iOS can't do AES encryption on device if input data size exceeds 1024 bytes

[vishalpatel]

Hi Guys,

This is CommonCrypto problem which is produces only on iPhone device, I can't encrypt data properly with CommonCrypto API ( CCCrypt ) please refere the following code.. and please tell me I am doing it correctly or not ??

Data size less than 1040 bytes encrypted correctly but when data size exceeds this function fails..


+ (NSMutableData *)encryptOrDecryptWithAES1 : ( NSData *)plainText
key : ( NSData *)aSymmetricKey
context : ( CCOperation)encryptOrDecrypt
{
CCCryptorStatus ccStatus = kCCSuccess;
// Cipher Text container.
NSMutableData * cipherOrPlainText = nil;

// Pointer to output buffer.
uint8_t * bufferPtr = NULL;

// Total size of the buffer.
size_t bufferPtrSize = 0;

// Number of bytes moved to buffer.
size_t movedBytes = 0;

// Length of plainText buffer.
size_t plainTextBufferSize = 0;


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

plainTextBufferSize = [plainText length];

bufferPtrSize = ((plainTextBufferSize / kChosenCipherBlockSize) + 1)
* kChosenCipherBlockSize;

// Allocate buffer.
bufferPtr = malloc( bufferPtrSize * sizeof(uint8_t) );
// Zero out buffer.
memset((void *)bufferPtr, 0x0, bufferPtrSize);

ccStatus = CCCrypt(encryptOrDecrypt,
kCCAlgorithmAES128,
kCCOptionPKCS7Padding,
(const void *) aSymmetricKey.bytes,//[self getSymmetricKeyBytes],
kChosenCipherKeySize,
iv,
(const void *) [plainText bytes],
plainTextBufferSize,
(void *)bufferPtr,
bufferPtrSize,
&movedBytes
);


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

if(bufferPtr)
free(bufferPtr);

return cipherOrPlainText;
}