The Talmud also deals with identity in the context of reputation and social networks See Tractate Sanhedrin – folio 23a https://www.sefaria.org/Sanhedrin.23a.22?lang=bi As Rav Yehuda says that Rav says: Witnesses do not sign a document unless they know who is signing with them. One does not sign a document unless he recognizes that those signing with him are fit to bear witness.
Returning to the matter itself, Rav Yehuda says that Rav says: Witnesses do not sign a document unless they know who is signing with them. That is also taught in a baraita: This is what the scrupulous people of Jerusalem would do: They would not sign a document unless they knew who was signing with them, and they would not sit in judgment unless they knew who was sitting with them, and they would not join a meal unless they knew who was reclining, i.e., eating, with them.
The medieval scholar Rashi (1040-1105) explains that one needs to know one’s co-witness, because of the potential reputational damage to oneself of countersigning a document which is invalidated because of character defects of one’s co-signatory. The concern is that third parties will hear that the document has been rendered invalid and may assume that you are the cause (no smoke without fire).