |
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314 /** Pointer to manipulate iCtrUnusedKeystream.*/ |
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315 TPtr8 iCtrUnusedKeystreamPtr; |
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316 }; |
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317 |
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318 |
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319 inline void CSymmetricBlockCipherImpl::Transform(TUint8* aBuffer, TUint aNumBlocks) |
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320 { |
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321 if (iCryptoMode.iUid == KCryptoModeEncrypt) //if in CTR mode always in crypto mode encrypt |
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322 { |
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323 TransformEncrypt(aBuffer, aNumBlocks); |
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324 } |
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325 else if (iCryptoMode.iUid == KCryptoModeDecrypt) |
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326 { |
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327 TransformDecrypt(aBuffer, aNumBlocks); |
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328 } |
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329 else |
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330 { |
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331 ASSERT(EFalse); |
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332 } |
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333 } |
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334 |
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335 inline void CSymmetricBlockCipherImpl::ModeEncryptStart(TUint8* aBuffer) |
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336 { |
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337 if (iOperationMode.iUid == KOperationModeCBC) |
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338 { |
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339 for (TInt i = 0; i < iBlockBytes; ++i) |
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340 { |
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341 aBuffer[i] ^= iRegisterPtr[i]; |
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342 } |
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343 } |
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344 else if (iOperationMode.iUid == KOperationModeCTR) |
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345 { |
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346 iBufferedPlaintextPtr.Copy(aBuffer, iBlockBytes); |
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347 Mem::Copy(aBuffer, iRegister, iBlockBytes); |
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348 } |
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349 } |
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350 |
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351 inline void CSymmetricBlockCipherImpl::ModeEncryptEnd(TUint8* aBuffer) |
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352 { |
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353 if (iOperationMode.iUid == KOperationModeCBC) |
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354 { |
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355 for (TInt i = 0; i < iBlockBytes; ++i) |
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356 { |
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357 iRegisterPtr[i] = aBuffer[i]; |
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358 } |
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359 } |
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360 else if (iOperationMode.iUid == KOperationModeCTR) |
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361 { |
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362 //XOR the plaintext with the keystream and increment counter |
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363 for (TInt i = 0; i < iBlockBytes; ++i) |
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364 { |
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365 aBuffer[i] ^= iBufferedPlaintextPtr[i]; |
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366 } |
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367 for (TInt i = iBlockBytes - 1; i >= 0; --i) |
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368 { |
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369 if (++(iRegisterPtr[i]) != 0) break; |
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370 } |
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371 } |
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372 } |
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373 |
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374 inline void CSymmetricBlockCipherImpl::ModeDecryptStart(TUint8* aBuffer) |
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375 { |
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376 __ASSERT_DEBUG((iOperationMode.iUid != KOperationModeCTR), User::Panic(_L("CSymmetricBlockCipherImpl.h"), 1)); |
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377 if (iOperationMode.iUid == KOperationModeCBC) |
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378 { |
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379 for (TInt i = 0; i < iBlockBytes; ++i) |
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380 { |
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381 iCurrentCipherTextPtr[i] = aBuffer[i]; |
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382 } |
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383 } |
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384 } |
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385 |
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386 inline void CSymmetricBlockCipherImpl::ModeDecryptEnd(TUint8* aBuffer) |
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387 { |
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388 __ASSERT_DEBUG((iOperationMode.iUid != KOperationModeCTR), User::Panic(_L("CSymmetricBlockCipherImpl.h"), 2)); |
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389 if (iOperationMode.iUid == KOperationModeCBC) |
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390 { |
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391 // xor the output with the previous cipher text |
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392 for (TInt i = 0; i < iBlockBytes; ++i) |
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393 { |
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394 aBuffer[i] ^= iRegisterPtr[i]; |
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395 iRegisterPtr[i] = iCurrentCipherTextPtr[i]; |
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396 } |
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397 } |
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398 } |
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399 } |
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400 |
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401 #endif // __SYMMETRICCIPHERIMPL_H__ |