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I am newbie so please pardon my naivete. I was wondering if there is any cryptographic procedure that allows for peer to peer matching.

Perhaps to illustrate my question I will use an example. Say I am in a country where marijuana is banned. I cannot put a post or advertise that I need marijuana. However, there exists a matcher. This matcher takes individual requests and attempts to match them up. However, I do not want the matcher to know my request else he/she will report me to the authorities.

Is it possible to cryptographically encode an order request such that this order can be matched but the matcher algorithm is unable to decode the information which is being matched. Thus, only the two matched peers can know what they want and understand the matching since they both created the request. Is this possible? Something tells me there might be a solution for peer matching/finding.

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    You're probably looking for a one-way hash... two hashes of the same password will result in the same hash. However, there is no way of getting the password from the hash. Security Exchange: One way hash – RubberStamp Nov 28 '17 at 2:28
  • @RubberStamp thank you for you swift response. But if the hashes of the password are the same, wont they be encoding the same message which won't work in this case. That is, the matcher could match my order with another order from another guy also wanting marijuana, since his hash will also be the same as mine. That will be a bad match as I would want to be matched with a marijuana seller and not another marijuana buyer. Do I make sense? – Chukwunonso Arinze Nov 28 '17 at 3:25
  • Just pair two hashes... one hash for type A, and one for type B. Type A looks for Type B, and vice-versa... the store of hashes doesn't know what is in either, but can match them to each other with a pre-determined rule... is your question how to create the rule with nothing pre-determined? – RubberStamp Nov 28 '17 at 3:32
  • @RubberStamp I did not know that hashes could be correlated. I had thought that since they are intractable. Forgive me as I am a learner. So are the hashes of two correlated passwords also correlated? By pre-determination do you mean having a rule for pairing hashes? To have such a rule would it not mean mapping back to the password? If that is the case, the objective is failed as the matcher would be able to decode the matching – Chukwunonso Arinze Nov 28 '17 at 3:49
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    @RubberStamp Yh that what I thought. The common feature will be the password. But I guess that such a common feature cannot in itself be a secret if the two parties are unknown to each other. Thank you for this response. It is very helpful. I guess perhaps the question i had asked in itself is logically inconsistent – Chukwunonso Arinze Nov 28 '17 at 4:50

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