bytes compressed and encrypted

[Jumper]

Hi,

If the size of the stored data is important this might be one way.

I ASSUME that you will only store numbers, and these numbers are from 0-9.

Imagine a number serie like this one where each number is one byte (8 bits):

1 1 1 2 3 4 ..... 9 9

Step one:

Group bytes 2 and 2 so you get this number serie stored as bytes, this I think you have already figured out:

when you do this you have to make sure you calculate in DECIMAL
3 4 -> 3 * 10 + 4 = 34 dec

11 12 34 ..... 99

Step 2:

Since the biggest number you will have to store this way is 99 it is enough to use 7 bits. So now we store 7 lower bits from the first byte + one bit from the next byte =8 and write to the eeprom.

This way will allow you to store 18 numbers using 8 Bytes. 44,4% size of the original data


This will also encrypt your data a little bit, if you want it to be more encrypted you just re-arrange the bit order in the BYTE you write to the ee-prom. If you have a good plan how to re-arrange the bits that covers 8 bytes it will be close to impossible to find out what you have stored. Bits inside this 8-byte block change places with each other.. or any other way of maipulating the bits with factor X .

To get the data back you just need to undo what you have done and put the bits back... extract the 7 + 1 bit into bytes... and split the Byte into 2.

So that would mean that you will work in block of 8 bytes compressing, encrypting and so on.

/me