如何使用CCCrypt（）加密文件？ [英] How to use CCCrypt() to encrypt a file?

问题描述

当我加密文件（doc，pdf等）时，我使用：

when I encrypt a file(doc, pdf, etc.), I use:

size_t bufferSize = dataLength + kCCBlockSizeAES128;    
CCCrypt( kCCEncrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,
                                 keyPtr, kCCKeySizeAES256,
                                 NULL /* initialization vector (optional) */,
                                 dataBytes, dataLength, /* input */
                                 buffer, bufferSize,/* output */
                                 &numBytesEncrypted );

解密时，我使用：

size_t bufferSize = dataLength + kCCBlockSizeAES128;
CCCryptorStatus result = CCCrypt( kCCDecrypt, kCCAlgorithmAES128,    kCCOptionPKCS7Padding,
                                 keyPtr, kCCKeySizeAES256,
                                 NULL /* initialization vector (optional) */,
                                 dataBytes, dataLength,/* input */
                                 buffer, bufferSize,/* output */
                                 &numBytesEncrypted );

但是当解密时，它会返回错误：kCCDecodeError = -4304。

But when decrypt, it returns error:kCCDecodeError = -4304.

如果我在解密时删除了kCCOptionPKCS7Padding的参数，则没有错误。但该文件也无法打开。

If I remove the param of kCCOptionPKCS7Padding when decrypt, there is no error. But the file cannot open either.

那么，你能告诉我如何传递这些参数吗？

So, could u tell me how to pass these params?

谢谢很多！

推荐答案

这用于加密

    NSString *key =@"YourKey";
    char keyPtr[kCCKeySizeAES256+1]; // room for terminator (unused)
    bzero( keyPtr, sizeof(keyPtr) ); // fill with zeroes (for padding)

    // fetch key data
    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];

    char *dataIn = "This is your data";
    char dataOut[500];// set it acc ur data
    bzero(dataOut, sizeof(dataOut));
    size_t numBytesEncrypted = 0;

    CCCryptorStatus result = CCCrypt(kCCEncrypt, kCCAlgorithmAES128,kCCOptionPKCS7Padding,  keyPtr,kCCKeySizeAES256, NULL, dataIn, strlen(dataIn), dataOut, sizeof(dataOut), &numBytesEncrypted);

这是用于解密

char dataOut2[500];
bzero(dataOut, sizeof(dataOut2));
size_t numBytesDecrypted = 0;   

CCCryptorStatus result = CCCrypt(kCCDecrypt, kCCAlgorithmAES128,kCCOptionPKCS7Padding, keyPtr,kCCKeySizeAES256, NULL, dataOut, numBytesEncrypted, dataOut2, sizeof(dataOut2), &numBytesDecrypted);

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