How to generate one number based on another?

Question

Programming

Task: There are numbers, 8 bytes each, on their basis another number is generated, also 8 bytes, you need to understand by what algorithm one turns into another,
nothing comes to my mind ...
initial value:
1) 0x0257ABE900000048 it turns out 0x35D57C087D1CE7B6
2 ) 0x028001EA0000000F it turns out 0x31D42C4829BCE7B6 3
) 0x026962С40000008A it turns out 0xB1D42C38FD9CB7B4 from it Connoisseurs, tell me if there is a solution in principle to a similar problem, or in my case there is no way to understand someone else's algorithm?

Answer 1

In general, no way.
Sample 2,2 and 4
Several variants of the algorithm:
1. 4=2+2
2. 4=2*2
But the set of algorithms is not limited to these two variants...
Perhaps a detailed description of the subject area will narrow the circle of algorithms.

Answer 2

In your case, the resulting numbers are very close to each other. This usually allows the chosen plain-text method to define the algorithm quite successfully. Try to find as many pairs of original numbers as possible that differ from each other in as few bits as possible, and analyze the changes that occur in the resulting numbers.

Answer 3

More specifically, if it can help in any way.
The initial numbers are the IDs of the DS1991 memory chips operating on the 1-Wire protocol
. This particular memory is organized as follows: divided into 4 areas:
1. Notepad (64 bytes) - not a closed area.
2. SubKey0 (48 bytes) - protected by a password
3. SubKey1 (48 bytes) - protected by a password
4. SubKey2 (48 bytes) - protected by a password
Password, 8 bytes, can be set by the user.
The device in which these microcircuits are installed generates a password for the SubKey0 / 1/2 areas, which is the same, but different for each instance of the microcircuit (DS1991), i.e. based on the specific memory ID. Now the passwords are known to me because there is a possibility, the device is not mine, but for now I have a sniffer to dump the data during the exchange and analyze it. The device will soon be unavailable, and it will not always be possible to analyze traffic on the 1-Wire bus. Therefore, the task arose to understand the logic of generating a password based on the chip ID.