split key

noun3

1. •
   A cryptographic key that is divided into two or more values that individually cannot be used to deduce the entire key.

   • Moreover, even those systems (such as split key systems) that can decrease these risks, do so with a marked increase in cost. — 1997
2. •
   A key split at one end like a split pin, for the same purpose.

   • A split pin is also a split key, because both are used to lock or fasten pieces of machinery together. — 1869
3. •
   A key value used to identify where to split the children of a parent node in a B-tree or similar data structure.

   • As with B+-trees, records with keys greater than or equal to the split key go to a new current node, records with keys less than the split key remain in the original node. — 1990