从txt文件中读取加密数据并在ios中解密

Question

我使用AES128加密和解密技术从文本文件中读取加密文本 和Decrypting但我无法解密它。 文本中的数据文件使用C＃

中的AES128进行加密

我使用以下代码解密它

请帮助我不熟悉AES12 *中的加密和解密

- (NSData *)doCipher:(NSData *)plainText key:(NSData *)aSymmetricKey
             context:(CCOperation)encryptOrDecrypt padding:(CCOptions *)pkcs7
{
    CCCryptorStatus ccStatus = kCCSuccess;
    // Symmetric crypto reference.
    CCCryptorRef thisEncipher = NULL;
    // Cipher Text container.
    NSData * cipherOrPlainText = nil;
    // Pointer to output buffer.
    uint8_t * bufferPtr = NULL;
    // Total size of the buffer.
    size_t bufferPtrSize = 0;
    // Remaining bytes to be performed on.
    size_t remainingBytes = 0;
    // Number of bytes moved to buffer.
    size_t movedBytes = 0;
    // Length of plainText buffer.
    size_t plainTextBufferSize = 0;
    // Placeholder for total written.
    size_t totalBytesWritten = 0;
    // A friendly helper pointer.
    uint8_t * ptr;

    // Initialization vector; dummy in this case 0's.
    uint8_t iv[kChosenCipherBlockSize];
    memset((void *) iv, 0x0, (size_t) sizeof(iv));

    NSLog(@"doCipher: plaintext: %@", plainText);
    NSLog(@"doCipher: key length: %d", [aSymmetricKey length]);

    //LOGGING_FACILITY(plainText != nil, @"PlainText object cannot be nil." );
    //LOGGING_FACILITY(aSymmetricKey != nil, @"Symmetric key object cannot be nil." );
    //LOGGING_FACILITY(pkcs7 != NULL, @"CCOptions * pkcs7 cannot be NULL." );
    //LOGGING_FACILITY([aSymmetricKey length] == kChosenCipherKeySize, @"Disjoint choices for key size." );

    plainTextBufferSize = [plainText length];//+kCCBlockSizeAES128;

    //LOGGING_FACILITY(plainTextBufferSize > 0, @"Empty plaintext passed in." );

    NSLog(@"pkcs7: %d", *pkcs7);
    // We don't want to toss padding on if we don't need to
    if(encryptOrDecrypt == kCCEncrypt)
    {
        if(*pkcs7 != kCCOptionECBMode)
        {
            if((plainTextBufferSize % kChosenCipherBlockSize) == 0)
            {
                *pkcs7 = 0x0000;
            }
            else
            {
                *pkcs7 = kCCOptionPKCS7Padding;
            }
        }
    }
    else if(encryptOrDecrypt != kCCDecrypt)
    {
        NSLog(@"Invalid CCOperation parameter [%d] for cipher context.", *pkcs7 );
    }

    // Create and Initialize the crypto reference.
    ccStatus = CCCryptorCreate(encryptOrDecrypt,
                               kCCAlgorithmAES128,
                               *pkcs7,
                               (const void *)[aSymmetricKey bytes],
                               kChosenCipherKeySize,
                               (const void *)iv,
                               &thisEncipher
                               );

    //LOGGING_FACILITY1( ccStatus == kCCSuccess, @"Problem creating the context, ccStatus == %d.", ccStatus );

    // Calculate byte block alignment for all calls through to and including final.
    bufferPtrSize = CCCryptorGetOutputLength(thisEncipher, plainTextBufferSize, true);

    // Allocate buffer.
    bufferPtr = malloc( bufferPtrSize * sizeof(uint8_t) );

    // Zero out buffer.
    memset((void *)bufferPtr, 0x0, bufferPtrSize);

    // Initialize some necessary book keeping.

    ptr = bufferPtr;

    // Set up initial size.
    remainingBytes = bufferPtrSize;

    // Actually perform the encryption or decryption.
    ccStatus = CCCryptorUpdate(thisEncipher,
                               (const void *) [plainText bytes],
                               plainTextBufferSize,
                               ptr,
                               remainingBytes,
                               &movedBytes
                               );

    //LOGGING_FACILITY1( ccStatus == kCCSuccess, @"Problem with CCCryptorUpdate, ccStatus == %d.", ccStatus );

    // Handle book keeping.
    ptr += movedBytes;
    remainingBytes -= movedBytes;
    totalBytesWritten += movedBytes;

    /* From CommonCryptor.h:

     @enum      CCCryptorStatus
     @abstract  Return values from CommonCryptor operations.

     @constant  kCCSuccess          Operation completed normally.
     @constant  kCCParamError       Illegal parameter value.
     @constant  kCCBufferTooSmall   Insufficent buffer provided for specified operation.
     @constant  kCCMemoryFailure    Memory allocation failure.
     @constant  kCCAlignmentError   Input size was not aligned properly.
     @constant  kCCDecodeError      Input data did not decode or decrypt properly.
     @constant  kCCUnimplemented    Function not implemented for the current algorithm.

     enum {
     kCCSuccess          = 0,
     kCCParamError       = -4300,
     kCCBufferTooSmall   = -4301,
     kCCMemoryFailure    = -4302,
     kCCAlignmentError   = -4303,
     kCCDecodeError      = -4304,
     kCCUnimplemented    = -4305
     };
     typedef int32_t CCCryptorStatus;
     */

    // Finalize everything to the output buffer.
    ccStatus = CCCryptorFinal(thisEncipher,
                              ptr,
                              remainingBytes,
                              &movedBytes
                              );

    totalBytesWritten += movedBytes;

    if(thisEncipher) {
        (void) CCCryptorRelease(thisEncipher);
        thisEncipher = NULL;
    }

    //LOGGING_FACILITY1( ccStatus == kCCSuccess, @"Problem with encipherment ccStatus == %d", ccStatus );

    if (ccStatus == kCCSuccess)
        cipherOrPlainText = [NSData dataWithBytes:(const void *)bufferPtr length:(NSUInteger)totalBytesWritten];
    else
        cipherOrPlainText = nil;

    if(bufferPtr) free(bufferPtr);
    NSString *string = [[NSString alloc] initWithData:cipherOrPlainText encoding:NSUTF8StringEncoding];
    return cipherOrPlainText;

    /*
     Or the corresponding one-shot call:

     ccStatus = CCCrypt(    encryptOrDecrypt,
     kCCAlgorithmAES128,
     typeOfSymmetricOpts,
     (const void *)[self getSymmetricKeyBytes],
     kChosenCipherKeySize,
     iv,
     (const void *) [plainText bytes],
     plainTextBufferSize,
     (void *)bufferPtr,
     bufferPtrSize,
     &movedBytes
     );
     */
}