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AES的文件加密算法

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Article Metadata

代码示例
文章
huwell 在 05 May 2009 创建
最后由 hamishwillee 在 15 Dec 2011 编辑
  • 开发伙伴平台:

S60 3rd Edition FP1, S60 3rd Edition FP2


  • 详细描述

根据Advanced Encryption Standard(AES),我们可以使用Symbian Cryptography API中的CAESEncryptor和CAESDecryptor类对一组数据分别进行加密解密。但这个类只能对16 bytes数据组进行转换,无法对大容量数据源进行加密解密操作,这样的操作需要使用到CBufferedEncryptor和CBufferedDecryptor。这些类需要一个解密加密类对象进行初始化,根据操作模式,还需要CPadding的子类。

  • 解决方案

下面示例演示了如何使用AES对一个纯文本进行加密

_LIT( KPlainInputFileName, "C:\\Data\\PlainInput.txt" );
_LIT( KEncryptedOutputFileName, "C:\\Data\\EnOutput.txt" );
_LIT8(KAESKey,"1234567890abcdef"); <br>
//Reading the plain text from the file
RFs fsSession;
User::LeaveIfError(fsSession.Connect());
RFile file;
User::LeaveIfError(file.Open(fsSession,KPlainInputFileName,EFileShareExclusive|EFileRead));
TInt plainTextsize;
file.Size(plainTextsize);
HBufC8* plainText = HBufC8::NewLC(plainTextsize);
TPtr8 plainTextPtr = plainText->Des();
file.Read(plainTextPtr);
file.Close(); <br>
//Initializing the encrytor and padding objects
CPaddingSSLv3* encryptPadding = CPaddingSSLv3::NewL(16);
CAESEncryptor* aesEncryptor = CAESEncryptor::NewL(KAESKey);
CBufferedEncryptor* bufEncryptor = CBufferedEncryptor::NewL(aesEncryptor, encryptPadding);<br>
 
 
HBufC8* encryptData = HBufC8::NewLC(bufEncryptor->MaxFinalOutputLength(plainTextPtr.Size()));
 
 
TPtr8 encryptDataPtr = encryptData->Des();<br>
//Encrypting the text and writing into an output file
bufEncryptor->ProcessFinalL(plainTextPtr,encryptDataPtr);<br>
TInt err=file.Open(fsSession,KEncryptedOutputFileName,EFileShareExclusive|EFileWrite);
if (err==KErrNotFound) // file does not exist - create it
err=file.Create(fsSession,KEncryptedOutputFileName,EFileShareExclusive|EFileWrite);
file.Write(encryptDataPtr);
file.Close();
CleanupStack::PopAndDestroy2);//encryptData,plainText
fsSession.Close();

使用下列代码进行文件解密:

_LIT( KEncryptedOutputFileName, "C:\\Data\\EnOutput.txt" );
_LIT( KPlainOutputFileName, "C:\\Data\\PlainOutput.txt" );
_LIT8(KAESKey,"1234567890abcdef"); <br>
//Reading the encrypted text from the file
RFs fsSession;
User::LeaveIfError(fsSession.Connect());
RFile file;
User::LeaveIfError(file.Open(fsSession,KEncryptedOutputFileName,EFileShareExclusive|EFileRead));
TInt fileSize;
file.Size(fileSize);<br>
HBufC8* encryptData = HBufC8::NewLC(fileSize);
TPtr8 encryptDataPtr = encryptData->Des();
file.Read(encryptDataPtr);
file.Close();<br>
//Initializing the encrytor and padding objects
CPaddingSSLv3* decryptPadding = CPaddingSSLv3::NewL(16);
CAESDecryptor* aesDecryptor = CAESDecryptor::NewL(KAESKey);
CBufferedDecryptor* bufDecryptor = CBufferedDecryptor::NewL(aesDecryptor, decryptPadding);<br>
HBufC8* decryptedText = HBufC8::NewLC(bufDecryptor->MaxFinalOutputLength(encryptDataPtr.Size()));
 
 
TPtr8 decryptedTextPtr = decryptedText->Des();<br>
//Decrypting the text and writing the output into a file.
bufDecryptor->ProcessFinalL(encryptDataPtr,decryptedTextPtr); <br>
TInt err=file.Open(fsSession,KPlainOutputFileName,EFileShareExclusive|EFileWrite);
if (err==KErrNotFound) // file does not exist - create it
err=file.Create(fsSession,KPlainOutputFileName,EFileShareExclusive|EFileWrite);
file.Write(decryptedTextPtr);
file.Close();<br>
CleanupStack::PopAndDestroy(2); // encryptData,decryptedText
fsSession.Close();
  • 示例代码

File:BufEnEx.zip

This page was last modified on 15 December 2011, at 08:42.
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