I'm gathering data about the origins of identification/authentication means. I remember having read about a way of identifying a friend, during the bronze age. Maybe during classical antiquity also.
It was by using a rock, or a pottery / ceramic shard that you broke in two or more pieces. Joining the fragments served as a mean to identify the holder. I remember this was used in ancient Iberia (this very name suggests a Roman source) but I could be mistaken.
This practice is described in several local legends, notably around the Pyrenean area (mountain range separating Spain and France), but from a much later age (medieval age, starting from the Xth century) and by using torn papers or broken jewelry. Such a legend, as an example, is the legend of Bos de Benac (english version (translated) and french original version).
The relevant excerpt is : "The Lord married a young woman full of virtues. Forced to follow the king to the crusade, he leaves his wife by agreeing to a sign of recognition: marriage contract (Bladé) torn in two, ring or diamond (Cordier) cut in half.".
My understanding is that this practice echoes an ancient practice, the one I'm seeking to identify.
Is there a name for this specific practice? I know about the "bulla", and the notion of "shibboleth", this is not the same usage and I believe there is a term and studies about this subject.