Encrypt/decrypt using update

Question

Hi,
can someone give me an encrypt/decrypt pair of code samples that use the cipher.update() call.
i am trying it like that but apparently it doesn't work
byte[] temp = new byte[message.length/2];
byte[] temp2 = new byte[message.length/2];
System.arraycopy(message, 0, temp, 0, temp.length);
System.arraycopy(message, temp.length, temp2, 0, temp.length);
ciphertext = new byte[message.length];
System.arraycopy(symmetricCipher.update(temp), 0, ciphertext, 0, temp.length);
System.arraycopy(symmetricCipher.doFinal(temp2), 0, ciphertext, temp.length, temp.length);

Answer 1

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I don't see how using the inputstream i would avoid
the memory error, when passing anything over
10,000,000. Unless you mean I split the input, and
write small chunks into disk as I encrypt them?Your basic problem is that you have the data as one large array. I don't know how and why you created this large array; I would not to create it unless there was no other way.
Since it does not make sense to create one large encrypted byte array and given that you have a byte array then you can use either
1) Create a ByteArrayInputStream and wrap it in a CipherinputStream. This would allow you to encrypt the array in a sequential manner a few KBytes at a time.
or
2) Encrypt the array a few KBytes at a time using a simple update(array, start, length) that returns the encrypted bytes.
But first, I would try to avoid creating the large 'cleartext' array.