In this report, we analyze the Windows, Android, and iOS versions of Tencents Sogou Input Method, the most popular Chinese-language input method in China. Our analysis found serious vulnerabilities in the apps custom encryption system and how it encrypts sensitive data. These vulnerabilities could allow a network eavesdropper to decrypt sensitive communications sent by the app, including revealing all keystrokes being typed by the user. Following our disclosure of these vulnerabilities, Sogou released updated versions of the app that identified all of the issues we disclosed.