Otherwise, the client asks instead for a dummy block from this bucket.
To preserve obliviousness, a dummy block is also written to the other child/sibling.
The buckets in Ring ORAM store z real blocks, s dummy blocks, and some meta-data.
The second invariant concerns the physical positions of the z real blocks and the s dummy blocks in every bucket in the tree; they are randomly permuted .
XOR Ring ORAM takes advantage of the fact that the blocks returned to the client are all dummy blocks except the desired block.
Indeed by adding some dummy blocks in each bucket (i.e., node of the tree) and some meta-data (storing the addresses of the blocks in the corresponding bucket), Ring ORAM constructs in an oblivious manner a path from the root of the tree to the designated leaf containing the real block and all the others are dummy.
Moreover, we set the number Z of real blocks in a bucket to 4 and the number s of dummy blocks in a bucket to 2.
The components of the piercing extrusion die included four parts, piercing mandrel, dummy block, container, and blanking plate, as shown in Figure 2.
The initial temperature of piercing mandrel and dummy block is 400[degrees]C, and the initial temperatures of container, blanking plate, and billet are 400[degrees]C, 200[degrees]C, and 950[degrees]C, respectively.
The piercing mandrel and dummy block move forward about 20 mm for the purpose of filling the container.