I am trying to understand file encryption. Basically suppose I created a lookup table that transformed each byte of a file per some lookup table that I developed. Such as
Input Byte Output Byte 0x00 0x54 0x01 0x9A . . . 0xFF 0x43
and then suppose I did this for each file. How could anyone recover the data assuming I applied the same rule to the file name and extension? For this exercise make the assumption that I do this on a personal computer and then move this to a flash drive. Then you are only given the flash drive. Could you uncover the original file?
I can obviously make this much more advanced by merging files (perhaps by merging all my files and creating some kind of key delimiter between the files. Then I shuffle the data according to some other algorithm I keep so I can reorganize it later.
- Suppose that the 256 byte transform (lookup) table is kept in my head.
- Suupose that the file delimiter is kept in my head
- Suppose the the algorithm to shuffle the data is kept in my head
It seems to me that a string of bits is meaningless unless you know how to interpret it. So even if you had this information I told you you would have to figure out how to shuffle the data to get the delimited file back. Then you would have to parse the data to get each file. Then you would have to reverse engineer my lookup table to generate a usable file. Of course that isn’t impossible, but then suppose all you are given is a chunk of data and you have no idea (and suppose I refuse to tell) how to interpret said data? Could you figure out what my data is?