Generate another Guid using one Guid and vice versa

Question

Is there a way/algorithm/method to generate a new Guid (x) using our old GUid (y) and then get y back whenever we want from x?

Something similar to below answer but it shows a way to old Guid(I can consider it as a string) to convert to Guid but not a way back.

https://stackoverflow.com/a/9386095/5887074

How can I generate a GUID for a string?

P.S.: This is not related to anything security. The two Guids will just be used to find records from the table. We can convert Guid to string in this conversion if required.

I don't get what you mean generating new GIUD from the old one, you want to have a function that given the old GUID you can find the new one? — Ashkan Mobayen Khiabani, Sep 15 '18 at 00:02
yes correct, but then I should be able to do vice versa like I should be able to get old Guid using new one as well. — Vicky, Sep 15 '18 at 00:03
well this can not be done, but I'm writing an answer how to achieve the same goal. — Ashkan Mobayen Khiabani, Sep 15 '18 at 00:04
@DavidG Removed the table part from the question so that it can be less confusing. Let me know if it is good now. — Vicky, Sep 15 '18 at 00:06
yes. there is not such an option generating one GUID from another, and even if created one, they would not be related in a way that you can find the other one from the old one, and even if you make a logic to do that it may interfer with other Guid's and it actually won't be a Guid but a string in Guid format. — Ashkan Mobayen Khiabani, Sep 15 '18 at 00:07
Are you asking for an algorithm that create one Guid from another and that would translate it back. Like just reversing all the hex digits? — juharr, Sep 15 '18 at 00:10
@CamiloTerevinto Nope, the data in RowKey has its own value which is same as old records. Also, updated the question so that it makes more sense now. — Vicky, Sep 15 '18 at 00:17
@Vicky, the link you have added, just converts a string to Guid. so its already a Guid but not in a Guid format (ie: a 32-byte hexadecimal string without hyphens). it only changes its format to match Guid and does not actually change its value. — Ashkan Mobayen Khiabani, Sep 15 '18 at 00:18
Does the second one have to be a GUID or any string would do? Because you might consider encrypting _(and later decrypting)_ the GUID using a known key. — 41686d6564 stands w. Palestine, Sep 15 '18 at 00:19
it can be string format. But, then Guid conversion on that should convert that to Guid again. — Vicky, Sep 15 '18 at 00:20
Well, I think something like [ROT13](https://en.wikipedia.org/wiki/ROT13) might be an option. — 41686d6564 stands w. Palestine, Sep 15 '18 at 00:22

score 2 · Answer 1 · answered Sep 15 '18 at 00:27

2

There are thousands of ways: a guid is 128 bits, so you could flip one bit which would make it simple to translate back and forth. Or you could do modulo 42 and make it look as if you made something unpredictable. Or you could reverse the order of the bits, do a NOT operation on all of them or rearrange the bits by some predefined pattern.

But I suspect that you have a use case which you do not define. Please tell a bit more about the problem you want to solve. Your request sounds a little bit dangerous as it sounds as if you want to enable some kind of tracking between seemingly unrelated entities. If there is some security issues involved you are very likely to get it wrong if both cleartext (guid pre translation) and cipher (guid after translation) are public. Perhaps simple AES encryption would suffice as a translation function, but I think you need to specify you problems in much more details to get a useful answer.

answered Sep 15 '18 at 00:27

faester

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This is not related to anything security. The two Guids will just be used to find records from the table. Each Guid will be related to one transaction. We just want to find related transaction by using new Guid generated based on previous Guid. – Vicky Sep 15 '18 at 01:11
Great. But I think that one of the comments suggesting an associative array is actually the best solution. Guids are constructed to avoid collisions, but if you derive one guid from another this property disappears: take the (stupid) flip-a-bit approach for the sake of the argument. It would work for the first derived bit, but if you need another derivate it would become the original guid. This would resemble other functions for linking guids. Associating two completely random guids would preserve the non-colliding property. – faester Sep 15 '18 at 07:05
But if you really need the linked guids without direct associations I *guess* a good function would be to AES encrypt the guid and use the encrypted value for the associated guid. Translation is then a matter of encrypting and decrypting and AES should make a deterministic yet close to random transformation of the input. But I would still worry about collisions with other guids. – faester Sep 15 '18 at 07:17

Generate another Guid using one Guid and vice versa

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