After my holiday to Latvia, I was doing my administration and I noticed that almost all receipts had cryptographic hashes on the bottom. One receipt defined them as SHA1. Adding hashes to receipts is something that I'm not familiar with. Some googeling around learns me that this is normal with cryptocurrencies, but these payments were all by card (whether by Apple Pay or by inserting the card into the terminal).
Two example receipts:
My question is: What is the meaning of these hashes, and what is stored in it?
I wonder why this is done, since I, as a customer, am probably not able to recalculate this exact hash from the layout of the receipt. Is this a checksum that the bank can use to verify the receipt?
- Yes, I know SHA1 isn't secure, and imo shouldn't be used anywhere anymore because of the fact that a collision can be created these days; and that there are better alternatives. This makes me wonder even more what it's purpose is.
- I chose to post my question here because this isn't a technical question as to how a SHA1 hash as a (presumably) checksum works. I know how to calculate a hash. The question relates to why these values are added to receipts, and what their purpose and content is. I won't find an answer to this on SO.
- This isn't normal in my country, The Netherlands. I have never seen this, and going back in my administration shows no signs of hashes on my (Dutch) receipts.