In which zone of ​​a flash memory could a write that will not get erase by formatting

[Gilberto Gil]

Hello, I'm new here, english is not my native language, but I'm gonna do my best.

I need to know in wich zone or byte(s) could I write a few lines (in flash memory) that do not get erase after format the flash.......

I really apreciate any help...thanks in advance

[mac11]

What are you trying to accomplish exactly?

In general, if your program can write to some flash you (or somebody else/the OS) can erase it later.

Also "flash" is a really general concept. What specific "flash" are you dealing with? SD card, thumb drive, etc?

[Gilberto Gil]

Sorry,, i've not been exact at all...

I have a group of flash memories, not sd, just the common memories that we use to transport information all the time. the problem is that i need to mark this flash and asociate this mark with some password that the user of the flash could has.. I could do this encripting some file and copying it like normal data into the flash memory, but the problem is that it is a common file that any user could see and erase as you said, i need to achieve that in a low level(I guess) that the common user could not see the mark and even could not erase it by normal ways.........

I apreciate you are helping me up......sorry my english

[Curtis Rutland]

There's nothing that will prevent the formatting of a disk, one way or another. Especially not in C#.

[Gilberto Gil]

Exactly, so i need to write my little thing in a part of the memory that doesn't erase by formating....do you know what I mean. the thing is to keep whatever i'v writen even after formating...
The question is...when a disk is formated is writen all it's sapace of the partition? or is there any part that is not writen?.....again, sorry my english

[Rabbit]

There's no way of doing it without creating custom firmware to replace what's on the USB. Much akin to what the U3 platform does on the SanDisk drives.

[Gilberto Gil]

But i have different types of memories, from diferents manufacturer,still could i do this?

[Rabbit]

I'm not sure what you mean. You can hack and crack almost anything. But we're talking about custom firmware here, it's not a simple task. We are talking about technical knowledge well beyond a vast majority of the population.

There's always option two, which is fabrication, but if the first option is difficult, option two will be near impossible for most people.

Do yourself a favor and just buy some encrypted flash drives. The work is already done for you.

[Curtis Rutland]

And there's no way that you can do this with C#, or .NET period. If it is even possible, you're looking at Assembler or C.

[johny10151981]

To understand what you want and what you can do, you need to know some issues. Like

What is Disk Format?

do you think format erase the disk?

No. Not completely. Format create the definition of the storage. i.e. How data will be stored, how they will be read and write, etc..

Do you know what is the format of your flash drive?

I can guess FAT32 or may be NTFS

To protect your specific data........ You better design your own FORMAT. Cause in typical formatting system like FAT, FAT32, NTFS, EXT or other file format they don't protect special memory portion.

[Gilberto Gil]

Thanks a lot everyone..
I can format all my flash mamories using FAT32, then a need to know if after i've formated the flash is there any part in wich could write my thing and where is this...
I could create my own format table(that is not an easy task, a think) or simply i could use FAT32 format if i really know if this format do not use some part of the memory then i could use it, that unused part.
Don't you think?

johny10151981.. you are rigth, but i need to mark the flash not simply to protect the data. But to protect the data is another that i've to do. and i've been thinking on your proposition.. to create my own format based on some format's architecture like some FATs formats

[Curtis Rutland]

You're not going to be able to protect it from low level formatting. Basically, if your USB is seen as a disk, disk-editing programs can do whatever they want to it. They can erase your allocation table and anything else on the disk. Without your own custom firmware to prevent disk access, there's simply no way to do this. Just because you come up with your own format doesn't mean that someone else can't just wipe it out.

[Gilberto Gil]

Curtis.....it doesn't matter to me. because if the memory is formated at a low level the information will be a little more dificult to recover. doesn't matter if the information inside the memory is lost.. it will be just one more security level to mantain my information far from the people outside... :)

[Rabbit]

I don't think you're understanding what we're trying to say. What you want to do can not be done without writing custom firmware. Or fabricating custom hardware.

[Gilberto Gil]

O.K...then we can't definitly write the memory without writing custom firmware or etc.. ok then I can't mark in that way my flash memories.......but....Sorry..are you saying that we can't write the flash memory in any way? neither at any hight level? if so... it's frustrating for me...i'm saying that for the other that i've to, create my own format and implement: copy, delete etc etc..do not forget that I don't care if the momery after my formating is formated again using for example FAT32 format.... i don't care if it happends. it will be just another security level, that common users couldn't using a FAT32 reader like windows to see what is inside the memory.

[Rabbit]

I don't know what it is that you're trying to accomplish. What you asked for at the beginning seems to have changed at this point. Originally, you asked if there's a way to write to flash memory so that it can't be erased. The answer to that is a resounding no, not without writing custom firmware. However, now it seems that you just want to make a file unreadable, not undeletable. In this case, there's no need to create a custom disk format, just encrypt the file or file system. The end result will be that the file will not be readable.

[Gilberto Gil]

Rabbit, maybe I have not been clear enough..so..
I've two thing to accomplish. the first was really that i posted here....In which zone of ​​a flash memory could a write that will not get erase by formatting......but, as you said it can't be done without writing custom firmware. I've already understood that..
The second that I need to do is to protect the information inside flash memories, it's right that I could encrypt the file but the file will be still seen by common users(and that is not what i want) otherwise I could use some encryption software(TrueCrypt for example) but it is not my own code, and i really dont't know if it has some back door or something like that..the other that you are telling me is to encrypt the file system. what do you mean with that, that i could encrypt for example FAT32 system wich is inside the flash that windows could not understand that and then couldn't see the information inside the flash memorie? if so it is really what i want to do.. for that reason I've been thinking in my own format because windows or another couldn't read that and common users couldn't see the information inside the flash without a program built by me that implement all the operation such as copy, paste, delete etc etc ... don't forget that i don't care if the memory is formated with another file system after mine..
I'm glad to see that there are people who help... thanks a lot

[Curtis Rutland]

otherwise I could use some encryption software(TrueCrypt for example) but it is not my own code, and i really dont't know if it has some back door or something like that

It's far, far, far more likely that your own custom code will have "backdoors" (or more likely bugs) than TrueCrypt will. TrueCrypt is a well-know, well-trusted name in whole and partial disk encryption that's been under active development for seven years now. It's crazy to think you'll be able to put together something similar by yourself in a short time.

Don't re-invent the wheel. If this isn't just some programming exercise, and it's something you actually need, and need to work well, use proven software.

We've understood what you've been saying, we're just telling you things you don't want to hear.

[Rabbit]

You do realize that if the user formats the drive after you've done whatever you want to do to the disk means you lose all the information on there right?

I would just use TrueCrypt to encrypt the entire disk, it does what you're attempting to do by yourself but at a security level much higher than you're going to be able to achieve. TrueCrypt is open source so if you're worried about backdoors, just go over the code yourself. And whatever encryption scheme you're going to come up with is going to be many many times less secure than using AES, Serpent, or Twofish. All of which come with TrueCrypt.

[Gilberto Gil]

Thanks a lot. really.....you have convinced me.. i'll check TrueCrypt out...really I'm very grateful...