bytes compressed and encrypted

Hello

I need to store 40 channels of digital characters in a 512k eeprom and we need to compress the chain of maximum 40 bytes
I saw an example or the result after compression is 18 bytes
The string is converted to decimal hexadecimal

Example: 1234567890 = 10 bytes
Becomes: 12 34 56 78 90 = 5 bytes

I do not know if there is another way to further reduce the minimum bytes?
And once the data I have to compress encrypt in the same
eeprom you have an idea?
Even with encrypted xor chain is still a length of 18 bytes
Because I have an encrypted text and no way to decrypt it, I do not see
how it was I wanted to emulate him.
But apparently it must have a high level of programming and
Encryption is very strong.

Is there another way to encrypt without taking up too much space?

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

Hello

Thank you for your help, we assume that the string stored voullons

9976710618889188 = 07002013512770340000 and the date: 27/02/2009 19:20:51

A maximum compression to save space in the eeprom.
I attached an example and I can not understand

thank you

I am sorry but I have no intention to decrypt or analyze numbers to find out how they have been encrypted.

You asked for a way to store data, I gave you a suggestion.

Properly done and using a long enough key i.e 128 bit there is a very big risk you will get old without ever finding what you are looking for.

Hello

This is an example I'm looking over, because the second part I did
not included.

Example this channel you compress how?

9976710618889188 = 07002013512770340000

Thank you