You are downloading the Signature Verifier XAP file v188.8.131.52 for Windows Phone. Signature Verifier is a free and useful Productivity app: Use this application to open and verify digitally signed files. Supported extensions: PDF, P7S and ... You can now download the offline XAP file to install & try it.
Download Locations for Signature Verifier 184.108.40.206 XAP file
Important Notice: Now Due To Unspecified Limitations, You Can Not Use The Offline XAP File To Install It Any More.
To try to install it manually from an SD card, you should choose one of the server location above to get the offline Signature Verifier XAP file, move the file to your phone's SD card and then tap 'Install local apps' in the phone's App list.