Mitek Systems Inc.'s patent portfolio is growing as the San Diego vendor seeks to protect its mobile check deposit technology.

The company said Monday that the Patent and Trademark Office has issued two patents in the last two weeks related to its software that enables banks' customers to deposit paper checks by taking a picture with their smartphones' cameras.

The office has granted two other patents for the technology that Mitek said it expects to receive soon. Mitek received its first patent for the technology last year.

Mitek licenses its technology to vendors, including Fiserv Inc., Fidelity National Information Services Inc. and Bluepoint Solutions, which resell it to banks as a part of their mobile banking applications. Mitek earlier this year announced that JPMorgan Chase & Co. had opted to license its software after having built its own version of the service internally.

In total, five of the 10 largest U.S. retail banks have struck deals to use the company's software, including JPMorgan Chase, U.S. Bancorp and Bank of America Corp. EBay Inc.'s subsidiary PayPal also uses the software in its mobile banking apps for Apple Inc.'s iPhone and Google Inc.'s Android operating system.