8. A computer program product for identifying a sketching matrix used by a linear sketch, the computer program product comprising: a non-transitory computer readable storage medium having program code embodied therewith, the program code executable by a processor to: receiving an initial output of the linear sketch; generating a query vector; inputting the query vector into the linear sketch; receiving an revised output of the linear sketch based on inputting the query vector; iteratively repeating the steps of generating the query vector, inputting the query vector into the linear sketch, and receiving an revised output of the linear sketch based on inputting the query vector until the sketching matrix used by the linear sketch can be identified.
8. A computer program product for identifying a sketching matrix used by a linear sketch, the computer program product comprising: a non-transitory computer readable storage medium having program code embodied therewith, the program code executable by a processor to: receiving an initial output of the linear sketch; generating a query vector; inputting the query vector into the linear sketch; receiving an revised output of the linear sketch based on inputting the query vector; iteratively repeating the steps of generating the query vector, inputting the query vector into the linear sketch, and receiving an revised output of the linear sketch based on inputting the query vector until the sketching matrix used by the linear sketch can be identified. 10. The computer program product of claim 8 , wherein the sketching matrix has a form of r×n, where r<<n.