CBC模式下的数据加密和解密

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文章信息

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代码示例

源文件: Media:CBCEx.zip

Dependencies: S60 3rd Edition

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文章

翻译:

翻译自: Archived:CBC mode encryption and decryption of data

由 hoolee

最后由 hamishwillee 在 09 Aug 2012 编辑

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• 详细描述

Cipher-block chaining(CBC)是一种加密方式，它将纯文本分块和之前加密的密文块进行XOR操作。这里每个密文块都取决于纯文本的这种处理。注意要确保消息独立，并在第一个块中使用初始向量。

Symbian Cryptography library的CModeCBCEncryptor可以用来加密数据，它使用CBlockTransformation子类在它随后拥有的CAESEncryptor中进行初始化。下列代码演示了对CBC模式下的数据块加密和解密的操作。

• 解决方案

CBC模式下对数据的加密

void CCBCExAppUi::CBCEncryption(TPtr8& aDataPtr)
 {
  CAESEncryptor* aesEncryptor = CAESEncryptor::NewL(iCipherkey);
  CModeCBCEncryptor* cbcEncryptor = CModeCBCEncryptor::NewLC(aesEncryptor, iIV);<br>	 		
 for(TInt i = 0; i<3; i++)
 {
   TPtr8 tempDataptr = aDataPtr.MidTPtr(16*i,16);
   cbcEncryptor->Transform(tempDataptr);		
   cbcEncryptor->SetIV(tempDataptr);				  
 } 
 CleanupStack::PopAndDestroy();
 }

CBC模式下对数据的解密：

void CCBCExAppUi::CBCDecryption(TPtr8& aDataPtr)
 {
 CAESDecryptor* aesdecryptor = CAESDecryptor::NewL(iCipherkey);
 CModeCBCDecryptor* cbcDecryptor = CModeCBCDecryptor::NewLC(aesdecryptor, iIV);<br>	
 TBuf8<16>tempBuf;
 for(TInt i = 0; i<3; i++)
 {
   TPtr8 tempDataptr = aDataPtr.MidTPtr(16*i,16);
   tempBuf.Copy(tempDataptr);			 
   cbcDecryptor->Transform(tempDataptr);	   
   cbcDecryptor->SetIV(tempBuf);
 }<br>		
 CleanupStack::PopAndDestroy();
 }

• 示例程序

File:CBCEx.zip